A method for inducing the self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction

Abstract

The present invention discloses a method for inducing self-assembly of poly(phenylacetylene) into films by photoirradiation cross-linking polymerization reaction. Two phenylacetylene monomers containing dendrimeric alkoxy ether units and acrylate functional groups are used. Based on the two phenylacetylene monomers, a dendritic phenylacetylene copolymer is prepared by metal-catalyzed copolymerization reaction. The copolymer has a radial amphiphilic structure and temperature-sensitive characteristics. When its aqueous solution is heated above the phase transition temperature, dehydration aggregation occurs to form film-like assemblies. A photoinitiator is added to the copolymer aqueous solution, and under the condition of ultraviolet light irradiation above the phase transition temperature of the copolymer, the polymer further undergoes cross-linking and self-assembly to directly obtain a thin film. The thin film has excellent temperature responsiveness, and its thickness can be regulated by the copolymer concentration, copolymerization ratio, and irradiation time. The invention provides a new way to prepare thin film materials, with short reaction time, simple steps, and the prepared intelligent thin films having good prospects in aspects such as material separation and molecular selective permeation.

Description

Technical Field

[0001] The present invention belongs to the field of preparing thin film materials by self-assembly, and particularly relates to a method for preparing dendritic poly(phenylacetylene) thin film materials by photo-crosslinking. A dendritic phenylacetylene copolymer with radial amphiphilicity is prepared through molecular design and synthesis. The copolymer is assembled into film-like aggregates during the phase transition process, and a film material with reversible temperature-responsive behavior is prepared by photo-crosslinking. It belongs to the field of polymer membrane materials and also belongs to the field of intelligent responsive materials. Background Art

[0002] During the self-assembly process, various weak interaction forces and their synergistic effects are used to prepare assemblies with specific sizes, structures, and functions, enabling the preparation of various ordered materials such as microspheres, nanotubes, vesicles, thin films, etc. Among them, the polymerization-induced self-assembly (PISA) technique provides new methods and strategies for the batch preparation of polymer nanomaterials with determined shape and size, adjustable surface chemistry, and properties. Compared with traditional self-assembly techniques that can only perform post-assembly on pre-synthesized polymers, this method not only combines the polymerization reaction and the self-assembly process in a one-pot method, allowing precise control of the assembly morphology through experimental design, effectively simplifying the preparation steps of polymer nanoparticles, but also can be prepared in large quantities under high solid content (5 - 50%) conditions to meet the requirements of industrial large-scale production. So far, most of the assemblies prepared by PISA use axial amphiphilic polymers, while there are few reports on radial amphiphilic polymers. Nanoscale assembly materials with morphologies such as spheres, nanowires, vesicles, and nanotubes can be prepared by PISA, which have great potential applications in fields such as drug and gene delivery, cell reactors, and coatings. In contrast, there are few reports on the preparation of membrane materials by PISA.

[0003] Membrane materials are a type of two-dimensional ordered materials with properties such as selectivity, permeability, and flux. With the development of intelligent materials, endowing membrane materials with the function of responding to external environmental stimuli has become a research hotspot in membrane materials, thus expanding the applications of intelligent membrane materials in aspects such as water treatment, separation and purification of biological and chemical substances, drug release control, artificial organs, and chemical sensors. There are various traditional methods for preparing membrane materials, such as spin coating method, layer-by-layer self-assembly method, etc. However, it is rare and difficult to directly prepare thin films from intelligent responsive materials. Most are indirectly prepared by introducing intelligent responsive motifs into membrane materials through modification methods, mainly including physical and chemical methods. Among them, although the physical method is simple and easy to operate, the uniformity and stability of the obtained membrane are impaired; while the solvents used in the chemical method are usually organic solvents, which cause great environmental pollution and have complex post-treatment, making it unfavorable for biological applications. Summary of the Invention

[0004] To solve the problems of the existing technologies, the purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for inducing the self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization, and at the same time provide a simple and effective method for preparing intelligent films. Through molecular design and synthesis, dendritic alkoxy ethers are grafted onto the side groups of phenylacetylene to prepare dendritic phenylacetylene copolymers with radial amphiphilicity. Utilizing the property of the dendritic phenylacetylene copolymers to induce dehydration aggregation and self-assembly into films by temperature, film materials are prepared in one step through ultraviolet light irradiation cross-linking. Such films have excellent reversible temperature-responsive behaviors, and the thickness of the films can be regulated by changing the copolymer concentration, irradiation time, and copolymerization ratio. The present invention develops a new approach for preparing films by novel photoirradiation cross-linking polymerization and solves the problem that traditional preparation of intelligent films requires modification. It has good prospects in the fields of material separation and purification, drug controlled release, cell culture, and biosensing, etc.

