WO2002068485A1 - Procede de preparation de polymeres greffes - Google Patents

Procede de preparation de polymeres greffes Download PDF

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WO2002068485A1
WO2002068485A1 PCT/US2001/049523 US0149523W WO02068485A1 WO 2002068485 A1 WO2002068485 A1 WO 2002068485A1 US 0149523 W US0149523 W US 0149523W WO 02068485 A1 WO02068485 A1 WO 02068485A1
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macromonomer
copolymer
graft
polymerization process
polymerization
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PCT/US2001/049523
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English (en)
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Krysztof Matyjaszewski
Jean-Francois Lutz
Hosei Shinoda
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Carnegie Mellon University
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F299/00—Macromolecular compounds obtained by interreacting polymers involving only carbon-to-carbon unsaturated bond reactions, in the absence of non-macromolecular monomers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F290/00—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups
    • C08F290/02—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups on to polymers modified by introduction of unsaturated end groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F290/00—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups
    • C08F290/02—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups on to polymers modified by introduction of unsaturated end groups
    • C08F290/04—Polymers provided for in subclasses C08C or C08F
    • C08F290/046—Polymers of unsaturated carboxylic acids or derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F293/00—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule

Definitions

  • This invention is directed toward a process for the preparation of graft (co)polymers. Specifically, graft (co)polymers prepared by "grafting through” macromonomers with a macroinitiator. The disclosed process is applicable to any (co)polymerization process.
  • Embodiments of the process of the present invention provides for the preparation of graft copolymers with a broad range of structures and compositions including, but not limited to, phase separable compositions and compositions with controlled distribution of the graft copolymers along the backbone polymer and graft copolymers comprising biologically compatible grafts or grafts comprising polyolefins.
  • the invention also allows for preparation of block-graft copolymers wherein each block is a graft copolymer.
  • graft (co)polymers are determined by many structural and chemical factors including, but not limited to, the chemical composition of the backbone of the (co)polymer, the chemical composition of the branch (co)polymers, the length of the backbone, the lengths of the branches, and the spacing of the branches along the backbone or the branch distribution.
  • the "grafting through” polymerization process is considered potentially one of the most useful ways to design and obtain well-defined graft (co)polymers.
  • the "grafting through” process for the preparation of graft (co)polymers comprises polymerizing macromonomers.
  • the macromonomers may preferably be copolymerized with a lower molecular weight comonomer to prepare a graft (co)polymer.
  • graft (co)polymers have many commercially important applications.
  • graft (co)polymers benefit from the phase separation of the graft (co)polymer between the backbone of the (co)polymer and the grafts of the (co)polymer. This phase separation of the polymer often results from a difference in phylicities between the grafts and the backbone.
  • the benefit derived from the phylicity differences in the graft copolymer can also create difficulty incorporating the macromonomers into polymer. Some of these difficulties may be attributed to the slow rate of diffusion of the polymerizable functional group on the macromonomer to the growing polymer chain end.
  • phase separation due to the differences of phylicities of the components of the polymerization medium also contributes to the copolymerization processing problems.
  • the phase separation is particularly significant in the preparation of high performance graft copolymers, such as organic/inorganic hybrid graft copolymers.
  • These high performance polymers can comprise dramatically different characteristics in the backbone and in the branches.
  • the effect of phase separation during polymerization may be reduced in some cases by using a compatible co-solvent for both the macromonomer and the copolymer.
  • the co- solvent may be not sufficient to decrease the incompatibility effect.
  • the polymerization medium of a radical polymerization process comprising macromonomers and monomers, for example, may undergo a phase separation early in the polymerization process as the backbone grows from the polymerization of the monomer, a high molecular weight copolymer is produced.
  • the phylicity of this high molecular weight copolymer may be different than the phylicity of the macromonomer. This difference in phylicities may lead to a two phase polymerization process, one phase comprising a substantial portion of the growing polymer chain and the low molecular weight monomer and the other phase comprising a substantial portion of the macromonomer.
  • This phenomenon leads to a heterogenous distribution of grafts among the chains, some polymer having many grafts and some polymer having few grafts.
  • the amount of grafts on a polymer depend on whether the polymer was formed early in the polymerization and later in the polymerization.
  • Prior art processes for the preparation of macromonomers have been limited primarily to ionic polymerization processes and this has limited the functionality that can be ultimately incorporated into polymers and thereby the control over factors effecting the properties of the graft copolymer. Attempts have been made to reduce the phase separation problem by addition of an appropriate solvent to the polymerization process but commercial processes are still severely limited in the range of compositions of the graft (co)polymers that can be prepared.
  • Figure 1 is a graphical depiction of graft copolymers
  • Polymer A is an example of a graft copolymer having homogeneously distributed grafts and
  • Polymer B is an example of a graft copolymer having a heterogeneous distribution of grafts
  • Figure 2 re graphs of the kinetic data of the copolymerization and Jaacks plot for the ATRP copolymerization of MMA and PDMS macromonomer in xylene solution at 90 °C (HS166), the data indicates slow consistent incorporation of the macromonomer into the copolymer;
  • Figure 3 is a graphical representation of examples of different structures of the block graft copolymers comprising PDLA and PDMS branches and PMMA backbone that may be produced by the process of the present invention
  • Figure 4 is a graphical representation of an example of the structure of the synthesized gradient graft copolymer comprising a gradient in the concentration of the concentration of the two grafts along the length of the backbone.
  • the present invention provides a polymerization process for the preparation of graft (co)polymers by the grafting through process.
  • An embodiment of the polymerization process of the present invention comprises copolymerizing macromonomers with (co)monomers utilizing a macroinitiator to form a graft (co)polymer.
  • Another embodiment of a polymerization process of the present invention comprises (co)polymerizing macromonomers and monomers with a graft copolymer macroinitiator to form a block-graft (co)polymer.
  • a polymerization process is a system comprising the components necessary to conduct a any polymerization, such as for example, in an embodiment of a standard free radical or addition polymerization system the polymerization process comprises radically polymerizable monomers and a standard free radical initiator, or in an embodiment of a nitroxide mediated polymerization comprises an initiator, a stable free radical and radically polymerizable monomers, etc.
  • Another embodiment of the process of the present invention comprises (co)polymerizing macromonomers and monomers with a compatible macroinitiator.
  • a "macroinitiator" is an oligomer, polymer or other large molecule which is capable of initiating a polymerization process.
  • a macroinitiator may comprise more than one polymerization initiation site.
  • a "compatible macroinitiator” is a macroinitiator which is at least partially soluble or miscible in the macromonomer and does not undergo a phase separation.
  • the compatible macroinitiator may be present in a system with mixtures of macromonomers or mixtures of macromonomers and other monomers.
  • a compatible macroinitiator if necessary, acts to compatibilize the macromonomer and at least one or a combination of the monomer, the initially produced polymer.
  • the compatible macroinitiator may have the same segment structure as the macromonomer, or more preferably, a macroinitiator that has a different composition than the macromonomer but is soluble in macromonomer thereby using entropy as an additional driving force for compatibility between the polymerization components and the forming copolymer, all in solution in remaining (co)monomer(s).
  • Improved reactivity for the macromonomer can be expected because the growing copolymer chain is a block copolymer comprising the (co)polymerization components and the first formed copolymer acts as a surfactant and retains compatibility with the macromonomer.
  • macromers are oligomers, polymers or other large molecules comprising at least one functional group suitable for further (co)polymerization, preferably the functional group is a terminal functional group.
  • One such terminal functional group is an unsaturated functional group suitable for free radical (co)polymerization.
  • a "radically copolymerizable macromonomer” is a macromonomer which is capable of reacting in a radical polymerization process, preferably a radically polymerizable macromonomer comprises a terminal unsaturated functional group capable of reacting with a radical.
  • An embodiment of the process of the present invention comprises macromonomers and compatible macroinitiators in a controlled radical polymerization process for the preparation graft copolymers by "grafting through” polymerization. This embodiment allows incorporation of macromonomers into a growing backbone polymer and controlled growth of the backbone polymer.
