CN108079982B - Modified silica gel filler, preparation method and application - Google Patents
Modified silica gel filler, preparation method and application Download PDFInfo
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Abstract
The invention relates to a modified silica gel filler, which comprises particles with the following structures: the silica gel microsphere is grafted with a functional group, and a polymer coating layer at least formed on the surface of the silica gel microsphere; the polymer is bonded with silicon hydroxyl on the surface of the silica gel microsphere. According to the invention, the silica gel particles are endowed with functionality by grafting functional groups on the surfaces of the silica gel particles, and the polymerized monomer groups are polymerized by grafting the polymerized monomer groups on the surfaces of the silica gel particles to obtain the polymer coating layer coated on the surfaces of the silica gel particles, so that the polymer coating layer can well coat the silica gel particles, prevent alkali liquor from reacting with silicon hydroxyl groups on the surfaces of the silica gel particles, and improve the alkali resistance and corrosion resistance of the silica gel particles.
Description
Technical Field
The invention belongs to the field of silica gel fillers, and particularly relates to a modified silica gel filler, a preparation method and application thereof.
Background
Silica gel-based packing materials are commonly used in HPLC (high performance liquid chromatography) and solid phase extraction. The porous silica gel can be prepared into various particle sizes (such as 5 μm, 3 μm and 2 μm) with narrow particle size distribution and various pore sizes (such as 8nm, 30nm and 100nm), and is suitable for analysis of small molecules and large molecules. Most silica gel has good mechanical tension, can be filled into a stable and efficient packed bed, does not deform under long-term high-pressure operation, has lower back pressure and has long service life of the column. The silica gel-based packed column has the outstanding advantage of higher column efficiency than columns made of other materials.
The silica gel surface can be chemically modified to prepare a bonding phase with various functional groups. Water and organic solvents can be used as the mobile phase, and the silica gel filler does not undergo a volume change (e.g., swelling) when the solvent is changed. Thus, the packed bed remains stable during different solvents encountered and gradient elution.
But silica gel will dissolve at high pH. The silica gel surface contains various silanol groups, is acidic, and is strongly combined with alkaline solute when alkaline compounds (such as amines) are separated, so that the alkaline compounds are kept increased, widened and trailing.
There is a need in the art to develop a silica gel filler with a high pH adaptation breadth that has good stability in alkaline, acidic environments.
Disclosure of Invention
In view of the deficiencies of the prior art, it is an object of the present invention to provide a modified silica gel filler comprising particles having the structure:
the silica gel microsphere is grafted with a functional group, and a polymer coating layer at least formed on the surface of the silica gel microsphere;
the polymer is bonded with silicon hydroxyl on the surface of the silica gel microsphere.
According to the modified silica gel filler provided by the invention, the polymer coating layer is used for protecting the silanol groups on the surface of the silica gel, so that the silica gel filler can be kept stable and does not react in a harsh environment, and the stability of the modified silica gel filler is improved. The partial structure schematic diagram of the surface of the modified silica gel filler provided by the invention is shown in figure 1. As can be seen from fig. 1, the polymer layer can protect the surface of the silica gel from being damaged by acid or alkali, maintain the stability of the silica gel, and simultaneously, the functional groups are exposed outside the polymer layer for functional function.
Preferably, the functional group comprises a substituted or unsubstituted C4-C30 alkyl group, such as any 1 or a combination of at least 2 of pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, pentadecyl, octadecanyl, docosyl, and pentadecyl.
Preferably, the substituent of the substituted C4-C30 alkyl group includes any 1 or a combination of at least 2 of epoxy, heterocycloalkyl, aryl, heteroaryl, amino, nitro, sulfo, and carbonyl groups.
Illustratively, the functional group can be n-octyl, n-octadecyl, or,
And the like.
Preferably, the main chain of the polymer is of a polyolefin structure, preferably a polyethylene structure.
The main chain of the polymer is a polyolefin structure, and the main chain of the polymer can be explained as polymerized olefin, namely, the polymer obtained by copolymerization and homopolymerization of substituted or unsubstituted olefin serving as a polymerization monomer.
Preferably, the polymer is bonded to the silicon atoms of the silica gel microspheres through grafted-Y-Si-O-bonds.
Preferably, the Y comprises any 1 of C1-C30 alkylene groups, preferably any 1 of methylene, ethyl, n-propyl, n-butyl and n-pentyl groups.
The polymer main chain is of a polyolefin structure, a branched chain (-Y-Si-O-) is grafted on the main chain, and the branched chain is connected with the silica gel microsphere, wherein Y is one end of the main chain of the grafted polymer, and O is a bond and one end of silicon.