[0005] To achieve the above-mentioned purpose of the invention, the inventive concept is as follows:

[0006] The present invention designs and synthesizes two kinds of phenylacetylene monomers. One is the first-generation dendritic alkoxy ether phenylacetylene monomer MN connected by amide bonds, and the other is the phenylacetylene monomer MAc with a carbon-carbon double bond at the end connected by amide bonds. Then, a rhodium catalyst [Rh(nbd)Cl 2 2 is used to successfully prepare dendritic phenylacetylene copolymers PG1 with different copolymerization ratios through coordination polymerization. m A n Utilizing the property of the phenylacetylene copolymer to form film-like aggregates by temperature-sensitive aggregation, film materials are prepared in one step through ultraviolet light irradiation cross-linking. This method is simple to operate, free of chemical pollution, has a fast polymerization rate, the thickness of the prepared film materials can be regulated, and it has excellent reversible temperature responsiveness.

[0007] Using the first-generation dendritic alkoxy ether unit G1-NH 2 with an amino end group as the raw material, dendritic macromonomer MN is prepared through amidation reaction. Then, using OEG-NH 2 as the raw material, phenylacetylene monomer MAc with an acrylate end group is prepared through esterification reaction and amidation reaction respectively. Dendritic phenylacetylene copolymers are prepared by copolymerizing the two monomers. The prepared dendritic phenylacetylene copolymers are dissolved in water, a photoinitiator is added, heated above the phase transition temperature to dehydrate and aggregate the copolymer, and the aggregates are cross-linked and cured by ultraviolet light irradiation to prepare films. At the same time, by changing the copolymer concentration and copolymerization ratio, the thickness and temperature-sensitive behavior of the films are controlled.

[0008] According to the above inventive concept, the present invention adopts the following technical solution:

[0009] A method for inducing the self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization, which designs and synthesizes dendritic phenylacetylene copolymers PG1 with radial amphiphilicity​m A n , its structural formula is as follows:

[0010]

[0011] where m:n = 3 - 25:1; a = 1 - 3, b = 1 - 3; X = OEt or X = OMe; wherein, when X = OEt, then PG1 m A n is PEtG1 m A n ; when X = OMe, then PG1 m A n is PMeG1 m A n ; wherein, in the dendritic alkoxy ether motif, the alkoxy chain adopts a three - arm, two - arm, four - arm or six - arm structure;

[0012] Dissolve the dendritic phenylacetylene copolymer with radial amphiphilicity in water to obtain an aqueous copolymer solution, and then heat the aqueous copolymer solution above the phase transition temperature. Through ultraviolet light irradiation, a dendritic polystyrene acetylene film with temperature - responsive behavior is prepared by a one - step cross - linking reaction.

[0013] As a preferred technical solution of the present invention, when synthesizing the dendritic phenylacetylene copolymer with radial amphiphilicity, two phenylacetylene monomers are used: one of the phenylacetylene monomers contains a first - generation dendritic alkoxy ether motif, and the other phenylacetylene monomer contains a carbon - carbon double - bond functional group; the two phenylacetylene monomers are used to prepare the dendritic phenylacetylene copolymer with radial amphiphilicity through a coordination copolymerization reaction; the double - bond functional group provides a photocross - linking site, the dendritic alkoxy ether motif provides hydrophilic and thermosensitive characteristic sites, and the phenylacetylene main chain provides hydrophobic and rigid structures.

[0014] As a preferred technical solution of the present invention, the aqueous copolymer solution aggregates and assembles into a film - like assembly above the phase transition temperature, and a film material is prepared through ultraviolet light cross - linking.

[0015] As a preferred technical solution of the present invention, by adjusting at least one of the condition parameters such as copolymer concentration, light intensity, light irradiation time, and copolymerization ratio, the thickness of the prepared film can be controlled. The film of the present invention has a uniform thickness and excellent reversible thermosensitive behavior.

[0016] As a further preferred technical solution of the present invention, copolymers under different copolymerization ratio conditions are prepared by changing the ratio of MN to MAc. By changing the copolymer concentration and copolymerization ratio, the regulation of the thermosensitive behavior of the film is realized.

[0017] As a further preferred technical solution of the present invention, the thickness of the film is regulated by changing the copolymer concentration and the copolymerization ratio. The thickness of the dendritic phenylacetylene film prepared in the present invention increases with the increase of the copolymer concentration, decreases with the increase of the copolymerization ratio, and increases with the increase of the irradiation time. When the irradiation time exceeds 10 s, the film thickness reaches saturation.

[0018] As a preferred technical solution of the present invention, the thermally induced volume shrinkage rate of the dendritic poly(phenylacetylene) film can be regulated by changing the copolymer concentration. The thermally induced volume shrinkage rate of the dendritic phenylacetylene film prepared in the present invention decreases with the increase of the copolymer concentration and is less significantly affected by the copolymerization ratio.

