CN120005196A

CN120005196A - High-strength and tough polydimethylsiloxane-polyurea composite material with amphiphilicity and preparation method and application thereof

Info

Publication number: CN120005196A
Application number: CN202510161993.9A
Authority: CN
Inventors: 金守壬
Original assignee: Shenyang Jusheng New Materials Technology Co ltd
Current assignee: Shenyang Jusheng New Materials Technology Co ltd
Priority date: 2025-02-14
Filing date: 2025-02-14
Publication date: 2025-05-16

Abstract

一种具有两亲性的高强韧聚二甲基硅氧烷‑聚脲复合材料及其制法和应用，属于聚脲材料技术领域。该具有两亲性的高强韧聚二甲基硅氧烷‑聚脲复合材料结构式如权利要求书和说明书所示，是一种用三官能度连接剂将PDMS分子链与PUA分子链结合在主链两侧，形成的刷状分子结构的复合材料。其制法为：将双羟基单端封端的PDMS与异氰酸酯反应得到预聚物A；大分子多元胺与异氰酸酯缩合生成含有脲键的预聚物后与端氨基扩链剂反应，形成聚脲侧链B。将具有三官能度连接剂在低温保护下先与预聚物A进行侧链扩链反应，再接枝聚脲侧链B，制备得到复合材料。解决了聚二甲基硅氧烷与聚脲相容性差、结构不均匀、性能不稳定、两类材料特性不可兼顾的问题。A high-strength and tough polydimethylsiloxane-polyurea composite material with amphiphilicity, and its preparation method and application, belong to the technical field of polyurea materials. The structural formula of the high-strength and tough polydimethylsiloxane-polyurea composite material with amphiphilicity is shown in the claims and the specification. It is a composite material with a brush-like molecular structure formed by combining PDMS molecular chains and PUA molecular chains on both sides of the main chain with a trifunctional linker. The preparation method is: PDMS with a single end capped with dihydroxy reacts with isocyanate to obtain a prepolymer A; a macromolecular polyamine condenses with isocyanate to generate a prepolymer containing a urea bond, which is then reacted with an amino-terminated chain extender to form a polyurea side chain B. The trifunctional linker is first subjected to a side chain extension reaction with the prepolymer A under low temperature protection, and then the polyurea side chain B is grafted to obtain a composite material. The problem of poor compatibility between polydimethylsiloxane and polyurea, uneven structure, unstable performance, and the inability to take into account the characteristics of the two types of materials is solved.

Description

Amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material and preparation method and application thereof

Technical Field

The invention relates to the technical field of polyurea materials, in particular to an amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, and a preparation method and application thereof.

Background

In recent years, the importance of high polymer materials in various applications is increasingly remarkable, especially in the fields of aerospace, automobile manufacturing, constructional engineering, electronic equipment and the like with higher requirements on the comprehensive performance of the materials. Among them, polydimethylsiloxane (PDMS) and Polyurea (PUA) have been widely studied as two kinds of elastic materials having excellent properties.

PDMS is known for its excellent optical transparency, biocompatibility, processability and thermal stability. However, with the rapid development of science and technology, the lower mechanical properties and limited chemical properties of traditional silicones have not fully satisfied the demands of complex use scenarios. Thus, research on the functionalization improvement of PDMS has made significant progress in the last few years. The modification of PDMS is typically accomplished by combining with functional fillers to produce an elastomer composite whose mechanical, electrical, thermal, chemical or surface properties can be systematically designed and tailored to meet specific needs or new applications. However, as most of the functional filler is solid, the functional filler has poor compatibility with liquid PDMS, and the stress concentration phenomenon is easy to generate while the performance of the matrix is enhanced, so that the material has new defects.

The PUA elastomer is a block copolymer formed by reacting amine compounds with isocyanate, has low density, high strength, high toughness, excellent wear resistance and corrosion resistance, and is widely used in the field of coatings. Nevertheless, as a coating, the direct adhesion to different substrates such as carbon steel, concrete and the like is limited, and higher adhesion can be achieved by enhancing the interfacial bonding force with the substrate by means of a primer. For hydrophobic polymer substrates such as PDMS, the PUA coating and the adhesion therebetween are greatly reduced due to chemical inertness, low surface energy, poor interfacial compatibility, and the like. Therefore, improving the compatibility and adhesion of PUA to polymeric substrates is critical to widening the application of PUA protective coatings.

PDMS and PUA are compounded, so that higher strength and toughness and wider applicability can be realized through synergistic effect on the basis of keeping the original excellent performances of the two materials. However, since the chemical properties of PDMS and PUA are greatly different, the interfacial incompatibility between the two is liable to occur during the compounding process, which may seriously affect the overall properties of the composite material, in particular, mechanical properties and durability. In addition, complex processing, structural uniformity, performance stability, etc. are all technical challenges faced in practical manufacturing processes. According to the disclosure of the prior document, PDMS-PUA composite material is only used as a soft segment to be added into the synthesis process of PUA or to form a comb-shaped side chain, and the molecular structure greatly weakens the self characteristics of PDMS or PUA material, so that the overall performance of the composite material is more similar to that of a single elastomer.

In view of the above, developing a protective coating that has both PDMS and PUA material properties, a simple synthesis process, excellent mechanical properties, and high adhesion to both hydrophobic and hydrophilic polymeric substrates is currently a problem to be solved.

Disclosure of Invention

Based on the problems faced by the application fields, the invention provides an amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, and a preparation method and application thereof. The urea bond in the PUA molecule can provide excellent mechanical properties for the composite material, and the PDMS molecule can improve the adhesiveness of the composite material on other high polymer substrates. The performance regulation and control of the composite material can be realized by designing the ratio of the molecular weights of the two types of side chains. The high-toughness polydimethylsiloxane-polyurea composite material with amphipathy prepared by the method solves the problems of poor compatibility, uneven structure, unstable performance and incomparable characteristics of two materials of polydimethylsiloxane and polyurea, and makes a bedding for future industrial production. The composite material has simple preparation process and excellent material performance, realizes one-material multi-purpose to a certain extent, is particularly used for the aspect of protective coating, and is hopeful to be applied to the wider technical field.

An amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has the following structure (formula 1):

wherein Y is any one or a mixture of the following structures or isomers thereof:

Wherein W is any one or a mixture of the following structures or isomers thereof:

wherein U is any one or a mixture of the following structures:

The method comprises the steps of carrying out a reaction on a substrate, wherein n, m, q, r is an average value of the corresponding number of repeated units, n is a positive integer, m is a positive integer, q is a positive integer, and r is a positive integer.

The invention also relates to a preparation method of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, which is a preparation method for combining PDMS molecular chains and PUA molecular chains on two sides of a main chain by using a trifunctional connecting agent to form a brush-shaped molecular structure. The preparation method specifically comprises the steps of reacting dihydroxy single-end capped PDMS with isocyanate to obtain a prepolymer A, and carrying out condensation reaction on hydroxyl and isocyanate to generate a carbamate group in the synthesis process. Meanwhile, macromolecular polyamine and isocyanate are condensed to form prepolymer containing urea bond, and then the prepolymer is further reacted with amino-terminated chain extender to form polyurea side chain B. The trifunctional linking agent (3, 5-diamine benzoic acid) and the prepolymer A are subjected to side chain extension reaction under low temperature protection, then polyurea side chains B are grafted, and finally the high-toughness polydimethylsiloxane-polyurea composite material with amphipathy is synthesized. The reaction equation is shown below (formula 15):

Wherein Y, W and U are as defined above for formulas 1-14.

The isocyanate is one or more of diphenylmethane-4, 4' -diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene Diisocyanate (HDI), toluene Diisocyanate (TDI) and dicyclohexylmethane diisocyanate (HMDI), and preferably IPDI and HDI are used.

The macromolecular polyamine is selected from one or more of polyether polyamine, polyester polyamine, polyolefin polyamine and amino-terminated block copolymer of the above materials with number average molecular weight Mn=2000-5000, preferably polyether polyamine, polyester polyamine and amino-terminated block copolymer, and most preferably amino-terminated block copolymer. Macromolecular polyamines having different molecular weights act as soft segments of the polydimethylsiloxane-polyurea molecular chain and will determine the deformability of the resin produced.

The amino-terminated chain extender is selected from but not limited to diaminoxylene, 4 '-bis-sec-butylaminodiphenyl methane, diethyltoluenediamine, isophoronediamine, adipic dihydrazide, ethylenediamine, 1, 2-propylenediamine, 2, 5-dimethyl-2, 5-hexamethylenediamine, 1, 11-undecyldiamine, 1, 12-dodecylenediamine, 2,4' -diamino-dicyclohexylmethane, 1-amino-3, 5-trimethyl-5-aminomethylcyclohexane, 2, 4-toluenediamine or 2, 6-toluenediamine, 2,4 '-diaminodiphenylmethane, 1, 4-butanediamine, 1, 6-hexamethylenediamine, 2, 4-trimethyl-1, 6-hexamethylenediamine, 4, -one or more of diamino-dicyclohexylmethane, 3, -dimethyl-4, -diamino-dicyclohexylmethane or 4,4' -diaminodiphenylmethane. Preferably 4,4' -di-sec-butylaminodiphenyl methane, diethyltoluenediamine, isophoronediamine and adipic acid dihydrazide.

The urea bond synthesized by different amino-terminated chain extenders and isocyanate serves as a hard segment of a polydimethylsiloxane-polyurea molecular chain, and hydrogen bonds are formed between the hard segments of different molecular chains, so that the prepared high-strength and high-toughness polydimethylsiloxane-polyurea composite material with amphipathy is endowed with good mechanical properties.

The preparation method of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material specifically comprises the following steps of:

Step (1), carrying out vacuum dehydration treatment on dihydroxy single-end capped polydimethylsiloxane, isocyanate, macromolecular polyamine and amino-end chain extender for more than 1.5 hours in an environment of more than 100 ℃ under the pressure of-0.9 MPa, and cooling to room temperature for later use;

dropwise adding and mixing dihydroxy single-end capped polydimethylsiloxane and isocyanate solution, stirring after the dropwise adding is finished, reacting at 100-110 ℃ for 2.5-3.5 hours at the rotating speed of 500-800 rpm, and protecting the process by nitrogen to avoid excessive side reaction to obtain isocyanate end capped prepolymer A;

Uniformly stirring and mixing macromolecular polyamine and isocyanate, and prepolymerizing for 2-3 hours at the speed of 500-800 rpm and the temperature of 80-90 ℃ under the protection of nitrogen in the process, so as to avoid excessive side reaction and obtain an isocyanate end-capped prepolymer B;

mechanically stirring the trifunctional connector and the isocyanate end-capped prepolymer A for 30-40 min at 0-10 ℃ at the rotating speed of 500-800 rpm to obtain an oligomer with a comb-shaped molecular structure, wherein a side chain of the oligomer is PDMS;

Adding an amino-terminated chain extender into the isocyanate-terminated prepolymer, performing chain extension reaction at 25-35 ℃, stirring at 500-800 rpm for 5-10 min to obtain an isocyanate-terminated polyurea side chain B;

And (6) adding the isocyanate-terminated polyurea side chain B into an oligomer with a comb-shaped molecular structure, wherein the side chain of the oligomer is PDMS, uniformly stirring for 30-60 min, and pouring into a mold for curing to obtain the final amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, wherein the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has a unique brush-shaped structure as shown in the structural formula (1).

In the step (2), the reaction rate is controlled by dripping, so that the phenomenon of partial pre-reaction is avoided, the non-uniform reaction is caused, and the product performance is further influenced. Preferably, the dihydroxy single-ended polydimethylsiloxane is added dropwise to the isocyanate solution.

