CN115093709B - Hydrolysis-resistant polyborosiloxane and preparation method thereof - Google Patents

Abstract

The invention provides hydrolysis-resistant polyborosiloxane and a preparation method thereof. The invention provides a preparation method of hydrolysis-resistant polyborosiloxane, which comprises the following steps: a) The preparation of the polyborosiloxane with high boron content and high polybasic borate content specifically comprises the following steps: a1 Reacting a terminal bishydroxy-terminated polydimethylsiloxane with boric acid to obtain a primary reactant; a2 Transferring the primary reactant to a vacuum condition for vacuum reaction to obtain a crude product of the polyborosiloxane; a3 Removing unreacted boric acid from the crude polyborosiloxane product to obtain purified polyborosiloxane; b) Blending: blending the purified polyborosiloxane with an amine compound to obtain a hydrolysis-resistant polyborosiloxane; the amine compound is an alkylamine compound and/or aminoalkyl terminated siloxane. The hydrolysis resistance of the polyborosiloxane prepared by the invention can be effectively improved.

Description

Hydrolysis-resistant polyborosiloxane and preparation method thereof

Technical Field

The invention relates to the field of organic materials, in particular to hydrolysis-resistant polyborosiloxane and a preparation method thereof.

Background

Polyborosiloxane is a silicone polymer containing B. The structure of the material comprises a Si-O-B chemical bond network formed by taking B as a chemical cross-linking point, and a physical network comprising a B: O dynamic coordination bond formed by B and O on the other chain and a chain end Si-O-B- (OH) ₂ Hydrogen bonds formed between them. In normal conditions, polyborosiloxane exhibits liquid-like viscous properties and, when subjected to rapid external forces, exhibits solid-like elastic properties. Based on such rate responsiveness, polyborosiloxane has wide application in the fields of impact-resistant protective materials and flexible sensors.

However, since the chemical bond Si-O-B is sensitive to water and is easy to hydrolyze in water environment, the viscoelastic responsiveness of the polyborosiloxane is affected, and the application of the polyborosiloxane is limited. Impact resistant composite suds prepared based on polyborosiloxane was reported by Amourgel brand founder Danialplant JamesHas great influence on the impact resistance, even can crack, and can not be used continuously (Plant, D.J. the optimization of flexible impact-protection systems for varying string rates and energines.2014.); tongfei Wu et al reported that a polyborosiloxane-based resistance responsive composite lost its resistance response after water vapor treatment (Wu, T.F. etc. A self-help, adaptive and conductive polymer composite in-k for 3D printing of gas sensors. Journal ofMaterials Chemistry C2018, 6 (23), 6200-6207). Therefore, the influence of hydrolysis on the viscoelastic responsiveness of the polyborosiloxane is irreversible, so that the improvement of the hydrolysis resistance of the polyborosiloxane is a problem to be solved.

Patent application No. 201910923910.X discloses a waterproof polyborosiloxane impact-resistant damping material and a preparation method thereof, and polyborosiloxane and a water-absorbing material are blended. However, the super absorbent resin adopted by the water absorbing material has slow volatilization speed after water absorption; meanwhile, the water-absorbing material has poor compatibility with the polyborosiloxane, and water-absorbing resin particles are separated from the polyborosiloxane after multiple cycles, so that the hydrolysis of the polyborosiloxane cannot be fundamentally solved. Yajima, S. et al earlier suggested that polyborosiloxanes prepared with phenyl-substituted silicone oils would be moisture resistant because OF the steric effect OF the phenyl ring to shield moisture (Yajima, S.; hayashi, J.; okamura, K.PYROLYSIS OF A POLYBORODINYLSILOXANE. Nature1977,266 (5602), 521-522). On the one hand, the steric effect of the benzene ring is almost ineffective in a large water environment; on the other hand, the steric effect simultaneously hinders the formation of dynamic coordination bonds of B to O, and accelerates the hydrolysis of the polyborosiloxane.

Disclosure of Invention

In view of the above, the present invention aims to provide a hydrolysis resistant polyborosiloxane and a preparation method thereof. The hydrolysis resistance of the polyborosiloxane can be effectively improved.