Preferably, the acid and alkali resistance range of the modified silica gel filler is 2-12, such as 3, 4, 5, 6, 7, 8, 9, 10, 11, etc.
The second purpose of the invention is to provide a preparation method of the modified silica gel filler, which comprises the following steps:
(1) carrying out surface activation on the silica gel microspheres to obtain surface-activated silica gel microspheres;
(2) introducing a functional group and then introducing a polymerized monomer group or simultaneously introducing the functional group and the polymerized monomer group on the surface-activated silica gel microsphere to obtain a functionalized silica gel microsphere;
(3) polymerizing the polymerized monomer group of the functionalized silica gel microsphere to form a polymer coating layer, thus obtaining the modified silica gel filler.
The functional groups and the polymeric monomer groups are introduced into the surface of the silica gel microspheres, and then the polymeric monomer groups are polymerized to obtain the modified silica gel microspheres coated with the polymer layer and grafted with the functional groups.
Preferably, the average particle size of the silica gel microsphere particles is 1.7-50 μm, such as 3.0 μm, 5.0 μm, 6.0 μm, 10.0 μm, 15.0 μm, 20.0 μm, 30.0 μm, 40.0 μm, 50.0 μm, and the like.
Preferably, the average pore diameter inside the silica gel microsphere particles is within the range of 100-1000 angstroms (e.g., 100 angstroms, 120 angstroms, 200 angstroms, 300 angstroms, 500 angstroms, 800 angstroms, 1000 angstroms, etc.).
Preferably, the average specific surface area of the silica gel microsphere particles is 30-600 m2G, e.g. 30m2/g、 100m2/g、150m2/g、200m2/g、250m2/g、300m2/g、350m2/g、400m2/g、450m2/g、 500m2/g、550m2/g、600m2And/g, etc.
Preferably, the surface activation comprises acid activation, preferably hydrochloric acid activation.
The surface activation can enable the surface of the silica gel particles to form more oxidizing groups, so that the subsequent grafting (including grafting functional groups and polymerizing monomer groups) is facilitated.
Preferably, the specific steps of surface activation are:
and soaking the silica gel microspheres in a hydrochloric acid solution to perform surface activation.
Alternatively, the silica gel microspheres may be refluxed when immersed in a hydrochloric acid solution for surface activation.
Preferably, the concentration of the hydrochloric acid solution is 8 to 15 wt%, such as 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, etc.
Preferably, the time for activating the surface is 5-8 h, such as 6h, 7h and the like.
Preferably, the step of introducing a functional group is: the functional group is introduced by a first silylating agent.
Preferably, the step of introducing a polymerized monomer group is: the polymeric monomer groups are introduced by a second silylating agent.
Since most of the silanization reagents are easy to hydrolyze, the introduction of functional groups and the introduction of polymeric monomer groups should be carried out in an anhydrous environment as much as possible in order to ensure that corresponding groups can be grafted.
Preferably, the steps of introducing functional groups and introducing groups of polymerized monomers are performed sequentially or simultaneously.
The step of introducing the functional group and the step of introducing the polymeric monomer group are sequentially carried out, namely the functional group is introduced firstly, and then the polymeric monomer group is introduced; the step of introducing the functional group and the step of introducing the polymeric monomer group are performed simultaneously means that the functional group and the polymeric monomer group are introduced simultaneously.
Preferably, the first and second silylating agents are each independently selected from any 1 or a combination of at least 2 of monofunctional, difunctional and trifunctional silane compounds.
The silicon atom itself may be bonded with 4 groups, a monofunctional silane compound if only 1 group is bonded, a bifunctional silane compound if 2 groups are bonded, and a trifunctional silane compound if 3 groups are bonded.
Preferably, the silicon atom of the first silylating agent is grafted with at least one leaving group and at least one functional group.
Preferably, the silicon atom of the second silane agent is grafted with at least one leaving group and at least one polymerized monomer group.
The silanization reagent is not specifically limited as long as the requirement of valence is met, and specifically, a plurality of leaving groups, a plurality of functional groups and a plurality of polymeric monomer groups are grafted on the silanization reagent.
The leaving group is a group which can form a free electron by bond breaking with a silicon atom, and the free electron formed after leaving of the leaving group is bonded to another pair of free electrons to graft the leaving group-removed silylation reagent on a target.
Preferably, the leaving groups in the first and second silylating agents are the same or different.
Preferably, the leaving group comprises any 1 of a halogen atom, a methoxy group, and an ethoxy group.
Preferably, the functional group comprises a substituted or unsubstituted C4-C30 alkyl group.
Preferably, the substituent of the substituted C4-C30 alkyl group includes any 1 or a combination of at least 2 of epoxy, heterocycloalkyl, aryl, heteroaryl, amino, nitro, sulfo, and carbonyl groups.
