CN111234303A

CN111234303A - Preparation method of hydrophobic star polymer porous membrane

Info

Publication number: CN111234303A
Application number: CN202010040398.7A
Authority: CN
Inventors: 张洪文; 李欣; 马媛媛; 丁颜; 郭秋月; 刘俊; 胡建; 顾钦天; 姜彦�
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2020-01-15
Filing date: 2020-01-15
Publication date: 2020-06-05
Anticipated expiration: 2040-01-15
Also published as: CN111234303B

Abstract

The invention relates to the field of porous materials and hydrophobic materials, in particular to a preparation method of a hydrophobic star polymer porous membrane. Synthesizing octachloropropyl polyhedral oligomeric silsesquioxane initiator by using 3- (chloropropyl) trimethoxy silane as a monomer, concentrated hydrochloric acid as a catalyst and anhydrous methanol as a solution through solution polymerization. Then synthesizing POSS-b-PS-b-PHEMA block copolymer by using octachloropropyl polyhedral oligomeric silsesquioxane, styrene, hydroxyethyl methacrylate, 2-2 bipyridine and cuprous chloride as raw materials through an atom transfer radical polymerization method, and preparing the porous film by using a breathing pattern method. And then the porous membrane is infused with the modified silicone oil to prepare the hydrophobic star polymer porous membrane. The preparation method is simple and easy to operate, and the prepared film has excellent hydrophobic antibacterial effect, is modified in transparency and has wide application prospect.

Description

Preparation method of hydrophobic star polymer porous membrane

Technical Field

The invention relates to the field of porous materials and hydrophobic materials, in particular to a preparation method of a hydrophobic star polymer porous membrane.

Background

Porous materials can be classified into microporous materials (smaller than 2nm), mesoporous materials (2-50 nm) and mesoporous materials (larger than 50nm) according to the pore size. The preparation method of the porous material comprises a direct template method, block copolymerization self-assembly and a direct synthesis method. The direct template method is a simple and commonly used method. The preparation method comprises the steps of infiltrating or adsorbing raw materials onto the surface of the template or in the gaps of the template, then polymerizing or solidifying the dispersed raw materials in situ, and finally removing the template. The block polymer for preparing the porous material can be used as a pore template to be self-assembled with the prepolymer, and then pores are formed by etching, or can be used as a raw material of a porous polymer framework. The porous material prepared by the direct synthesis method is influenced by factors such as monomer structure, reaction type, reaction conditions and the like. The porous material has the advantages of high porosity, large specific surface area, uniform pore canal size, ordered arrangement, adjustable pore diameter, biological activity and the like, and can be applied to the fields of adsorption and separation media, catalysis, biomedical molecular recognition, energy storage, photoelectric materials and the like.

Materials can be classified into hydrophilic materials and hydrophobic materials according to their water-repellent ability on the surface. The surface of the material with the water contact angle smaller than 90 degrees is hydrophilic material, and the material with the water contact angle larger than 90 degrees is hydrophobic material. Reducing the surface energy of the material and building a rough surface structure are key to the study of hydrophobic materials. Accordingly, the hydrophobic material may be prepared by etching, vapor deposition, electrospinning, sol-gel, self-assembly, polymer swelling, spraying, and the like. Due to the unique advantages, the hydrophobic material is widely applied to the aspects of fluid transportation, antifouling, antifogging, anti-icing, self-cleaning, oil-water separation, antibiosis and the like.

At present, there are reports related to the hydrophobic porous membrane in the prior art, such as "CN 201710661229.3, a preparation method of hydrophobic surface" which adopts a water drop template method to form a porous structure on the surface of a block copolymer PS-b-PMMA thin film, and then the hydrophobic surface is obtained by reducing immersion in silicone oil. Wherein the amphiphilic polymer forming the porous structure has one hydrophilic end and one hydrophobic end, i.e. the inside is oleophilic and the outside is hydrophilic; after the silicone oil is poured, the holes can contract inwards due to the affinity effect, so that the silicone oil is coated more tightly, the oil locking capacity is stronger compared with that of a common polymer, the loss speed of the silicone oil is reduced, and the service life of the hydrophobic surface is prolonged. Although the amphiphilic polymer is taught to be more beneficial to the preparation of the hydrophobic surface, the porous structure obtained by the method is poor in regularity, the sizes of pores are seriously uneven, the contact angle of the obtained hydrophobic film is 108.7 degrees at best, and the contact angle of the obtained hydrophobic film is obviously reduced along with the increase of time when the hydrophobic film is placed in an air environment. Further research is needed to improve the regularity of the porous membrane, improve the hydrophobic property, and improve the stability and durability of the hydrophobic surface.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method of a hydrophobic star polymer porous membrane, which has simple and convenient process and simple reaction conditions.