  • the chemical and structural properties of the product graft (co)polymer may be controlled by use of a compatible macroinitiator and the functional group on the macromonomer which effect the relative rates of incorporation of the macromonomer and the monomer.
  • a copolymer with well-defined branches or grafts with predetermined molecular weights and low polydispersities can be obtained by preparing macromonomers by a living or a living/controlled polymerization process.
  • the meaning of these terms are discussed in the following references: Szwarc, M. Nature 1956, 178, 1168-1169; Matyjaszewski, K. J. Phys. Org. Chem. 1995, 8, 197-207; Matyjaszewski, K.; Lin, C. H. Makromol. Chem., Macromol. Symp. 1991 , 47, 221-237; Litvinenko, G.; Mueller, A. H. E.
  • the backbone is also polymerized with using a controlled polymerization process of the macromonomer and the low molecular weight comonomer with a macroinitiator thereby producing a backbone copolymer with a controlled molecular weight distribution.
  • monomer or “comonomer” is a molecule that is capable of conversion to polymers, synthetic resins or elastomers by combination with itself or other similar molecules or compounds.
  • monomer as used herein, is not limited to small molecules, but includes oligomers, polymers and other large molecules capable of combining with themselves or other similar molecules or compounds.
  • the reactivity ratio of the macromonomer with the comonomer has been used to measure incorporation of macromonomers into a graft (co)polymer.
  • a reactivity ratio close to 1 indicates a more statistical incorporation of the macromonomer into the graft (co)polymer and would result in the preparation of a graft (co)polymer with a homogeneous distribution of grafts along the backbone (co)polymer.
  • Reactivity ratios different than 1 indicate either a more rapid incorporation or a less rapid incorporation of the macromonomer or the comonomer and result in a more hetrogenous distribution of grafts along the backbone of the (co)polymer.
  • One embodiment of the process of the present invention comprises copolymerizing a macromonomer with a vinyl-end group and a radically (co)polymerizable monomer in a controlled radical polymerization process, such as atom transfer radical polymerization ("ATRP"), is described in detail.
  • ARP atom transfer radical polymerization
  • This embodiment exemplifies the criteria for grafting through macromonomers into graft (co)polymers, not only for controlled radical polymerization processes but also for any other polymerization process, such as nitroxide mediated polymerization, ionic or cationic polymerization, RAFT processes and addition polymerization processes.
  • inventions of the process of the present invention include the preparation of hybrid graft (co)polymers with grafts or backbones comprising inorganic monomer units, grafts or backbones comprising biodegradable monomer units, grafts or backbones comprising polyolefin monomer units and the preparation of block (co)polymers wherein each block comprises a graft (co)polymer, and preferably each block comprises graft segments of different compositions. Also described are embodiments which can be utilized to prepare gradient-graft copolymers, gradient-graft-(co)macroinitiators and gradient-graft-(co)macromonomers. ATRP processes are disclosed in the commonly assigned U.S.
  • Embodiments of the process of the present invention may also be used for the preparation of well-defined homogeneous graft (co)polymers, biphasic graft copolymers and triphasic graft copolymers.
  • a biphasic copolymer is a polymer which contains segments which form into two separate phases either alone or in at least one solvent, such as, for example, a segment soluble in an organic phase and a segment soluble in an aqueous phase.
  • a triphasic copolymer is a polymer which contains segments which form into three separate phases either alone or in at least one solvent, such as, for example, a segment soluble in an organic phase, a segment soluble in an aqueous phase and a crystalline phase or a low Tg segment, a high Tg segment and a crystalline phase.
  • the properties of graft (co)polymers are determined by many structural and chemical factors including, but not limited to, the chemical composition of the backbone of the (co)polymer, the chemical composition of the branch (co)polymers, the length of the backbone, the lengths of the branches, and spacing of the branches along the backbone or the branch distribution.
  • the average spacing of the side chains, and the overall (co)polymer composition will be determined by the molar ratio of macromonomer to comonomer in the feed, their reactivity ratios and the ratio of comonomers incorporated into graft copolymer.
  • both Polymer A and Polymer B have the similar backbone lengths, similar branch lengths, and the similar number of branches, but clearly a different branch spacing distribution.
  • Polymer A has homogeneously distributed branch spacing
  • polymer B has heterogeneously distributed branch spacing structures.
  • homogeneously distributed branch spacing means that the branches are distributed generally evenly throughout the backbone.
  • the (co)polymer has regions with higher concentrations of branches.
  • the process of the present invention may be used to control the spacing distribution of the branches or grafts along the polymer backbone with the modification of the components or parameters of the polymerization, such as, but not limited to, selection of the macroinitiator, the reactive functional group on the macromonomer, polymerizing a mixture of macromonomers or monomers and by changing the order of (co)polymehzation in the formation of block-graft copolymers.
  • the spacing distribution is influenced by the relative reactivity ratios and the concentration of the macromonomer and the low molecular weight comonomer.
  • the reactivity ratios are influenced by many complicated factors, but are mainly affected by: 1) the diffusion control effect, or the kinetic excluded volume effect, associated with the large size of a macromonomer;
  • the incompatibility effect potentially due to the thermodynamic repulsive interactions between a macromonomer and a propagating polymer chain.
  • the incompatibility effect is particularly important when preparing graft copolymers displaying micro-phase separation in the formed copolymer due to the chemical and structural differences between the macromonomer and the monomer.
  • the diffusion control effect was studied by Radke, W.; M ⁇ ller, A. H.
  • the increase in macromonomer increased the viscosity of the reaction medium and hence lowered the rate of diffusion of the functional end group on the macromonomer to the growing polymer chain end. This result indicates that the diffusion effect cannot be ignored in grafting through polymerization processes. This phenomenon is exacerbated in the case of macromonomer copolymerization when there is a difference in compatibility between the macromonomer and backbone copolymer as described in factor 3.
  • the incompatibility may be influenced by differences in phylicity of the polymerization components, for example. In such a process, as the backbone polymer is formed the resulting solution of the backbone polymer and macromonomer in unreacted monomer, and optionally added solvent, may phase separate.
  • the reactivity of the macromonomer is significantly reduced and uncontrolled polymerizations may occur. Therefore, graft copolymers with heterogeneously distributed compositions along the copolymer chains are formed and the process does not produce well-defined copolymers. For certain specific applications, well-defined copolymers are desired.
  • the chemical composition of the branches and backbone of the graft are desired.
  • (co)polymers are determined by the chemical composition of the initiator, the macromonomer and the monomer used in the process.
  • Macromonomers and macroinitiators for use in the present invention may be prepared by any chemical process.
  • macromonomers may be prepared by controlled or living polymerization processes.
  • Macromonomers may be prepared by controlled radical polymerization processes, such as ATRP utilizing a functional initiator. Therefore, the micro- and macro-functionality may be incorporated into graft (co)polymers prepared by embodiments of the processes of the present invention.
  • a polymer or oligomer comprising a radically transferable atom or group prepared by ATRP may be further used as a macroinitiator in an embodiment of the process of the present invention.
  • a polymer or oligomer comprising a polymerizable functional group and a radically transferable atom or group may be prepared by ATRP.
  • the radically transferable atom or group may then be transformed into a non-reactive, non-transferable group before the polymer is further polymerized by a process of the present invention as a macromonomer.
  • a general method for this process of preparing one such macromonomer is exemplified in Scheme 1.
  • a hydroxy functionalized initiator was used to polymerize /7-butyl acrylate and f-butyl acrylate (polymerization of many other monomers have been described elsewhere).
  • the halogen end group was then removed using tributyltin hydride and AIBN.
  • the hydroxyl end group was then estenfied with methacryloyl chloride to provide the polymerizable double bond.
  • Scheme 1 The reactions of Scheme 1 may be employed to provide at least three useful categories of functional materials applicable to the present invention. These include a macroinitiator, a macromonomer, and a bi-functional macro-AB * - monomer.
  • the first formed polymer Prior to removal of the halogen, the first formed polymer comprises a hydroxy group and a radically transferable end group.
