CN113024854A - Preparation method of gel material with controllable and regular structure - Google Patents

Abstract

The invention discloses a preparation method of a gel material with a controllable and regular structure, which comprises the following steps: s1, preparing a chain transfer agent; s2, adding a chain transfer agent, azodiisobutyronitrile, dimethylaminoethyl methacrylate and 1, 4-dioxane into a reaction container, vacuumizing, introducing nitrogen, and then placing in a constant-temperature oil bath at 70 ℃ for reacting for 6 hours; after the reaction is finished, exposing the reaction system to air, placing the reaction system in an ice bath, finally dialyzing and drying to obtain a chain polymer; s3, modifying the chain polymer by hydrazine hydrate; s4, dissolving the modified chain polymer and the cross-linking agent in dimethylformamide, adding a photoinitiator, introducing nitrogen to expel oxygen, and then performing light-induced reaction to form the mesh gel. The method can construct the reticular gel with controllable and regular structure and good mechanical property, and solves the problems of wide molecular weight distribution, uncontrollable molecular weight, irregular reticular structure and the like of the product.

Description

Preparation method of gel material with controllable and regular structure

Technical Field

The invention relates to the technical field of oilfield chemistry, in particular to a preparation method of a gel material with a controllable and regular structure.

Background

Conventional gels are typically random polymers made by free radical polymerization. Free radical polymerization itself has a number of disadvantages; the structure of the product is difficult to control, the double-base termination is easy, and side reactions such as chain transfer exist, so that the molecular weight distribution of the product is wide, and the molecular weight cannot be controlled due to the branched chain structure. The irregular structure of the polymer is likely to cause uneven stress under the action of external force, so that the gel is broken or damaged, and the mechanical property is very poor.

Hibom and the like firstly adopt click chemistry to prepare hydrogel of a three-dimensional network, prepare alkynyl functionalized PVA through catalysis of N-N carbonyl diimidazole, and then carry out click reaction on the alkynyl functionalized polyvinyl alcohol (PVA) and a, w azido-telechelic polyethylene glycol cross-linking agent to prepare a loose hydrogel network. However, the prepared hydrogel has poor mechanical properties and weak strength, and limits the practical clinical application.

In the prior art, raw materials for preparing the controllable gel comprise pentaerythritol, cyclodextrin, benzenediol, phenol and the like. Among them, the use of pentaerythritol as a raw material for the raft and click reactions allows the control of the molecular structure and is widely regarded. However, some problems faced by this method also severely restrict its practical application, the chain length and molecular weight of the prepared gel are not easy to control, and the measured value and the numerical value of the cross-linking density are different.

Disclosure of Invention

The invention aims to provide a preparation method of a gel material with a controllable and regular structure, aiming at the problems that the molecular weight of the existing polymer gel is not easy to control and the mechanical property of the gel is extremely poor.

The preparation method of the gel material provided by the invention comprises the following steps:

s1, preparing the chain transfer agent, comprising two substeps:

s11, adding butyl mercaptan, acetone, deionized water and a NaOH solution into a reaction container, stirring and dissolving, then dropwise adding carbon disulfide under an ice bath condition, uniformly stirring, adding 2-bromopropionic acid, stirring and reacting at room temperature for 24 hours, after the reaction is finished, carrying out reduced pressure distillation to remove redundant acetone, adding deionized water for dilution, then adding hydrochloric acid for acidification under an ice bath, continuing ice bath stirring until solid is separated out, filtering, washing and recrystallizing to finally obtain a purified chain transfer agent precursor, and storing at low temperature;

s12, dissolving the chain transfer agent precursor, ethylene glycol and 4-dimethylamino pyridine in anhydrous dichloromethane, then dropwise adding dicyclohexyl carbodiimide, and reacting for 24 hours at normal temperature to obtain the chain transfer agent.