The invention provides a preparation method of hydrolysis-resistant polyborosiloxane, which comprises the following steps:

a) The preparation of the polyborosiloxane with high boron content and high polybasic borate content specifically comprises the following steps:

a1 Reacting a terminal bishydroxy-terminated polydimethylsiloxane with boric acid to obtain a primary reactant;

a2 Transferring the primary reactant to a vacuum condition for vacuum reaction to obtain a crude product of the polyborosiloxane;

a3 Removing unreacted boric acid from the crude polyborosiloxane product to obtain purified polyborosiloxane;

b) Blending:

blending the purified polyborosiloxane with an amine compound to obtain a hydrolysis-resistant polyborosiloxane;

the amine compound is an alkylamine compound and/or aminoalkyl terminated siloxane.

Preferably, in the step a 1), the molar ratio of the boric acid to the hydroxyl in the end-dihydroxy-terminated polydimethylsiloxane is (0.5-1) to 1;

the end-dihydroxy-terminated polydimethylsiloxane is dihydroxy-terminated polydimethylsiloxane with kinematic viscosity of 60-3000 cst at 25 ℃;

in the step b), the alkylamine compound is a C4-C6 alkylamine compound.

Preferably, in the step b), the amine compound is one or more selected from diethylamine, triethylamine, tetramethylmethanediamine, triethylenediamine and bis (3-aminopropyl) terminated polydimethylsiloxane.

Preferably, in the step B), the amine compound and the purified polyborosiloxane are blended according to the molar ratio of N to B of (0.2-1) to 1.

Preferably, the terminal dihydroxy terminated polydimethylsiloxane is selected from one or more of dihydroxy terminated polydimethylsiloxanes with kinematic viscosity of 60cst, 100cst, 300cst, 1000cst and 3000cst at 25 ℃.

Preferably, the bis (3-aminopropyl) terminated polydimethylsiloxane has a number average molecular weight of 1000 to 50000g/mol.

Preferably, in the step a 1), the reaction temperature is 80-140 ℃ and the reaction time is 12-48 h.

Preferably, in the step a 2), the temperature of the vacuum reaction is 100-150 ℃ and the time is 8-16 h.

Preferably, the step b) specifically comprises:

dissolving the purified polyborosiloxane in an organic solvent, adding an amine compound for mixing, and then removing the organic solvent to obtain the hydrolysis-resistant polyborosiloxane;

the step a 3) specifically comprises the following steps:

dissolving the crude polyborosiloxane in an organic solvent, carrying out solid-liquid separation, and removing the organic solvent from the obtained separated liquid to obtain purified polyborosiloxane;

in the step a 2), the vacuum degree under the vacuum condition is as follows: the vacuum degree is more than or equal to 0.06MPa and less than 0.1MPa;

the specification of the purified polyborosiloxane obtained in the step a) is as follows: the boron content is more than or equal to 300ppm, the content of the ternary borate unit is 30-60 wt%, and the content of the binary borate unit is 30-50 wt%.

The invention also provides hydrolysis-resistant polyborosiloxane prepared by the preparation method in the technical scheme.

The preparation method provided by the invention comprises the steps of a 1) to a 3) preparing the polyborosiloxane with high boron content and high polybasic borate content, then blending the polyborosiloxane with a certain amine compound, introducing N: B dynamic coordination bonds into the polyborosiloxane, and effectively improving the hydrolysis resistance of the polyborosiloxane under the combined action of the structural improvement of the two aspects. Compared with the means of adding water absorbing material in the prior art, the invention has the advantages that the structure is adopted, the double pipes are adopted, and the hydrolysis resistance of the polyborosiloxane is fundamentally improved.

Experimental results show that the hydrolysis-resistant polyborosiloxane provided by the invention is completely soaked in water at room temperature, the boric acid dropping rate is below 18% after the polyborosiloxane is soaked in water for 12 hours, the boric acid dropping rate is below 25% after the polyborosiloxane is soaked in water for 14 hours, the polyborosiloxane can still keep a gel form after 24 hours, and the polyborosiloxane shows excellent hydrolysis resistance. In addition, the elasticity modulus of the hydrolysis-resistant boron siloxane is more than 20000Pa and can reach 20000-400000 Pa; the relaxation time is 1-10 s, and the material shows good mechanical property.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a graph showing the change of boric acid content with respect to the time of soaking water in example 1 and comparative example 1;

FIG. 2 is a schematic diagram of the morphology of the samples of example 1 and comparative examples 1-3 at different soaking times.

