Silicon-containing block copolymer, method for preparing the same, and use thereof

Abstract

The application discloses a kind of silicon-containing block copolymer and its preparation method and application, with carboxyl-terminated polystyrene, single end hydroxypropyl polydimethylsiloxane as raw material, to prepare the above-mentioned silicon-containing block copolymer;With the fabric of polymer solution in steam environment Induced phase separation, build water-repellent durable coating on the surface of fabric, obtain water-repellent fabric.The application adopts steam induced phase separation method, by controlling process parameters such as steam type, solvent type and the silicon content of polymer, etc., try to build rough structure coating on the surface of different structure polyester, prepare super-hydrophobic fabric, microsphere structure surface is more conducive to the improvement of polyester hydrophobicity, the highest static water contact angle can reach 166.9±0.2°, and finishing fabric has good wearability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of advanced materials, and relates to a silicon-containing block copolymer, in particular to application of the silicon-containing block copolymer in preparation of super-hydrophobic fabric. BACKGROUND

[0002] Super-hydrophobic function can help to keep the surface clean and reduce the load and movement resistance in a short time, but the durability is the biggest test of the hydrophobic function, and the waterproof ability can be rapidly weakened or even disappeared under the harsh environment or abrasion. Polydimethylsiloxane (PDMS) is most commonly applied in self-cleaning, oil-water separation and anti-icing fields, and the disadvantage of PDMS is insufficient strength, so that other materials, such as commonly used nano materials (silver nanowires, carbon nanotubes, etc.) and inorganic fillers (silicon dioxide, titanium dioxide, etc.), are often added when PDMS is used as a coating material, which limits the application of the coating material in fabric finishing. SUMMARY

[0003] The present application adopts a RAFT polymerization method to synthesize block copolymers with different silicon contents, and adopts FT-IR, 1 H-NMR to characterize the chemical structure of the target product. A steam-induced phase separation method is adopted to try to construct a rough structure coating on the surface of different structures of polyester and prepare super-hydrophobic fabric by controlling process parameters such as steam type, solvent type and silicon content of the polymer.

[0004] The present application adopts the following technical solutions.

[0005] A silicon-containing block copolymer has the following chemical structure:

[0006] .

[0007] In the present application, the above-mentioned silicon-containing block copolymer is PS- b -PDMS, and the number average molecular weight thereof is 2000-20000, and the preferred number average molecular weight is 3000-15000; in the silicon-containing block copolymer, the number average molecular weight of the trithiopolyphenyl ethylene segment is 1000-9000.

[0008] Further preferably, in the above-mentioned silicon-containing block copolymer, the number average molecular weight of the polydimethylsiloxane is 30%-70% of the number average molecular weight of the silicon-containing block copolymer, preferably 40%-60%, and more preferably 50%-60%.

[0009] The present application discloses a preparation method of the above-mentioned silicon-containing block copolymer, which comprises the following steps: taking carboxyl-terminated polystyrene and single-end hydroxypropyl polydimethylsiloxane as raw materials to prepare the above-mentioned silicon-containing block copolymer.

[0010] Further, in the imidazole compound, such asN,N Carbonyl diimidazole, with carboxyl-terminated polystyrene, single end hydroxypropyl polydimethylsiloxane as raw material, preparation of the above-mentioned containing silicon block copolymer.

[0011] In the present application, with S,S' - double (α, α'-dimethyl-α''-acetic acid) trithiocarbonate, styrene as raw material, preparation of carboxyl-terminated polystyrene. Further, in the presence of azo initiator, such as azobisisobutyronitrile, with S,S' - double (α, α'-dimethyl-α''-acetic acid) trithiocarbonate, styrene as raw material, preparation of carboxyl-terminated polystyrene.

[0012] Preferably, the number average molecular weight of carboxyl-terminated polystyrene is 1000-9000, preferably 2000-6000; the number average molecular weight of single end hydroxypropyl polydimethylsiloxane is 500-5000, preferably 1000-3000.

[0013] Preferably, with carboxyl-terminated polystyrene, single end hydroxypropyl polydimethylsiloxane as raw material, incubated at 50-90℃ for 3-10h, preferably incubated at 60-80℃ for 4-8h, preparation of the above-mentioned containing silicon block copolymer.

[0014] Preferably, with S,S' - double (α, α'-dimethyl-α''-acetic acid) trithiocarbonate, styrene as raw material, incubated at 50-90℃ for 10-30h, preferably incubated at 60-80℃ for 15-25h, preparation of carboxyl-terminated polystyrene.

[0015] The application discloses a water-repellent fabric and a preparation method thereof, comprising the following steps: inducing phase separation of a fabric with a polymer solution in a steam environment, constructing a water-repellent and durable coating on the surface of the fabric, and obtaining the water-repellent fabric; the polymer is the above-mentioned containing silicon block copolymer.

[0016] In the polymer solution of the present application, the polymer is the above-mentioned containing silicon block copolymer PS- b -PDMS, the solvent comprises THF (tetrahydrofuran), CS2; the concentration of the polymer solution is 20-80 mg / mL, preferably 30-60 mg / mL.

[0017] In the present application, the polymer solution is poured on the surface of the fabric to form a fabric with a polymer solution. Preferably, the ratio of the upper surface area of the fabric to the polymer solution is 4 cm 2 : (10-100) μL, further, the ratio of the upper surface area of the fabric to the polymer solution is 4 cm 2 : (20-80) μL, further, the ratio of the upper surface area of the fabric to the polymer solution is 4 cm 2: (25-50) μL; as common sense, the upper surface of the fabric is the surface for receiving the polymer solution.

[0018] In the present application, the steam includes water vapor and organic solvent vapor, preferably, the organic solvent includes small molecule alcohol such as ethanol. Preferably, the steam environment is a saturated steam environment.

[0019] In the present application, the fabric is placed in the steam environment, the polymer solution is added to the surface of the fabric, and the water-repellent durable coating is constructed. Preferably, the preparation of the water-repellent fabric is carried out at room temperature.

[0020] The present application discloses the application of the above-mentioned silicon-containing block copolymer in the preparation of water-repellent materials, especially in the preparation of water-repellent fabrics.