In the step (2), the isocyanate solution is a mixture of isocyanate and solvent. The solvent is preferably N, N dimethylformamide.

In the step (2), the dihydroxyl single-end capped polydimethylsiloxane is 1 (2-3) of isocyanate, and the preferable molar ratio is 1:2.3;

in the step (3), the molar ratio of the macromolecular polyamine to the isocyanate is 1 (2-3), and the preferable molar ratio is 1:2.3;

In the step (4), the trifunctional linker is selected from one of 3, 5-diamine benzoic acid, 1, 2-diamino ethanol, 2, 3-diamino-1-propanol, 1, 2-diamino-3-chloropropanol, 1, 3-diamino-2-propanol, 2, 3-dihydroxypropylamine, 1, 2-dihydroxyethylamine, 1, 2-dihydroxy-3-aminopropane, 4, 5-dihydroxy-1, 3-diaminobenzene, 1, 2-dihydroxy-4-aminobenzene, 1, 2-dihydroxycyclohexylamine and 2, 4-dihydroxyphenethylamine, and preferably 3, 5-diamine benzoic acid.

In the step (4), the molar ratio of the trifunctional connector to the isocyanate end-capped prepolymer A is 1:2;

In the step (5), the molar ratio of the amino-terminated chain extender to the isocyanate-terminated prepolymer B is (2-3) 1;

In the step (6), the number average molecular weight of the isocyanate-terminated polyurea side chain depends on the number average molecular weight of the initially added macromolecular polyamine in the synthesis process of the step (3), the ratio of the number average molecular weight of the isocyanate-terminated polyurea side chain to the number average molecular weight of the oligomer with the comb-shaped molecular structure, the side chain of which is PDMS, is (0.68-14.79): 1, the preferred ratio of the number average molecular weight is (0.68-5.92): 1, and the more preferred ratio of the number average molecular weight is (2.96-5.92): 1.

In the step (6), the curing is carried out by placing the mixture in a 65-85 ℃ oven for 24-72 h.

The amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has the tensile strength ranging from 35MPa to 56MPa, the elongation at break ranging from 414% to 1091%, the impact strength being improved by 83% to 152% compared with that of a pure aluminum sheet, the tearing strength being 34 to 60N/mm, the adhesive force to carbon steel being 8 to 13MPa, the adhesive force to concrete being 5 to 9MPa, the adhesive force to a hydrophobic polymer substrate being 5 to 10MPa, and the adhesive force to a hydrophilic polymer substrate being 6 to 13MPa, under the condition of no primer.

The invention further relates to a preparation method of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, which comprises the following steps of:

the side chain is an oligomer of PDMS with a comb-shaped molecular structure, wherein the Y structure in the oligomer (main chain) of PDMS with the comb-shaped molecular structure can be selected from a single structure or an isomer structure in formulas 2-6, or a mixture of more than two structures, and the mass ratio of the mixture can be in any proportion.

The polydimethylsiloxane component (A component) is the oligomer with the comb-shaped molecular structure, and one or more of a diluent, a filler, a coupling agent, a dispersing agent, a thixotropic agent, a pigment, a leveling agent, a defoaming agent, an ultraviolet light absorber and an antioxidant can be added into the polydimethylsiloxane component (A component) according to the requirement.

The diluent is selected from one or more of ethyl acetate (EAc), butyl acetate (BAc), propylene glycol methyl ether acetate (PMA) and ethyl 3-ethoxypropionate (EEP). The usage amount of the diluent can be 10-30% of the total mass of the polydimethylsiloxane component, and preferably 5-15%.

The filler is one or more of calcium carbonate, talcum powder, titanium dioxide, silicon micropowder and barium sulfate. The total amount of filler used may be 10 to 50%, preferably 15 to 30% of the total mass of the polydimethylsiloxane component.

The coupling agent is one or more of KH550, KH560 and KH 602. The usage amount of the coupling agent is 0.1% -1% of the total mass of the filler in the polydimethylsiloxane component. Preferably, 0.1 to 0.5% is used.

The dispersing agent is one or more of BYK110, BYK163 and BYK 180. The amount of dispersant used is based on the supplier's recommendations.

The thixotropic agent is one or more of fumed silica, kaolin and attapulgite. The total amount of the thixotropic agent is 0-20%, preferably 0-15% of the total mass of the polydimethylsiloxane component.

The pigment is one or more of carbon black, titanium dioxide, iron oxide yellow, iron oxide red and phthalocyanine blue. The amount of pigment used depends on the color requirements of the paint.

The leveling agent is one or more of BYK333 and BYK354, and the use amount is according to the proposal of the supplier.

The defoamer is one or more of BYK066N, BYK085, and the use amount is according to the proposal of suppliers.

The ultraviolet light absorber is one or more selected from BASF1130, BASF770 and BASF292, and the usage amount is according to the proposal of the supplier.

The antioxidant is one or more of BASF1010, BASF B225 and BASF1330, and the usage amount is according to the proposal of the supplier.

The polydimethylsiloxane component can be added with the auxiliary agents according to the requirements according to the following sequence:

Firstly, weighing a certain amount of oligomer with a comb-shaped molecular structure and a side chain of which is PDMS, and adding the oligomer into a container.

And (2) adding a metered coupling agent, a dispersing agent, a leveling agent, a defoaming agent, an ultraviolet light absorber and an antioxidant according to the requirement, and fully and uniformly stirring.

And (3) adding the diluent, the filler, the thixotropic agent and the pigment, and fully and uniformly stirring to obtain the polydimethylsiloxane component.

In the preparation method of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea protective coating, the polyurea component (B component) is the isocyanate-terminated polyurea side chain.