S2, adding a chain transfer agent, azodiisobutyronitrile, dimethylaminoethyl methacrylate and 1, 4-dioxane into a reaction container, vacuumizing, introducing nitrogen, and then placing in a constant-temperature oil bath at 70 ℃ for reacting for 6 hours; and (3) after the reaction is finished, exposing the reaction system to air, placing the reaction system in an ice bath for several minutes to quickly cool the reaction system, and finally dialyzing and drying the reaction system to obtain the chain polymer.

S3, dissolving the chain polymer in dimethylformamide, adding hydrazine hydrate, stirring for reaction for 1 hour, and dialyzing, freezing and drying to obtain the modified chain polymer.

S4, dissolving the modified chain polymer and the cross-linking agent in dimethylformamide, adding a photoinitiator, introducing nitrogen to expel oxygen, and then performing light-induced reaction to form the mesh gel. In step S4, the photoinitiator is 1-hydroxy cyclohexyl phenyl ketone, and after nitrogen is introduced for 20min, the reaction is initiated by ultraviolet light irradiation for 2 hours under ultrasound to form the reticular gel.

The cross-linking agent is pentaerythritol (tetra) allyl ether. The preparation method of the cross-linking agent comprises the following steps: dissolving pentaerythritol and NaOH in tetrahydrofuran, stirring and heating until reflux, dropwise adding 3-bromopropylene, continuing reflux reaction for 16h after the dropwise adding is finished, and filtering after the reaction is finished to obtain a solid serving as a cross-linking agent.

Compared with the prior art, the invention has the advantages that:

the invention utilizes living radical polymerization to prepare 'net twine' with narrow molecular weight distribution and adjustable chain length, and then constructs the 'net twine' into a 'network' with controllable cross-linking points through a cross-linking agent, so as to synthesize the polymer gel material with the net structure with controllable distance between the cross-linking points and cross-linking density. The problems that the molecular weight distribution of the existing gel polymer is wide, the molecular weight cannot be controlled, the network structure is irregular and the like are solved, and the mechanical property of the gel is improved. The distance between the crosslinking points is the chain length of the chain polymer. The crosslinking density is controlled by the number of the end group reactive groups of the crosslinking agent and the end group reactive groups of the chain polymer.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 shows the structural formula and nuclear magnetic spectrum of the chain transfer agent precursor in example 1.

FIG. 2 shows the structural formula and nuclear magnetic spectrum of the chain transfer agent in example 1.

FIG. 3 shows the nuclear magnetic spectrum of the crosslinker 4-arm allyl ether in example 1.

FIG. 4 is a graph showing the results of measuring the compression properties of a cylindrical gel.

FIG. 5 is an outline view of a dumbbell gel.

FIG. 6 is a graph showing the results of measurement of tensile properties of dumbbell gels.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Example 1

A preparation method of a gel material with a controllable and regular structure comprises the following specific steps:

s1 preparation of chain transfer agent

(1) Adding 4.5g of butyl mercaptan, 40ml of acetone and 5ml of deionized water into a three-neck flask, and then adding 2.0106g of sodium hydroxide (firstly preparing the sodium hydroxide into a NaOH solution with the mass concentration of 50%, and then adding the NaOH solution into the three-neck flask); stirring at room temperature for 20min, after complete dissolution, slowly adding 3.38ml of carbon disulfide by using a constant-pressure dropping pipe in an ice bath, then stirring for 30min, and adding 6.808g of 2-bromopropionic acid; and stirring and reacting for 24 hours at room temperature, after the reaction is finished, carrying out reduced pressure distillation to remove redundant acetone, adding 80ml of deionized water for dilution, adding 20ml of concentrated hydrochloric acid with the concentration of 12mol/L under the ice bath condition for acidification, continuously keeping in the ice bath, stirring until solid is separated out, then filtering, washing and recrystallizing the mixture to obtain a purified chain transfer agent precursor, and storing at low temperature. The chain transfer agent precursor prepared was 2- ((butylsulfanyl) -thiocarbonyl)) -propionic acid.