[0019] As a preferred technical solution of the present invention, the method for inducing the self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction of the present invention comprises the following steps:

[0020] (1) Synthesis of monomer MN:

[0021] Using the amino-terminated first-generation dendritic alkoxy ether unit G1-NH 2 as the raw material, dissolve the compound G1-NH 2 in dry dichloromethane at no higher than 0 °C, then add N,N-diisopropylethylamine and 4-ethynylpentafluorophenyl ester, raise the temperature to room temperature after at least 30 minutes, and react for at least 6 hours under nitrogen protection; after determining the completion of the reaction by TLC plate, rotary evaporate the solvent, and then purify by column chromatography. After rotary evaporating the solvent, the obtained product is a colorless transparent oily liquid for standby; the synthesis route of monomer MN is as follows:

[0022]

[0023] (2) Synthesis of monomer MAc:

[0024] Dissolve OEG-NH 2 in dry dichloromethane, add N,N-diisopropylethylamine, and at the same time dissolve 4-ethynylpentafluorophenyl ester in dry dichloromethane and transfer it to a constant pressure funnel. Slowly drop 4-ethynylpentafluorophenyl ester under ice-salt bath and nitrogen protection, and react for at least 8 h; after determining the completion of the reaction by TLC plate, rotary evaporate the solvent, and purify by column chromatography. After rotary evaporating the solvent, a colorless transparent oily liquid product PA-OH is obtained; then add Et 3 N and acryloyl chloride to react in the dichloromethane of PA-OH for at least 8 h; after determining the completion of the reaction by TLC plate, add a few drops of methanol to quench the reaction, wash with saturated brine at least three times, take the lower organic phase and rotary evaporate the solvent, and then purify by column chromatography. After rotary evaporating the solvent, the obtained product is a white solid; the synthesis route of monomer MAc is as follows:

[0025]

[0026] (3) Copolymer PG1 m A n Synthesis:

[0027] Dissolve the monomer MN prepared in the step (1) and the monomer MAc prepared in the step (2) in dry tetrahydrofuran according to a certain mass ratio, and feed them according to a molar ratio of MN to MAc of 3-25:1; freeze with liquid nitrogen and freeze-pump under high vacuum for at least 15 minutes, repeat at least three times to remove the residual moisture and impurities in the monomers; then thaw and return to room temperature, and add a tetrahydrofuran solution of [Rh(nbd)Cl] 2 and Et 3 N with a syringe under a nitrogen atmosphere; and react at room temperature under nitrogen protection for at least 8 hours, spin-dry the solvent and purify it by column chromatography with dichloromethane to obtain an orange-red copolymer PG1 m A n , and its structural formula is as follows:

[0028]

[0029] where m:n = 3-25:1; a = 1-3, b = 1-3; X = OEt or X = OMe; wherein, when X = OEt, then PG1 m A n is PEtG1 m A n ; when X = OMe, then PG1 m A n is PMeG1 m A n ; wherein, in the dendritic alkoxy ether unit, the alkoxy chain adopts a three-arm, two-arm, four-arm or six-arm structure;

[0030] (4) Preparation of the reaction mixture:

[0031] Dissolve the copolymer prepared in the step (3) in deionized water, then add a photoinitiator and stir evenly to obtain a reaction mixture for standby; in the prepared reaction mixture solution, the mass fraction of the copolymer is 2-20 wt%, and the mass fraction of the photoinitiator is 0.5-1 wt%; completely dissolve the copolymer in water;

[0032] (5) Light-induced cross-linking polymerization reaction to regulate the synchronous assembly of dendritic poly(phenylacetylene) into a film:

[0033] Heat the reaction mixture prepared in the step (4) above the phase transition temperature, and prepare a branched poly(phenylacetylene) film in one step by ultraviolet light irradiation.

[0034] As a preferred technical solution of the present invention, in the step (5), the ultraviolet light irradiation time is controlled to be 3-20 s.

[0035] As a preferred technical solution of the present invention, in the step (5), the controlled light intensity is set to be not less than 250 mJ / cm 2 .

[0036] As a preferred technical solution of the present invention, in the step (5), a branched poly(phenylacetylene) film is prepared by one-step ultraviolet light irradiation, and then transferred onto a glass slide with grooves, and washed with deionized water at least three times to remove the uncured copolymer aqueous solution on the surface, obtaining a branched poly(phenylacetylene) film product.

[0037] As a preferred technical solution of the present invention, in the step (4), the photoinitiator used is photoinitiator 2959.