The method comprises the following specific steps:

(1) synthesis of octachloropropyl cage type silsesquioxane initiator

Mixing 3- (chloropropyl) trimethoxy silane, concentrated hydrochloric acid and anhydrous methanol, and stirring and reacting at the heating temperature of 40 ℃ and the rotation speed of 400rpm for 7 days to obtain the octachloropropyl polyhedral oligomeric silsesquioxane initiator.

Wherein the volume ratio of the 3- (chloropropyl) trimethoxy silane to the concentrated hydrochloric acid to the anhydrous methanol is 5: 4: 100.

(2) synthesis of POSS-b-PS-b-PHEMA star copolymer

Adding styrene, octachloropropyl polyhedral oligomeric silsesquioxane, cuprous chloride, 2' -bipyridyl, hydroxyethyl methacrylate and a solvent into a Schlenk bottle, and reacting for 24 hours at an oxygen-free and anhydrous temperature of 110 ℃ by an Atom Transfer Radical Polymerization (ATRP) method to synthesize the POSS-b-PS-b-PHEMA star-shaped copolymer.

Wherein the mol ratio of the octachloropropyl polyhedral oligomeric silsesquioxane to the cuprous chloride to the 2, 2' -bipyridyl is 1: 1: 3. the mol ratio of the styrene to the hydroxyethyl methacrylate is 50-200: 5-10.

(3) Modifying the silicone oil;

the hydrophobic nano silicon dioxide with a certain proportion, room temperature curing silicone rubber and silicone oil are mechanically stirred and mixed evenly to prepare the improved silicone oil.

The hydrophobic nano silicon dioxide can be well dispersed in the silicone oil to form a micro-nano structure, so that the hydrophobicity can be improved. The room temperature cured silicone rubber can be used as an adhesive, and the silicone oil can also be swelled in the cured silicone rubber, when a surface oil layer is destroyed, the silicone oil swelled in the cured silicone rubber can be diffused to the surface, and the silicone oil can be self-supplied, so that the oil locking capacity is improved. The stable contact angle of the film can be improved, and the hydrophobic durability can be improved.

(4) Preparation of porous film

Weighing POSS-b-PS-b-PHEMA star-shaped copolymer, dissolving in chloroform, and carrying out ultrasonic treatment until the copolymer is dissolved. And (3) coating the polymer solution after complete dissolution on a glass slide in a constant-temperature water bath heating and wetting environment at 40 ℃, and evaporating the solvent along with steam to obtain a porous film of the polymer on the glass slide by a breathing pattern method. And then pouring silicone oil into the porous film, and vertically hanging to remove the redundant silicone oil to obtain the hydrophobic star polymer porous film.

Wherein the concentration of the polymer solution is in the range of 12.5mg/ml to 37.5mg/ml, pore formation is difficult at a concentration of less than 12.5mg/ml, and pore collapse is caused at a concentration of more than 37.5 mg/ml. According to the invention, through selection of components and concentration, the porous membrane with uniform size is finally prepared, so that the hydrophobic property of the membrane is obviously improved.

(5) Preparation of hydrophobic films

Dissolving the POSS-b-PS-b-PHEMA star-shaped copolymer in chloroform, carrying out ultrasonic treatment until the POSS-b-PS-b-PHEMA star-shaped copolymer is dissolved, heating in a constant-temperature water bath under a humid environment (40-60 ℃), coating the polymer solution which is completely dissolved on a glass slide, evaporating the solvent along with steam, obtaining a porous film of a polymer on the glass slide by a breathing pattern method, pouring improved silicone oil into the porous film, and vertically hanging to remove redundant silicone oil to obtain the hydrophobic star-shaped polymer porous film.