  • This first formed polymer is an active macroinitiator that can be utilized for initiation of the copolymerization of macromonomers by ATRP or can be employed for further polymerization to form block copolymers which may be used as block co-macroinitiators.
  • the block copolymers may then be converted into block-macromonomers by removal of the halogen, by the method of Scheme 1 or any other method, and esterification of the hydroxy-group remaining available on the initiator residue, using any known chemistry, such as, the procedures described below or the method described in Scheme 1.
  • the resulting block-macromonomers may be incorporated in a polymerization process of the present invention initiated with a macroinitiator compatible with at least one segment of the block-macromonomer.
  • the block macromonomers may be (co)polymerized by any polymerization process, such as, but not limited to, ATRP, ionic polymerization, standard free radical copolymerization or any other standard or controlled polymerization process incorporating a macroinitiator.
  • the radically transferable end functionality on the first formed (co)polymer should, preferably, be substantially removed to avoid the formation of a bifunctional macromonomer, if this is not desired. More preferably, the radically transferable atom or group should be almost completely removed if one desires to form bottle brush polymers or fully controlled graft copolymers. Otherwise, the presence of such a bi-functional macromonomer may lead to the formation of (hyper)branched polymers during subsequent ATRP (co)polymerization.
  • such materials prepared from a bi-functional macromonomer as a comonomer in a process of the present invention would be expected to produce useful materials, since the degree of branching in the final copolymer can be controlled by the molar ratio of functionality on the AB* macromonomer.
  • such branched copolymers are known to have useful rheological properties.
  • the desired product is obtained in high yield and the co-products, the lithium salt and diisoproylamine may be easily and effectively removed from the macromonomer.
  • This reaction may also performed to remove bromine from more sterically hindered ⁇ -bromides.
  • a conventional ATRP polymerization process was modeled including using one equivalent of a homogeneous copper-based catalyst complexed with a soluble bipyridine ligand, relative to a small molecule initiator, such as, ethyl 2- bromoisobutyrate.
  • the kinetic data used to determine k p , the polymerization rate constant; and k t , the termination rate constant in the literature for Controlled Free Radical Polymerization (CFRP) was modeled. Subsequently, kinetic parameters were generated which identified conditions under which polymerization of a macromonomer could be controlled. The principles derived from this model were then extended to a model of an embodiment of the present invention comprising ATRP.
  • the rate of propagation was slow.
  • the rate of polymerization may be increase by using multiple equivalents of catalyst, as high as 10:1 , to drive the polymerization forward.
  • k d the deactivation rate of the radical formed from the initiator, or growing polymer chain end, remains constant this would lead to a substantial decrease in initiation efficiency of a small molecule alkyl halide.
  • the backbone may comprise any free radically polymerizable (co)monomers and one only need consider the reactivity of the terminal functionality with the selected comonomers and composition of the macromonomer to attain similar results in different polymerization processes. Indeed such consideration is amplified in the discussion describing a process for the preparation of a graft (co)polymer with a homogeneous distribution of grafts.
  • the preferred embodiment of the present invention comprises the atom transfer radical copolymerization of a compatible macroinitiator with a macromonomer.
  • This approach led to enhanced incorporation of the macromonomer into the controllably, growing backbone polymer.
  • other radical polymerization processes where the rate of propagation for backbone copolymerization is faster, and less controlled than ATRP, there was a less pronounced, but still significant positive effect seen by use of a macroinitiator instead of a small molecule initiator.
  • the other radical polymerization systems evaluated were RAFT, redox initiated polymerization, and conventional radical polymerization.
  • Embodiments of the process of the present invention described in the examples include the copolymerization of polydimethylsiloxane macromonomers with incompatible monomers forming an incompatible backbone to form graft copolymers to form graft copolymers.
  • the macromonomer and macroinitiator were prepared by a non-radical polymerization process.
  • the copolymer selected to exemplify this approach comprised poly(methyl methacrylate) for the organic backbone polymer and poly(dimethylsiloxane) for the inorganic branches.
  • Such organic/inorganic hybrid graft copolymers are of interest because polymers comprising inorganic substituents generally have unique and specific properties that organic analogues do not possess. Such hybrid graft copolymers exhibit good micro-phase separation and find use in a variety of applications, such as impact-resistant plastics, thermoplastic elastomers, compatibilizers and polymeric emulsifiers. Additionally, branched polymers comprising inorganic subsituents generally show decreased melt viscosities which provides important advantages, especially for processing. Since the graft copolymers disclosed have many structural factors that can be varied (composition, backbone length, branch length, branch spacing, branch distribution, etc.), the process of the present invention has great potential to realize materials with new properties with high performance in specific applications.
  • a further example of the use of the process of the present invention is provided by the description of the preparation of a novel low viscosity graft copolymer with a backbone comprising a controlled molecular weight distribution and either heterogeneously or homogeneously distributed graft macromonomers prepared with biologically compatible and biologically degradable monomers.
  • This example provides direction on the importance of the inherent reactivity of the end group and how end group reactivity can be manipulated in a controlled radical polymerization process to provide a graft copolymer with a narrow molecular weight distribution and selected distribution of grafts along a backbone chain.
  • the graft copolymers prepared with biologically compatible grafts additionally exemplifies a process for development of bulk physical properties.
  • the graft copolymer prepared by a process of the present invention comprises grafts that are soluble in the backbone copolymer at elevated temperature and additionally exemplifies a graft copolymer wherein the grafts comprise segments that can under certain circumstances crystallize thereby providing a phase separated bulk material while converting to a homogeneous material above the T m of the crystallizing phase. While the specific examples describe the preparation of a backbone polymer with a moderately high T g the procedure can be applied to copolymerization with monomers that provide polymers with low T g matrices (i.e. below room temperature) and thereby can act as elastomers or impact resistant resins.
  • a further example of the level of macromolecular architectural control attainable from the process of the present invention is the preparation of block copolymers in which one or more of the blocks comprise a graft copolymer.
  • the preparation of an AB and an ABC block-graft copolymers are described for specific examples but the approach can be applied to the preparation of block copolymers of any topology.
  • the distribution of the graft segments in the backbone copolymer can be significantly modified by the order of formation of each graft-block copolymer segment.
  • block copolymers additionally comprising graft segments of differing composition
  • the composition of each graft, and the backbone so that the resulting copolymer can be homogeneous, or can phase separate in a bulk copolymer into two or three discrete phases.
  • the PDMS phase may phase separate due to the difference in phylicity between the graft and the backbone, and the PLLA, or a derivative of PLLA, can phase separate as a result of crystallization from the matrix, if the appropriate matrix composition is selected.
  • the resulting triphasic morphology of a block-graft copolymer can be transitory, and dependent on the conditions employed for fabrication of the material, however once the desired morphology is obtained it can be stabilized by incorporation and reaction of additional reactive functionality on the grafts or backbone that allows crosslinking reactions to occur either within the copolymer or with added materials. Examples of such functionality have been described in earlier applications incorporated by reference but include glycidyl- functionality or silyl- functionality, the latter of which can be crosslinked by exposure to moisture.
  • the crosslinkable functionality can be incorporated into one or more of the macromonomers or into the backbone during copolymerization or by transformation of a functional group on the copolymer after preparation of the material. The site of the reactive functionality would impact the bulk properties of the formed resin while stabilizing the morphology.
  • Triphasic copolymers may also be prepared by the process of the present invention by preparation of copolymers with more than one macromonomer or by formation of gradient copolymers with more than one macromonomer.
  • a biocompatible material is a material which is biologically compatible by not producing a toxic, injurious, or immunological response in living tissue or other undesirable effect.
  • the process of the present invention allows preparation of well- defined graft (co)polymers with either homogenously or heterogenously distributed branches.
  • the distribution of the branches is primarily controlled by the relative reactivity ratio of the macromonomer and the monomer and the compatibilizing effect of the macroinitiator.
  • Copolymerizations of poly(dimethylsiloxane)-macromonomer and methyl methacrylate were performed in four different systems: a standard radical polymerization with a low molecular weight initiator and with a macroinitiator and an ATRP with a low molecular weight initiator and with a macroinitiator.
