Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
  • C08C19/00—Chemical modification of rubber
  • C08C19/30—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule
  • C08C19/42—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule reacting with metals or metal-containing groups
  • C08C19/44—Addition of a reagent which reacts with a hetero atom or a group containing hetero atoms of the macromolecule reacting with metals or metal-containing groups of polymers containing metal atoms exclusively at one or both ends of the skeleton
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G81/00—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers
  • C08G81/02—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers at least one of the polymers being obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C08G81/021—Block or graft polymers containing only sequences of polymers of C08C or C08F

Definitions

• This invention relates to a method for preparing polymers. More particularly, this invention relates to a method for preparing asymmetric radial polymers.
• radial polymers comprise three or more arms extending outwardly from a nucleus.
• the asymmetric radial polymers generally, contain arms of at least two different polymers, which polymers may vary as to chemical composition, structure and/or molecular weights.
• Asymmetric radial polymers having arms of different molecular weights are sometimes referred to as polymodal polymers.
• a principal difference in the methods frequently used to prepare both asymmetric and polymodal radial polymers resides in the selection of a coupling agent which forms the nucleus of the radial polymer.
• the coupling agent may contain a fixed, though sometimes variable, number of functional sites such as the coupling agents taught in U.S. Pat. Nos. 3,281,383; 3,598,884; 3,639,517; 3,646,161; 3,993,613 and 4,086,298 or the coupling agent may itself be a monomer which polymerizes during the coupling reaction such as taught in U.S. Pat. No. 3,985,830.
• a blend of polymeric arms is first prepared containing the various polymeric arms in the desired ratio and the blend of polymeric arms is then added to the coupling agent or the coupling agent is added to the blend of polymeric arms.
• a blend of polymeric arms comprising both living homopolymers and living copolymers in a ratio of three to one would be combined with the silicon tetrachloride and the coupling reaction allowed to proceed to completion.
• the resulting asymmetric polymer would, of course, on average contain three homopolymer arms per copolymer arm.
• the actual product obtained would, however, be a blend of radial polymers, some of which contain four homopolymer arms and no copolymer arms, some of which contain three homopolymer arms and one copolymer arm (the desired product), some of which contain two homopolymer arms and two copolymer arms, some of which contain one homopolymer and three copolymer arms and some of which contain no homopolymer arms and four copolymer arms.
• the expected statistical distribution for an asymmetric radial copolymer having the average composition (SI)-X-I 3 made in this manner, wherein X is silicon, is given in Table 1.
• a blend of polymeric arms comprising both living homopolymers and living copolymers in a ratio of one to one would be combined with the silicon tetrachloride and the coupling reaction allowed to proceed to completion.
• the resulting asymmetric polymer would, of course, on average contain two homopolymer arms and two copolymer arms.
• the actual product obtained would, however, be a blend of radial polymers, some of which contain four homopolymer arms and no copolymer arms, some of which contain three homopolymer arms and one copolymer arm, some of which contain two homopolymer arms and two copolymer arms (the desired product), some of which contain one homopolymer and three copolymer arms, and some of which contain no homopolymer arms and four copolymer arms.
• the expected statistical distribution for an asymmetric radial copolymer having the average composition (SI) 2 I 2 made in this manner is given in Table 2.
• the foregoing and other objects and advantages are accomplished with a process wherein the different arms to be contained in the asymmetric radial polymer are contacted sequentially with the coupling agent.
• the coupling sequence will be controlled by the relative number of each arm sought in the final product with that polymer intended to provide the greater number of arms contacted with the coupling agent first and that polymer intended to provide the next greatest number of arms contacted with the coupling agent second.
• the order of addition is immaterial.
• asymmetric radial polymers contain a plurality (three or more) of arms of at least two different polymers.
• the polymeric arms may differ as to chemical composition, structure and/or molecular weight.
• the different arms are contacted sequentially with the coupling agent.
• the polymer intended to provide the greater number of arms in the asymmetric polymer product could be a mixture of different polymers.
• the product therefrom will be contacted with the arm intended to be present in the next greatest number and this reaction allowed to proceed until completed or at least substantially completed.
• the order of contacting with the coupling agent is not critical and each of the arms may be added in any order (sequence).