[0038] Compared with the prior art, the present invention has the following obvious outstanding substantive features and remarkable advantages:

[0039] 1. The method of the present invention prepares a novel dendritic phenylacetylene copolymer. The carbon-carbon double bond groups provide photo-crosslinking sites, the dendritic alkoxy ether units endow the copolymer with hydrophilicity and excellent temperature-responsive properties, and the phenylacetylene main chain provides hydrophobicity and rigidity, and the copolymer exhibits radial amphiphilic properties. Such copolymers exhibit fast and small hysteresis phase transition behaviors. And the radial amphiphilicity causes the copolymer to aggregate and assemble into film-like aggregates during phase transition;

[0040] 2. The present invention prepares a branched poly(phenylacetylene) film material by a one-step photo-crosslinking polymer synchronous assembly method;

[0041] 3. The thickness of the branched poly(phenylacetylene) film of the present invention is relatively uniform, and the film thickness can be regulated by changing the copolymer concentration (2-20 wt%), the copolymerization ratio (the molar ratio of MN:MAc is 3-25:1) and the light irradiation time (3-20 s);

[0042] 4. The branched poly(phenylacetylene) film of the present invention has excellent thermosensitive properties, and the thermally induced volume shrinkage rate of the film can be changed by adjusting the copolymer concentration (2-20 wt%). Description of the Drawings

[0043] Figure 1 For the monomers MN, MAc and the copolymer PG1 prepared in Examples 1 to 5 of the present invention m A n Synthesis route. Reagents and conditions: (a) 4-ethynylpentafluorophenol, DIEA, DCM, overnight reaction at 0 °C (97%), (b) C 3 H 3ClO, TEA, DCM, reacted overnight at 0 °C (92%), (c) 4-ethynylpentafluorophenol, DIEA, DCM, reacted overnight at 0 °C (94%), (d) MAc, [Rh(nbd)Cl] 2 , TEA, THF, reacted for 8 h (81 - 86%).

[0044] Figure 2 The copolymer PEt 5.9 G1A 1 、PEt 10.6 G1A 1 、PEt 25.5 G1A 1 turbidity curves prepared in the preferred embodiment of the present invention.

[0045] Figure 3 The hydrodynamic radius R h of the copolymer prepared in the preferred embodiment of the present invention as a function of temperature. (a)(b)(c) are respectively the copolymer PEt 5.9 G1A 1 、PEt 10.6 G1A 1 、PEt 25.5 G1A 1 hydrodynamic radius variation curves with temperature.

[0046] Figure 4 Morphology characterization of the dendrimerized poly(phenylacetylene) film in Example 6 of the present invention. Among them Figure 4 (a) is the optical microscope photograph of the film, Figure 4 (b) is the scanning electron microscope photograph of the film, Figure 4 (c) is the orthogonal three-view of the confocal microscope of the film, Figure 4 (d) is the 3D photograph of the film.

[0047] Figure 5 Confocal microscope photograph and thickness measurement of the dendrimerized poly(phenylacetylene) film in Example 6 of the present invention.

[0048] Figure 6 Thermosensitive behavior of the dendrimerized poly(phenylacetylene) film in the preferred embodiment of the present invention. Among them, Figure (a) is the optical microscope photographs of the films prepared under different conditions at 25 °C, 35 °C, 40 °C and returned to 25 °C, Figure (b) is the size change curve of the copolymer film at different temperatures, and Figure (c) is the size change of the film PG1A during 5 thermosensitive cycles.

[0049] Figure 7 Schematic diagram of the method for inducing self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction in the preferred embodiment of the present invention. Detailed implementation mode

[0050] The above solution will be further described below in conjunction with specific implementation examples. Refer to Figure 1 and Figure 7 , a method for inducing the self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction according to the present invention. First, two phenylacetylene monomers were designed and synthesized, which respectively contain a dendrimeric alkoxy ether unit and an acrylate functional group. Based on the two phenylacetylene monomers, a class of dendritic phenylacetylene copolymers was prepared by metal-catalyzed copolymerization reaction. The copolymer has a radial amphiphilic structure and temperature-sensitive characteristics, and its aqueous solution can undergo dehydration aggregation to form a film-like assembly when heated above the phase transition temperature. Based on this, a photoinitiator was added to the copolymer aqueous solution, and under the condition of ultraviolet light irradiation above the phase transition temperature of the copolymer, the polymer further underwent cross-linking and assembly to directly obtain a thin film. The thin film has excellent temperature responsiveness, and its thickness can be regulated by the copolymer concentration, copolymerization ratio, and irradiation time. The present invention provides a new way to prepare thin film materials, and its advantage lies in the short reaction time and simple steps. The intelligent thin film prepared by the present invention has good prospects in aspects such as material separation and molecular selective permeation.