Detailed Description

The invention provides a preparation method of hydrolysis-resistant polyborosiloxane, which comprises the following steps:

a) The preparation of the polyborosiloxane with high boron content and high polybasic borate content specifically comprises the following steps:

a1 Reacting a terminal bishydroxy terminated polydimethylsiloxane with boric acid to obtain a primary reactant;

a2 Transferring the primary reactant to a vacuum condition for vacuum reaction to obtain a crude product of the polyborosiloxane;

a3 Removing unreacted boric acid from the crude polyborosiloxane product to obtain purified polyborosiloxane;

b) Blending:

blending the purified polyborosiloxane with an amine compound to obtain a hydrolysis-resistant polyborosiloxane;

the amine compound is an alkylamine compound and/or aminoalkyl terminated siloxane.

In the present invention, step a) is the preparation of a polyborosiloxane having a high boron content and a high polyboronate content. Boric acid is a 3-functionality raw material, and is reacted with the end-dihydroxy-terminated polydimethylsiloxane to generate three structural units shown in the following formulas (a) to (c): a ternary borate structural unit (a), a binary borate structural unit (b) and a monobasic borate structural unit (c). The aim of step a) of the invention is to obtain a high content of a polybasic borate (i.e. ternary and binary borates) which is beneficial to improving the hydrolysis resistance of the polyorgano siloxane product.

The invention specifically prepares the target product through the steps a 1) to a 3).

[ with respect to step a1]:

a1 A terminal bishydroxy terminated polydimethylsiloxane was reacted with boric acid to give a primary reactant.

In the invention, the terminal dihydroxy terminated polydimethylsiloxane is preferably dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 60-3000 cst at 25 ℃, and more preferably one or more of dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 60cst, 100cst, 300cst, 1000cst and 3000cst at 25 ℃. The source of the terminal dihydroxy terminated polydimethylsiloxane is not particularly limited in the invention, and the terminal dihydroxy terminated polydimethylsiloxane is a commercial product.

In the present invention, the boric acid is preferably sieved and dried before use. In the present invention, the source of the boric acid is not particularly limited, and may be a commercially available product.

In the present invention, the molar ratio of the boric acid to the hydroxyl group in the terminal bishydroxy-terminated polydimethylsiloxane is preferably (0.5 to 1) to 1, and specifically may be 0.5: 1, 0.6: 1, 0.7: 1, 0.8: 1, 0.9: 1, 1:1, and more preferably 1: 1. In the invention, the proportion is one of the key points of the invention, the control of the proportion is favorable for obtaining the polyborosiloxane with high boron content and high polybasic borate content, if the using amount of boric acid is too low, the polydimethylsiloxane with the end double hydroxyl end-capped can not completely react, so that the boron content of the product is too low; if the amount of boric acid is too high, a large amount of a low-valent borate (e.g., monobasic borate) is caused, and the low amount of the polybasic borate is disadvantageous in improving hydrolysis resistance.

In the invention, the reaction temperature is preferably 80-140 ℃, the temperature is controlled in the temperature range, the reaction efficiency can be ensured, the target product can be generated smoothly, and if the temperature is too high, the boric acid can cause the silicon oil molecular chain to break; the reaction temperature may be 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, and more preferably 120 ℃. The reaction time is preferably 12 to 48 hours, specifically 12 hours, 16 hours, 20 hours, 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours and 48 hours, and more preferably 48 hours. In the present invention, the above reaction is preferably carried out under stirring. After the reaction, a primary reactant is obtained.

[ with respect to step a2]:

a2 Transferring the primary reactant to a vacuum condition for vacuum reaction to obtain a crude product of the polyborosiloxane.