  • a standard radical polymerization with a low molecular weight initiator and with a macroinitiator
  • ATRP with a low molecular weight initiator and with a macroinitiator.
  • redox initiated polymerizations were also performed with a low molecular weight initiator and with a macroinitiator. The relative reactivity of the macromonomer in the copolymerization was compared for each polymerization.
  • the copolymerization of methyl methacrylate and poly(dimethylsiloxane) macromonomer using a polydimethyl siloxane macroinitiator was conducted with a similar catalyst system to that employed for ATRP.
  • the examples clearly indicate that a compatible macroinitiator increases the rate of incorporation of the macromonomer into the copolymer.
  • the reactivity ratio of the macromonomer in the presence of a macroinitiator was 0.53. This can be compared to slower incorporation of the macromonomer, as measured by a reactivity ratio of 0.39 for the macromonomer, when no macroinitiator was employed.
  • the reactivity ratio of this polymerization process is a little higher than that of the prior art conventional radical polymerization process.
  • Polydispersity of the obtained copolymer was high (>2.7).
  • the beneficial effect of the macroinitiator is clearly seen in spite of the fact that the propagation rate is high and the effect of diffusion on the macromonomer can't be ignored.
  • a compatible macroinitiator can accelerate the incorporation of a macromonomer into the copolymer in the case of less controlled radical polymerizations in addition to fully controlled radical polymerization processes.
  • the beneficial effect of the use of a compatible macroinitiator was most obvious when the polymerization was done at higher macromonomer concentration because the low molecular weight growing copolymer chain and macromonomer remain compatible.
  • Graft copolymers with heterogeneous distribution of grafts with a gradient of grafted chains close to the chain end comprising the initiator residue can be prepared or graft copolymers with heterogeneous distribution of grafts with a gradient of grafted chains close to the chain end comprising the growing polymer chain can be prepared or graft copolymers with a homogeneous distribution of grafts can be obtained when the functional end groups on the poly(lactic acid) macromonomers are selected to have an average reactivity ratio close 1.0.
  • the reactive end groups comprise an equimolar concentration of both methacryloyl and acryloyl functionality.
  • Other functional end groups can be selected to allow similar "homogeneous" incorporation into backbone copolymers when different low molecular weight monomer units form the backbone copolymer or can be selected to afford the desired gradient heterogeneous distribution of grafts in a graft copolymer.
  • the process of the present invention therefore comprises polymerizing a mixture of macromonomers, comprising different reactive end groups to control the rate of incorporation of the macronomomers into the graft (co)polymer.
  • Poly(lactic acid) is a biodegradable aliphatic polyester derived from renewable resources and shows interesting properties: Vert, M.; Schwarch, G.; Coudane, J. J. Macromol. Sci., Pure Appl. Chem. 1995, A32, 787-796; and Lipinsky, E. S.; Sinclair, R. G. Chem. Eng. Prog. 1986, 82, 26- 32. It has been investigated as a biomaterial for controlled drug delivery, Jackanicz, T. M.; Nash, H. K.; Wise, D.
  • graft copolymers are known to exhibit excellent properties, and have possibilities for a variety of applications, such as compatibilizers, emulsifiers, thermoplastic elastomers, or impact-resistant plastics, the study of precise structural control of graft copolymers containing poly(lactic acid) branches is of significant interest.
  • One application for graft copolymers comprising such degradable graft segments would be in the preparation of porous membranes. The concentration of the grafted degradable polymer is selected so that the bulk graft-copolymer phase separated into a continuous bi-phasic morphology and then the degradable segment is removed allowing thereby forming a porous membrane.
  • Atom transfer radical copolymerization of methyl methacrylate and methacrylate-terminated poly(L-lactic acid) macromonomer (M-PLLA), methacrylate-terminated poly(D,L-lactic acid) macromonomer (M-PDLLA), and acrylate-terminated poly(L-lactic acid) macromoner (A-PLLA) was investigated and is herein disclosed as one example of the present invention.
  • the poly(L-lactic acid) macromonomers containing either a methacryloyl end group, or an acryloyl end group, were prepared by the ring opening polymerization of L-lactide using a tin catalyst, and using 2-hydroxyethyl methacrylate or 2-hydroxymethyl acrylate as the initiator, Scheme 3 shows the use of 2-hydroxyethyl methacrylate.
  • a homogeneous polymerization was conducted in the presence of a mixed diphenyl ether/xylene solvent and the poly(L-lactic acid) macromonomer was efficiently incorporated into the copolymer.
  • the resulting reactivity ratio of methyl methacrylate ( ⁇ M A ) was calculated to be 0.58. This indicates a gradient copolymer was formed with preferential incorporation of the grafts closer to the terminus of the backbone containing the attached initiator residue.
  • poly(L-lactic acid) macromonomer can allow preparation of an elastomeric material; one with an acrylate backbone, that comprises the matrix, and a crystallizable graft, that is further susceptible to biological degradation during recycle processes.
  • the acrylate selected for the exemplary backbone copolymer is butyl acrylate.
  • This interesting graft copolymer has a soft segment backbone and biodegradable hard segments, which have the ability to undergo phase separation and aggregation through crystallization. Such a graft copolymer may be useful as a biodegradable thermoplastic elastomeric material.
  • the graft copolymers prepared above are examples of the type of materials that can be prepared by an embodiment of the present invention by a controlled radical polymerization process such as, but not limited to, ATRP, NMP or RAFT copolymerization, of a macromonomer with radically (co)polymerizable monomer(s).
  • a further extension of this control over the composition of graft copolymers is the copolymerization of at least two macromonomers with different compositions with one or more low molecular weight monomers.
  • the result of such a copolymerization would be a graft copolymer with grafted polymer chains comprising two different compositions attached to the same backbone (co)polymer.
  • gradient-graft-copolymers were prepared by the process of the present invention wherein the distribution of each macromonomer along the backbone copolymer was heterogeneous, however, by applying the principles discussed above the graft distribution of each macromonomer can be changed.
  • the composition of the components of such a material can be selected to allow phase separation into a constrained bi-phasic or tri-phasic structure.
  • graft copolymers were used as macroinitiators for the (co)polymerization of macromonomers.
  • Block-graft-copolymers were prepared wherein each block comprises a graft copolymer.
  • a potential application for the exemplary material prepared below in the examples would be for one graft, for example, a PLLA macromonomer based graft, to provide biocompatibility, or selective permeability and for another graft, for example a PDMS graft, to provide increased toughness.
  • Appropriate selection of the graft segments could also provide for a toughened matrix material with cylindrical or gyroidal channels for proton transfer.
  • a further series of examples builds on this recognition that the end group reactivity has to be considered when constructing graft copolymers.
  • the copolymerization of (meth)acrylate terminated polyethylene macromonomers and (meth)acrylates and (meth)acrylate terminated polypropylene macromonomers providing graft copolymers with polyolefin grafts is described.
  • Such graft copolymers can act as surfactants in stabilizing blends of polymers found in municipal recycle streams providing for improved "polymeric wood" formed by melt blending such streams.
  • Scheme 4 First route for the synthesis of polypropylene-based macroinitiator. Within this reaction scheme there is an extra step, the synthesis of allyl-2-bromoisobutyrate. The reaction scheme for this step is presented in Scheme 5.
  • Scheme 5 Synthesis of allyl-2-bromoisobutyrate.
  • a second route started with the functional initiator prepared by the first reaction in Scheme 4 and used tetramethyldisiloxane to form a linking species.
  • the second route is presented in Scheme 6.
  • Scheme 6 Second route for the synthesis of polypropylene-based macroinitiator. This route permits one to avoid the reduction step By avoiding the reduction step, the coupling reaction with the unsaturated polypropylene is the final step, thus reducing the number of steps involving the latter species from three to one.
  • the major drawback of the reaction in Scheme 6 is that it leads to a polymer with a siloxane bond, which is not the case of the route described in Schemes 4 and 5 using chlorodimethylsilane. Consequently, copolymers prepared from the macroinitiator prepared according to Scheme 6 have a lower stability toward strong acids and bases.
  • Scheme 7 Variant of the second route with inverted order.