The structural formula and nuclear magnetic spectrum of the chain transfer agent precursor are shown in figure 1. It can be seen that: the integrated area ratio of each nuclear magnetic peak of the product is clear, and the specific resonance signal is (ppm from TMS): 4.87(1H, -SCHCH₃)，3.37-3.45(2H,-SCH₂C₃H₇)，1.67-1.76(2H,-SCH₂CH₂C₂H₅)，1.64(3H,-SCHCH₃)，1.45(2H,-SC₂H₄CH₂CH₃)，0.94(3H,-SC₃H₆CH₃). Through the analysis, the 2- (((butylthio) carbonyl sulfonyl) thio) propionic acid can be successfully synthesized, and a nuclear magnetic spectrum has no impurity peak, which indicates that the product is pure.

(2) 47ml of anhydrous methylene chloride, 2.0392g of a chain transfer agent precursor, 0.2ml of ethylene glycol, and 0.5236g of 4-dimethylaminopyridine were sequentially added to a reaction flask, and the mixture was stirred for 15 minutes to dissolve the reaction productCompletely decomposing, slowly dripping 1.7637g of liquid dicyclohexylcarbodiimide into the reaction solution, and reacting for 24 hours at normal temperature; then purifying the mixture, wherein the specific purification operation is as follows: firstly, the mixture after the reaction is finished is filtered by suction to remove the precipitate, and the filtrate is sequentially treated by K₂CO₃Washing with a solution (pH of 9-10), deionized water and a saturated sodium chloride solution, repeatedly washing for three times, and then using anhydrous MgSO₄Drying for two days to obtain the chain transfer agent. The structural formula and nuclear magnetic spectrum of the chain transfer agent are shown in figure 2.

It can be seen that the integrated area ratio of each nuclear magnetic peak of the product is clear, and the specific resonance signal is assigned as (ppm from TMS): 4.88(1H, -SCHCH₃)，4.37-4.41(4H,-OCH₂CH₂O-)，3.38-3.44(2H,-SCH₂C₃H₇)，1.67-1.76(4H,-SCH₂CH₂C₂H₅)，1.64(6H,-SCHCH₃)，1.41-1.46(4H,-SC₂H₄CH₂CH₃)，0.89-0.92(6H,-SC₃H₆CH₃). From this it can be demonstrated that the chain transfer agent ethane-1, 2-dialkylbis (2- ((((butylthio) carbonylthiocarbonyl) thio) propanoate) was successfully synthesized.

S2, adding 0.1896g of chain transfer agent, 0.0132g of Azobisisobutyronitrile (AIBN), 0.6288g of dimethylaminoethyl methacrylate monomer and 2ml of 1, 4-dioxane into a reaction container in sequence, vacuumizing for 20min, repeatedly vacuumizing and introducing nitrogen for three times, and then placing the mixture in a constant-temperature oil bath at 70 ℃ for reacting for 6 hours; after the reaction is finished, the reaction system is exposed in the air and placed in an ice bath for several minutes to be rapidly cooled, and then dialyzed and dried to obtain a chain polymer (named CTA-PDMAEMA)₁₀)。

S3, mixing 0.1739g chain polymer CTA-PDMAEMA₁₀Adding the mixture into a reaction container, adding 0.6ml of DMF (dimethyl formamide) to fully dissolve the DMF, adding 0.0154g of hydrazine hydrate, stirring and reacting for 1 hour, and dialyzing and freeze-drying after the reaction is finished to obtain the modified chain polymer.

S4, dissolving 0.2620g of modified chain polymer and 0.0071g of cross-linking agent in 0.8ml of DMF, adding 0.0052g of photoinitiator 1-hydroxycyclohexyl phenyl ketone, ultrasonically dissolving, introducing nitrogen for 20 minutes, and irradiating for 2 hours to form a reticular gel.