Preferably, the polymerized monomer group comprises a group having a double bond, preferably any 1 or a combination of at least 2 of vinyl, propenyl, allyl.
Preferably, the first silylating agent comprises
Any 1 or a combination of at least 2 of them.
Preferably, the second silylating agent comprises
CH2＝CH—SiCl3、CH2＝CHSi(OC2H5)3、
Any 1 or a combination of at least 2 of them.
Preferably, the polymerization in step (3) comprises the following specific steps: adding a polymerization monomer and a free radical initiator into the reaction liquid to initiate double bond polymerization;
the double bond polymerization can occur between the polymerized monomer groups grafted on the silica gel and between the polymerized monomer groups and the polymerized monomers added independently, and the random combination can increase the length of the main chain of the polymer, so that the polymer can better coat the silica gel particles, protect the silicon hydroxyl groups of the silica gel particles, and endow the silica gel particles with better alkali resistance and stability.
Preferably, the radical initiator comprises any 1 of 4,4' -azobis (cyanovaleric acid), azobisisobutyronitrile, benzoyl peroxide.
Preferably, the polymerized monomer comprises any 1 or a combination of at least 2 of styrene, divinylbenzene, allylbenzene, diallylbenzene.
It is a further object of the present invention to provide the use of a modified silica gel packing according to one of the objects for chromatographic separations, preferably for liquid chromatographic separations, further preferably for high performance liquid chromatographic separations.
Preferably, the modified silica gel packing is used as a stationary phase for chromatographic separation.
Preferably, in the chromatographic separation process, the pH value of the mobile phase is 2-12.
Compared with the prior art, the invention has the following beneficial effects:
compared with the prior art, the invention has the following beneficial effects:
according to the invention, the silica gel particles are endowed with functionality by grafting functional groups on the surfaces of the silica gel particles, and the polymerized monomer groups are grafted and polymerized on the surfaces of the silica gel particles to obtain the polymer coating layer coated on the surfaces of the silica gel particles, so that the polymer coating layer can well coat the silica gel particles, prevent alkali liquor from reacting with silicon hydroxyl on the surfaces of the silica gel particles, improve the alkali resistance and corrosion resistance of the silica gel particles, and obviously prolong the service life of a chromatographic column, especially when alkaline substances are separated or target substances are separated by using an alkaline solution.
Drawings
Fig. 1 is a schematic view of a partial structure of the surface of the modified silica gel filler provided by the invention, as shown in fig. 1.
In fig. 1, 1 is a silica gel particle, 2 is a functional group, and 3 is a polymer coating layer;
FIG. 2 is a chromatogram given in application example 1.
Detailed Description
For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
A preparation method of a modified silica gel filler comprises the following steps:
(1) surface activation of silica gel microspheres
20g of 5 μm silica gel (average pore diameter 12nm, average specific surface area about 400 m)2/g) immersing in 200mL of 10 v% hydrochloric acid, stirring to prevent the silica gel from settling, and heating in an oil bath until the hydrochloric acid is subjected to reflux treatment for 7h for acid activation; after the acid activation product is subjected to suction filtration, washing filter residues with water until the pH value of a washing liquid is 6-7, and drying in an oven at 100-110 ℃ to obtain surface activated silica gel particles;
(2) introduction of functional groups
Heating the surface activated silica gel particles to 100 ℃, preserving heat for 2 hours, drying at normal pressure, heating to 150-180 ℃ under the environment pressure of 5mmHg, and keeping for 4-10 hours for vacuum drying; and then cooling to room temperature, adding 0.04mol of silylation reagent octadecyl trichlorosilane and 200mL of toluene solution in nitrogen atmosphere under anhydrous condition, heating and refluxing for 24-48 h, filtering after the reaction is finished, washing filter residues with toluene, acetone and methanol, placing the washed solid in a Soxhlet extractor, extracting for 24h with acetone, washing and drying to obtain the silica gel particles with the introduced functional groups.
(3) Introduction of polymeric monomer groups
In nitrogen atmosphere, adding 200mL of anhydrous toluene and 0.04mol of silylation reagent vinyl triethoxysilane into silica gel particles introduced with functional groups, mechanically stirring, and carrying out reflux reaction at 110 ℃ for 12 h; and after the reaction is finished, carrying out suction filtration, transferring filter residues into a Soxhlet extractor, extracting for 10h by using absolute ethyl alcohol, and finally carrying out vacuum drying for 48h at 50 ℃ to obtain the silica gel particles bonded with the functional groups and the vinyl at the same time.