In the present invention, the degree of vacuum of the vacuum condition is preferably: the vacuum degree is more than or equal to 0.06MPa and less than 0.1MPa. The vacuum = atmospheric pressure-absolute pressure. In the invention, the temperature of the vacuum reaction is preferably 100-150 ℃, the temperature is controlled to be the temperature, the reaction efficiency can be ensured, the target product can be generated smoothly, if the temperature is too high, the unreacted boric acid can lead the silicon oil to be randomly broken, and the molecular weight distribution of the polyborosiloxane is widened; the reaction temperature may be 100 deg.C, 110 deg.C, 120 deg.C, 130 deg.C, 140 deg.C, 150 deg.C. The time of the vacuum reaction is preferably 8 to 16 hours, and specifically may be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, and 16 hours. According to the invention, after the reaction in the step a 1) is finished, the reaction is continued again instead of post-treatment, and the reaction is carried out under a certain vacuum condition, so that the reaction of boric acid and silicone oil can be promoted, more polyboronate structures are generated, and the polymer with high polyboronate content is obtained, thereby obtaining the crude polyborosiloxane.

In the step a 2), the reaction of boric acid and silicone oil is promoted by further reaction through a vacuum method, and part of unreacted silicone oil in the system can be removed. In the vacuum reaction process, water as a by-product and volatile unreacted silicone oil are generated, so that the vacuum degree of the vacuum oven is lowered, and at the moment, the vacuum oven is continuously vacuumized until the vacuum degree of the vacuum oven is not changed and is kept stable.

[ with respect to step a3]:

a3 Removing unreacted boric acid from the crude polyborosiloxane product to obtain purified polyborosiloxane.

In the invention, after the step a 2) is finished, the reaction is not carried out hundred percent, unreacted boric acid exists in the crude polyborosiloxane product and can influence the hydrolysis resistance of the product, and the polyborosiloxane is removed by the method and further purified, thereby improving the hydrolysis resistance.

In the present invention, the mode of removing unreacted boric acid preferably includes: and dissolving the crude polyborosiloxane in an organic solvent, carrying out solid-liquid separation, and removing the organic solvent from the obtained separated liquid to obtain the purified polyborosiloxane.

The organic solvent is preferably at least one of chloroform, n-hexane, tetrahydrofuran and acetone. The dosage ratio of the crude polyborosiloxane to the organic solvent is not particularly limited, and the crude polyborosiloxane can be fully dissolved, wherein boric acid is insoluble in the organic solvent, and therefore can be removed by solid-liquid separation. The solid-liquid separation mode is not particularly limited in the invention, and can be a conventional mode in the field, such as filtration and the like. After solid-liquid separation, the organic solvent is removed from the resulting separated liquid. In the present invention, the organic solvent is preferably removed by: rotary evaporation (i.e. rotary evaporation) and vacuum drying. Wherein the rotary steaming temperature is preferably 30-80 ℃, and specifically can be 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃ and 80 ℃. The temperature of the vacuum drying is preferably 40-120 ℃, and the time is preferably 3-12 h. After all the above treatments, a purified polyborosiloxane was obtained.

In the present invention, the specifications of the purified polyborosiloxane obtained in step a) are as follows: the boron content is more than or equal to 300ppm, and can be more specifically 300-1500 ppm; the content of the ternary borate unit is 30-60 wt%, and the content of the binary borate unit is 30-50 wt%.

[ with respect to step b ]:

blending: and blending the purified polyborosiloxane with an amine compound to obtain the hydrolysis-resistant polyborosiloxane.

In the invention, the amine compound is an alkylamine compound and/or aminoalkyl terminated siloxane. According to the invention, the purified polyborosiloxane and the amine compound are blended to form B: N dynamic coordination between the purified polyborosiloxane and the amine compound, and the newly formed B: N dynamic coordination bond replaces the B: O dynamic coordination bond in the polyborosiloxane obtained in the step a), so that the hydrolysis resistance of the material is improved.