• the method of this invention may be used to prepare asymmetric radial polymers with any polymer containing a reactive end group which will react with one or more functional groups contained in a selected coupling agent.
• the method is particularly suitable for the preparation of asymmetric radial polymers from so-called "living" polymers containing a single terminal metal ion.
• the coupling agent used in the preparation must, then, contain at least three functional groups which will react with the polymer at the site of the metal ion.
• "living" polymers are polymers containing at least one active group such as a metal atom bonded directly to a carbon atom.
• “Living" polymers are readily prepared via anionic polymerization.
• the present invention is particularly well suited to the preparation of asymmetric radial polymers using "living" polymers to form the arms thereof, the invention will be described by reference to such polymers. It will, however, be appreciated that the invention would be equally useful with polymers having different reactive groups so long as the selected coupling agent contains functional groups which are reactive with the reactive site contained in the polymer.
• Living polymers containing a single terminal group are, of course, well known in the prior art. Methods for preparing such polymers are taught, for example, in U.S. Pat. Nos. 3,150,209; 3,496,154; 3,498,960; 4,145,298 and 4,238,202, the disclosure of which patents are herein incorporated by reference.
• the polymers produced with the processes taught in the foregoing patents may be polymers of one or more conjugated dienes containing from 4 to about 12 carbon atoms such as 1,3-butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4-dimethyl-1,3-hexadiene, 4,5-diethyl-1,3-octadiene and the like, preferably those conjugated diolefins containing 4 to 8 carbon atoms.
• one or more of the hydrogen atoms in the conjugated diolefins may be substituted with halogen.
• the polymers produced by these processes may also be copolymers of one or more of the aforementioned conjugated diolefins and one or more other monomers particularly monoalkenyl aromatic hydrocarbon monomers such as styrene, various alkyl-substituted styrenes, alkoxy-substituted styrenes, vinyl naphthalene, vinyl toluene and the like.
• monoalkenyl aromatic hydrocarbon monomers such as styrene, various alkyl-substituted styrenes, alkoxy-substituted styrenes, vinyl naphthalene, vinyl toluene and the like.
• Homopolymers and copolymers of monoalkenyl aromatic hydrocarbons can also be prepared by the methods taught in the aforementioned patents, particularly the methods taught in U.S. Pat. Nos. 3,150,209; 3,496,154; 3,498,960; 4,145,2
• the monomers are, generally, added at the same time, although the faster reacting monomer may be added slowly in some cases, while, when the product is a block copolymer, the monomer used to form the separate blocks are added sequentially.
• the polymers useful as arms in both the method of this invention and the asymmetric radial polymer of this invention may be prepared by contacting the monomer or monomers with an organoalkali metal compound in a suitable solvent at a temperature within the range from about -150° C. to about 300° C., preferably at a temperature within the range from about 0° C. to about 100° C.
• organoalkali metal compound in a suitable solvent at a temperature within the range from about -150° C. to about 300° C., preferably at a temperature within the range from about 0° C. to about 100° C.
• Particularly effective polymerization initiators are organolithium compounds having the general formula:
• R is an aliphatic, cycloaliphatic, alkyl-substituted cycloaliphatic, aromatic or alkyl-substituted aromatic hydrocarbon radial having from 1 to about 20 carbon atoms.
• the polymers useful as arms in both the method of this invention and the asymmetric radial polymer of this invention will have a weight-average molecular weight within the range from about 1000 to about 500,000 and when the polymer is a copolymer of one or more conjugated diolefins and one or more other monomers, the copolymer will comprise from about 1 wt % to about 99 wt % monomeric diolefin units and from about 99 wt % to about 1 wt % monoalkenyl aromatic hydrocarbon monomer units.
• the different polymer arms will be prepared separately and maintained separately until each is sequentially contacted with the coupling agent.
• any of the coupling agents known in the prior art to be useful in forming a radial polymer by contacting the same with a living polymer may be used in both the method of this invention and the asymmetric radial polymers of this invention.
• suitable coupling agents will contain three or more functional groups which will react with the living polymer at the metal-carbon bond. While the method of the present invention will, at least, improve the relative distribution of different arms in an asymmetric radial polymer having any number of arms, the method offers significant improvement when the coupling agent contains from three to about twelve functional groups reactive with the metal-carbon bond of the "living" polymer.
• Suitable coupling agents include SiX 4 , RSiX 3 , HSiX 3 , RX 2 Si--(CH 2 ) x --SiX 2 R, X 3 Si--SiX 3 , X 3 Si--O--SiX 3 , X 3 Si--(CH 2 ) x --SiX 3 , RX 2 Si--(CH 2 ) x --SiX 2 --(CH 2 ) x --SiX 2 R, R--C(SiX 3 ) 3 , R--C(CH 2 SiX 3 ) 3 , C(CH 2 SiX 3 ) 4 and the like, particularly those containing from three to about six functional groups.