The POSS-b-PS-b-PHEMA star-shaped copolymer takes POSS as a core, PS as a near-core layer (hydrophobic end), PHEMA as a far-core layer (hydrophilic end), the hydrophobic end is arranged inside, and the hydrophilic end is arranged outside. The structural formula is as follows:

according to the invention, the porous membrane with uniform pore size and pore distribution is prepared by determining the dissolution concentration of the polymer, and after oil filling modification, the regular structure can obviously improve the stability and oil locking capacity of the hydrophobic surface.

Compared with the conventional silicone oil, the filling of the improved silicone oil can further improve the oil locking capacity and the hydrophobic durability of the film, and moreover, the light transmission of the film can be obviously improved after the silicone oil is filled, and the light transmission is close to that of glass. The improvement of the material, whether in hydrophobic property or optical property, is obviously improved, and the material has wide application prospect in transparent materials and self-cleaning materials.

Drawings

FIG. 1 is a Fourier IR spectrum of POSS and POSS-b-PS-b-PHEMA of example 1, where a is POSS and 1274cm^-1Is the stretching vibration peak of Si-C, 1110cm^-1Is the stretching vibration peak of Si-O-Si, 698cm^-1Is the peak of C-CL stretching vibration. b is POSS-b-PS-b-PHEMA, 3457cm^-1Is the stretching vibration peak of-OH, 3100-^-1Is the stretching vibration peak of benzene ring C-H, 1629cm^-1Is the stretching vibration peak of benzene ring C ═ O, 1620-^-1Is the stretching vibration peak of benzene ring C ═ C. Thus, the POSS and the POSS-b-PS-b-PHEMA are successfully synthesized.

FIG. 2 is a diagram of POSS and POSS-b-PS-b-PHEMA in example 1₁H nuclear magnetic map. In the figure, a is POSS, and delta-0.8 ppm is-CH₂Hydrogen of-Si,. delta.1.8 ppm is-CH₂-CH₂-hydrogen, δ ═ 3.62ppm is-CH₂-hydrogen of Cl. b is POSS-b-PS-b-PHEMA, delta is 6.55ppm,7.07ppm is hydrogen of benzene ring, and delta is-CH at 1.8ppm₂-CH₂-hydrogen, δ ═ 1.42ppm, 1.85ppm are vinyl hydrogens, δ ═ 3.6ppm are methylene hydrogens attached to the ester group. Thus, the POSS and the POSS-b-PS-b-PHEMA are successfully synthesized.

FIG. 3 is a scanning electron micrograph of a POSS-b-PS-b-PHEMA porous membrane prepared in example 1; as can be seen from FIG. 3, the pores with uniform size are formed on the surface of the membrane and are uniformly distributed, and the pore diameter is about 2 um.

FIG. 4 a is a graph showing the contact angle of the aqueous phase of the porous membrane impregnated with the modified silicone oil in example 1, in which the static contact angle reached 113 ℃ and the membrane was hydrophobic. b is a water phase contact angle diagram of the porous membrane impregnated with the unmodified silicone oil in comparative example 1, the static contact angle reaches 107 degrees, and the porous membrane is in a hydrophobic state.

In FIG. 5, the left image is a light transmittance of the porous film without pouring the modified silicone oil in example 1, the middle image is a light transmittance of the porous film with pouring the modified silicone oil in example 1, and the right image is a light transmittance of the glass sheet. The light transmittance of the porous membrane after being infused with the silicone oil is close to that of glass and is better than that of the porous membrane without being infused with the silicone oil.

FIG. 6 is a scanning electron micrograph of a POSS-b-PS-b-PHEMA porous membrane prepared in comparative example 4.

Detailed Description

Embodiments of the present invention will now be described in detail with reference to the following examples, which are intended to be illustrative of the present invention and should not be construed as limiting the scope of the invention. The conditions in the examples are not specifically mentioned, and are selected according to the conventional conditions. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1

(1) Synthesis of octachloropropyl cage type silsesquioxane initiator

10ml of 3- (chloropropyl) trimethoxysilane, 8ml of concentrated hydrochloric acid and 200ml of anhydrous methanol are added into a single-neck flask, and the mixture is stirred and reacted for 7 days at the heating temperature of 40 ℃ and the rpm of 400 to obtain the octachloropropyl polyhedral oligomeric silsesquioxane initiator.