(4) Formation of polymer coating
In the nitrogen atmosphere, adding the silica gel particles bonded with the functional groups and the vinyl at the same time into a three-necked bottle, sequentially adding 200mL of acetonitrile, 40mL of n-hexanol, 10mL of styrene and 84mg of azodiisobutyronitrile, mechanically stirring, introducing nitrogen for protection, and carrying out reflux reaction at 80 ℃ for 12 hours; and after the reaction is finished, washing the product with methanol, washing the product with acetonitrile for multiple times, performing suction filtration, performing Soxhlet extraction on filter residues respectively with acetonitrile and acetone for 10h, and performing vacuum drying at 50 ℃ for 48h to obtain the modified silica gel filler.
The modified silica gel filler was subjected to thermogravimetric analysis (TGA) testing to give a carbon content of 31 wt%.
Example 2
A preparation method of a modified silica gel filler comprises the following steps:
(1) surface activation of silica gel microspheres
20g of 10 μm silica gel (average pore diameter 100nm, average specific surface area about 30 m)2/g) immersing in 200mL of 15 v% hydrochloric acid, stirring to prevent the silica gel from settling, and heating in an oil bath until the hydrochloric acid is subjected to reflux treatment for 8h to perform acid activation; after the acid activation product is subjected to suction filtration, washing filter residues with water until the pH value of a washing liquid is 6-7, and drying in an oven at 100-110 ℃ to obtain surface activated silica gel particles;
(2) introduction of functional groups
Heating the surface activated silica gel particles to 100 ℃, preserving heat for 2 hours, drying at normal pressure, heating to 150-180 ℃ under the environment pressure of 5mmHg, and keeping for 4-10 hours for vacuum drying; then cooling to room temperature, adding 0.01mol of silanization reagent under anhydrous condition and nitrogen atmosphere
And heating and refluxing the mixture and 200mL of toluene solution for 24-48 h, filtering after the reaction is finished, washing filter residues with toluene, acetone and methanol, placing the washed solid in a Soxhlet extractor, extracting with acetone for 24h, washing and drying to obtain the silica gel particles with the introduced functional groups.
(3) Introduction of polymeric monomer groups
Adding the silica gel particles introduced with the functional groups into 200mL of anhydrous toluene and 0.01mol of silanization reagent in nitrogen atmosphere
Mechanically stirring, and carrying out reflux reaction at 110 ℃ for 12 h; after the reaction is finished, carrying out suction filtration, transferring filter residue into a Soxhlet extractor, extracting for 10h by using absolute ethyl alcohol, and finally carrying out vacuum drying for 48h at 50 ℃ to obtain the product with functional groups bonded at the same timeAnd vinyl silica gel particles.
(4) Formation of polymer coating
In the nitrogen atmosphere, adding the silica gel particles bonded with the functional groups and the vinyl at the same time into a three-necked bottle, sequentially adding 200mL of acetonitrile, 40mL of n-hexanol, 10mL of styrene and 84mg of azodiisobutyronitrile, mechanically stirring, introducing nitrogen for protection, and carrying out reflux reaction at 80 ℃ for 12 hours; and after the reaction is finished, washing the product with methanol, washing the product with acetonitrile for multiple times, performing suction filtration, performing Soxhlet extraction on filter residues respectively with acetonitrile and acetone for 10h, and performing vacuum drying at 50 ℃ for 48h to obtain the modified silica gel filler.
The modified silica gel filler was subjected to TGA testing to give a carbon content of 15 wt%.
Example 3
A preparation method of a modified silica gel filler comprises the following steps:
(1) surface activation of silica gel microspheres
20g of 1.7 μm silica gel (average pore diameter 10nm, average specific surface area about 600 m)2/g) immersing in 200mL of 8 v% hydrochloric acid, stirring to prevent the silica gel from settling, and heating in an oil bath until the hydrochloric acid is subjected to reflux treatment for 5h to perform acid activation; after the acid activation product is subjected to suction filtration, washing filter residues with water until the pH value of a washing liquid is 6-7, and drying in an oven at 100-110 ℃ to obtain surface activated silica gel particles;
(2) introduction of functional groups
Heating the surface activated silica gel particles to 100 ℃, preserving heat for 2 hours, drying at normal pressure, heating to 150-180 ℃ under the environment pressure of 5mmHg, and keeping for 4-10 hours for vacuum drying; then cooling to room temperature, adding 0.05mol of silanization reagent under anhydrous condition and nitrogen atmosphere
And heating and refluxing the mixture and 200mL of toluene solution for 24-48 h, filtering after the reaction is finished, washing filter residues with toluene, acetone and methanol, placing the washed solid in a Soxhlet extractor, extracting with acetone for 24h, washing and drying to obtain the silica gel particles with the introduced functional groups.