• each X may, independently, be fluorine, chlorine, bromine, iodine, alkoxide radicals, carboxylate radicals, hydride and the like;
• R is a hydrocarbyl radical having from 1 to about 10 carbon atoms, preferably from 1 to about 6 carbon atoms; and
• x is a whole number from 1 to about 6.
• Particularly useful coupling agents include the silicon tetrahalides such as silicon tetrafluoride, silicon tetrachloride, silicon tetrabromide and the like.
• the living polymers used as arms in the asymmetric radial polymer will be contacted with the coupling agent at a temperature within the range from about 0° C. to about 100° C. at a pressure within the range from about 0 psig to about 100 psig and the contacting in each step will be maintained until reaction between the arms and the coupling agent is complete, generally for a period of time within the range from about 1 to about 180 minutes. While the inventor does not wish to be bound by any particular theory, it is believed that the method of this invention results in an improved relative arm distribution because the reactivity of the functional groups contained in the coupling agent become progressively less active as the number of functional groups contained in the coupling agent is reduced as the result of reaction with the metal-carbon bond contained in the living polymer.
• the method of this invention allows for the use of more economical, commercially available coupling agents.
• a precise asymmetric radial polymer containing two copolymer arms and two homopolymer arms may be synthesized using the first described method if the coupling agent RCl 2 Si(CH 2 ) 2 SiCl 2 R is used.
• SiCl 4 may be used in the second described method to produce an asymmetric radial polymer having on average two copolymer arms and two homopolymer arms.
• the product will, in actuality, be a mixture of asymmetric radial polymers, some having three copolymer arms and one homopolymer arm, the majority having two copolymer arms and two homopolymer arms, and some having one copolymer arm and three homopolymer arms.
• the product will not contain symmetric radial polymers containing four copolymer arms and no homopolymer arms, or four homopolymer arms and no copolymer arms.
• the method of this invention provides a simple, economical method to obtain significantly higher amounts of the desired product while avoiding the presence of undesired radial polymers.
• the method of the present invention is particularly useful for the production of an asymmetric polymer wherein equal numbers of each different polymer arm type are desired.
• the distribution of the different arms on each of the asymmetric radial polymers formed will be statistical and can range from polymers having all arms of one type of polymer to all arms of another type of polymer as shown in Tables 1 and 2.
• the polymers useful as arms in the asymmetric radial polymers of this invention will be in solution when contacted with the coupling agent.
• Suitable solvents include those useful in the solution polymerization of the polymer and include aliphatic, cycloaliphatic, alkyl-substituted cycloaliphatic, aromatic and alkyl-substituted aromatic hydrocarbons, ethers and mixtures thereof.
• Suitable solvents include aliphatic hydrocarbons such as butane, pentane, hexane, heptane and the like, cycloaliphatic hydrocarbons such as cylohexane, cycloheptane and the like, alkyl-substituted cycloaliphatic hydrocarbons such as methylcyclohexane, methylcycloheptane and the like, aromatic hydrocarbons such as benzene and alkyl-substituted aromatic hydrocarbons such as toluene, xylene and the like and ethers such as tetrahydrofuran, diethylether, di-n-butyl ether and the like.
• aliphatic hydrocarbons such as butane, pentane, hexane, heptane and the like
• cycloaliphatic hydrocarbons such as cylohexane, cycloheptane and the like
• the polymers useful in making the asymmetric radial polymers of this invention will contain a single terminal reactive group, the polymers used in preparation of the asymmetric radial polymers will be retained in solution after preparation without deactivating the reactive (living) site.
• the coupling agent may be added to a solution of the polymer or a solution of the polymer may be added to the coupling agent.
• the method of preparing the asymmetric radial polymers of this invention will comprise a plurality of steps.
• a polymer containing a single terminal reactive group will be contacted with a coupling agent containing a plurality of functional groups which are reactive with the terminal group of the polymer.
• the reaction product from the first step will be combined with a solution of a second polymer which is different from the polymer used in the first step. The difference may be in chemical composition, relative chemical composition, structure, molecular weight or the like.
• contacting between the second polymer and the reaction product from the first step will be continued until reaction between the second polymer and the remaining functional groups of the coupling agent is complete.
• asymmetric radial polymers of this invention may be used in any of the applications for which asymmetric radial polymers having the same average relative arm structure can be used. Suitable end use applications, then, include impact modification of engineering thermoplastics, impact modification of unsaturated thermosetting polyesters, asphalt modification, viscosity index improvers, adhesives and the like.