(2) Synthesis of POSS-b-PS-b-PHEMA star copolymer

0.2g of octachloropropyl polyhedral oligomeric silsesquioxane, 0.02g of cuprous chloride and 0.1g of 2, 2' -bipyridyl, 4ml of styrene, 0.24ml of hydroxyethyl methacrylate and 1-2ml of N, N-dimethylformamide or toluene are added into a Schlenk bottle and reacted for 24 hours at the temperature of 110 ℃ in the absence of oxygen and water by an Atom Transfer Radical Polymerization (ATRP) method to synthesize the POSS-b-PS-b-PHEMA star-shaped copolymer.

(3) Improved silicone oil

0.5g of hydrophobic nano silicon dioxide, 0.1g of room temperature curing silicone rubber (prepared in situ by adopting a traditional method, and the preparation method is the room temperature vulcanized silicone rubber in CN 201410378042.9) and 10g of silicone oil are uniformly mixed to prepare the improved silicone oil.

(4) Preparation of porous film Material

12.5mg of POSS-b-PS-b-PHEMA star copolymer is weighed and dissolved in 1ml of chloroform, and the ultrasonic treatment is carried out until the solubility is 12.5 mg/ml. And (3) coating the polymer solution after complete dissolution on a glass slide in a constant-temperature water bath heating and wetting environment at 40 ℃, and evaporating the solvent along with steam to obtain a porous film of the polymer on the glass slide by a breathing pattern method. And then pouring improved silicone oil into the porous membrane, and vertically hanging to remove the redundant silicone oil to obtain the hydrophobic star polymer porous membrane.

FIG. 1 is a graph showing the water contact angle of the POSS-b-PS-b-PHEMA porous membrane of example 1, and the static contact angle reaches 113 deg. There was substantially no change in contact angle after 5 days at room temperature.

Comparative example 1

Comparative example 1 is different from example 1 in that: and (4) replacing the silicone oil which is improved in the step (4) by conventional silicone oil, and keeping the rest operations unchanged.

Comparative example 1a

Comparative example 1a differs from example 1 in that: and (4) replacing the silicone oil which is improved in the step (4) with silicone oil which is not poured, and keeping the rest operations unchanged.

When the film without silicone oil is used for detecting the contact angle, a liquid-gas interface is formed between water and the surface of the porous film, but the surface is not a liquid-liquid interface, although the surface is hydrophobic (90 degrees), the hydrophobic stability is poor, and the transparency of the film is poor.

Example 2

(1) Synthesis of octachloropropyl cage silsesquioxane initiator as in example 1;

(2) POSS-b-PS-b-PHEMA star copolymer is synthesized, and the same as the example 1;

(3) modified silicone oil, as in example 1;

(4) preparing a porous film material, changing the solution concentration of 12.5mg/ml POSS-b-PS-b-PHEMA star copolymer in the step (4) of the example 1 into 25mg/ml, and carrying out the rest operations.

Comparative example 2

Comparative example 2 differs from example 2 in that: the modified silicone oil is replaced by unmodified silicone oil, namely pure silicone oil, and other operations and conditions are not changed.

Example 3

Example 3 compared to example 1, the main differences are: 12.5mg of POSS-b-PS-b-PHEMA star copolymer is changed into 37.5mg, and the rest operations are unchanged.

Comparative example 3

Comparative example 3 differs from example 3 in that: the modified silicone oil is replaced by unmodified silicone oil, namely pure silicone oil, and other operations and conditions are not changed.

Comparative example 4

Comparative example 4 is different from example 1 in that: the 12.5mg POSS-b-PS-b-PHEMA star copolymer is changed into 40.0mg, and the rest operations are unchanged.

The surface contact angle of the film was found to be 93 °, and the contact angle was found to be 90 ° after 5 days at room temperature.

FIG. 6 is a scanning electron micrograph of a POSS-b-PS-b-PHEMA porous membrane prepared in comparative example 4. As can be seen from fig. 6, the porous membrane has poor uniformity of pore size on the surface thereof, so that both hydrophobicity and hydrophobic stability thereof are reduced.

Table 1 shows the contact angle data measured directly after pouring silicone oil into examples 1 to 3 and comparative examples 1 to 3.