Wherein the cross-linking agent is prepared by the following method: 7.1407g of pentaerythritol and 10.5060g of NaOH are sequentially added into a three-necked flask provided with a constant-pressure dropping funnel and a spherical condenser tube, and then 35ml of tetrahydrofuran is added for dissolution; slowly stirring and heating until reflux, adding 28ml of 3-bromopropylene into a constant-pressure dropping funnel, starting dropping, and continuing reflux reaction for 16 hours after dropping is finished; after the reaction is finished, the excessive solvent and the volatile matters with low boiling points are removed by the purification modes of filtering, washing and the like of the mixture, and the cross-linking agent is obtained. The cross-linking agent is 4-arm allyl ether, namely pentaerythritol (tetra) allyl ether, and a nuclear magnetic spectrum is shown in figure 3. It can be seen that: the integrated area ratio of each nuclear magnetic peak of the product is clear, and the specific resonance signal is (ppm from TMS): 3.39-3.47(8H, -CH)₂OCH₂-)，3.84-3.90(8H,-OCH₂CH＝CH₂)，5.12-5.32(8H,-OCH₂CH＝CH₂)，5.75-5.87(4H,-OCH₂CH＝CH₂). This demonstrates the successful synthesis of a four-arm allyl ether.

And (3) performance testing:

(1) when chain polymers with different chain lengths are prepared, the chain length of the chain polymer is adjusted by changing the ratio of the polymerizable monomer to the chain transfer agent. Here, the following chain polymers CTA-PDMAEMA of two chain lengths were prepared₁₀And CTA-PDMAEMA₁₀₀。CTA-PDMAEMA₁₀₀The preparation method comprises the following steps: sequentially adding 0.202g of chain transfer agent, 0.013g of Azodiisobutyronitrile (AIBN), 6.288g of dimethylaminoethyl methacrylate monomer and 20ml of 1, 4-dioxane into a reaction vessel, vacuumizing for 20min, repeatedly vacuumizing and introducing nitrogen for three times, and then placing in a constant-temperature oil bath at 70 ℃ for reacting for 6 h; and (3) after the reaction is finished, exposing the reaction system to the air, placing the reaction system in an ice bath for several minutes to rapidly cool the reaction system, and then dialyzing and drying the reaction system to obtain the chain polymer. The molecular weights and distributions of the two polymers are shown in Table 1.

TABLE 1 molecular weights and distributions of two chain-length chain polymers

Chain polymer	Mn	Mw	PDI
				CTA-PDMAEMA10	1035	1276	1.23
CTA-PDMAEMA100	12735	19353	1.51

As can be seen, CTA-PDMAEMA was used in the preparation of the chain polymer₁₀Small molecular weight distribution PDI, CTA-PDMAEMA₁₀₀The molecular weight distribution PDI is large. Therefore, when the preparation method of the invention is used for preparing the chain polymer with smaller molecular weight, the preparation method can better control the molecular weight and the distribution of the polymer, and the prepared polymer chain has narrower molecular weight distribution.

(2) And testing the compression performance and the tensile performance of the gel by using an electronic universal testing machine.

The compressive property of the cylindrical gel is measured, and the result is shown in figure 4, wherein the gel I is a net-shaped gel assembled by CTA-PDMAEMA 10; gel II is a CTA-PDMAEMA100 assembled reticular gel. The sigma-epsilon curves of the prepared gels I and II in the compression test are shown. As can be seen from the graph, when ε was 70%, σ increased sharplyAnd when ε is 85%, gel I (CTA-PDMAEMA)₁₀) And gel II (CTA-PDMAEMA)₁₀₀) The gel has no damage, shows that the compression performance of the gel is good, the stress in all directions of the gel is uniform in the compression process, and the gel is not easy to damage, particularly, when epsilon is 85%, the sigma of the gel I reaches 35 Mpa. It was thus demonstrated that the structured gel did have better compression properties.