[0021] The present application discloses the application of the above-mentioned water-repellent fabric in the preparation of functional fabrics; preferably, in the preparation of hydrophobic fabric, ultraviolet-resistant fabric, acid and alkali-resistant fabric or self-cleaning fabric.

[0022] In the present application, the fabric is a natural fiber fabric or a chemical fiber fabric, such as cotton fabric, polyester fabric, etc.

[0023] In the present application, different silicon-containing block copolymers (PS- b -PDMS) are synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) method and used for finishing fabrics: the chemical structure of the target product is determined by FT-IR and 1 H-NMR; the molecular weight and molecular weight distribution of different carboxyl-terminated polystyrene are characterized by GPC, further proving the success and controllability of polymerization. Subsequently, PS- b -PDMS is finished on four different textured polyesters by vapor-induced phase separation process (VIPS). Water vapor and ethanol vapor are used as atmosphere variables, respectively, and the changes of the surface morphology and hydrophobicity of the polyester under the conditions of solvent (THF and CS2), silicon content and fabric texture are studied. The research shows that in the water vapor atmosphere, the polyester surface has a tendency to form microporous structure, but the distribution is very small; in the ethanol vapor atmosphere, more microsphere structures are formed, but mainly distributed in the fiber gullies. In addition, the surface of the microsphere structure is more conducive to the improvement of the hydrophobicity of the polyester, and the highest static water contact angle can reach 166.9 ± 0.2°, and the finished fabric has good wearability. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 In order to synthesize S,S' -bis (α, α'-dimethyl-α''-acetic acid) trithiocarbonate, carboxyl-terminated polystyrene by RAFT method, and the route for synthesizing PS- b -PDMS block copolymer.

[0025] Figure 2 for S,S' IR spectrum (top) and H NMR spectrum (bottom) of -bis(α,α'-dimethyl-α"-acetic acid) trithiocarbonate.

[0026] Figure 3 The GPC spectra of carboxyl-terminated polystyrene synthesized with different feed ratios.

[0027] Figure 4 For carboxyl-terminated polystyrene (black line) and PS- b -Infrared spectrum of PDMS (red line).

[0028] Figure 5 For carboxyl-terminated polystyrene and PS- b -H NMR spectrum of PDMS: the black line is carboxyl-terminated polystyrene, the red line is PS- b -PDMS, * is deuterated chloroform, ** is deuterated dimethyl sulfoxide.

[0029] Figure 6 Schematic diagram of the steam-induced phase separation reaction device.

[0030] Figure 7 SEM images and static water contact angles of untreated polyester surfaces: (a) polyester taffeta, (b) thick polyester, (c) combed polyester, and (d) cotton-like polyester.

[0031] Figure 8 SEM images of the comparative experiment of vacuum drying film formation of polyester taffeta: (a) 30% silicon content, (b) 50% silicon content, and (c) 60% silicon content.

[0032] Figure 9 With THF as solvent, PS- b -SEM images of PDMS phase separation in a water vapor atmosphere: (a1-a3) polyester taffeta, (b1-b3) thick polyester, (c1-c3) combed polyester, (d1-d3) cotton-like polyester; (a1, b1, c1, d1) 30% silicon content, (a2, b2, c2, d2) 50% silicon content, (a3, b3, c3, d3) 60% silicon content.

[0033] Figure 10 With CS2 as solvent, PS- b -SEM images of PDMS phase separation under water vapor atmosphere: (a1-a3) polyester taffeta, (b1-b3) thick polyester, (c1-c3) combed polyester, (d1-d3) cotton-like polyester; (a1, b1, c1, d1) 30% silicon content, (a2, b2, c2, d2) 50% silicon content, (a3, b3, c3, d3) 60% silicon content.

[0034] Figure 11 SEM images of phase separation of PS-PDMS in ethanol vapor atmosphere: (a1-a3) terry, (b1-b3) thick polyester, (c1-c3) combed polyester, (d1-d3) cotton-like polyester; (a1, b1, c1, d1) 30% of block copolymer silicon content, (a2, b2, c2, d2) 50% of block copolymer silicon content, (a3, b3, c3, d3) 60% of block copolymer silicon content. b

[0035] SEM images of phase separation of PS-PDMS in ethanol vapor atmosphere: (a1-a3) terry, (b1-b3) thick polyester, (c1-c3) combed polyester, (d1-d3) cotton-like polyester; (a1, b1, c1, d1) 30% of block copolymer silicon content, (a2, b2, c2, d2) 50% of block copolymer silicon content, (a3, b3, c3, d3) 60% of block copolymer silicon content. Figure 12 b

[0036] Figure 13 Particle size distribution of microspheres with THF as solvent and ethanol as atmosphere: (a) 60% of block copolymer silicon content, terry fabric, (b) 50% of block copolymer silicon content, combed polyester fabric.

[0037] Figure 14 Infrared spectrum of combed polyester before and after treatment (a) and XPS spectrum of combed polyester after treatment (b).

[0038] Figure 15 Contact angle of water on the surface of different polyesters treated with block copolymer: (a) water vapor atmosphere, THF as solvent; (b) water vapor atmosphere, CS2 as solvent; (c) ethanol atmosphere, THF as solvent; (d) ethanol atmosphere, CS2 as solvent.

[0039] Figure 16 Combed polyester treated with 50% of block copolymer silicon content in THF as solvent under ethanol vapor atmosphere: (a) untreated polyester exposed in water solution; (b) treated polyester exposed in water solution; (c) state of different liquid droplets on the surface of treated fabric.

[0040] Figure 17 Combed polyester treated with 50% of block copolymer silicon content in THF as solvent under ethanol vapor atmosphere: (a) ability to adsorb carbon tetrachloride (heavy oil) in water solution; (b) ability to adsorb corn oil in water solution.

[0041] Figure 18 TG and DTG curves of combed polyester after treatment by ethanol vapor induced phase separation (nitrogen atmosphere).​​

[0042] Figure 19 Histograms of static contact angles of combed polyester to water after ethanol vapor-induced phase separation: (a) adhesive resistance and (b) washability.

[0043] Figure 20 pH stability of combed polyester finished by ethanol vapor-induced phase separation: (a) static contact angle bar graph and (b) SEM images after acid and base immersion for 24 h.