(3) Introduction of polymeric monomer groups
Adding the silica gel particles introduced with the functional groups into 200mL of anhydrous toluene and 0.05mol of silanization reagent in nitrogen atmosphere
Mechanically stirring, and carrying out reflux reaction at 110 ℃ for 12 h; and after the reaction is finished, carrying out suction filtration, transferring filter residues into a Soxhlet extractor, extracting for 10h by using absolute ethyl alcohol, and finally carrying out vacuum drying for 48h at 50 ℃ to obtain the silica gel particles bonded with the functional groups and the vinyl at the same time.
(4) Formation of polymer coating
In the nitrogen atmosphere, adding the silica gel particles bonded with the functional groups and the vinyl at the same time into a three-necked bottle, sequentially adding 200mL of acetonitrile, 40mL of n-hexanol, 10mL of styrene and 84mg of azodiisobutyronitrile, mechanically stirring, introducing nitrogen for protection, and carrying out reflux reaction at 80 ℃ for 12 hours; and after the reaction is finished, washing the product with methanol, washing the product with acetonitrile for multiple times, performing suction filtration, performing Soxhlet extraction on filter residues respectively with acetonitrile and acetone for 10h, and performing vacuum drying at 50 ℃ for 48h to obtain the modified silica gel filler.
The modified silica gel filler was subjected to TGA testing to give a carbon content of 34 wt%.
Example 4
A preparation method of a modified silica gel filler comprises the following steps:
(1) surface activation of silica gel microspheres
20g of 50 μm silica gel (average pore diameter 30nm, average specific surface area about 150 m)2/g) immersing in 200mL of 8 v% hydrochloric acid, stirring to prevent the silica gel from settling, and heating in an oil bath until the hydrochloric acid is subjected to reflux treatment for 5h to perform acid activation; after the acid activation product is subjected to suction filtration, washing filter residues with water until the pH value of a washing liquid is 6-7, and drying in an oven at 100-110 ℃ to obtain surface activated silica gel particles;
(2) introduction of functional groups
Heating the surface activated silica gel particles to 100 ℃, preserving heat for 2 hours, drying at normal pressure, heating to 150-180 ℃ under the environment pressure of 5mmHg, and keeping for 4-10 hours for vacuum drying; then cooling to room temperature, under anhydrous condition, nitrogen atmosphereIn the enclosure, 0.02mol of silanization reagent is added
And heating and refluxing the mixture and 200mL of toluene solution for 24-48 h, filtering after the reaction is finished, washing filter residues with toluene, acetone and methanol, placing the washed solid in a Soxhlet extractor, extracting with acetone for 24h, washing and drying to obtain the silica gel particles with the introduced functional groups.
(3) Introduction of polymeric monomer groups
Adding the silica gel particles introduced with the functional groups into 200mL of anhydrous toluene and 0.02mol of silanization reagent in nitrogen atmosphere
Mechanically stirring, and carrying out reflux reaction at 110 ℃ for 12 h; and after the reaction is finished, carrying out suction filtration, transferring filter residues into a Soxhlet extractor, extracting for 10h by using absolute ethyl alcohol, and finally carrying out vacuum drying for 48h at 50 ℃ to obtain the silica gel particles bonded with the functional groups and the vinyl at the same time.
(4) Formation of polymer coating
In the nitrogen atmosphere, adding the silica gel particles bonded with the functional groups and the vinyl at the same time into a three-necked bottle, sequentially adding 200mL of acetonitrile, 40mL of n-hexanol, 10mL of styrene and 84mg of azodiisobutyronitrile, mechanically stirring, introducing nitrogen for protection, and carrying out reflux reaction at 80 ℃ for 12 hours; and after the reaction is finished, washing the product with methanol, washing the product with acetonitrile for multiple times, performing suction filtration, performing Soxhlet extraction on filter residues respectively with acetonitrile and acetone for 10h, and performing vacuum drying at 50 ℃ for 48h to obtain the modified silica gel filler.
The modified silica gel filler was subjected to TGA testing to give a carbon content of 19.2 wt%.
Example 5
The difference from example 1 is that no styrene is added in step (4).
The modified silica gel filler was subjected to TGA testing to give a carbon content of 16 wt%.