[0051] The preferred embodiments of the present invention are described in detail as follows:

[0052] Example 1

[0053] In this embodiment, a preparation method of a phenylacetylene monomer MN with a first-generation dendrimeric alkoxy ether unit having an amide bond-linked end group of ethoxy can be synthesized by referring to the literature (Wang F., et al. Macromolecules 2019, 52, 8631–8642), and the steps are as follows:

[0054] At 0 °C, compound G1-NH 2 (4.14 g, 6.15 mmol), N,N-diisopropylethylamine (3.18 g, 24.6 mmol), and 4-ethynylpentafluorophenyl ester (2.11 g, 6.76 mmol) were dissolved in dry dichloromethane (50 mL). After 30 minutes, the temperature was raised to room temperature and the reaction was carried out for 6 hours under nitrogen protection; after determining the completion of the reaction by TLC plate, the solvent was evaporated, and then purified by column chromatography (DCM / MeOH, 200 / 1, v / v). After evaporating the solvent, the product was obtained as a colorless transparent oily liquid (4.58 g, 97.6%).

[0055] Example 2

[0056] In this embodiment, a preparation method of a phenylacetylene monomer MAc with a triethylene glycol having an amide bond-linked end group of acrylate includes the following steps:

[0057] The synthesis of monomer MAc is to use TEG-NH 2(0.66 g, 4.82 mmol) was dissolved in dry dichloromethane, and N,N-diisopropylethylamine (1.60 mL, 9.60 mmol) was added. Meanwhile, 4-ethynylpentafluorophenyl ester (1.65 g, 5.29 mmol) was dissolved in dry dichloromethane and transferred to a constant-pressure funnel. Under an ice-salt bath and nitrogen protection, 4-ethynylpentafluorophenyl ester was slowly added dropwise, and the reaction was carried out overnight. After the reaction was completed as determined by TLC plate, the solvent was evaporated, and the product was purified by column chromatography (DCM / MeOH, 50 / 1, v / v). After evaporation of the solvent, a colorless transparent oily liquid (1.09 g, 85.72%) was obtained. Then, compound 2 (1.09 g, 4.13 mmol) was dissolved in dry dichloromethane and placed in an ice-salt bath. Under a nitrogen atmosphere, Et 3 N (2.30 mL, 16.52 mmol) was added. Acryloyl chloride (0.50 mL, 6.20 mmol) was diluted to 5 mL with dry dichloromethane and slowly injected into the reaction flask with a syringe, and the reaction was carried out overnight. After the reaction was completed as determined by TLC plate, a few drops of methanol were added to quench the reaction, and it was washed three times with saturated brine. The lower organic phase was taken and the solvent was evaporated, and then it was purified by column chromatography (DCM / MeOH, 150 / 1, v / v). After evaporation of the solvent, a white solid was obtained.

[0058] Example 3

[0059] In this example, a preparation method of a novel dendritic phenylacetylene copolymer PEtG1 m A n (m:n = 3:1) includes the following steps:

[0060] 300.0 mg (0.39 mmol) of monomer MN and 43.1 mg (0.13 mmol) of monomer MAc were dissolved in dry tetrahydrofuran, frozen with liquid nitrogen and freeze-pumped under high vacuum for 15 minutes, and repeated three times to remove residual moisture and impurities in the monomers. After thawing and returning to room temperature, [monomer] / [TEA] / [Rh(nbd)Cl] 2 = 250 / 300 / 1 ratio, and a solution of [Rh(nbd)Cl] 2 and Et 3 N in tetrahydrofuran (0.30 mL) was added with a syringe under a nitrogen atmosphere. The reaction was carried out at room temperature under nitrogen protection for 8 hours, and the solvent was evaporated and purified by column chromatography with dichloromethane.

[0061] Example 4

[0062] This example is basically the same as Example 3, with the special feature that:

[0063] In this example, a novel dendritic phenylacetylene copolymer PEtG1 m A n(The preparation method of (m:n = 5.9:1) includes the following steps:

[0064] Dissolve 300.0 mg (0.39 mmol) of monomer MN and 6.85 mg (0.08 mmol) of monomer MAc in dry tetrahydrofuran, freeze with liquid nitrogen and freeze-dry under high vacuum for 15 minutes, repeat three times to remove the residual moisture and impurities in the monomers. After thawing and returning to room temperature, according to [monomer] / [TEA] / [Rh(nbd)Cl] 2 = 250 / 300 / 1 ratio, add [Rh(nbd)Cl] with a syringe under a nitrogen atmosphere 2 and Et 3 N's tetrahydrofuran (0.30 mL) solution. React under nitrogen protection at room temperature for 8 hours, spin-dry the solvent and purify by column chromatography with dichloromethane.