• the process of this invention will be used to prepare an asymmetric radial polymer having four arms.
• the arms will be, partly, polymers containing only conjugated diolefins, most preferably conjugated diolefin homopolymers and, partly, block copolymers containing at least one monoalkenyl aromatic hydrocarbon polymer block and at least one conjugated diolefin polymer block.
• the block copolymer will comprise a single polystyrene block and a single polybutadiene or polyisoprene block.
• the weight-average molecular weight of those polymeric arms containing only polymerized conjugated diolefins will be within the range from 1,000 to about 150,000, preferably from about 15,000 to about 150,000.
• the weight-average molecular weight of the monoalkenyl aromatic hydrocarbon polymer blocks will be within the range from about 5,000 to about 100,000 and the weight-average molecular weight of the conjugated diolefin polymer blocks will be within the range from about 15,000 to about 150,000.
• Both the conjugated diolefin polymer arms and the block copolymer arms will be living polymers containing a single lithium atom bonded to a terminal carbon atom. In the first preferred embodiment, any of the known coupling agents containing four functional groups which are reactive with the lithium-carbon bond may be used.
• the coupling agent will be silicon tetrachloride.
• the ratio of conjugated diolefin homopolymer arms to the styrene-butadiene or styrene-isoprene block copolymer arms will be 3:1.
• the polymer intended to constitute the three arms will be contacted with the coupling agent first and the reaction between the lithium-carbon bond and the functional groups allowed to proceed to completion.
• the polymer is intended to contain two of both kinds of arms, either polymer may be first contacted with the coupling agent.
• the sequential coupling reactions will be completed at a temperature within the range from 20° C. to about 80° C., preferably from about 50° C.
• the process of this invention is used to prepare a four-arm radial polymer having a ratio of first arms to second arms of 2:2.
• the arms are, partly, polymers containing only conjugated diolefins, most preferably conjugated diolefin homopolymers and, partly, block copolymers containing at least one monoalkenyl aromatic hydrocarbon polymer block and at least one conjugated diolefin polymer block.
• the block copolymer will comprise a single polystyrene block and a single polybutadiene or polyisoprene block.
• the weight-average molecular weight of those polymeric arms containing only polymerized conjugated diolefins will be within the range from 1,000 to about 150,000, preferably from about 15,000 to about 150,000.
• the weight-average molecular weight of the monoalkenyl aromatic hydrocarbon polymer blocks will be within the range from about 5,000 to about 100,000 and the weight-average molecular weight of the conjugated diolefin polymer blocks will be within the range from about 15,000 to about 150,000.
• Both the conjugated diolefin polymer arms and the block copolymer arms will be living polymers containing a single lithium atom bonded to a terminal carbon atom.
• any of the known coupling agents containing four functional groups which are reactive with the lithium-carbon bond may be used.
• the coupling agent will be silicon tetrachloride.
• either polymer may be first contacted with the coupling agent.
• the sequential coupling reactions will be completed at a temperature within the range from 20° C. to about 80° C., preferably from about 50° C. to about 80° C., at a pressure within the range from about 0 psig to about 30 psig with a nominal holding time within the range from 10 minutes to about 100 minutes, preferably from about 20 to about 100 minutes. Stoichiometric quantities of all reactants will be used in each step.
• Ethers such as glyme, diethylether, dimethoxybenzene, or tetramethylene ethylenediamine are added before the second coupling step to accelerate the reaction between the last halogen on each silicon atom and the terminal functional group on the second polymeric arms. Stoichiometric quantities of all reactants are used in each step.
• an asymmetric radial polymer within the scope of the present invention containing, on average, three homopolymer arms and one block copolymer arm was prepared.
• the homopolymer arm was a polybutadiene having a weight-average molecular weight of 44,800.
• the block copolymer was a block copolymer comprising a single polystyrene block having a weight-average molecular weight of 18,000 and a single polybutadiene block having a weight-average molecular weight of 41,600.
• a sufficient amount of a living polybutadiene polymer to provide three moles of living polymer per mole of silicon tetrachloride was contacted with silicon tetrachloride at a temperature of 60° C. and at ambient pressure.
• the living polymer was dissolved in cyclohexane at a concentration of 12 wt % of polybutadiene and the contacting was accomplished by adding the silicon tetrachloride to the polymer solution. The contacting was maintained for 30 minutes with mild agitation.
• the method of this invention more than doubled the amount of polymer produced having the desired ratio of arms; viz., three homopolymer arms and one copolymer arm (86% vs. 42%).