A B-component diluent can be added into the polyurea component to adjust the viscosity, and the B-component diluent is selected from one or more of ethyl acetate (EAc), butyl acetate (BAc), propylene glycol methyl ether acetate (PMA) and ethyl 3-ethoxypropionate (EEP). The usage amount of the diluent of the component B can account for 5-30% of the total mass of the polyurea component. Preferably 10 to 20%.

The preparation method of the polyurea component can be carried out according to the following sequence:

and (1) weighing the side chains of the isocyanate end-capped polyurea according to a proportion.

And (2) adding the diluent of the component B in calculated amount, and uniformly mixing to obtain the polyurea component.

The mixing ratio of the polydimethylsiloxane component (A component) and the polyurea component (B component) of the amphiphilic high-strength and toughness polydimethylsiloxane-polyurea composite material is calculated according to the ratio of the equivalent of 3, 5-diamine benzoic acid in the synthesis process of the A component to the equivalent of the amino-terminated chain extender in the synthesis process of the B component, and is preferably 1:1-1.2.

And (3) fully mixing the component A and the component B for 10-15 min, and curing for 24-72 h at room temperature to obtain the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material.

The application of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material is used as a protective coating, and is particularly applied to the field of aerospace coatings.

Compared with the existing polyurea coating and silicone rubber/polyurea coating, the amphiphilic high-strength and toughness polydimethylsiloxane-polyurea composite material and the preparation method and application thereof have the advantages that:

(1) The amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material provided by the invention introduces a polydimethylsiloxane molecular chain and a polyurea molecular chain into a main chain in a side chain mode in a synthesis stage, so that a brush polymer is formed. Compared with the existing polydimethylsiloxane/polyurea/polydimethylsiloxane-polyurea comb-shaped polymer manufacturing method, the preparation method has the advantages that the molecular structures of two types of polymers are reserved to a greater extent, the compatibility and the structural stability of the two types of materials are improved, and the prepared composite material has the double physical and chemical characteristics of polydimethylsiloxane and polyurea.

(2) According to the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, by utilizing the preparation method, the polydimethylsiloxane side chain and the polyurea side chain are simultaneously introduced into the molecular chain of the composite material, and the novel coating with higher mechanical properties (the tensile strength is less than 20MPa and the elongation at break is less than 300%) than other polyurea/polydimethylsiloxane-polyurea protective coatings is prepared by adjusting the molecular weight ratio of the two side chains, so that macroscopic regulation and control of mechanical properties can be realized;

(3) The high-toughness polydimethylsiloxane-polyurea composite material with amphipathy has the polydimethylsiloxane hydrophobic group and the polyurea hydrophilic group inside, can macroscopically regulate and control the surface energy of the coating, further endows the coating with excellent amphipathy, and can realize high adhesive force on different substrates (carbon steel, concrete, hydrophilic polymer substrate and hydrophobic polymer substrate) under the condition of no primer;

(4) The amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material can be coated on the surfaces of different substrates through a specific process, and has good weather resistance, namely certain ultraviolet ageing resistance, acid resistance, alkali resistance and salt fog resistance;

(5) The polydimethylsiloxane-polyurea composite material can be used as a protective coating for protecting an airplane lattice structure and a ship rubber component, and the aim of light assembly is fulfilled without introducing too much mass.

Drawings

FIG. 1 is a graph showing the change trend of tensile strength and elongation at break of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material prepared in examples 1-6 according to the invention, wherein the tensile test is carried out by adopting test example 1, and the change trend of tensile strength and elongation at break of the material is shown under the molecular weight ratio of different polyurea side chains to polydimethylsiloxane side chains;

FIG. 2 is a graph showing the trend of increasing the impact strength of aluminum sheets coated with the material compared with that of pure aluminum sheets under the molecular weight ratio of different polyurea side chains to polydimethylsiloxane side chains after the impact resistance test of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material prepared in examples 1 to 6 according to the invention is adopted in test example 2;

FIG. 3 is a graph showing the trend of increasing tear strength of the amphiphilic high strength and toughness polydimethylsiloxane-polyurea composite material prepared in examples 1-6 according to the invention, after the tear performance test of test example 3, under the molecular weight ratios of different polyurea side chains and polydimethylsiloxane side chains;

FIG. 4 is a graph showing the variation trend of the adhesion force of the coating on the substrate under the molecular weight ratio of different polyurea side chains to polydimethylsiloxane side chains after the high-toughness polydimethylsiloxane-polyurea composite material with amphipathy prepared in the examples 1 to 6 of the invention is subjected to the adhesion force test for carbon steel under the condition of no primer by adopting the test example 4;

FIG. 5 is a graph showing the variation trend of the adhesive force of the paint on the substrate under the molecular weight ratio of different polyurea side chains to polydimethylsiloxane side chains after the test of the adhesive force of the concrete under the condition of no primer by adopting the test example 4 to the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material prepared in the embodiments 1 to 6 of the invention;

FIG. 6 is a graph showing the trend of the adhesion of the coating on the substrate under the molecular weight ratios of different polyurea side chains and polydimethylsiloxane side chains after the adhesion test of the hydrophobic polymer substrate under the primer-free condition by adopting the test example 4 of the amphiphilic high-strength and toughness polydimethylsiloxane-polyurea composite material prepared in the embodiments 1 to 6 of the invention;

FIG. 7 is a graph showing the change trend of the adhesion of the coating on the substrate under the molecular weight ratio of different polyurea side chains to polydimethylsiloxane side chains after the adhesion test of the hydrophilic polymer substrate under the condition of no primer by adopting the test example 4 to prepare the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material prepared in the examples 1 to 6.

Detailed Description

The present invention will be described in further detail with reference to examples.