The tensile properties of the dumbbell-shaped gel (see FIG. 5) were measured, and the results are shown in FIG. 6. Wherein the gel I is a net gel assembled by CTA-PDMAEMA 10; gel II is a CTA-PDMAEMA100 assembled reticular gel. The tensile curves of the two gels are shown. As can be seen, gel I (CTA-PDMAEMA)₁₀) And gel II (CTA-PDMAEMA)₁₀₀) Have high stretchability. But gel I (CTA-PDMAEMA)₁₀) The tensile property of the gel is obviously stronger than that of gel II (CTA-PDMAEMA)₁₀₀). This is due to the formation of gel I (CTA-PDMAEMA)₁₀) The molecular weight distribution of the chain polymer is narrower, the reticular gel structure is more uniform and regular, and the force can be better transmitted to the whole gel under the action of external force, so that each molecular chain in the gel is uniformly stressed, and the molecular weight is not easy to break, so that the gel I has high tensile property.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (7)

1. A preparation method of a gel material with a controllable and regular structure is characterized by comprising the following steps:

s1, preparing the chain transfer agent, comprising two substeps:

s11, adding butyl mercaptan, acetone, deionized water and a NaOH solution into a reaction container, stirring and dissolving, then dropwise adding carbon disulfide under an ice bath condition, uniformly stirring, adding 2-bromopropionic acid, stirring and reacting at room temperature for 24 hours, removing excess acetone and adding deionized water for dilution after the reaction is finished, then adding hydrochloric acid under an ice bath for acidification, and continuing ice bath stirring until a solid is separated out, wherein the solid is a chain transfer agent precursor;

s12, dissolving a chain transfer agent precursor, ethylene glycol and 4-dimethylaminopyridine in anhydrous dichloromethane, then dropwise adding dicyclohexylcarbodiimide, and reacting at normal temperature for 24 hours to obtain a chain transfer agent;

s2, adding a chain transfer agent, azodiisobutyronitrile, dimethylaminoethyl methacrylate and 1, 4-dioxane into a reaction container, vacuumizing, introducing nitrogen, and then placing in a constant-temperature oil bath at 70 ℃ for reacting for 6 hours; after the reaction is finished, exposing the reaction system to air, placing the reaction system in an ice bath for rapid cooling, and then dialyzing and drying to obtain a chain polymer;

s3, modifying the chain polymer by hydrazine hydrate;

s4, dissolving the modified chain polymer and the cross-linking agent in dimethylformamide, adding a photoinitiator, introducing nitrogen to expel oxygen, and then performing light-induced reaction to form the mesh gel.

2. A method of preparing a structurally controlled and structured gel material as claimed in claim 1, wherein said cross-linking agent is pentaerythritol (tetra) allyl ether.

3. The method of preparing a structurally controlled and structured gel material as claimed in claim 2, wherein the cross-linking agent is prepared by: dissolving pentaerythritol and NaOH in tetrahydrofuran, stirring and heating until reflux, dropwise adding 3-bromopropylene, continuing reflux reaction for 16h after the dropwise adding is finished, and filtering after the reaction is finished to obtain a solid serving as a cross-linking agent.

4. The method for preparing a structurally controlled and structured gel material as claimed in claim 1, wherein the step S3 is specifically: dissolving the chain polymer in dimethylformamide, adding hydrazine hydrate, stirring for reaction for 1h, and dialyzing, and freeze-drying to obtain the modified chain polymer.

5. The method for preparing a controlled-structure regular gel material as claimed in claim 1, wherein in step S4, the photoinitiator is 1-hydroxycyclohexyl phenyl ketone, and after introducing nitrogen for 20min, the reaction is initiated by ultraviolet light irradiation for 2 hours under ultrasonic vibration to form a network gel.

6. The method for preparing a structurally controlled and structured gel material as claimed in claim 1, wherein in step S11, the excess acetone is distilled off under reduced pressure after the reaction is completed.

7. The method for preparing a structurally controlled and regular gel material as claimed in claim 6, wherein in step S11, the mixture is stirred in an ice bath until a solid is precipitated, and then the solid is filtered, washed and recrystallized to obtain a purified chain transfer agent precursor, which is then stored at a low temperature.

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