[0044] Figure 21 These are the water contact angle stability test results of fabrics treated with block polymer PDMS-b-PS and block polymer PS-b-PDMS. DETAILED DESCRIPTION

[0045] The reagents and raw materials involved in this invention are existing products. The specific preparation operations and performance tests are all conventional technologies. Weigh 1.2 g of tris (hydroxymethyl)aminomethane and dissolve it in water. The solution is controlled to pH = 8.5 by adding hydrochloric acid dropwise to prepare a 10 mM Tris-HCl buffer solution. Polyester taffeta, 70 g / m 2 Combed polyester, 117 g / m 2 Cotton-like polyester, 123 g / m 2 Thick polyester, 182g / m 2 .

[0046] The synthesized intermediates and final polymers were tested using a Thermo Scientific Nicolet iS5 infrared spectrometer. The synthesized products were analyzed by hydrogen nuclear magnetic resonance spectroscopy using a BRUKER AVANCE NEO 400MHz nuclear magnetic resonance spectrometer. After the sample was placed in an NMR tube, deuterated reagents (deuterated chloroform and deuterated DMSO) were added to dissolve it, and tetramethylsilane (TMS) in the deuterated reagent was used as an internal standard for testing. The number average molecular weight (Mn) and molecular weight distribution (PDI) of the polymer were determined at 40°C using a Tosoh HLC-8320 size exclusion chromatography column (SEC) and a TSK GelMULTIITE HZ-N (3) 4.6×150 mm column. Tetrahydrofuran (THF) was used as the eluent at a flow rate of 0.35 mL·min. -1. SEC samples were injected using a Tosoh HLC-8320 GPC plus automatic sampler. The molecular weight was calibrated using a narrow polydispersity PS standard. The morphology of the samples was characterized using a cold field emission scanning electron microscope (SU8100). A scanning electron microscope (EVO 18SEM) equipped with an energy dispersive X-ray spectrometer was used to obtain the element content and distribution on the fabric surface. The ThermoScientific Nexsa X-ray photoelectron spectrometer was used to test the elemental analysis of the fabric surface. The energy of the monochromated AlKa source (MonoAlKa) was 1486.6 eV, and the working pressure in the cabin was 4.0×10 -9 The thermal properties of the fabrics were analyzed using a Diamond 5700 thermogravimeter (TGA) at a 45° angle of incidence and the binding energy of carbon in saturated hydrocarbons (284.6 eV). The samples were finely chopped, and approximately 5 mg was placed in a crucible before being placed in the instrument for testing. The test atmosphere was nitrogen, and the temperature range was 30°C to 700°C at a heating rate of 10°C / min.

[0047] The fully automated micro-droplet wettability tester (SDC-200S) characterizes the wettability of finished fabric surfaces. Double-sided tape is used to secure the polyester fabric flatly to a glass slide. A 5 μL droplet of deionized water is used as the test liquid. Measurements are made at three random points on the sample, and the average value is calculated.

[0048] Fabric air permeability was tested using a fully automatic air permeability tester (Model: YG461G) in accordance with GB / T5453-1997, "Determination of Air Permeability of Textile Fabrics." The test pressure was 100 Pa, the test area was 20 cm², and the nozzle diameter was Φ4. The final value was the average of five tests.

[0049] Fabric stiffness is measured by flexural rigidity according to GB / T 18318.1-2009, "Textiles — Determination of Flexural Properties." Following GB / T 3923.1-2013, "Tensile Properties of Textile Fabrics," the tensile strength of polyester fabrics before and after finishing was tested using a universal testing machine (Model: INSTRON 5967). Example 1

[0050] S,S' -Bis(α,α'-dimethyl-α''-acetic acid) trithiocarbonate (BDATC) synthesis route Figure 1The mixture of carbon disulfide (13.70 g, 0.18 mol), chloroform (53.75 g, 0.45 mol), acetone (26.15 g, 0.45 mol), tetrabutylammonium hydrogen sulfate (1.21 g, 3.55 mol) and 60.00 mL petroleum ether was stirred at 10°C (three times vacuum-pumping) in a 1000 mL single-necked flask under nitrogen protection, and then 50% NaOH (50.40 g, 1.26 mol) was added dropwise in about 90 min. The reaction was stirred overnight, 450 mL water was added to dissolve the solid, and then the water layer was acidified with 60.00 mL concentrated HCL, stirred with N2 for 30 min, and then the solid was filtered and rinsed with water to obtain 12.88 g of dark yellow crude product. The crude product was dissolved in a mixture of toluene and acetone (4:1 by volume), and then filtered and dried under vacuum to obtain 10.00 g of light yellow solid powder S,S' - Bis (α, α'-dimethyl-α''-acetic acid) trithiocarbonate as a small molecule chain transfer agent.

[0051] Figure 2 For S,S' - The hydrogen nuclear magnetic spectrum and infrared spectrum of bis (α, α'-dimethyl-α''-acetic acid) trithiocarbonate. The characteristic absorption peak at 1701.8 cm -1 -1 of the carboxyl group is the characteristic absorption peak of the stretching vibration of C=O, the characteristic absorption peak at 1067.2 cm -1 -1 belongs to the C=S double bond, and the characteristic absorption peak at 685.6 cm -1 -1 belongs to the stretching vibration of -C-S-, which indicates that the target product BDATC is synthesized. The hydrogen nuclear magnetic spectrum result shows that the characteristic peak at a δ = 1.58 ppm belongs to the hydrogen on the methyl group of the side chain of the small molecule chain transfer agent BDATC, and the characteristic peak at b δ = 12.91 ppm belongs to the hydrogen on the carboxyl group at both ends of the BDATC molecule, which can prove the successful synthesis of the trithiocarbonate with carboxyl groups at both ends.