Example 6
A preparation method of a modified silica gel filler does not carry out a surface activation step, and specifically comprises the following steps:
(1) introduction of functional groups
20g of 5 μm silica gel (average pore diameter 12nm, average specific surface area about 400 m)2Heating the particles to 100 ℃, preserving heat for 2 hours, drying at normal pressure, heating to 150-180 ℃ under the environment pressure of 5mmHg, and keeping the temperature for 4-10 hours for vacuum drying; and then cooling to room temperature, adding 0.04mol of silylation reagent octadecyl trichlorosilane and 200mL of toluene solution in nitrogen atmosphere under anhydrous condition, heating and refluxing for 24-48 h, filtering after the reaction is finished, washing filter residues with toluene, acetone and methanol, placing the washed solid in a Soxhlet extractor, extracting for 24h with acetone, washing and drying to obtain the silica gel particles with the introduced functional groups.
(3) Introduction of polymeric monomer groups
In nitrogen atmosphere, adding 200mL of anhydrous toluene and 0.04mol of silylation reagent vinyl triethoxysilane into silica gel particles introduced with functional groups, mechanically stirring, and carrying out reflux reaction at 110 ℃ for 12 h; and after the reaction is finished, carrying out suction filtration, transferring filter residues into a Soxhlet extractor, extracting for 10h by using absolute ethyl alcohol, and finally carrying out vacuum drying for 48h at 50 ℃ to obtain the silica gel particles bonded with the functional groups and the vinyl at the same time.
(4) Formation of polymer coating
In the nitrogen atmosphere, adding the silica gel particles bonded with the functional groups and the vinyl at the same time into a three-necked bottle, sequentially adding 200mL of acetonitrile, 40mL of n-hexanol, 10mL of styrene and 84mg of azodiisobutyronitrile, mechanically stirring, introducing nitrogen for protection, and carrying out reflux reaction at 80 ℃ for 12 hours; and after the reaction is finished, washing the product with methanol, washing the product with acetonitrile for multiple times, performing suction filtration, performing Soxhlet extraction on filter residues respectively with acetonitrile and acetone for 10h, and performing vacuum drying at 50 ℃ for 48h to obtain the modified silica gel filler.
The modified silica gel filler was subjected to TGA testing to give it a carbon content of 24 wt%.
Comparative example 1
A preparation method of a modified silica gel filler does not introduce a polymerized monomer group and form a polymer wrapping material, and specifically comprises the following steps:
(1) surface activation of silica gel microspheres
20g of 5 μm silica gel (average pore diameter 12nm, average specific surface area about 400 m)2/g) immersing in 200mL of 10 v% hydrochloric acid, stirring to prevent the silica gel from settling, and heating in an oil bath until the hydrochloric acid is subjected to reflux treatment for 7h for acid activation; after the acid activation product is subjected to suction filtration, washing filter residues with water until the pH value of a washing liquid is 6-7, and drying in an oven at 100-110 ℃ to obtain surface activated silica gel particles;
(2) introduction of functional groups
Heating the surface activated silica gel particles to 100 ℃, preserving heat for 2 hours, drying at normal pressure, heating to 150-180 ℃ under the environment pressure of 5mmHg, and keeping for 4-10 hours for vacuum drying; and then cooling to room temperature, adding 0.04mol of silylation reagent octadecyl trichlorosilane and 200mL of toluene solution in nitrogen atmosphere under anhydrous condition, heating and refluxing for 24-48 h, filtering after the reaction is finished, washing filter residues with toluene, acetone and methanol, placing the washed solid in a Soxhlet extractor, extracting for 24h with acetone, washing and drying to obtain the silica gel particles with the introduced functional groups.
The silica gel particles into which the functional group was introduced were subjected to TGA test to obtain a carbon content of 18.7 wt%.
Comparative example 2
A preparation method of a modified silica gel filler comprises the following steps:
(1) surface activation of silica gel microspheres
20g of 5 μm silica gel (average pore diameter 12nm, average specific surface area about 400 m)2/g) immersing in 200mL of 10 v% hydrochloric acid, stirring to prevent the silica gel from settling, and heating in an oil bath until the hydrochloric acid is subjected to reflux treatment for 7h for acid activation; after the acid activation product is subjected to suction filtration, washing filter residues with water until the pH value of a washing liquid is 6-7, and drying in an oven at 100-110 ℃ to obtain surface activated silica gel particles;
(2) introduction of functional groups
Heating the surface activated silica gel particles to 100 ℃, preserving heat for 2 hours, drying at normal pressure, heating to 150-180 ℃ under the environment pressure of 5mmHg, and keeping for 4-10 hours for vacuum drying; and then cooling to room temperature, adding 0.04mol of silylation reagent octadecyl trichlorosilane and 200mL of toluene solution in nitrogen atmosphere under anhydrous condition, heating and refluxing for 24-48 h, filtering after the reaction is finished, washing filter residues with toluene, acetone and methanol, placing the washed solid in a Soxhlet extractor, extracting for 24h with acetone, washing and drying to obtain the silica gel particles with the introduced functional groups.