[0065] Example Five

[0066] This example is basically the same as Example Three, with the special feature being:

[0067] In this example, a novel dendritic phenylacetylene copolymer PEtG1 m A n (The preparation method of (m:n = 25.5:1) includes the following steps:

[0068] Dissolve 300.0 mg (0.39 mmol) of monomer MN and 6.85 mg (0.02 mmol) of monomer MAc in dry tetrahydrofuran, freeze with liquid nitrogen and freeze-dry under high vacuum for 15 minutes, repeat three times to remove the residual moisture and impurities in the monomers. After thawing and returning to room temperature, according to [monomer] / [TEA] / [Rh(nbd)Cl] 2 = 250 / 300 / 1 ratio, add [Rh(nbd)Cl] with a syringe under a nitrogen atmosphere 2 and Et 3 N's tetrahydrofuran (0.30 mL) solution. React under nitrogen protection at room temperature for 8 hours, spin-dry the solvent and purify by column chromatography with dichloromethane.

[0069] For the above Examples Three to Five, Figure 2 For the copolymers PEt 5.9 G1A 1 、PEt 10.6 G1A 1 、PEt 25.5 G1A 1 's turbidity curves. From Figure 2 it can be seen that the phase transition temperatures (T cp)Between 33.5 °C and 35 °C, with a relatively small hysteresis, approximately around 1 °C. Among them, PEtG1 5.9 A 1 has a phase transition temperature of 33.6 °C. As the content of the alkoxy ether unit increases, the hydrophilicity of the copolymer improves, and the phase transition temperature slightly increases. PEtG1 10.6 A 1 and PEtG1 25.5 A 1 have phase transition temperatures of 34.2 °C and 34.6 °C respectively; Figure 3 is the relationship curve of the hydrodynamic radius R h of the copolymer prepared in the above examples with temperature. (a)(b)(c) are the curves of the hydrodynamic radius of the copolymers PEt 5.9 G1A 1 , PEt 10.6 G1A 1 , PEt 25.5 G1A 1 changing with temperature. It can be seen from Figure 3 that at room temperature, the average hydrodynamic radius of the three copolymers is about 40 nm, and no obvious aggregation behavior occurs. When the temperature rises to their respective phase transition temperatures, due to the thermally induced phase transition, the alkoxy ether units dehydrate and collapse, and the molecular chains aggregate, and the hydrodynamic radius increases to about 140 nm. As the temperature further increases, the alkoxy ether units inside the aggregates further dehydrate, resulting in a slight decrease in the hydrodynamic radius of the aggregates, about 120 nm.

[0070] Example Six

[0071] In this example, a method for one-step photo-crosslinking to prepare a temperature-sensitive dendritic poly(phenylacetylene) film includes the following steps:

[0072] Prepare an aqueous solution of a dendritic phenylacetylene copolymer with a solid content of 5 wt%, and add 0.5 wt% of photoinitiator 2959 (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone). After fully dissolving and mixing evenly, place the solution in a temperature control device and heat it above the phase transition temperature, set the light intensity to 250 mJ / cm 2 , and crosslink it into a film under ultraviolet light irradiation. Slowly lift the film from the bottom of the solution with a clean copper mesh and place it on a grooved glass slide, and wash it three times with deionized water.

[0073] Figure 4 is the morphological characterization of the dendritic poly(phenylacetylene) film in this example. Among them Figure 4 (a) is the optical microscope photo of the film. After partial magnification, it can be clearly seen that the surface of the film is aggregates crosslinked after light irradiation. Figure 4(b) is a scanning electron microscope photograph of the thin film. It can be clearly seen that after freeze-drying, the dendritic poly(phenylacetylene) thin film has uniformly distributed micropores with a pore size of 1 - 20 μm, indicating that the formed thin film is a hydrogel thin film. After freeze-drying, water molecules are removed to form a porous network framework structure. Figure 4 (c) Orthogonal three-view confocal microscope images of the thin film Figure 4 (d) 3D photograph of the thin film Figure 5 These are the confocal microscope photographs and thickness measurements of the dendritic poly(phenylacetylene) thin film in this example. It can be proven that the formed thin film is relatively uniform with a thickness of approximately 16.1 μm.

[0074] Example Seven

[0075] In this example, the effects of copolymer concentration, copolymerization ratio, and light irradiation time on the thin film thickness were investigated, including the following steps:

[0076] a. Prepare aqueous solutions of PG1A with concentrations of 1 wt% and 20 wt% to fabricate copolymer thin films with different solid contents.

[0077] b. Prepare an aqueous solution of PEt m G1A n (m:n = 5 - 25) to fabricate copolymer thin films with different crosslinking degrees.

[0078] c. Prepare an aqueous solution of PEt m G1A n (m:n = 5.9) and set the light irradiation time from 3.0 - 20.0 s to fabricate copolymer thin films with different light irradiation times.