In the following examples, the mechanical properties of the prepared high-strength and high-toughness polydimethylsiloxane-polyurea composite material with amphipathy were tested, including the following test works:

(1) Curing the prepared high-toughness polydimethylsiloxane-polyurea composite material with amphipathy for 1-3 days at 25-35 ℃ to realize complete curing;

(2) The mechanical property test was performed using a general tensile tester (GX-SF 001) from Shenzhen shared instrumentation Co., ltd. The test was performed at a strain rate of 50mm/min and at least four samples were tested according to ISO 37-2005. The length of the tensile test piece is 35mm, the middle width is 2mm, the thickness is 1mm, and the gauge length is 10mm;

In the following examples, impact protection performance tests on the prepared high-strength and high-toughness polydimethylsiloxane-polyurea composite material with amphipathy include the following test works:

The amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material is cut into rectangular samples with the thickness of 12.5mm multiplied by 35mm, and the rectangular samples are stuck on an aluminum alloy substrate with the thickness of 100mm multiplied by 12.5mm multiplied by 1.5mm by using glue. Performing an impact test on a composite structure formed by a high-strength and toughness polydimethylsiloxane-polyurea composite material sample with amphipathy and an aluminum alloy substrate by using a paint film impact tester;

the thickness of the composite material sample is 1-1.5 mm, the impact speed of impact resistance test setting is 3.8m/s, and the hammer body selects a simple beam 25J;

in the following examples, the tear strength test of the prepared high strength and toughness polydimethylsiloxane-polyurea composites with amphipathy includes the following test works:

Tear strength testing was still performed using the Shenzhen shared instrumentation Co., ltd. Universal tensile tester (GX-SF 001). The test was performed at a strain rate of 50mm/min, and at least four samples were tested according to ASTM D1938-2014. The tear specimen was 150mm long, 50.8mm wide and 1mm thick, and a predetermined incision was cut in the center of the specimen to a length of about 43mm.

In the following examples, adhesion tests on the prepared high-strength and high-toughness polydimethylsiloxane-polyurea composite material with amphipathy against different substrates (carbon steel, concrete, hydrophobic polymer substrate and hydrophilic polymer substrate) comprise the following test works:

The adhesion test was performed using a pullout adhesion tester from DeFelsko Co., USA AT). At least four samples were tested according to ASTM D4541. Before testing, ensuring the surface of the coating on the substrate to be clean and free of pollution, sticking a spindle with proper size on the surface of the coating by proper adhesive to ensure the adhesive to be fully cured, recording the maximum pulling force value when the coating is separated, and observing and recording the separation mode (such as the self-destruction of the coating, the separation of the coating from the interface of the substrate, the destruction of the substrate and the like).

In the following examples, the corrosion resistance of the prepared high-strength and high-toughness polydimethylsiloxane-polyurea composite material with amphipathy is tested, and the test work comprises the following steps:

The composite material is respectively put into 10% H ₂SO₄ solution, 10% HCl solution, 10% NaOH solution and 10% NaCl solution to be soaked for 30 days, and whether the surface is rusted, foamed, shed and the like is observed.

Example 1

The preparation method of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material comprises the following steps of:

(1) Carrying out vacuum dehydration on dihydroxyl single-end capped PDMS, isoparaffin diisocyanate (IPDI), polyetheramine D230 and diethyltoluenediamine (E-100) at 110 ℃ and minus 0.9MPa for 1.5 hours, taking out, and cooling to room temperature for standby;

(2) 1.78g of IPDI is weighed and poured into a beaker, 5g of dihydroxyl single-end capped PDMS is slowly dripped at the speed of 5 s/drop, and the mixture is stirred for 3 hours at the high speed of 500-800 rpm under the nitrogen environment at the temperature of 100 ℃ to obtain isocyanate capped prepolymer A;

(3) 1.78g of IPDI is put into an environment of 85 ℃, 0.575g of D230 is added dropwise, and the mixture is stirred for 3 hours at a high speed of 500-800 rpm to obtain an isocyanate end-capped prepolymer B;

(4) Weighing 0.38g of 3, 5-Diamine Benzoic Acid (DBA), adding into a reaction kettle filled with isocyanate end-capped prepolymer A, and mechanically stirring for 30min in an ice water bath to obtain an oligomer with a comb-shaped molecular structure and a PDMS side chain;

(5) Slowly adding 5g of N, N Dimethylformamide (DMF) solution dissolved with 0.82-g E g to 100 g into a reaction kettle filled with isocyanate end-capped prepolymer B, and continuously stirring at room temperature for reacting for 5min to obtain isocyanate end-capped PUA side chains;

(6) Uniformly and mechanically dispersing the obtained isocyanate-terminated PUA side chain in an oligomer solution with a PDMS side chain and a dressing structure at room temperature, stirring for 40min, pouring into a mold for curing to obtain the final high-toughness polydimethylsiloxane-polyurea composite material with amphipathy, and confirming by nuclear magnetism to prove that the material with the following structural formula is formed.

In this embodiment, Y has the following structure:

Wherein W is the following structure

Wherein U is as follows:

In the prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, the ratio of the molecular weight of a PUA side chain to the molecular weight of a PDMS side chain is 0.68:1;

The prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has the tensile strength of 55.97MPa, the elongation at break of 414.00%, the impact strength of 83.035% higher than that of a pure aluminum sheet, the tearing strength of 59.71N/mm, the adhesive force for carbon steel of 12.71MPa, the adhesive force for concrete of 7.035MPa, the adhesive force for a hydrophobic polymer substrate of 9.71MPa and the adhesive force for a hydrophilic polymer substrate of 12.275MPa under the condition of no primer.

Example 2

(1) Carrying out vacuum dehydration on dihydroxyl single-end capped PDMS, isoparaffin diisocyanate (IPDI), polyetheramine D400 and diethyltoluenediamine (E-100) at 110 ℃ and minus 0.9MPa for 1.5 hours, taking out, and cooling to room temperature for standby;

(3) 1.78g of IPDI is put into an environment of 85 ℃, 1g of D400 is added dropwise, and the mixture is stirred for 3 hours at a high speed of 500-800 rpm, so as to obtain an isocyanate end-capped prepolymer B;

(4) Weighing 0.38g of DBA, adding into a reaction kettle filled with isocyanate end-capped prepolymer A, and mechanically stirring for 30min in an ice water bath to obtain an oligomer with a comb-shaped molecular structure and a PDMS side chain;

(6) Uniformly and mechanically dispersing the obtained isocyanate-terminated PUA side chain in an oligomer solution with a PDMS side chain and a dressing structure at room temperature, stirring for 40min, and introducing into a mold for curing to obtain the final amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material.