  • Both approaches allow the preparation of suitable macroinitiators to allow the successful preparation of block copolymers with an A block comprising polypropylene or a graft copolymer comprising improved incorporation of polypropylene macromonomers, according to the process of the present invention.
  • the use of a compatible macroinitiator to control the efficiency of initiation of a copolymerization also operates in inherently biphasic systems. When a catalyst for ATRP is dissolved in an ionic liquid and dispersed in a polymerization mixture containing a low molecular weight initiator the initiator initially migrates to the ionic liquid, forms a high concentration of radical species which undergo termination reactions, thereby leading to low initiator efficiency.
  • a "living" polymerization is a polymerization process where termination reactions are minimal.
  • control and/or “controlled” in reference to polymerization processes means that the polymerization process conditions are defined whereby the contributions of the chain breaking processes are insignificant compared to chain propagation, so that polymers with predetermined molecular weights, low polydispersities and tailorable, selected functionalities are achievable.
  • polymers include homopolymers and copolymers (unless the specific context indicates otherwise), which may be block, random, statistical periodic, gradient star, graft, comb, (hyper)branched or dendritic.
  • (co)polymer means a copolymer or polymer including homopolymer
  • (co)polymerizable means a monomer that is directly polymerized by the polymerization mechanism being discussed and additionally a comonomer which can only be incorporated into the polymer by copolymerization.
  • (hyper) is meant to incorporate the concept that the degree of branching along the polymer backbone can vary from a low degree of branching up to a very high degree of branching.
  • GPC Polymer molecular weights were estimated by a GPC equipped with a Waters WISP 712 autosampler, column setup (guard, 10 2 A, 10 3 A, 10 5 A; 5 ⁇ m; Polymer Standard Service (PSS), Germany), and a Waters 410 Rl detector in THF (35°C), at a flow rate of 1 mL/min.
  • the setup was calibrated against low polydispersity poly(methyl methacrylate) (pMMA) or polystyrene (pS) standards (PSS, Germany) with toluene as internal standard.
  • Weight average molecular weights were determined by using size exclusion chromatography equipped with Waters microstyragel columns (pore size 10 5 , 10 4 , 10 3 A) in THF as a solvent) a differential refractometer (Waters Model 410), light-scattering detector (DAWN Model F), a differential viscometer (Viscotek Model H502) and GPC Win software.
  • AFM Scanning force micrographs were recorded at ambient conditions with a Nanoscope III instrument (Digital Instruments, St. Barbara, USA) operating in the tapping mode. The measurements were performed at ambient conditions (in air, 56% RH, 23°C) using Si cantilevers with a spring constant of « 50 N/m, a tip radius of 8 nm, and a resonance frequency of about 300 kHz. The set-point amplitude ratio was maintained at 0.9 to minimize the sample deformation induced by the tip.
  • the samples for tapping mode SFM measurements were prepared by spin casting at 2000 rpm of dilute solutions (0.15 g/l) of brush molecules in chloroform.
  • the general procedure for preparation of macroinitiators and macromonomers was to polymerize n-butyl acrylate and f-butyl acrylate with a hydroxyl functionalized initiator.
  • These first formed polymers may be macroinitiators for ATRP before the halogen end group is removed.
  • the halogen end group may be transformed into a functionality capable of initiating any polymerization process.
  • the halogen end group may be removed using tributyltin hydride and AIBN.
  • the hydroxyl end group may then be esterified with methacryloyl chloride to provide a polymerizable double bond.
  • End group analysis was carried out on the first formed polymers, the macroinitiator form, using 1 H NMR and ESI-MS.
  • the resonances from the methine proton adjacent to the halogen end group (4.1 ppm) and the terminal hydroxyl group (3.1 ppm) are not detectable.
  • the vinyl protons are clearly visible (5.6 and 6.2 ppm).
  • the molecular weight of the macromonomer that was injected exceeded the detection limit of the instrument, however, the low molecular weight edge of the distribution is visible and shows the distribution of end group functionalities clearly.
  • There is no evidence of residual halogen terminated polymer (m 132 + 128.2n + 79/81 + 23) after reaction with tin bromide.
  • the first polymers prepared above may also be used as macroinitiators prior to removal of the radically active halogen on the chain end. They can therefore also be used for the preparation of block macromonomers by chain extension with different free radically polymerizable monomers prior to removal of the first halogen and esterification of the hydroxy group on the other polymer terminus.
  • the reaction conditions had been defined by the polymerization of t- butyl acrylate using ⁇ -bromo-isobutyrate ethylester as initiator.
  • a block co-macroinitiator is a macroinitiator comprising a block copolymer and a block co-macromonomer is a macromonomer comprising a block copolymer.
  • the preparation of a block co-macroinitiator or co-macromonomer precursor was accomplished by chain extension using the HO-ptBA-Br prepared in example 1 A, as a macroinitiator to further polymerize styrene thereby preparing a block copolymer macroinitiator, or a block-co-macromonomer precursor.
  • PMMA-g- poly(dimethylsiloxane) (PDMS) graft copolymers samples were prepared using ATRP, RAFT, redox initiated polymerization and a conventional radical polymerization.
  • Materials Copper chloride (CuCI) (98%, Aldrich) was purified by known procedures; 4,4'-Di-n-nonyl-2,2'-bipyridine (dnNbpy) was synthesized by a modified disclosed literature procedure.
  • Methacrylate-terminated PDMS macromonomer (PDMS-MA) was prepared by the ring opening polymerization of hexamethylcyclotrisiloxane (D3) (98%, Aldrich) followed by reaction with 3-methacryloxypropyldimethylchlorosilane.
  • D3 hexamethylcyclotrisiloxane
  • Mw/Mn 1.25
  • the functionality of the terminal methacrylate group was 1.0 (H-NMR, in CDCI3).
  • the conversion of MMA was measured using a Shimadzu GC-14A gas chromatograph (GC) equipped with a widebore capillary column (30 m, DB-Wax, J&W Sci.).
  • the conversion of PDMS-MA was determined by the gel permeation chromatography measurements in toluene (toluene-GPC) using a Waters 510 liquid chromatograph pump (1 ml/min, 30°C) equipped with columns (guard, 10 5 A, 10 2 A; Polymer Standards Service) in series with a Waters 2410 differential refractometer.
  • the molecular weight of the polymer was measured by GPC in tetrahydrofuran (THF-GPC) based on linear poly(methyl methacrylate) standards using a Waters 515 liquid chromatograph pump (1 ml/min, 30°C) equipped with four columns (guard, 10 5 A, 10 3 A, 100 A; Polymer Standards Service) in series with a Waters 2410 differential refractometer.
  • THF-GPC tetrahydrofuran
  • a PDMS-macroinitiator containing a 2-bromoisobutyrate terminal group was synthesized by anionic polymerization of D3 terminated by chlorodimethylsilane, followed by reaction with 3-butenyl 2- bromoisobutyrate. Yield, 78%.
  • Macromonorner HS134
  • Copolymer was isolated by reprecipitation (MeOH/Acetone).
  • RAFT Polymerization of MMA Materials 2-Phenylprop-2-yl dithiobenzoate (cumyl dithiobenzoate,
  • CDB dithiobenzoic acid
  • ⁇ - methylstyrene in carbon tetrachloride at 70 °C for 4 hours and then purified by column chromatography on alumina with hexane as eluent.
  • the dithiobenzoic acid was prepared by the reaction of benzyl chloride with elemental sulfur and sodium methoxide.
  • Benzoyl peroxide (BPO) (Fisher, 75%) and 2,2'- azobisisobutyronitrile (AIBN) (98%, Aldrich) were used as received.
  • BPO Benzoyl peroxide
  • AIBN 2,2'- azobisisobutyronitrile
  • CDB 2- phenylprop-2-yl dithiobenzoate
  • the molecular weight of the resulting copolymer was higher than the theoretical line. This was attributed to the rather high reaction temperature leading to rapid decomposition of the AIBN so that many radicals were initially generated and transfer agent (CDB) didn't work well.