(3) Encapsulation of polymers
In a nitrogen atmosphere, adding the silica gel particles introduced with the functional groups into a three-necked bottle, sequentially adding 200mL of acetonitrile, 40mL of n-hexanol, 10mL of styrene and 84mg of azodiisobutyronitrile, mechanically stirring, introducing nitrogen for protection, and carrying out reflux reaction at 80 ℃ for 12 hours; and after the reaction is finished, washing the product with methanol, washing the product with acetonitrile for multiple times, performing suction filtration, performing Soxhlet extraction on filter residues respectively with acetonitrile and acetone for 10h, and performing vacuum drying at 50 ℃ for 48h to obtain the modified silica gel filler.
The modified silica gel filler was subjected to TGA testing to give a carbon content of 27 wt%.
And (3) performance testing:
(1) and (3) chromatographic performance test:
the test method comprises the following steps:
(i) the chromatographic packing prepared in the above examples and comparative examples was packed into a 4.6X 250mm size column, setting the flow rate at 1.0 ml/min; taking toluene as a sample to be tested, testing the initial theoretical plate number of the sample, and recording the initial theoretical plate number as N0(ii) a Theoretical plate number 5.54 × (toluene peak retention time/toluene peak width at half height)2；
(ii) Repeatedly washing the packed chromatographic column with 0.1mol/L sodium hydroxide/methanol solution, and re-testing the theoretical plate number of the chromatographic column after each washing for 0.5 hour under the same condition, wherein the theoretical plate number after the jth washing is NjJ is a positive integer of 100 or less;
(iii) record (N)0-Nj)/N0The frequency is more than or equal to 10 percent; the higher the value of the obtained times, the better the chromatographic performance, the better the product stability and the stronger the alkali resistance.
The results of the performance tests are shown in Table 1.
TABLE 1
| Sample (I) | Chromatographic Properties |
| Example 1 | ≥100 |
| Example 2 | ≥100 |
| Example 3 | ≥100 |
| Example 4 | ≥100 |
| Example 5 | 89 |
| Example 6 | ≥100 |
| Comparative example 1 | 48 |
| Comparative example 2 | 70 |
As can be seen from table 1, the modified silica gel filler provided by the present invention protects the silanol groups on the silica gel surface through the polymer coating layer, so that the modified silica gel filler can be kept stable without reaction in a harsh environment, the stability of the modified silica gel filler is improved, the service life of the chromatographic column is significantly improved, and especially when an alkaline substance is separated or a target substance is separated by an alkaline solution. As can be seen from the comparison between the embodiment 1 and the comparative example 1, the chromatographic column filled with the filler has higher theoretical plate number for separating substances under alkaline conditions, has stronger alkali resistance, and can effectively maintain the stability of silica gel particles in alkaline environment after the surface of the chromatographic column is coated with a polymer layer; compared with comparative example 2, the filler-filled chromatographic column provided by the invention has higher theoretical plate number for separation of substances under alkaline conditions, presumably because the grafting of the surface-coated polymer layer on the surface of silica gel can firmly bond silica gel particles with the polymer to play a coating role.
Application example 1
The column (4.6 mm. times.250 mm) was packed with the chromatography packing prepared in example 1, and the basic substance was separated at a flow rate: 0.7mL/min, column temperature: 30 ℃, detection wavelength: 260 nm;
the mobile phase is as follows: 20mM formic acid ammonium formate (pH 3.5), B20 mM formic acid ammonium formate (pH 3.5), methanol 9: 1;
gradient elution: (0-5min) 30% B, (5-13min) 30% -100% B, (13-30min) 100% B;
the sample is a mixture of ① Cytosine, ② Uracil Uracil, ③ Guanine, ④ Hypoxanthine, ⑤ Uridine, ⑥ Thymine Thymine, ⑦ Guanine nucleoside Guanosine, ⑧ Adenosine Adenosine.
FIG. 2 is a chromatogram given in application example 1.
The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (32)
1. A modified silica gel filler, comprising particles having the structure:
the silica gel microsphere is grafted with a functional group, and a polymer coating layer at least formed on the surface of the silica gel microsphere;
the polymer is bonded with the silicon hydroxyl on the surface of the silica gel microsphere;
the preparation method of the modified silica gel filler comprises the following steps:
(1) carrying out surface activation on the silica gel microspheres to obtain surface-activated silica gel microspheres;
(2) introducing a functional group and then introducing a polymerized monomer group or simultaneously introducing the functional group and the polymerized monomer group on the surface-activated silica gel microsphere to obtain a functionalized silica gel microsphere;
(3) polymerizing the polymerized monomer group of the functionalized silica gel microsphere to form a polymer coating layer, thereby obtaining the modified silica gel filler;
the step of introducing the functional group is as follows: introducing a functional group through a first silylating agent; the first silylating agent comprises
Any 1 or a combination of at least 2 of them.