In the prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, the ratio of the molecular weight of a PUA side chain to the molecular weight of a PDMS side chain is 1.18:1;

The prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has the tensile strength of 53.104MPa, the elongation at break of 619.061 percent, the impact strength of 102.924 percent, the tearing strength of 53.182N/mm, the adhesion force for carbon steel of 12.182MPa, the adhesion force for concrete of 6.924MPa, the adhesion force for hydrophobic polymer base material of 8.182MPa and the adhesion force for hydrophilic polymer base material of 11.446MPa compared with a pure aluminum sheet.

Example 3

(1) Carrying out vacuum dehydration on dihydroxyl single-end capped PDMS, isoparaffin diisocyanate (IPDI), polyetheramine D1000 and diethyltoluenediamine (E-100) at 110 ℃ and minus 0.9MPa for 1.5 hours, taking out, and cooling to room temperature for standby;

(2) 1.78g of IPDI is weighed and poured into a beaker, 5g of dihydroxyl single-end capped PDMS is slowly dripped at the speed of 5 s/drop, and the mixture is stirred for 3 hours at a high speed in a nitrogen environment at the temperature of 100 ℃ to obtain isocyanate capped prepolymer A;

(3) 1.78g of IPDI was put under an environment of 85 ℃, 2.5g of D1000 was added dropwise, and stirred at high speed for 3 hours to obtain isocyanate terminated prepolymer B;

In the prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, the ratio of the molecular weight of a PUA side chain to the molecular weight of a PDMS side chain is 2.96:1;

The prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has the tensile strength of 50.343MPa, the elongation at break of 790.821 percent, the impact strength of 131.813 percent, the tearing strength of 46.265N/mm, the adhesion force for carbon steel of 11.265MPa, the adhesion force for concrete of 6.813MPa, the adhesion force for hydrophobic polymer base material of 7.265MPa and the adhesion force for hydrophilic polymer base material of 10.194MPa compared with a pure aluminum sheet.

Example 4

(1) Carrying out vacuum dehydration on dihydroxyl single-end capped PDMS, isoparaffin diisocyanate (IPDI), polyetheramine D2000 and diethyltoluenediamine (E-100) at 110 ℃ and minus 0.9MPa for 1.5 hours, taking out, and cooling to room temperature for standby;

(3) 1.78g of IPDI is put into an environment of 85 ℃, 5g of D2000 is added dropwise, and the mixture is stirred for 3 hours at a high speed to obtain isocyanate end-capped prepolymer B;

In the prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, the ratio of the molecular weight of a PUA side chain to the molecular weight of a PDMS side chain is 5.92:1;

The prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has the tensile strength of 46.276MPa, the elongation at break of 872.194 percent, the impact strength of 151.793 percent, the tearing strength of 42.091N/mm, the adhesion force for carbon steel of 10.991MPa, the adhesion force for concrete of 6.793MPa, the adhesion force for hydrophobic polymer base material of 7.091MPa and the adhesion force for hydrophilic polymer base material of 9.821MPa compared with a pure aluminum sheet.

Example 5

(1) Carrying out vacuum dehydration on dihydroxyl single-end capped PDMS, isoparaffin diisocyanate (IPDI), polyetheramine T3000 and diethyl toluenediamine (E-100) at 110 ℃ and minus 0.9MPa for 1.5 hours, taking out, and cooling to room temperature for standby;

(3) 1.78g of IPDI was put under an environment of 85 ℃, 7.5g of T3000 was added dropwise, and stirred at high speed for 3 hours to obtain isocyanate terminated prepolymer B;

The structural formula is different from that of examples 1-4 in that U is of the following structureFormula 15.

The above, t, s and x are all average values of the corresponding number of the repeating units, t is a positive integer, s is a positive integer, and x is a positive integer.

In the prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, the ratio of the molecular weight of a PUA side chain to the molecular weight of a PDMS side chain is 8.88:1;

The prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has the tensile strength of 37.261MPa, the elongation at break of 939.446 percent, the impact strength of 142.945 percent, the tearing strength of 39.938N/mm, the adhesion force for carbon steel of 9.938MPa, the adhesion force for concrete of 5.945MPa, the adhesion force for hydrophobic polymer base material of 6.531MPa and the adhesion force for hydrophilic polymer base material of 8.061MPa compared with a pure aluminum sheet.

Example 6

(1) Carrying out vacuum dehydration on dihydroxyl single-end capped PDMS, isoparaffin diisocyanate (IPDI), polyetheramine T5000 and diethyl toluenediamine (E-100) at 110 ℃ and minus 0.9MPa for 1.5 hours, taking out, and cooling to room temperature for standby;

(3) 1.78g of IPDI was put under an environment of 85 ℃, 12.5g of T5000 was added dropwise, and stirred at high speed for 3 hours to obtain isocyanate terminated prepolymer B;

In the prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, the ratio of the molecular weight of a PUA side chain to the molecular weight of a PDMS side chain is 14.79:1;

The prepared amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has the tensile strength of 35.049MPa, the elongation at break of 1090.275 percent, the impact strength of 134.597 percent, the tearing strength of 34.531N/mm, the adhesion force for carbon steel of 8.531MPa, the adhesion force for concrete of 5.597MPa, the adhesion force for hydrophobic polymer base material of 5.938MPa and the adhesion force for hydrophilic polymer base material of 6.938MPa compared with a pure aluminum sheet.