TABLE 1

Table 2 shows contact angle data measured 5 days after the silicone oil infusion of examples 1 to 3 and comparative examples 1 to 3.

TABLE 2

The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified. The foregoing describes alternative embodiments of the invention to teach those skilled in the art how to make and reproduce the invention. Some conventional technical aspects have been simplified and omitted for the purpose of teaching the inventive arrangements. Those skilled in the art will appreciate variations from this aspect that fall within the scope of the invention.

Claims

1. A method for producing a hydrophobic star polymer porous membrane, characterized in that: the preparation method comprises the following steps:

(1) synthesizing an octachloropropyl cage type silsesquioxane initiator, and then synthesizing a POSS-b-PS-b-PHEMA star copolymer;

(2) preparing improved silicone oil: uniformly mixing hydrophobic nano silicon dioxide, room-temperature cured silicone rubber and silicone oil to prepare improved silicone oil;

(3) weighing POSS-b-PS-b-PHEMA star-shaped copolymer, dissolving in an organic solvent, carrying out ultrasonic treatment until the POSS-b-PS-b-PHEMA star-shaped copolymer is dissolved, and obtaining a porous film of the polymer by a respiratory pattern method; and then pouring improved silicone oil into the porous film, and vertically hanging to remove the redundant silicone oil to obtain the hydrophobic star polymer porous film.

2. The method for producing a hydrophobic star polymer porous membrane according to claim 1, characterized in that: the specific synthetic method of the octachloropropyl cage type silsesquioxane in the step (1) comprises the following steps: mixing 3- (chloropropyl) trimethoxy silane, concentrated hydrochloric acid and anhydrous methanol, and stirring to react under heating condition to obtain octachloropropyl polyhedral oligomeric silsesquioxane initiator.

3. The method for producing a hydrophobic star polymer porous membrane according to claim 2, characterized in that: 3- (chloropropyl) trimethoxy silane, concentrated hydrochloric acid and anhydrous methanol in a volume ratio of 5: 4-5: 100.

4. the method for producing a hydrophobic star polymer porous membrane according to claim 1, characterized in that: the specific method of the POSS-b-PS-b-PHEMA star copolymer comprises the following steps: octa-chloropropyl polyhedral oligomeric silsesquioxane is used as an initiator, styrene is used as a monomer, cuprous chloride, 2' -bipyridyl, hydroxyethyl methacrylate and a solvent are added, and the POSS-b-PS-b-PHEMA star-shaped copolymer is synthesized by an Atom Transfer Radical Polymerization (ATRP) method in an oxygen-free and water-free environment.

5. The method for producing a hydrophobic star polymer porous membrane according to claim 4, characterized in that: the solvent is N, N-dimethyl amide or toluene.

6. The method for producing a hydrophobic star polymer porous membrane according to claim 5, characterized in that: octachloropropyl polyhedral oligomeric silsesquioxane, cuprous chloride, 2, 2' -bipyridyl, styrene and hydroxyethyl methacrylate in a molar ratio of 1: 1: 3: 50-200: 5-10.

7. The method for producing a hydrophobic star polymer porous membrane according to claim 1, characterized in that: the mass ratio of the hydrophobic nano silicon dioxide, the room temperature curing silicone rubber and the silicone oil is 0.5-2: 0.01-0.1: 10.

8. the method for producing a hydrophobic star polymer porous membrane according to claim 1, characterized in that: the specific method of the hydrophobic star polymer porous membrane in the step (3) is as follows: dissolving the POSS-b-PS-b-PHEMA star-shaped copolymer in chloroform, carrying out ultrasonic treatment until the POSS-b-PS-b-PHEMA star-shaped copolymer is dissolved, coating the polymer solution which is completely dissolved on a glass slide under a constant-temperature water bath heating and wetting environment at 40-60 ℃, evaporating the solvent along with steam to obtain a porous film of the polymer on the glass slide, then pouring improved silicone oil into the porous film, and vertically hanging to remove the redundant silicone oil to obtain the hydrophobic star-shaped polymer porous film.

9. The method for producing a hydrophobic star polymer porous membrane according to claim 8, characterized in that: the concentration of the polymer solution is 12.5 mg/ml-37.5 mg/ml.