[0079] Take 3D photographs of the thin films prepared under different conditions using a confocal microscope and measure their thickness. The measurement results show that as the concentration of the copolymer aqueous solution increases, the thickness of the thin film increases. As the light irradiation time increases, the thickness of the thin film increases. When the light irradiation time reaches 10 s, further increasing the light irradiation time results in a less obvious change in the thin film thickness, and the thin film thickness basically reaches saturation. As the content of monomer MAc in the copolymer decreases, the thickness of the thin film decreases.

[0080] Example Eight

[0081] In this example, an optical microscope equipped with a heating stage device was used to determine the thermosensitive properties of the thin film prepared in Example Six:

[0082] The prepared film was cut into small pieces with a blade, heated from room temperature to 40 °C on a hot stage, and then restored to room temperature of 25 °C. Photographs of the film were taken at room temperatures of 25 °C, 35 °C, and 40 °C using a microscope. Since the shape of the cut film was uneven, a line was drawn between any two points on the film, and the image pro software was used to measure the length change before and after the phase transition process to calculate the shrinkage rate. Three different positions were statistically analyzed as parallel data, and the average shrinkage rate of the film was taken as the average shrinkage rate of the film. The thermosensitive experiment was repeated 5 times to explore the recovery of the film size with the increase in the number of thermosensitive cycles. The results showed that the average thermally induced volume shrinkage rate of the film decreased with the increase in the concentration of the copolymer PEtG1A.

[0083] Figure 6 This is the thermosensitive behavior of the dendrimerized poly(phenylacetylene) film in this example. Among them, Figure (a) is the optical microscope photographs of the films prepared under different conditions at 25 °C, 35 °C, 40 °C, and restored to 25 °C. Figure (b) is the curve of the copolymer film size change at different temperatures. Figure (c) is the size change of the film PG1A during 5 thermosensitive cycles. Changing the ratio of MN and MAc had less obvious influence on the average shrinkage rate of the film. The thermosensitive recovery behavior of the copolymer film was further explored. The size change of the copolymer film during multiple heating and cooling processes was observed with an optical microscope. After five thermosensitive cycles, the size of the film was basically the same as the initial state. It shows that this kind of dendrimerized phenylacetylene copolymer film has completely reversible thermosensitive shrinkage and swelling behaviors.

[0084] In summary, the above examples prepared two phenylacetylene monomers through molecular design and synthesis, and prepared a new type of radially amphiphilic dendrimerized phenylacetylene copolymer through copolymerization of the two monomers. The dendritic alkoxy ether units provided excellent thermosensitive properties for the copolymer, and the carbon-carbon double bond groups provided crosslinking sites for the copolymer. Due to the property of the copolymer to form a film by thermosensitive induction aggregation, the dendrimerized poly(phenylacetylene) film was directly prepared by ultraviolet crosslinking above the phase transition temperature. The thickness of the film was regulated by the copolymer concentration, copolymerization ratio, and illumination time. In addition, the film had excellent thermosensitive behavior, and the size did not change after multiple thermosensitive cycles. The present invention provides a new method for preparing polymer films by cross-linking polymerization reaction-induced assembly, and at the same time obtains intelligent responsive films, which have application prospects in the fields of intelligent separation, biomedicine, sensors, etc.

[0085] The above described the embodiments of the present invention in conjunction with the drawings, but the present invention is not limited to the above embodiments, and various changes can be made according to the purpose of the invention of the present invention. Any changes, modifications, substitutions, combinations, or simplifications made based on the spirit and principle of the technical solution of the present invention shall be equivalent replacement methods, as long as they meet the invention purpose of the present invention and do not deviate from the technical principle and inventive concept of the present invention, they all belong to the protection scope of the present invention.

Claims

1. A method for inducing self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction, characterized in that: A dendritic phenylacetylene copolymer PG1 with radial amphiphilicity was designed and synthesized m A n , and its structural formula is as follows: where m:n = 3 to 25:1; a = 1 to 3, b = 1 to 3; X = OEt or X = OMe; wherein, when X = OEt, then PG1 m A n is PEtG1 m A n ; when X = OMe, then PG1 m A n is PMeG1 m A n ; wherein, in the dendrimeric alkoxy ether moiety, the alkoxy chain adopts a three-arm structure; dissolve the dendritic phenylacetylene copolymer with radial amphiphilicity in water to obtain an aqueous copolymer solution, then heat the aqueous copolymer solution above the phase transition temperature, and prepare a dendritic poly(phenylacetylene) film with temperature-responsive behavior by ultraviolet light irradiation using a one-step cross-linking reaction.