Wherein:

the alkylamine compound is preferably a C4-C6 alkylamine compound. The invention adopts the micromolecular alkylamine monomer compound with shorter carbon chain length, can effectively improve the hydrolysis resistance of the material, although the amine compound absorbs water, the amine compound has short carbon chain length and lower boiling point, and can easily remove the amine compound which is not successfully coordinated during post-treatment, thereby effectively improving the hydrolysis resistance of the polyborosiloxane, and if the carbon chain length is too long, the long carbon chain amine and the polyborosiloxane are easy to separate and are difficult to be effectively coordinated, so that the hydrolysis resistance of the material can not be effectively improved. The C4 to C6 alkylamine compound is a small molecule containing a primary amine, a secondary amine or a tertiary amine, and more preferably at least one of diethylamine, triethylamine, tetramethylmethanediamine and triethylenediamine.

The aminoalkyl-terminated siloxane is preferably bis (3-aminopropyl) -terminated polydimethylsiloxane. Although the substances are polymers and have higher molecular weight, the main structure of the polyborosiloxane is also a polysiloxane structure, the polyborosiloxane has good compatibility with the polyborosiloxane and does not generate phase separation, and an interpenetrating network can be formed when amino at the tail end of a chain is coordinated with B of the polyborosiloxane, so that the hydrolysis resistance of the polyborosiloxane can be effectively improved. In the invention, the number average molecular weight of the bis (3-aminopropyl) terminated polydimethylsiloxane is preferably 1000-50000 g/mol, specifically 1000g/mol, 5000g/mol, 10000g/mol, 15000g/mol, 20000g/mol, 25000g/mol, 30000g/mol, 35000g/mol, 40000g/mol, 45000g/mol and 50000g/mol.

The structures of the above 5 specific amine compounds are respectively as follows:

diethylamine:

triethylamine: />

Tetramethylmethanediamine:

triethylene diamine: />

Bis (3-aminopropyl) terminated polydimethylsiloxane:

in the invention, the amine compound and the purified polyborosiloxane are blended according to the molar ratio of N to B of (0.2-1) to 1, namely the molar ratio of N in the amine compound to B in the purified polyborosiloxane is (0.2-1) to 1, and specifically can be 0.2: 1, 0.3:1, 0.4: 1, 0.5: 1, 0.6: 1, 0.7: 1, 0.8: 1, 0.9: 1 and 1: 1. The hydrolysis resistance of the polyborosiloxane can be effectively improved by controlling the proportion, and the hydrolysis resistance can not be effectively improved if the N/B ratio is too low or too high.

In the present invention, preferably, the step b) specifically includes: dissolving the purified polyborosiloxane in an organic solvent, adding an amine compound for mixing, and then removing the organic solvent to obtain the hydrolysis-resistant polyborosiloxane.

Wherein:

the organic solvent is preferably at least one of chloroform, n-hexane, tetrahydrofuran and acetone. The amine compound is preferably added and mixed by stirring. The mixing is carried out at room temperature, and specifically may be 10 to 30 ℃, more preferably 25 ℃. The stirring time is preferably 1 to 3 hours, and more preferably 3 hours. In the invention, the amine compound is in a liquid state, and the purified polyborosiloxane and the amine compound are blended in the organic solvent, so that the blending is more sufficient and uniform.

After blending, the organic solvent is removed. In the present invention, the organic solvent is preferably removed by: the solvent is removed by rotary evaporation and then dried in vacuum. The rotary evaporation is preferably performed at room temperature, and specifically may be 10 to 30 ℃, and more preferably is 25 ℃. The temperature condition of the vacuum drying is preferably room temperature, and specifically can be 10-30 ℃, and more preferably is 25 ℃; the time for vacuum drying is preferably 24h. The invention controls the blending and solvent removal under the condition of room temperature, which is beneficial to ensuring the formation and the stability of the N: B dynamic coordination bond; the N: B dynamic coordination bond is temperature sensitive, and if the temperature is too high, the dissociation will occur at 60 ℃, and if the N: B dynamic coordination bond is dissociated, the amine compound is easy to volatilize from the system, and the effective coordination cannot be carried out, so that the hydrolysis resistance cannot be improved. After the solvent is removed, the hydrolysis resistant polyborosiloxane is obtained.

The invention also provides hydrolysis-resistant polyborosiloxane, which is prepared by the preparation method in the technical scheme. The elasticity modulus of the hydrolysis-resistant boron siloxane obtained by the invention is more than 20000Pa and can reach 20000-400000 Pa; the relaxation time is 1 to 10s.