Example 7

The difference from example 1 is that an auxiliary agent is added to an oligomer having a comb-shaped molecular structure with a PDMS side chain as needed by the following method:

Example 8

The procedure is as in example 1, except that the B-component diluent is added to the isocyanate-terminated polyurea side chains and prepared as follows:

Comparative example 1

The polydimethylsiloxane and the polyurea are directly mixed, so that two physical mixed networks are formed in the system, the compatibility is poor, layering phenomenon in a sample piece is easy to generate, and the performances of mechanics, adhesive force, weather resistance and the like are poor.

Test example 1

The tensile property test of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material comprises the following steps of:

The high-toughness polydimethylsiloxane-polyurea composite material with amphipathy obtained in the method in the examples 1-6 is subjected to a tensile test by a tensile testing machine, the tensile strength and the elongation at break of the material are analyzed according to the recorded test data, the test is carried out at a strain rate of 50mm/min, and at least four samples are tested according to ISO 37-2005. The tensile test piece is 35mm long, 2mm wide in the middle, 1mm thick and 10mm in gauge length.

As can be seen from the variation trend of the tensile strength and the elongation at break of the graph 1, the shorter PUA side chain molecular chain can improve the tensile strength of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material, and the elongation at break is increased along with the increase of the molecular weight of the PUA side chain. The maximum tensile strength and elongation at break of the material respectively appear when the molecular weight ratio of the PUA side chain to the PDMS side chain is 0.68:1 and 14.79:1, respectively, and are 55.97MPa and 1090.275 percent respectively. The elongation at break of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material gradually increases along with the increase of the molecular weight of the PUA side chain, and the elongation at break of the high-strength and high-toughness polydimethylsiloxane-polyurea composite material has a certain softening effect due to the increase of the molecular weight of a soft segment in the PUA side chain, namely a larger flexible region formed in the synthesis reaction process. The tensile strength of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material gradually increases along with the reduction of the molecular weight of the PUA side chain, and the tensile strength is due to the fact that the molecular weight of a soft segment in the PUA side chain is reduced, namely, hard domains formed in the synthetic reaction process are denser, and the high-strength and high-toughness polydimethylsiloxane-polyurea composite material has a certain reinforcing and toughening effect.

As is clear from FIG. 1, the two curves have a distinct intersection point, between the molecular weights of the PUA side chains and the PDMS side chains of a ratio of 2.96:1 and 5.92:1. The result shows that under the formula, the tensile strength and the elongation at break of the sample can be simultaneously considered, and the requirements are met.

Test example 2

An impact resistance test of a high-strength and toughness polydimethylsiloxane-polyurea composite material with amphipathy, comprising the following steps of:

The amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material obtained in the methods in examples 1-6 is subjected to impact resistance test by a simple beam impact tester, the impact resistance change of the material is analyzed by recording experimental data, and a rectangular sample with the test piece size of 12.5mm multiplied by 35mm multiplied by 1mm is placed on an aluminum alloy substrate with the size of 100mm multiplied by 12.5mm multiplied by 1.5 mm. Impact speed set by the impact resistance test is 3.8m/s, and the hammer body selects a simple beam 25J.

The impact resistance trend of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material is shown in fig. 2, and the impact resistance of an aluminum sheet after the material is attached is improved as shown in fig. 2. Compared with a pure aluminum sheet, after the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material is attached, the impact strength is increased by 83.035% at the minimum and increased by 151.793% at the maximum.

Test example 3

The tearing strength test of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material comprises the following steps of:

FIG. 3 is a pant-type tear test result according to ASTM D1938-2014. The tear strength of the composites with different ratios of PUA side chains to PDMS side chain molecular weights were 59.71, 53.182, 46.265, 42.091, 39.938 and 34.531N/mm, respectively. Compared to a composite with a longer PUA side chain, a composite with a shorter PUA side chain has higher tear strength because the hard domains within the PUA short chain molecules are bound together by strong intermolecular interactions between dense hydrogen bonds, which are stronger than the more distant hydrogen bond sequences in the PUA long chain. The dense hard domains are beneficial in preventing crack propagation, can provide more physical entanglement points and efficient chemical crosslinking, which can also explain why short-chain PUAs are effective in enhancing tear resistance of composites.

Test example 4

The adhesive force test of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material for different substrates (carbon steel, concrete, hydrophobic polymer substrate and hydrophilic polymer substrate) comprises the following steps:

Fig. 4-7 are adhesion test results performed according to ASTM D4541. Composite materials having different ratios of PUA side chains to PDMS side chain molecular weights exhibit different adhesion forces for different substrates. For carbon steel substrates, the adhesive force of 12.71MPa can be achieved at the highest, for concrete substrates, the adhesive force of 7.035MPa can be achieved at the highest, for hydrophobic polymer substrates, the adhesive force of 9.71MPa can be achieved at the highest, and for hydrophilic polymer substrates, the adhesive force of 12.275MPa can be achieved at the highest. The different adhesion between the coating and the substrate is due to the different compatibility and surface energy of the two. The composite material with shorter PUA side chains has higher adhesive force with the substrate, and because the PUA short chain molecules have more dense hydrogen bonds, the interface bonding strength between the PUA short chain molecules and the substrate is higher due to the strong intermolecular interaction, so that the composite material has excellent adhesive strength.

Test example 5

A corrosion resistance test of an amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material comprises the following steps:

The test results are shown in the following table:

through the data analysis of the embodiment, the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material prepared by the invention has excellent corrosion resistance and can be applied to harsh environments such as acid, alkali, salt and the like.

Claims

1. The amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite is characterized by having a structure shown in a formula 1:

in the formula 1, Y is any one or a mixture of the following structures or isomers thereof:

in the formula 1, W is any one or a mixture of the following structures or isomers thereof:

In the formula 1, U is any one or a mixture of the following structures:

2. The amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material according to claim 1, wherein the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material is a composite material with a brush-shaped molecular structure, wherein a three-functionality connecting agent is used for bonding a PDMS molecular chain and a PUA molecular chain on two sides of a main chain.