  • CDB 2-phenylprop-2-yl dithiobenzoate (cumyl dithiobenzoate)
  • a typical RAFT copolymerization a 25 mL Schlenk flask equipped with a stir bar and containing a PDMS-MA (1.00g) was evacuated overnight and then filled with nitrogen.
  • the free radical initiator and addition-transfer fragmentation agent and deoxygenated MMA (0.80 g) were mixed in a separate 25 mL round bottom flask under nitrogen and dissolved in deoxygenated xylene (0.80 g). This solution was cannula-transferred to the Schlenk flask under a nitrogen flow.
  • reaction mixture A 0.1 mL aliquot of the reaction mixture was removed and the flask was placed into a 75 °C oil bath under nitrogen. Periodically, 0.1 mL aliquots of the reaction mixture were removed for the kinetic and molecular weight analysis. The conditions are summarized below.
  • CDB 2-phenylprop-2-yl dithiobenzoate (cumyl dithiobenzoate)
  • CDB 2-phenylprop-2-yl dithiobenzoate (cumyl dithiobenzoate)
  • Deoxygenated p- xylene (0.97 mL) and deoxygenated MMA (0.84 g, 8.36 mmol) were added via syringes. After the AIBN dissolved, the clear solution was cannula-transferred to the Schlenk flask under a nitrogen flow. A 0.1 mL aliquot of the reaction mixture was removed and the flask was placed into a 75 °C oil bath under nitrogen.
  • a PDMS-macroazo initiator (0.23 g, 0.023 mmol of azo group) was placed in a separate 25 mL round bottom flask, equipped with a stir bar, and sealed with a rubber septa. This flask was also evacuated overnight. These two flasks were filled with nitrogen and evacuated again. After this degassing/back-filling procedure was repeated three times, both the flasks were filled with nitrogen.
  • Deoxygenated p-xylene (1.41 mL) and deoxygenated MMA (0.87 g, 8.63 mmol) were added to the round bottom flask via syringes. After the PDMS-macroazo initiator dissolved, the clear solution was cannula-transferred to the Schlenk flask under a nitrogen flow. The polymerization was performed at 75 °C and periodical sampling and measurements were done in the same way as in the case of AIBN initiated reaction described above.
  • Copolymer was isolated by reprecipitation (MeOH/Acetone). n and M ⁇ M n were calculated from THF-GPC.
  • a 25 mL Schlenk flask were placed a stir bar, CuBr (4.2 mg, 0.029 mmol), copper (Cu ° ) powder (7.4 mg, 0.117 mmol), Me4-cyclam (7.5 mg, 0.029 mmol).
  • deoxygenated MMA (0.83 g, 8.3 mmol
  • the reduced reactivity of macromonomer will affect the final copolymer structure in different ways in RAFT and in the conventional free radical systems.
  • RAFT a RAFT process
  • all chains propagate simultaneously, therefore, every polymer chain will have similar branching structure although it may be intramolecularly heterogeneous.
  • the copolymer generated at the early stage of the polymerization has a totally different structure from that of the copolymer generated at the later stage. This phenomenon is due to the slow initiation throughout the reaction and progressive change in the feed composition as the comonomers are consumed at different rates. This leads to an intermolecularly heterogeneous structure for the copolymer although the degree of heterogeneity between the chains is less when a macroinitiator is employed.
  • ATRP can be used to prepare homogeneously branched graft copolymers.
  • the copolymers prepared using a conventional free radical method were heterogeneous in terms of copolymer composition, branching regularity, and molecular weights.
  • control of concentration of macromonomers and other monomers during the polymerization and selection of the reactive end groups could produce more homogenously branched polymers by conventional free radical polymerization.
  • Graft copolymers obtained by ATRP (in both solution and semi-bulk) have predetermined molecular weights with much lower polydispersities than obtained in the conventional radical systems.
  • the combination of ATRP and a macroinitiator that is soluble in the macromonomer is an effective way to control the graft copolymer structure in terms of main chain length/polydispersity and branch distribution/homogeneity.
  • RAFT also prepares a homogeneous graft copolymer but one with a more heterogeneous distribution of grafts along the backbone. Such a distribution can be considered a gradient copolymer between the low molecular weight monomer and the macromonomer.
  • RAFT polymerizations may also prepare homogenously distributed grafts by modification of the reactive end groups of the macromonomers using blends of macromonomers or controlling the concentrations of macromonomers in the polymerization process.
  • MMA and p-xylene were deoxygenated by bubbling nitrogen gas through them for more than one hour just before the polymerization.
  • High purity L-lactide (L-LTD) (>99.9%) and D-lactide (D- LTD) (>99.9%) were supplied by Mitsui Chemicals and purified by recrystallization from toluene and dried in vacuum ( ⁇ 3 mmHg) overnight at room temperature.
  • Copper chloride (CuCI) (98%, Aldrich) was stirred in glacial acetic acid overnight, filtered, and washed with absolute ethanol and ethyl ether under nitrogen. The solid was dried under vacuum at room temperature overnight.
  • 4,4'-Di-n-nonyl-2,2'-bipyridine (dnNbpy) was synthesized by a modified literature procedure.
  • the molecular weights of the copolymers were determined based on low polydispersity poly(methyl methacrylate) (PMMA) standards.
  • PMMA polydispersity poly(methyl methacrylate)
  • the conversion of MMA was measured on a Shimadzu GC-14A gas chromatograph (GC) equipped with a FID detector using a widebore capillary column (30 m, DB-Wax, J&W Sci.). Injector and detector temperature: 250 °C; column temperature: 40 °C for 2 minutes followed by an increase to 160 °C at the rate of 40 °C/min and held for 2 minutes.
  • the 1 H-NMR in deuteratred chloroform (CDCI3) was measured with a 300 MHz Bruker spectrometer using Tecmag data acquisition software.
  • PLA macromonomers were prepared by a ring opening polymerization of lactide using 2-hydroxyethyl methacrylate or 2- hydroxymethyl acrylate as the initiator. Lactide is often contaminated by a small amount of hydroxy-compounds such as lactic acid, lactic acid dimer, and water.31 It is extremely important to use highly purified lactide for the macromonomer preparation because these impurities can act as undesirable initiators in the lactide polymerization and produce non- functionalized PLA and decrease the functionality. 8 A. ATRP of MMA in the presence ofstannous octoate.
  • a polylactic acid macromonomer with a methyl methacrylate end group (PLA-macromonomer), prepared by the ring-opening polymerization of lactide using stannous octoate (SnOct) as a catalyst, may contain a certain amount of Sn catalyst residue, the effect of tin on an ATRP polymerization was determined. Under optimal conditions for lactide polymerization, 0.08 wt% SnOct may be used. If this crude macromonomer was used at 5 mol% PLA- macromonomer for copolymerization with MMA, a maximum of 7.5 mol% of SnOct per MMA could be contained in the reaction mixture. Therefore, MMA was polymerized by ATRP in the presence and in the absence of SnOct to determine whether SnOct will interfere the ATRP. The results are shown in Table 6. Table 6. ATRP of MMA.
  • Methacrylate-terminated Poly(L-lactic acid) Macromonomer (M-PLLA)(Run HS-168) L-LTD (20.0 g, 0.14 mol) was placed into a 100 mL round bottom flask equipped with a stir bar. After a toluene solution of SnOct (16 mg/mL- toluene) was added, the flask was capped with a rubber septa and vacuumed (1 mmHg) through a needle for more than three hours. The flask was filled with nitrogen gas, and HEMA (0.9 g, 5 mol %/LTD) was added via a syringe.
  • SnOct 16 mg/mL- toluene
  • A-PLLA was prepared by replacing HEMA with HEA in the method for M-PLLA synthesis.
  • F 0.98 (by 1 H-NMR).
  • Mn 2690 (by 1 H-NMR).
  • Mw/Mn 1.22 (by GPC).
  • Table 7. Summary of ring-opening polymerizations of lactide (LTD).
  • HEMA 2-hydroxyethyl methacrylate
  • HEA- 2-hydroxy acrylate 2-hydroxy acrylate
  • SnOct stannous octoate.