• the method of this invention resulted in a product containing only 5% of polymer molecules having two or more copolymer arms while the prior art method results in a product containing greater than 26% of polymer molecules having two or more copolymer arms. It is important, particularly in some impact modification end uses, that polymers containing two or more copolymer arms be minimized.
• the method of the present invention is, then, quite effective in narrowing the relative distribution of the arms in the asymmetric radial polymer produced.
• an asymmetric radial polymer within the scope of the present invention containing two isoprene homopolymer arms and two styrene-butadiene block copolymer arms was prepared.
• the polyisoprene arms had a weight-average molecular weight of 18,000.
• the block copolymer arms had a polystyrene block weight-average molecular weight of 10,400 and a polybutadiene block weight-average molecular weight of 24000.
• a sufficient amount of a living isoprene homopolymer to provide two moles of living polymer per mole of silicon tetrachloride was contacted with silicon tetrachloride at a temperature of 60° C.
• the living polymer was dissolved in cyclohexane at a concentration of 20 wt % of polyisoprene and the contacting was accomplished by adding the silicon tetrachloride to the polymer solution. The contacting was maintained for 60 minutes with mild agitation.
• a styrene-butadiene block copolymer was synthesized in the presence of 6% diethylether on a total solution basis which resulted in a 41% 1,2-butadiene content as determined by 1H NMR analysis.
• the asymmetric radial polymer was then partially hydrogenated using a nickel-aluminum catalyst under conditions that do not hydrogenate aromatic double bonds and will preferentially hydrogenate polybutadiene double bonds rather than polyisoprene double bonds.
• an asymmetric radial polymer within the scope of the present invention containing two isoprene homopolymer arms and two styrene-isoprene block copolymer arms was prepared according to the procedure of Example 2 with the following changes.
• the isoprene homopolymer arms had a weight-average molecular weight of 9,200.
• the styrene-isoprene block copolymer arms had a polystyrene block weight-average molecular weight of 6,300 and a polyisoprene block weight-average molecular weight of 22,000.
• the living polyisoprene was contacted with the silicon tetrachloride at 25° C. for 60 minutes.
• a sufficient amount of living styrene-isoprene block polymer was added to the solution to provide two moles of block polymer per mole of silicon tetrachloride. After reaction of the block polymer and the coupling agent was complete, the asymmetric radial polymer was recovered.
• the asymmetric radial polymer was fully hydrogenated using a nickel-aluminum catalyst under conditions that do not hydrogenate aromatic double bonds and will hydrogenate the polyisoprene double bonds.
• an asymmetric radial polymer within the scope of the present invention containing two isoprene homopolymer arms and two styrene-butadiene block copolymer arms was prepared according to the procedure of Example 2 with the following changes.
• the polyisoprene arms had a weight-average molecular weight of 18,400.
• the styrene-butadiene block copolymer arms had a polystyrene block weight-average molecular weight of 5,500 and a polybutadiene block weight-average molecular weight of 19,400.
• the living polyisoprene was contacted with the silicon tetrachloride at 25° C. for 60 minutes.
• the second coupling step was conducted at 70° C. for 60 minutes in the presence of 300 ppm glyme on a total solution basis. After reaction of the block polymer and the coupling agent was complete, the asymmetric radial polymer was recovered. The 1,2-butadiene content of the resulting polymer was 39.6% as determined by 1 H NMR analysis.
• Example 2 A portion of this asymmetric radial polymer was partially hydrogenated as indicated in Example 2 and another portion was fully hydrogenated as indicated in Example 3.
• an asymmetric radial polymer within the scope of the present invention containing two isoprene homopolymer arms and two styrene-butadiene block copolymer arms was prepared according to the procedure of Example 2 with the following changes.
• the polyisoprene arms had a weight-average molecular weight of 19,600.
• the styrene-butadiene block copolymer arms had a polystyrene block weight-average molecular weight of 5,800 and a polybutadiene block weight-average molecular weight of 21,500.
• the second coupling step was conducted at 70° C. for 60 minutes. After reaction of the block polymer and the coupling agent was complete, the asymmetric radial polymer was recovered.
• the 1,2-butadiene content of the resulting polymer was 40% as determined by 1 H NMR analysis.
• Example 2 A portion of this asymmetric radial polymer was partially hydrogenated as indicated in Example 2 and another portion was fully hydrogenated as indicated in Example 3.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Graft Or Block Polymers (AREA)

Priority Applications (4)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22531009

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (8)

Citations (18)

• 1993
  • 1993-11-09 US US08/149,596 patent/USH1464H/en not_active Abandoned
• 1994
  • 1994-11-03 EP EP94203208A patent/EP0653453A1/en not_active Ceased
  • 1994-11-07 JP JP6272346A patent/JPH07188360A/ja active Pending
  • 1994-11-07 BR BR9404367A patent/BR9404367A/pt not_active Application Discontinuation

Patent Citations (20)

Also Published As

Similar Documents

Legal Events