3. The amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material according to claim 1 or 2, wherein the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material has a tensile strength ranging from 35MPa to 56MPa, an elongation at break ranging from 414% to 1091%, an impact strength which is improved by 83% to 152% as compared with a pure aluminum sheet, a tear strength of 34 to 60N/mm, and an adhesion to carbon steel of 8 to 13MPa, an adhesion to concrete of 5 to 9MPa, an adhesion to a hydrophobic polymer substrate of 5 to 10MPa and an adhesion to a hydrophilic polymer substrate of 6 to 13MPa.

4. The method for preparing the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material according to any one of claims 1 to 3 is characterized by comprising the following steps of reacting dihydroxy single-ended PDMS with isocyanate to obtain a prepolymer A;

The macromolecular polyamine is condensed with isocyanate to generate prepolymer containing urea bond, and then the prepolymer is further reacted with an amino-terminated chain extender to form polyurea side chains B;

And (3) carrying out side chain extension reaction on the trifunctional connecting agent with the prepolymer A under low-temperature protection, and then grafting the polyurea side chain B to finally synthesize the amphiphilic high-strength and toughness polydimethylsiloxane-polyurea composite material.

5. The method for preparing an amphiphilic high-strength and toughness polydimethylsiloxane-polyurea composite material according to claim 4, wherein the isocyanate is one or more selected from diphenylmethane-4, 4' -diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate and dicyclohexylmethane diisocyanate, and/or the macromolecular polyamine is one or more selected from polyether polyamine with a number average molecular weight Mn=2000-5000, polyester polyamine, polyolefin polyamine and terminal amino block copolymer of the above materials, and/or the terminal amino chain extender is selected from diaminoxylene, 4' -bis-sec-butylaminodiphenyl methane, diethyl toluenediamine, isophorone diamine, adipic acid dihydrazide, ethylenediamine, 1, 2-propylenediamine, 2, 5-dimethyl-2, 5-hexamethylenediamine, 1, 11-undecyl diamine, 1, 12-dodecyldiamine, 2,4' -diamino-dicyclohexylmethane, 1,3, 5-trimethyl-2, 4' -diamino-hexamethylenediamine, 4-diamino-4, 4-trimethyl-2, 4-diamino-4-cyclohexane or 2, 4-diamino-1, 4' -dicyclohexyl-diamine.

6. The method for preparing the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material as recited in claim 4, comprising the following steps:

dropwise adding and mixing dihydroxy single-end capped polydimethylsiloxane and isocyanate solution, stirring after the dropwise adding, reacting at 100-110 ℃ for 2.5-3.5 hours at the rotating speed of 500-800 rpm, and adopting nitrogen protection in the process to obtain isocyanate end capped prepolymer A;

uniformly stirring and mixing macromolecular polyamine and isocyanate, and prepolymerizing for 2-3 hours at 80-90 ℃ at the rotating speed of 500-800 rpm, wherein nitrogen protection is adopted in the process to obtain an isocyanate end-capped prepolymer;

And (6) adding the isocyanate-terminated polyurea side chain B into an oligomer with a comb-shaped molecular structure, wherein the side chain of the oligomer is PDMS at the temperature of 25-35 ℃, uniformly stirring for 30-60 min, and pouring the mixture into a mold for curing to obtain the final high-strength and high-toughness polydimethylsiloxane-polyurea composite material with amphipathy.

7. The method of preparing a high-toughness polydimethylsiloxane-polyurea composite with amphipathy according to claim 6, wherein in the step (2), the dihydroxyl single-end-capped polydimethylsiloxane is 1 (2-3), and/or in the step (3), the macromolecular polyamine is 1 (2-3), and/or in the step (4), the trifunctional linker is 3, 5-diamine benzoic acid, 1, 2-diaminoethanol, 2, 3-diamino-1-propanol, 1, 2-diamino-3-chloropropanol, 1, 3-diamino-2-propanol, 2, 3-dihydroxypropylamine, 1, 2-dihydroxyethylamine, 1, 2-dihydroxy-3-aminopropane, 4, 5-dihydroxy-1, 3-diaminobenzene, 1, 2-dihydroxy-4-aminobenzene, 1, 2-dihydroxycyclohexylamine, 2, 4-dihydroxybenzene, one-isocyanic acid and/or in the step (3), the molecular weight is determined by the mole ratio of the prepolymer, and/or in the step (1, 3) the prepolymer is synthesized, and the molecular weight is terminated by the prepolymer, the ratio of the number average molecular weight of the isocyanate end-capped polyurea side chain to the number average molecular weight of the oligomer with the comb-shaped molecular structure, the side chain of which is PDMS, is (0.68-14.79): 1.

8. The preparation method of the amphiphilic high-strength and high-toughness polydimethylsiloxane-polyurea composite material according to claim 6, wherein the side chain is an oligomer of PDMS with a comb-shaped molecular structure, and one or more of a diluent, a filler, a coupling agent, a dispersing agent, a thixotropic agent, a pigment, a leveling agent, a defoaming agent, an ultraviolet absorber and an antioxidant are added according to requirements.

9. The preparation method of the amphiphilic high-toughness polydimethylsiloxane-polyurea composite material is characterized in that the isocyanate-terminated polyurea side chain B is added with a B component diluent to adjust viscosity, wherein the B component diluent is one or more of ethyl acetate, butyl acetate, propylene glycol methyl ether acetate and ethyl 3-ethoxypropionate, and the usage amount of the B component diluent can account for 5-30% of the total mass of the isocyanate-terminated polyurea side chain B.

10. Use of the high strength and toughness polydimethylsiloxane-polyurea composite with amphipathy according to any one of claims 1 to 3 as a protective coating.