[0052] The synthesis route of the carboxyl-terminated polystyrene PS-BDATC is as Figure 1As shown. Under nitrogen, 10.40 g of styrene (purified by vacuum distillation) and 282 mg of BDATC trithiocarbonate were added to a single-necked flask containing 5 mL of ultra-dry tetrahydrofuran. 16.42 mg of azobisisobutyronitrile (AIBN, purified by recrystallization) was also added. The reaction apparatus was placed in a pre-cooled low-temperature magnetic stirrer. A vacuum pump was used to evacuate the single-necked flask on the low-temperature magnetic stirrer and then purge it with nitrogen three times. The oil bath was heated to 70°C, and the reaction apparatus was transferred to the oil bath and kept at this temperature for 17 hours. After the reaction was completed, the polymerization was terminated by immediate cooling. The reaction solution was then precipitated in ice-cold anhydrous methanol, filtered, and dried under vacuum for 6 hours to obtain 6.89 g of a yellow solid (PS-BDATC, Mn=3802) in a yield of 66%.

[0053] Referring to the above method, the amount of styrene was changed to 6.24 g to obtain the product PS-BDATC with Mn=2658.

[0054] Gel permeation chromatography (GPC) was used to test the molecular weight and molecular weight distribution of the carboxyl-terminated polystyrene products synthesized by different feed ratios of monomer styrene and small molecule chain transfer agent. The test results are as follows: Figure 3 As shown in Table 1. As the molar ratio of styrene monomer to small molecule chain transfer agent increases, the molecular weight of the resulting product, carboxyl-terminated polystyrene, increases accordingly. It is worth noting that when a low molar ratio is used, the molecular weight distribution of the prepared polymer is narrow and close to 1.0; when the molar ratio of the small molecule chain transfer agent is increased to 200:1 and 300:1, the molecular weight distribution of the resulting product becomes wider and increases to above 1.3. This result shows that the synthesis of carboxyl-terminated polystyrene in this article conforms to the characteristics of RAFT active polymerization. According to the design requirements of the subsequent coupling method for synthesizing block polymers, the carboxyl-terminated polystyrene obtained by feeding at a molar ratio of 60:1 and 100:1 was selected as the carboxylation coupling component to obtain PS- b -PDMS block copolymer.

[0055] Table 1 GPC test results of carboxyl-terminated polystyrene with different feed (molar) ratios

[0056]

[0057] Block copolymer PS- b -The synthetic route of PDMS is as follows Figure 1 Under nitrogen protection, 2.0 g of carboxyl-terminated polystyrene (PS-BDATC, Mn=3802) and 20 mL of anhydrous toluene were placed in a three-necked flask, and 196.2 mg of N,NCarbonyldiimidazole (CDI) was reacted at room temperature for 2 h, and then 2.1 g of single-end hydroxypropyl polydimethylsiloxane (Mn=2000) was added to the reaction system. The temperature was raised to 70°C and kept for 6 h. After the reaction, the by-product imidazole was filtered off, the toluene was removed by vacuum rotary evaporation, and the product was dried in vacuo to obtain a light yellow solid (block polymer PS- b -PDMS) 3.2 g, yield 80%. In the infrared absorption curve, 1732.8 cm -1 The characteristic peak at is attributed to PS- b -C=O double bond of ester group in PDMS copolymer, 1061.9 cm -1 The absorption peak at δ = 0.10-0.50 ppm is attributed to the stretching vibration absorption peak of Si-O-Si; in H NMR, δ = 0.10-0.50 ppm is the chemical shift of the hydrogen proton on the silicon methyl group, and the vibration peak at δ = 4.28 ppm is attributed to the methylene hydrogen (-CH2-OOC-) generated by the reaction of hydroxypropyl and terminal carboxyl groups, thus confirming the successful esterification reaction and the formation of block copolymers.

[0058] Figure 4 For carboxyl-terminated polystyrene and block copolymer PS- b -Infrared spectrum of PDMS. 1696.3 cm -1 The characteristic absorption peak at 3019.4 cm is the stretching vibration peak of the carboxyl group C=O of carboxyl-terminated polystyrene. -1 The characteristic absorption peak of CH at 1732.8 cm-1 belongs to the benzene ring, indicating that the carboxyl-terminated polystyrene was generated. After further esterification, the infrared absorption curve of the product was measured. -1 The characteristic peak at is attributed to PS- b -C=O double bond of ester group in PDMS copolymer, 1061.9 cm -1 The absorption peak at 37° belongs to the stretching vibration absorption peak of Si-O-Si, indicating that the esterification is successful.

[0059] Hydrogen nuclear magnetic Figure 5 As shown, the black curve is carboxyl-terminated polystyrene, the chemical shifts of vinyl CH2 and CH protons in the polystyrene structure are located at δ = 1.48 and 1.77 ppm, respectively. The hydrogen protons on the benzene ring are at δ = 6.30 ~ 7.30 ppm, and the hydrogen protons at the carboxyl group at the end of polystyrene are at δ = 12.06 ppm. The red curve is PS- b -PDMS block copolymer, where δ = 0.10 ~ 0.50 ppm is the chemical shift of hydrogen protons on the silyl methyl group, and a vibration peak appears at δ = 4.28 ppm, which is attributed to the methylene hydrogen (-CH2-OOC-) generated by the reaction of hydroxypropyl and terminal carboxyl groups, thus confirming the successful esterification reaction and the formation of block copolymer.

[0060] Referring to the above method, PS-PDMS with different PDMS content was obtained. b The PDMS block copolymer, the molar amount of carboxyl and hydroxyl is the same during esterification reaction; the silicon content is expressed by the molecular weight of PDMS segment (Mn=2000 or 1000) in the total block molecular weight ratio. PS-PDMS (50%) is a copolymer of PS-BDATC (Mn=3802) and monohydroxypropyl polydimethylsiloxane PDMS (Mn=2000). b The PDMS block copolymer, the molar amount of carboxyl and hydroxyl is the same during esterification reaction; the silicon content is expressed by the molecular weight of PDMS segment (Mn=2000 or 1000) in the total block molecular weight ratio. PS-PDMS (50%) is a copolymer of PS-BDATC (Mn=3802) and monohydroxypropyl polydimethylsiloxane PDMS (Mn=2000). b The PDMS block copolymer, the molar amount of carboxyl and hydroxyl is the same during esterification reaction; the silicon content is expressed by the molecular weight of PDMS segment (Mn=2000 or 1000) in the total block molecular weight ratio. PS-PDMS (50%) is a copolymer of PS-BDATC (Mn=3802) and monohydroxypropyl polydimethylsiloxane PDMS (Mn=2000). b The PDMS block copolymer, the molar amount of carboxyl and hydroxyl is the same during esterification reaction; the silicon content is expressed by the molecular weight of PDMS segment (Mn=2000 or 1000) in the total block molecular weight ratio. PS-PDMS (50%) is a copolymer of PS-BDATC (Mn=3802) and monohydroxypropyl polydimethylsiloxane PDMS (Mn=2000).