2. The method for inducing self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction according to claim 1, characterized in that: when synthesizing the dendritic phenylacetylene copolymer with radial amphiphilicity, two phenylacetylene monomers are used: one of the phenylacetylene monomers contains a first-generation dendrimeric alkoxyether unit, and the other phenylacetylene monomer contains a carbon-carbon double bond functional group; the two phenylacetylene monomers are used to prepare a dendritic phenylacetylene copolymer with radial amphiphilicity by coordination copolymerization reaction; the double bond functional group provides a photocrosslinking site, the dendrimeric alkoxyether unit provides a hydrophilic and thermosensitive characteristic site, and the phenylacetylene main chain provides a hydrophobic and rigid structure.

3. The method for inducing self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction according to claim 1, characterized in that: the aqueous copolymer solution aggregates and assembles into a film-like assembly above the phase transition temperature, and a film material is prepared by ultraviolet light cross-linking.

4. The method for inducing self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction according to claim 1, characterized in that: by adjusting at least one of the condition parameters of copolymer concentration, light intensity, light irradiation time and copolymerization ratio, the thickness of the prepared film can be controlled.

5. The method for inducing self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction according to claim 1, characterized in that: the thermally induced volume shrinkage rate of the formed dendritic poly(phenylacetylene) film can be regulated by changing the copolymer concentration.

6. The method for inducing self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction according to claim 1, characterized in that, comprises the following steps: (1) Synthesis of monomer MN: Using the amino-terminated first-generation dendritic alkoxy ether unit G1-NH 2 as the raw material, dissolve the compound G1-NH 2 in dry dichloromethane at a temperature not higher than 0 °C, then add N,N-diisopropylethylamine and 4-ethynyl pentafluorophenol ester, raise the temperature to room temperature after at least 30 minutes, and react under nitrogen protection for at least 6 hours; after determining the completion of the reaction by TLC plate, spin-dry the solvent, and then purify by column chromatography. After spinning-drying the solvent, the product obtained is a colorless transparent oily liquid and is reserved for use; the monomer MN synthesis route is as follows: (2) Synthesis of monomer MAc: Dissolve OEG-NH 2 in dry dichloromethane, add N,N-diisopropylethylamine. At the same time, dissolve 4-ethynylpentafluorophenyl ester in dry dichloromethane and transfer it to a constant pressure funnel. Slowly add the 4-ethynylpentafluorophenyl ester dropwise under an ice-salt bath and nitrogen protection, and react for at least 8 h. After determining the completion of the reaction by TLC plate, rotary evaporate the solvent, and purify it by column chromatography. After rotary evaporating the solvent, a colorless transparent oily liquid product PA-OH is obtained. Then add Et 3 N to the dichloromethane of PA-OH and react with acryloyl chloride for at least 8 h. After determining the completion of the reaction by TLC plate, add a few drops of methanol to quench the reaction, wash it with saturated brine at least three times, take the lower organic phase and rotary evaporate the solvent, and then purify it by column chromatography. After rotary evaporating the solvent, the product obtained is a white solid. The synthetic route of monomer MAc is as follows: (3) Copolymer PG1 m A n Synthesis: Dissolve the monomer MN prepared in the step (1) and the monomer MAc prepared in the step (2) in dry tetrahydrofuran according to a certain mass ratio, and feed them according to a molar ratio of MN to MAc of 3 to 25:1; freeze with liquid nitrogen and freeze-dry under high vacuum for at least 15 minutes, repeat at least three times to remove the residual water and impurities in the monomers; then thaw and restore to room temperature, and add [Rh(nbd)Cl] with a syringe under a nitrogen atmosphere 2 and Et 3 N tetrahydrofuran solution; and react under nitrogen protection at room temperature for at least 8 hours, spin-dry the solvent and purify by column chromatography with dichloromethane to obtain an orange-red copolymer PG1 m A n ; (4) Preparation of the reaction mixture: dissolve the copolymer prepared in the step (3) in deionized water, then add a photoinitiator, stir evenly to obtain a reaction mixture for standby; in the prepared reactant mixed solution, the mass fraction of the copolymer is 2-20 wt%, and the mass fraction of the photoinitiator is 0.5-1 wt%; (5) Photoirradiation cross-linking polymerization reaction to regulate the synchronous self-assembly of dendritic poly(phenylacetylene) into a film: heat the reaction mixture prepared in the step (4) above the phase transition temperature, and prepare a branched poly(phenylacetylene) film by ultraviolet light irradiation in one step.

7. The method for inducing self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction according to claim 6, characterized in that: in the step (5), control the ultraviolet light irradiation time to be 3-20 s.

8. The method for inducing self-assembly of poly(phenylacetylene) into a film by photoirradiation cross-linking polymerization reaction according to claim 6, characterized in that: In the step (5), control the light intensity setting to be not less than 250 mJ / cm 2 .

Images