  • Sample HS177-1 was prepared to improve the solubility of the macromonomer and reduce the viscosity in the copolymerization mixture.
  • HS177-2 was prepared in order to determine if the solubility and crystallinity had an affect on the macromonomer reactivity.
  • HS 177-3 was initially prepared for its copolymerization with acrylate monomer such as butyl acrylate. All of the macromonomers were
  • the methacryloyl terminated PLLA macromonomers will be called as M-PLLA- macromonomer and acryloyl terminated PLLA macromonomer will be called as A- PLLA- macromonomer.
  • Poly(L-lactide) will be called PLLA
  • poly(DL-lactide) will be called PDLLA
  • poly(D-lactide) will be called PDLA.
  • GPC study Similar to the study of PDMS-macromonomer, a GPC study was done for the PLLA-macromonomers.
  • THF solutions of the mixture of PLLA-macromonomer and PMMA with their various compositions were prepared and subjected to the THF-GPC measurement. Polymer composition and their peak intensities (area) showed a good linearity. The peak intensity ratio of PMMA to PLLA was found to be 2.17.
  • THF solutions of the mixture of PLLA- macromonomer and PBA with their various compositions were prepared and subjected to THF-GPC measurement. Polymer composition and their peak intensities (area) showed a good linearity. The peak intensity ratio of PBA to PLLA was found to be 1.29.
  • ⁇ MMA ln([MMA] 0 /[MMA]) / ln([macromonomer] 0 /[macromonomer])
  • 1 /r A 1.75. This value means that the rate constant for the reaction of the methacrylate radical at the growing chain with M-PLLA is 1.75 times higher than that with MMA. 8F.
  • M-PLLA-macromonomer were incorporated into copolymer at a similar rate.
  • the reactivity ratio of MMA ( ⁇ M A ) was 1.09.
  • the molecular weight changes showed a typical behavior of the conventional radical polymerization.
  • Jose L. Eguiburu, Jose F-Berridi, Julio S. Roman, Polymer 1996, 37(16), 3615; reported the free radical polymerization of M-PLLA-macromonomer (M n 4500) with MMA and MA using AIBN as the initiator in dioxane at 60° C.
  • M-PLLA- macromonomer methacrylate-terminated PLLA macromonomer
  • A-PLLA-macromonomer acrylate- terminated PLLA-macromonomer
  • Initiator ethyl 2-bromoisobutyrate Ligand: 4,4'-di(n-nonyl)2,2'-bipyridine [dnNBPy]
  • Methacrylate-terminated poly(D,L-lactic acid) macromonomer, Mn 3350.
  • Methacrylate-terminated poly(L-lactic acid) macromonomer, Mn 4500.
  • Macromonomer(A-PLLA-MM): HS 177-3, Mn 2690
  • Ligand 4,4'-di(n-nonyl)2,2'-bipyridine [dnNBPy] macromonomer.
  • This material is an interesting graft copolymer since the polymer has a soft segment backbone and biodegradable hard segments which have some ability of aggregation (crystallization). It may be useful as biodegradable thermoplastic elastomeric materials.
  • This experiment was just the first attempt to make polyacrylate-g-PLLA copolymer because the poor solubility of the PLLA in toluene, a large excess of solvent was employed and that made the reaction very slow.
  • Initiator Methyl 2-bromopropionate.
  • Ligand N,N-Bis(2-pyridylmethyl)octylamine [BPMOA].
  • c 0.4 ml of anisol was added as the internal standard.
  • reaction in toluene was very slow probably due to the poor solubility of catalyst.
  • the reaction mixture was a little turbid yellow however when DMF was used as solvent the reaction mixture was clear yellow, and polymerization did occur
  • the amounts of each component of this reaction are summarized in the following Table 14. Table 14.
  • THF-GPC The average molecular weights and the polydispersity indices we obtained are summarized in Table 15. Table 15
  • the macromonomer, and the first block of the block copolymer, PMMA-g-PDLA were prepared as described above.
  • the molecular weight of the first block (macroinitiator) is 36800 g.mol "1 (THF GPC measurement) and the molecular weight of the PDMS macromonomer is 3000 g.mol "1 ( 1 H NMR measurement).
  • the targeted degree of polymerization for the MMA backbone for the second block is 150.
  • the targeted degree of polymerization for the macromonomer PDMS is 5. Therefore, the targeted molecular weight for the second block is 30000 g.mol "1 .
  • the targeted molecular weight of the final polymer is consequently 66800 g.mol "1 .
  • the grafting segments are mostly located towards each the terminii of the backbone (upper structure shown in Figure 3). I.e. it is almost an ABC triblock copolymer.
  • the A block is PMMA-g-PDLA
  • the B block a pure PMMA segment
  • the C block PMMA-g-PDMS.
  • the overall structure of the copolymer is symmetric, the distribution of the branching on the backbone is not regular with each of the graft segments concentrated at the chain ends.
  • each block is a graft copolymer
  • the order of synthesis of each block significantly impacts the structure or topology of the final product and the distribution of the macromonomers, or grafts, along the backbone polymer can be changed by order of block formation even when the block copolymers contain the same concentration of the same macromonomers and the block copolymer segments were prepared under the same conditions.
  • THF-GPC The average molecular weights and the polydispersities of the dual gradient graft copolymer were determined by THF-GPC based on PMMA standards calibration. There are three different populations seen in the GPC curves, due to diphenyl ether, PDLA macromonomer and the synthesized polymer. Conversions of PDLA-MM was calculated by comparing the areas of the corresponding signal.
  • Toluene-GPC was also run and the chromatograms obtained show four different populations; due to MMA, diphenyl ether, PDMS macromonomer and the synthesized polymer. Conversion of PDMS-MM was calculated by comparing the areas of the corresponding signal.
  • PLA macromonomer (5 eq.), PDMS macromonomer (5 eq.), p- xylene and phenyl ether were added in a dry schlenk flask. The mixture was thoroughly purged by nitrogen flushing then heated in order to obtain a perfect solubilization of the crystalline PLA macromonomer. Then, a dispersion of (CuBr/PS-dMBpy) (2 eq.) in methyl methacrylate (250 eq.) was added into the schlenk flask. A solution of (CuBr 2 (Me 6 TREN)) (0.01 eq.) in acetone was added via a degassed syringe.
  • PDMS macromonomer conversion was calculated by toluene-GPC by comparing the macromonomer pick area to the pick area of the diphenyl ether standard.
  • PLA macromonomer conversion was calculated by GC by comparing the monomer pick area to the pick area of diphenyl ether and p-xylene.
  • hybrid catalyst In the presence of the hybrid catalyst, the control of molecular weight is as good as in the presence of the homogeneous catalyst. However, polydispersity is slightly broader in the case of hybrid catalyst. These results prove that the hybrid catalyst system (CuBr/PS- dMBpy)/(CuBr 2 (Me 6 TREN)) allows one to control the synthesis of well- defined graft copolymer as efficiently as the classic homogeneous system (CuBr (d-n-Bipy) 2 ).
  • PP (0.1 mmol) was dissolved into 3 mL of xylene, and placed into a 25 mL three- neck round bottom flask under nitrogen. 1.04 mg (6 mmol) of methylnaphtoquinone was then added, followed by 31.1 mL (0.096 mol/L; 3 mmol) of Karstedt's catalyst in xylene. Then, 104 mg (0.5 mmol) of allyl-2- bromoisobutyrate was added at once. An initial sample was removed and the mixture was stirred under nitrogen at 30°C for 12 h, then at 50°C for 8 h and finally at 80°C for 30 h.
  • the flask was then put into an ice bath and a mixture of Karstedt's catalyst (0.096 mol/L; 8.32 mL; 0.8 mmol) and methylnaphtoquinone (0.274 g; 1.6 mmol) in xylene solution was then added dropwise, leading to a gold homogeneous solution.
  • the mixture was stirred under nitrogen at 20°C for 2 h, then at 50°C for 16 h.
  • the excess of tetramethyldisiloxane was evaporated at 50°C under reduced pressure (50 mmHg then 5 mmHg). Aliquots were removed after 30, 60 and 120 minutes of reaction at room temperature and after 2 h and 16 h at 50°C.