[0061] Figure 6 The schematic diagram of the device for preparing coating by vapor induced phase separation (VIPS). The finishing process of the fabric was carried out in a wide-mouth bottle with a sealed cover, a sponge holder was placed in the container, and an appropriate amount of atmospheric solvent (water or anhydrous ethanol) was added in the container in advance, a rubber plug was used to keep the container sealed, the atmosphere was cultured, and the saturated vapor pressure was reached. Clean cover glass and fabric were placed on the sponge holder in turn, the distance between the substrate and the vapor atmosphere solvent liquid surface was ensured, a microsyringe was used to cast the block copolymer solution (referred to as finishing liquid, the concentration was 40 mg / mL unless otherwise specified) onto the fabric, and the fabric was taken out after the organic solvent in the block copolymer solution was completely evaporated, and the coating with microstructure was formed on the surface of the fabric.

[0062] Example two: preparation of "roughened" coating by vapor induced phase separation

[0063] The polyester fabric was subjected to coating finishing in a 30 mL wide-mouth bottle with a sealed cover, and the process was as follows: a sponge holder was placed in the container, and an atmospheric solvent (water or anhydrous ethanol) was added in the container in advance, a rubber plug was used to keep the container sealed, the atmosphere was cultured in an oven at 25°C for 4 hours, and the saturated vapor pressure was reached; then clean cover glass (2.2×2.2 cm²) and fabric (2×2 cm²) were placed on the sponge holder in turn, the distance between the substrate (cover glass) and the vapor atmosphere solvent liquid surface was 1 cm; after being closed and standing for 30 min, 50 μL of polymer (PS-PDMS) solution (solvent: THF or CS2) was cast onto the fabric using a microsyringe, and the fabric was taken out after the organic solvent in the polymer solution was completely evaporated, and the coating with microstructure was formed on the surface of the fabric. b The PDMS block copolymer, the molar amount of carboxyl and hydroxyl is the same during esterification reaction; the silicon content is expressed by the molecular weight of PDMS segment (Mn=2000 or 1000) in the total block molecular weight ratio. PS-PDMS (50%) is a copolymer of PS-BDATC (Mn=3802) and monohydroxypropyl polydimethylsiloxane PDMS (Mn=2000).

[0064] Polyester taffeta, combed polyester and cotton-like polyester were chosen as the finishing objects. The microstructure on the surface of the fabrics was formed by changing the silicon content of the block copolymer, the type of solvent and the type of fabric structure in the water or ethanol vapor induced phase separation process. The surface wettability of the fabrics was studied.

[0065] Comparative example

[0066] The surface morphology of the four kinds of fabrics (such as Figure 7 ) was tested. The untreated polyester fabric was obviously woven directly by many fibers. There were obvious differences among the four kinds of fabrics in terms of fabric material texture, weaving structure, thickness and density, and the wettability of water was also different.

[0067] In order to compare the changes in the morphology and performance of the fabric finishing caused by the vapor induced phase separation process, the fabric was coated with the finishing liquid and dried. It was found that the surface of the finished fabric was completely covered by the polymer film (such as Figure 8 ), and the hydrophobic performance of the finished fabric was basically unchanged. Example three

[0068] The conditions for forming microstructure on the surface of the fabric by the vapor induced phase separation process and the surface wettability of the fabric were studied by changing the silicon content of the block copolymer, the type of solvent and the type of fabric structure in the water vapor atmosphere.

[0069] Under the water vapor induced phase separation, the finishing liquid was prepared with THF as the solvent, and the surface morphology of the fabric coated and finished was as shown in Figure 9 . The surface of the untreated polyester was smooth, and the polyester fabric finished by the water vapor induced phase separation (VIPS) generated disordered porous microstructure between the fibers. When the percentage of silicon content of the block copolymer increased to 60%, the continuity of the block copolymer film increased and the porous material between the fibers on the surface of the fabric increased; different polyester fabrics also showed different performances. A small amount of porous film was formed on the surface of the fibers when the polyester taffeta and combed polyester were treated, while the thick polyester and cotton-like polyester were covered with a smooth film.

[0070] The water vapor induced phase separation method can generate a film layer with porous structure on a flat substrate, and the fabric finished by this method only forms a small amount of pores in the film layer. The reason is that the fabric substrate has a complex surface shape with fiber interlacing, the surface of the substrate is no longer flat, and the adsorption of the capillary effect of the fiber material on the treatment liquid makes the vapor induced phase separation process and the result different. Adjusting the concentration of the treatment liquid, using 5 mg / mL~30 mg / mL of polymer treatment liquid cannot form a good film on the fabric; the film is well formed on the surface of the fibers when the concentration of the finishing liquid is 40 mg / mL; when the concentration of the treatment liquid is increased to more than 60 mg / mL, the film layer can cover the fibers, but the film cracks.

[0071] Keeping other conditions unchanged, the solvent was replaced by CS2, and four kinds of fabrics were treated by water vapor induced phase separation. The surface of the obtained fabrics is shown in Figure 10 When CS2 was used as the solvent, the polymer on the surface of the treated fabric accumulated more obviously, which was not conducive to the formation of microporous morphology in the film layer. Example Four

[0072] The steam type was changed to ethanol, and the changes in the microstructure formed on the surface of the treated fabric and its surface wetting performance were studied by adjusting the silicon content of the block copolymer, the type of solvent, and the structure of different fabrics.

[0073] With ethanol as the steam atmosphere, three block copolymers PS- b -PDMS with different silicon contents were used to treat four kinds of polyester fabrics. The concentration of the treatment solution used was 40 mg / mL, and the solvent was THF. The surface morphology of the fabrics thus obtained is shown in Figure 11 Among them, when the silicon content was 30%, the treatment agent formed microspheres on the surface of the fabric, but the microspheres mostly grew in the gap between the fibers.