2. The modified silica gel filler of claim 1 wherein the backbone of said polymer is a polyolefin structure.
3. The modified silica gel filler of claim 2 wherein the backbone of said polymer is of polyethylene structure.
4. The modified silica gel filler of claim 1 wherein said polymer is bonded to the silicon atoms of the silica gel microspheres by grafted-Y-Si-O-bonds.
5. The modified silica gel filler of claim 4, wherein Y comprises any 1 of C1 to C30 alkylene groups.
6. The modified silica gel filler of claim 5 wherein Y comprises any 1 of methylene, ethyl, n-propyl, n-butyl, n-pentyl.
7. The modified silica gel filler of claim 1, wherein the modified silica gel filler is acid and alkali resistant in the range of pH 2 to 12.
8. A process for the preparation of a modified silica gel filler according to any one of claims 1 to 7, characterised in that it comprises the following steps:
(1) carrying out surface activation on the silica gel microspheres to obtain surface-activated silica gel microspheres;
(2) introducing a functional group and then introducing a polymerized monomer group or simultaneously introducing the functional group and the polymerized monomer group on the surface-activated silica gel microsphere to obtain a functionalized silica gel microsphere;
(3) polymerizing the polymerized monomer group of the functionalized silica gel microsphere to form a polymer coating layer, thereby obtaining the modified silica gel filler;
the step of introducing the functional group is as follows: introducing a functional group through a first silylating agent comprising
Any 1 or a combination of at least 2 of them.
9. The method of claim 8, wherein the silica gel microsphere particles have an average particle size of 1.7 to 50 μm.
10. The method of claim 8, wherein the silica gel microsphere particles have an average pore size within the range of 100 to 1000 angstroms.
11. The method according to claim 8, wherein the silica gel microsphere particles have an average specific surface area of 30 to 600m2/g。
12. The method of claim 8, wherein the surface activation comprises acid activation.
13. The method of claim 12, wherein the surface activation is hydrochloric acid activation.
14. The method according to claim 8, wherein the surface activation comprises the following steps:
and soaking the silica gel microspheres in a hydrochloric acid solution to perform surface activation.
15. The method according to claim 14, wherein the hydrochloric acid solution has a concentration of 8 to 15 wt%.
16. The method of claim 14, wherein the surface activation time is 5 to 8 hours.
17. The method of claim 8, wherein the step of introducing a polymerized monomer group comprises: the polymeric monomer groups are introduced by a second silylating agent.
18. The method of claim 8, wherein the steps of introducing the functional group and introducing the polymerized monomer group are performed sequentially or simultaneously.
19. The method of claim 17, wherein the second silylating agent is selected from any 1 or a combination of at least 2 of monofunctional silane compounds, difunctional silane compounds, and trifunctional silane compounds.
20. The method of claim 19, wherein the silicon atom of the second silane agent is grafted with at least one leaving group and at least one polymeric monomer group.
21. The method of claim 20, wherein the leaving group comprises any 1 of a halogen atom, a methoxy group, and an ethoxy group.
22. The method of claim 8, wherein the polymerized monomer group comprises a group having a double bond.
23. The method of claim 22, wherein the polymeric monomer group comprises any 1 or a combination of at least 2 of vinyl, propenyl, allyl.
24. The method of claim 20, wherein the second silylating agent comprises
CH2＝CH—SiCl3、CH2＝CHSi(OC2H5)3、
Any 1 or a combination of at least 2 of them.
25. The method according to claim 8, wherein the polymerization in step (3) comprises the following steps: adding a polymerization monomer and a free radical initiator into the reaction liquid to initiate double bond polymerization.
26. The method of claim 25, wherein the radical initiator comprises any 1 of 4,4' -azobis (cyanovaleric acid), azobisisobutyronitrile, and benzoyl peroxide.
27. The method of claim 25, wherein the polymerized monomer comprises any 1 or a combination of at least 2 of styrene, divinylbenzene, allylbenzene, and diallylbenzene.
28. Use of a modified silica gel filler according to any one of claims 1 to 7 for chromatographic separations.
29. The use of claim 28, wherein the modified silica gel filler is used in liquid chromatography separations.
30. The use of claim 29, wherein the modified silica gel packing is used in high performance liquid chromatography separations.
31. Use according to claim 28, wherein the modified silica gel packing is used as a stationary phase for chromatographic separations.
32. The use according to claim 28, wherein the mobile phase has a pH of 2 to 12 during the chromatographic separation.
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