  • the polymer was precipitated into 50 mL C, re-dissolved into 10 mL of anhydrous ether and filtrated through a 0.2-mm filtration membrane. Ether was evaporated under reduced pressure and a sample was removed for analysis. The polymer was dissolved again in 10 mL of anhydrous ether and precipitated into 100 mL of methanol. The solvents were then evaporated under low (10 2 mmHg) to high vacuum (10 7 mmHg) for 2 h and 4 h respectively. Another sample was removed for analysis. The disappearance of the vinylic protons signal, from 6 to 5.8 ppm and from 5.1 to 5 ppm, was clearly observed by 1 H NMR after 2 h at 50 °C, indicating that the hydrosilation reaction was successful.
  • ATRP can thus be carried out with this macro-initiator B3.
  • a TRP of MMA using polypropylene-based macro-initiator preparation of a block copolymer
  • the quantity of macro-initiator in the polypropylene blend was assessed from the content of bromine found by elemental analysis (1.94 %).
  • the polypropylene- based macro-initiator (11 B2 - 0.46 g ; 1.94 % of Br; 0.112 mmol) in 1.2 mL of xylene and 1.195 mL (11.2 mmol) of MMA were placed into a sealed Schlenk flask and were cleaned of oxygen by a bubbling of nitrogen for 30 min. The mixture was frozen into a liquid nitrogen bath and the Schlenk flask was degassed and backfilled with liquid nitrogen.
  • first step was performed again, at a lower temperature.
  • evaporation of the excess of tetramethyldisiloxane was conducted while the product was still under nitrogen (rather than transferring the mixture into a round-bottom flak to use the rotavapor) and at room temperature, as formation of Si-O-Si based products can be observed with Karstedt's catalyst in the presence of water; Britcherm L.G., Kehoe, D.C.; Matisons, J.G., Swinser, A.G. "Siloxane Coupling Agents" Macromolecules 1995, 28, 3110-3118.
  • the reaction was conducted in xylene.
  • a 50 mL three-neck round bottom flask was backfilled with nitrogen and charged with vinyl-terminated polypropylene (1.5 g; 0.5 mmol).
  • the polymer was dissolved into 3 mL of xylene and tetramethyldisiloxanepropyl-2-bromoisobutyrate (1.71 g; purity ⁇ 50%; ⁇ 2.5 mmol.
  • a mixture of Karstedt's catalyst (0.096 mol/L; 104.16 mL; 0.01 mmol) and methylnaphtoquinone (3.45 mg; 0.02 mmol) in xylene solution was then added dropwise, leading to an orange homogeneous solution.
  • the mixture was then filtrated, leaving a white powder that was dried under high vacuum (10 7 mmHg) for 4 h.
  • a nice shift toward the high molecular weights was observed, as well as the progressive disappearance of the PP-based macro-initiator.
  • the final molecular weight of the copolymer was significantly higher than expected (27,000 g/mol rather than 15,000 g/mol expected. This indicates either a very slow initiation process or poor macro-initiator efficiency which can be attributed to the lower degree of functionality of the starting polypropylene (1.16 % bromine versus 1.94 % previously). Thanks to a much better homogeneity of the mixture, the final monomer conversion obtained is significantly higher, around 80 % (61 % previously). 13.
  • the GPC traces of polymer samples taken at intervals throughout the polymerization show an initial bimodal molecular weight distribution with progressively and continuously occurring initiation as the macroinitiator signal is converted to higher molecular weight polymer.
  • the first- order kinetic plots were linear, showing a constant concentration of radicals throughout the reaction. The reaction rates depend strongly on the amount of the deactivator in the ionic liquid phase. Thus, when the concentration of Fe" was increased from 0.7 to 0.9 mole vs.
  • ATRP in ionic liquids proceeds with low initiation efficiency. This can be ascribed to relatively low concentration of the catalyst in organic medium and very high concentration of catalyst in ionic liquid phase.
  • low molecular weight initiator enters ionic liquid phase, it generates large concentration of radicals, which terminate and result in low initiator efficiency.
  • polymerization is controlled and molecular weights evolve linearly with conversion, resulting in polymers with low polydispersities.
  • the initiation efficiency can be significantly increased in the presence of macroinitiators, which cannot enter ionic liquid phase.

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  • Health & Medical Sciences (AREA)
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  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Macromonomer-Based Addition Polymer (AREA)

Abstract

L'invention concerne un procédé de polymérisation comprenant la polymérisation de macromères, et éventuellement de comonomères, avec un macro-initiateur afin de former un (co)polymère greffé.
PCT/US2001/049523 2000-12-22 2001-12-21 Procede de preparation de polymeres greffes WO2002068485A1 (fr)

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US25773800P 2000-12-22 2000-12-22
US60/257,738 2000-12-22

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1399487A1 (fr) * 2001-03-30 2004-03-24 UAB Research Foundation Formation de polymeres dans des liquides ioniques a temperature ambiante
EP2017293A1 (fr) * 2007-07-19 2009-01-21 Basf Se Inhibiteurs contenant des mélanges de la polymérisation radicale, liquides ioniques et leur utilisation pour la stabilisation de monomères pouvant être polymérisés radicalement
US7847021B2 (en) * 2004-02-16 2010-12-07 Mitsui Chemicals, Inc. Aliphatic polyester resin composition containing copolymer
US8349410B2 (en) 2006-08-17 2013-01-08 University of Pittsburgh—of the Commonwealth System of Higher Education Modification of surfaces with polymers

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5626863A (en) * 1992-02-28 1997-05-06 Board Of Regents, The University Of Texas System Photopolymerizable biodegradable hydrogels as tissue contacting materials and controlled-release carriers
US5789487A (en) * 1996-07-10 1998-08-04 Carnegie-Mellon University Preparation of novel homo- and copolymers using atom transfer radical polymerization
EP0870809A2 (fr) * 1997-04-10 1998-10-14 Fuji Photo Film Co., Ltd. Composition de pigment et composition photosensible
WO2000056795A1 (fr) * 1999-03-23 2000-09-28 Carnegie Mellon University Procedes catalytiques de polymerisation controlee de monomeres (co)polymerisables par des radicaux libres et systemes de polymeres fonctionnels prepares de la sorte

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5626863A (en) * 1992-02-28 1997-05-06 Board Of Regents, The University Of Texas System Photopolymerizable biodegradable hydrogels as tissue contacting materials and controlled-release carriers
US5789487A (en) * 1996-07-10 1998-08-04 Carnegie-Mellon University Preparation of novel homo- and copolymers using atom transfer radical polymerization
EP0870809A2 (fr) * 1997-04-10 1998-10-14 Fuji Photo Film Co., Ltd. Composition de pigment et composition photosensible
WO2000056795A1 (fr) * 1999-03-23 2000-09-28 Carnegie Mellon University Procedes catalytiques de polymerisation controlee de monomeres (co)polymerisables par des radicaux libres et systemes de polymeres fonctionnels prepares de la sorte

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1399487A1 (fr) * 2001-03-30 2004-03-24 UAB Research Foundation Formation de polymeres dans des liquides ioniques a temperature ambiante
EP1399487A4 (fr) * 2001-03-30 2005-08-17 Uab Research Foundation Formation de polymeres dans des liquides ioniques a temperature ambiante
US7847021B2 (en) * 2004-02-16 2010-12-07 Mitsui Chemicals, Inc. Aliphatic polyester resin composition containing copolymer
US8349410B2 (en) 2006-08-17 2013-01-08 University of Pittsburgh—of the Commonwealth System of Higher Education Modification of surfaces with polymers
US8871831B2 (en) 2006-08-17 2014-10-28 University of Pittsburgh—of the Commonwealth System of Higher Education Modification of surfaces with polymers
EP2017293A1 (fr) * 2007-07-19 2009-01-21 Basf Se Inhibiteurs contenant des mélanges de la polymérisation radicale, liquides ioniques et leur utilisation pour la stabilisation de monomères pouvant être polymérisés radicalement

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