[0074] Different fabric structures also produced differences. For example, when the taffeta fabric was treated with block polymers with silicon contents of 30% and 50%, a small amount of microspheres were generated on the surface of the fibers, while when the block polymer had a silicon content of 60%, uniformly distributed microspheres grew on the surface of the fibers; when thick polyester was used as the base material, the block polymer with a silicon content of 30% only generated a small amount of microspheres in the gap between the fibers, and when the block copolymer had a silicon content of 50%, the phase separation tendency of the treatment agent increased, and the treated thick polyester fabric had a uniform spherical coating on the surface of the fibers. It is worth noting that these spherical particles were embedded in the film layer on the surface of the fibers, which was consistent with the characteristics of the thick polyester surface being rough and easily adsorbing and absorbing the treatment agent to form a film.

[0075] When combing polyester and cotton-like polyester were treated with block copolymers with a silicon content of 50%, uniformly distributed microspheres were formed on the surface of the fabric. Among them, the surface of the combing polyester was the flattest, and when it was treated with a block copolymer with a silicon content of 50%, the microspheres on the surface of the fibers were uniformly distributed and closely arranged.

[0076] When the silicon content of the block copolymer was further increased to 60%, the spherical particles of the remaining three kinds of polyester after treatment were squeezed and merged with each other, eventually forming a characteristic morphology of the fiber covered by a hill-like undulating film, and the microspheres were no longer dispersed. When the polysiloxane segment accounted for a large proportion in the block copolymer, the low glass transition temperature provided by it caused the block copolymer to become soft, and the polymer was more likely to form a film-like coating on the surface of the fiber.

[0077] The solvent was replaced by CS2, and the four kinds of fabric surfaces were treated by ethanol vapor induced phase separation of the block copolymer. The surface morphology of the treated fabric is shown in Figure 12 The block copolymer formed a film layer covering in the morphology formed on the fabric surface by aggregation from CS2, and the surface spherical particles were reduced or even close to disappearing, unlike the polymer microphase separation and the molecular chain curling into balls when treated by THF solution in ethanol vapor. A large amount of treatment liquid remained in the fiber gap, and spherical particles were generated by microphase separation of the block copolymer; and the treatment liquid remained on the fiber surface was less, and only a thin film-like coating was generated.

[0078] The particle size of the particles in the microsphere coating on the treated fabric surface was statistically analyzed, and the results are shown in Figure 13 Among them, the taffeta fabric was treated with a block copolymer THF solution containing 60% silicon, and the steam atmosphere was ethanol, and the average size of the microspheres obtained was 2.90 ± 0.64 μm, and the particle size distribution was uniform; for combed polyester, the treatment effect was good when treated with a block copolymer containing 50% silicon, and the average size of the surface microspheres in the coating obtained was 5.87 ± 1.71 μm, and the particle size and particle size distribution were larger and wider.

[0079] Chemical analysis was performed on the treated fabric surface by ATR-FTIR and XPS, and combed polyester treated with THF as the solvent under ethanol vapor atmosphere was selected for testing, and the silicon content was 50%. The ATR-FTIR spectra of the combed polyester before and after treatment are shown in Figure 14 Compared with the untreated combed polyester, the combed polyester treated with the block copolymer coating appeared a new wide peak at 1000~1100 cm -1 , which was attributed to the Si-O-Si stretching vibration absorption peak in the surface layer structure of the microspheres; the very strong C=O absorption peak at 1710.6 cm -1 of the original fabric was weakened after treatment, which indicated that the surface of the combed polyester was covered by the PS- b -PDMS block copolymer microsphere coating after treatment by vapor-induced phase separation. In addition, the sharp peak at 1260.4 cm -1 and the strong peak at 799.8 cm -1 were attributed to the Si-(CH3)2 stretching vibration absorption peak in the PDMS chain segment of the block copolymer. Figure 14As shown in (b), the XPS spectrum of the finished combed polyester fiber contains C, O, Si, and S. The presence of S is attributed to the sulfur-containing small molecule chain transfer agent. The C 1s narrow scan spectrum reveals five chemically related carbon elements: C-Si (283.93 eV), CC / CH (284.80 eV), CO (286.13 eV), C=O (288.63 eV), and C=C (282.43 eV). The O 1s narrow scan spectrum confirms the presence of Si-O-Si (532.13 eV), C=O (533.23 eV), and CO (531.43 eV). The Si 2p narrow scan spectrum shows two peaks, attributed to Si-O-Si (102.08 eV) and Si-C (101.48 eV), respectively. Example 5

[0080] Figure 15 The static water contact angle of polyester fabric treated with steam-induced phase separation is shown. The test found that treating the fabric with a polymer containing 30% silicon did not improve its hydrophobicity. However, treating the fabric with a block copolymer containing 50% silicon showed better hydrophobicity when phase separation was induced in a steam atmosphere using THF as the solvent. Figure 15 (a). The contact angle of combed polyester after treatment reached 151.0 ± 1.2°. When the fabric was treated with CS2 as a solvent, the hydrophobicity of the treated fabric gradually increased with the increase of the silicon content in the polymer ( Figure 15 (b) Combed polyester treated with a block copolymer coating containing 50% and 60% silicon exhibited a superhydrophobic effect, with water contact angles of 157.5 ± 1.1° and 150.5 ± 0.9°, respectively.

[0081] When phase separation is induced in an ethanol vapor atmosphere, Figure 15 As can be seen in Figure c, when THF is used as the solvent, the two block copolymers have better hydrophobicity. The contact angles of combed polyester after finishing with water reach 166.9 ± 0.2° and 152.6 ± 0.6° respectively. The contact angle of cotton-like polyester after finishing with a polymer containing 50% silicon also reaches 160.2 ± 0.2°. Compared with THF, when CS2 is used as the solvent for the treatment, the contact angle of the water of the combed polyester reaches 166.9 ± 0.2° and 152.6 ± 0.6° respectively. Figure 15 The figure d indicates that the hydrophobicity of the treated fabric was poorly improved. The study also found that both combed polyester and cotton-like polyester achieved superhydrophobicity under these finishing conditions. This is related to the formation of more independent, complete spherical coatings on the surfaces of both fabrics during finishing. This indicates that the morphology of the coating significantly influences the hydrophobicity of the treated fabric.

[0082] The wettability of the finished fabric to water and other liquids was tested. Figure 16 As shown in a and b). The original polyester fabric quickly sinks when immersed in Rhodamine B-dyed water, while the combed polyester fabric after finishing floats on the surface of the liquid. Due to the strong capillary effect provided by the fiber structure of the untreated fabric, water droplets easily penetrate and diffuse into the fabric fibers; however, due to the super-hydrophobic surface of the combed polyester after finishing, water does not penetrate and is also difficult to diffuse into the fabric fibers. Figure 16 As shown in c, the fabric has excellent repellency to liquids such as water, acid, alkali, tea and milk.

[0083] The adsorption of oil components in the aqueous phase by the treated fabric was tested. The treated fabric was immersed in water with carbon tetrachloride oil droplets (dyed red by Oil Red O) at the bottom. The carbon tetrachloride droplets were completely absorbed within a few seconds, leaving transparent water ( Figure 17 Similarly, Figure 17 In Figure b, two drops of corn oil dyed with Oil Red O were added to water, and the treated fabric was then placed in contact with the edge of the oil droplets. The corn oil was completely absorbed by the fabric immediately upon contact. This demonstrates that the superhydrophobic polyester fabric has excellent oil absorption and water repellency. Example 6

[0084] The thermal stability of the fabric before and after finishing was characterized by thermogravimetric analysis. Figure 18 As shown in the figure, combed polyester was treated with a block polymer containing 50% silicon using THF as the solvent. The thermogravimetric curve shows that the original polyester primarily decomposes between 370°C and 480°C, while the decomposition range of the treated polyester shifts to lower temperatures, between 280°C and 440°C. This indicates that the block polymer, applied to the fabric surface, decomposes earlier than the fiber matrix when heated at high temperatures, resulting in mass loss. When the treated fabrics were heated to 700°C, the residual mass percentages were 0.43% and 12.85%, respectively. Clearly, the significantly increased residual mass percentage of the treated fabric is due to the formation of residual inorganic oxides such as SiO2 by the organosilicon component in the finishing agent under high-temperature heating. Example 7

[0085] Washing fastness test: The treated polyester fabric was treated using a wash fastness tester (model: WASHTEC-P) with a detergent solution formula of 1:30 and a neutral detergent concentration of 2 g / L. The test conditions were a temperature of 40°C for 30 minutes, followed by a 1-minute deionized water rinse. Adhesion resistance test: 3M high-quality transparent tape was used to test the fabric's adhesion resistance. The treated polyester fabric was placed on a glass slide and transparent tape was applied evenly to the fabric. The tape was then slowly removed from left to right, then from right to left. This process was considered one cycle, and the number of cycles and the corresponding contact angle change were recorded.

[0086] The durability of the fabric surface coating was tested. Among them, after washing and adhesion, the coating durability was evaluated by testing the change of the static water contact angle of the fabric surface, and the test results are shown in Figure 19 (a) adhesion resistance, (b) water washing resistance; the block polymer finishing of combed polyester with 50% silicon content and THF as solvent.

[0087] Block copolymer PS- b The chemical stability of the microsphere coating finished fabric was characterized by immersing the polyester fabric sample in a solution with pH = 3 or pH = 13 (acid prepared from HCl, base prepared from NaOH) for 24 h, taking out and washing and drying, observing the SEM surface morphology and the change of WCA. The stability of the finishing combed polyester to different pH was tested. Selecting pH = 1-14 aqueous solution as the test liquid, the static contact angle of the fabric to different pH aqueous solution was tested, and the results are shown in Figure 20 a of the middle. From the figure, it can be seen that the finished fabric has certain stability to acidic and alkaline aqueous solution (pH = 3-11). In order to further explore the stability of the coating in acid and alkali solution, the finished fabric was immersed in aqueous solution with pH = 3 and pH = 13 for 24 h, and the results are shown in Figure 20 b of the middle; the block polymer finishing of combed polyester with 50% silicon content and THF as solvent.

[0088] Example Eight Wearability Test of Steam Induced Phase Separation Method Coating Finished Polyester Fabric

[0089] The wearability of the finished combed polyester was evaluated by breaking strength, bending stiffness and air permeability test; the block polymer finishing of combed polyester with 50% silicon content and THF as solvent and ethanol as steam. As shown in Table 2, the breaking strength and elongation at break of the original combed polyester fabric are 257.64 N and 18.29% respectively, and the breaking strength and elongation at break of the finished fabric are 287.1 N and 21.19% respectively. The breaking strength and elongation at break of the treated combed polyester are increased to a certain extent. The bending stiffness of the original combed polyester is 0.32 mN·cm, and the bending stiffness after finishing increases to 1.18 mN·cm. The air permeability of the combed polyester before and after finishing is 257.04 mm·s -1 and 268.22 mm·s -1 , the air permeability is improved, and the finished fabric still retains the inherent softness of textiles. It can be seen that the steam induced phase separation process for coating treatment improves the wearability of the fabric.

[0090] Table 2 Comparison of physical properties of untreated polyester and coating finished combed polyester

[0091]

[0092] Comparative Example

[0093] In a 10°C water bath under nitrogen, add 20.19 g of dodecanethiol, 48.10 g of acetone, and 1.29 g of tetrabutylammonium bromide to a four-necked flask. While stirring, add 8.40 g of 50% NaOH solution dropwise for at least 20 minutes. After the addition is complete, hold the mixture for 15 minutes. Then, slowly add a mixed solution of CS2 (7.61 g) and acetone (10.09 g) dropwise to the flask for at least 20 minutes. The solution color gradually changes from orange to wine red. Then, add 17.81 g of chloroform and 40.00 g of 50% NaOH solution dropwise for over 30 minutes. Stir overnight. After that, 150 mL of distilled water was added to the four-necked flask, followed by 25 mL of concentrated hydrochloric acid for acidification. After stirring for 30 min, a large amount of nitrogen was introduced while stirring. Finally, the filtered solid was dissolved in 250 mL of isopropanol to remove the insoluble matter. The filtrate was concentrated by rotary evaporation at 45°C, and finally the product was recrystallized using n-hexane and dried to obtain 20.60 g of a light yellow small molecule chain transfer agent DDMAT.

[0094] Under nitrogen, 10.40 g of styrene (purified by vacuum distillation) and 0.47 g of DDMAT trithiocarbonate were added to a single-necked flask containing 5 mL of ultra-dry tetrahydrofuran. 27.37 mg of azobisisobutyronitrile (AIBN, purified by recrystallization) was also added. The reaction apparatus was placed in a pre-cooled low-temperature magnetic stirrer. A vacuum pump was used to evacuate the single-necked flask on the low-temperature magnetic stirrer and then purge it with nitrogen three times. The oil bath was heated to 70°C, and the reaction apparatus was transferred to the oil bath and kept at this temperature for 17 hours. After the reaction was completed, the polymerization was immediately terminated by cooling. The reaction solution was then precipitated in ice-cold anhydrous methanol, filtered, and dried under vacuum for 6 hours to yield 6.23 g of a yellow solid (PS-DDMAT) in a 60% yield.

[0095] Under nitrogen protection, 2.00 g of carboxyl-terminated polystyrene (PS-DDMAT, Mn=3428) and 20 mL of anhydrous toluene were placed in a three-necked flask, and 94.6 mg of N,N Carbonyldiimidazole (CDI) was reacted at room temperature for 2 h, and then 1.46 g of double-terminal hydroxypropyl polydimethylsiloxane (Mn=5000) was added to the reaction system. The temperature was raised to 70°C and kept for 6 h. After the reaction, the by-product imidazole was filtered off, the toluene was removed by vacuum rotary evaporation, and vacuum drying was performed to obtain 2.98 g of a yellow solid (block polymer PDMS- b -PS), yield 86%.

[0096]

[0097]

[0098] Referring to Example 1, carboxyl-terminated polystyrene (PS-BDATC, Mn = 2658) reacts with monohydroxypropyl terminated polydimethylsiloxane (Mn = 1000) to obtain PS- b -PDMS block polymer.

[0099] The steam-induced combing of polyester is carried out according to the method of Example 3, and the solvent is THF, and the concentration of the polymer solution is 40 mg / mL. The block polymer PDMS- b -PS after finishing is tested for water contact angle, and the photo after standing for 15 minutes is shown in b Figure 21 The block polymer PS- b -PDMS after finishing has good hydrophobic stability.

[0100] Summary:

[0101] The present application synthesizes carboxyl-terminated polystyrene (number average molecular weight is 2658 and 3802, respectively) of different molecular weights by RAFT polymerization, and esterifies and condenses with monohydroxypropyl terminated PDMS (number average molecular weight is 1000 and 2000, respectively) using N,N -carbonyl diimidazole (CDI) as an esterification activator to synthesize three block copolymers PS- b -PDMS containing different silicon contents. The structure of the target product is characterized by FT-IR, 1 H-NMR and GPC.

[0102] The block copolymer PS- b -PDMS is used as a coating treatment agent for steam-induced phase separation (VIPS) on the surface of fabrics (polyester taffeta, thick polyester, combing polyester and imitation cotton polyester), and the influence of factors such as the silicon content of the block polymer and the type of solvent on the morphology is disclosed. The coating morphology formed on the surface is observed by SEM, and the change in surface wettability is tested by a contact angle instrument. The results show that in the water vapor-induced phase separation, a porous coating can be obtained on the surface of the fabric when CS2 is used as the solvent, and the combing polyester can obtain hydrophobic effect after coating finishing, and the static contact angle with water can reach 157.5 ± 1.1°, but the durability is not strong, and it is observed that the water droplets on the fabric are quickly wetted; in the ethanol vapor-induced phase separation, a microsphere coating can be obtained on the surface of the fabric when THF is used as the solvent. The static contact angle of the fabric with water before and after treatment is tested, and the results show that the contact angle of the combing polyester under the condition of THF solvent and 50% silicon content can reach 166.9 ± 0.2°, which has superhydrophobicity and oil absorption capacity.

[0103] ​The mechanical stability of the finished fabric was tested. The results showed that the microsphere coating could maintain good hydrophobic effect after 6 cycles of adhesive resistance and 5 cycles of water resistance test. The finished fabric had good stability to acid and alkali. In addition, the finished fabric was still hydrophobic after 24 h acid and alkali immersion. Finally, the air permeability, breaking strength and bending stiffness of the finished fabric were tested, and the results showed that the finished fabric had good comprehensive performance.

Claims

1. A silicon-containing block copolymer having the following chemical formula: ； The number average molecular weight of the silicon-containing block copolymer is 2,000 to 20,000; in the silicon-containing block copolymer, the number average molecular weight of polydimethylsiloxane is 30% to 70% of the number average molecular weight of the silicon-containing block copolymer.

2. The silicon-containing block copolymer according to claim 1, characterized in that In the silicon-containing block copolymer, the number average molecular weight of the trisulfide polystyrene segment is 1000-9000.

3. The method for preparing the silicon-containing block copolymer according to claim 1, comprising the following steps: preparing carboxyl-terminated polystyrene using S,S'-bis(α,α'-dimethyl-α''-acetic acid) trithiocarbonate and styrene as raw materials; and preparing the silicon-containing block copolymer using carboxyl-terminated polystyrene and single-terminated hydroxypropyl polydimethylsiloxane as raw materials.

4. A method for preparing a water-repellent fabric, comprising the following steps: inducing phase separation of a fabric containing a polymer solution in a steam environment to obtain a water-repellent fabric; the polymer is the silicon-containing block copolymer according to claim 1.

5. The method for preparing a water-repellent fabric according to claim 4, wherein: In the polymer solution, the solvent includes THF or CS2; the concentration of the polymer solution is 20 to 80 mg / mL; and the steam includes water vapor or organic solvent vapor.

6. The water-repellent fabric prepared according to the method for preparing the water-repellent fabric according to claim 4.

7. Use of the silicon-containing block copolymer according to claim 1 in the preparation of water-repellent materials.

8. Use of the water-repellent fabric according to claim 6 in preparing functional fabrics.

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