The preparation method provided by the invention comprises the steps of a 1) to a 3) to prepare the polyborosiloxane with high boron content and high polybasic borate content, wherein the key points are as follows: controlling the dosage ratio of boric acid and the end-dihydroxy-terminated polydimethylsiloxane in the step a 1), increasing the step a 2) and controlling the vacuum degree condition and temperature in the step, and setting the step a 3), wherein the three steps are matched in sequence, so that the polyborosiloxane with high boron content and high polybasic borate content can be obtained, and the hydrolysis rate can be slowed down. In addition, the polyborosiloxane obtained in the step a) is blended with certain amine compounds, and N: B dynamic coordination bonds are introduced into the polyborosiloxane, so that the polyborosiloxane is more stable and not easily damaged by water, the hydrolysis resistance of the polyborosiloxane can be further improved, and good mechanical properties are ensured.

The polyborosiloxane has a chemical bond structure of Si-O-B with boric acid as a crosslinking point, such as the borate structural unit, and also has a hydrogen bond formed by a dynamic coordination bond of Si-B: O and Si-O-B (OH) 22. The B atom in the polyborosiloxane is of an electron-deficient structure, and when water exists, water molecules attack the B atom to firstly destroy a B: O dynamic coordination bond formed by the B atom and an O atom on the other chain, so that a Si-O-B bond is further broken until the B atom is shed in a boric acid form. The preparation method starts from the structure of the polyborosiloxane, on one hand, the polyborosiloxane with high boron content and high polybasic borate content is prepared, on the other hand, N: B dynamic coordination bonds are introduced, and the improved combined action of the two structures can effectively improve the hydrolysis resistance of the polyborosiloxane. Compared with the means of adding water absorbing material in the prior art, the invention has the advantages that the structure is adopted, the double pipes are adopted, and the hydrolysis resistance of the polyborosiloxane is fundamentally improved.

Experimental results show that the hydrolysis-resistant polyborosiloxane provided by the invention is completely soaked in water at room temperature, the boric acid dropping rate is below 18% after the polyborosiloxane is soaked in water for 12 hours, the boric acid dropping rate is below 25% after the polyborosiloxane is soaked in water for 14 hours, the polyborosiloxane can still keep a gel form after 24 hours, and the polyborosiloxane shows excellent hydrolysis resistance. In addition, the elasticity modulus of the hydrolysis-resistant boron siloxane is more than 20000Pa and can reach 20000-400000 Pa; the relaxation time is 1-10 s, and the material shows good mechanical property.

For a further understanding of the present invention, reference will now be made to the following preferred embodiments of the invention in conjunction with the examples, but it is to be understood that the description is intended to further illustrate the features and advantages of the invention and is not intended to limit the scope of the claims which follow.

In the following examples, unless otherwise specified, the starting materials used were commercially available products, wherein the terminal bishydroxy terminated polydimethylsiloxanes were obtained from Lanzhou, inc., china, having kinematic viscosities of 60cst, 100cst, 300cst, 1000cst, and 3000cst at 25 ℃. Boric acid was purchased from Sigma Aldrich, usa. The amine compounds are available from Anyi chemical Co., ltd, china.

Example 1

S1, preparing polyborosiloxane with high boron content and high polybasic borate content:

mixing the end-dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 60cst at 25 ℃ and the boric acid which is ground, sieved and dried according to the molar ratio of hydroxyl (boric acid: silicone oil) of 1:1, and reacting for 48 hours at 120 ℃. And directly transferring the reacted polyborosiloxane to a vacuum oven, controlling the vacuum degree within the range specified above, and carrying out vacuum reaction for 12 hours at 120 ℃ to obtain a crude polyborosiloxane product. The crude product was dissolved in chloroform, filtered to remove unreacted boric acid, and the filtrate was subjected to rotary evaporation to remove the solvent, and then dried in a vacuum oven at 60 ℃ for 24 hours. Purified polyborosiloxane was obtained.

The boron content is 1117ppm, the ternary borate content is 53.7 percent, and the binary borate content is 34.8 percent.

S2, preparing hydrolysis-resistant borosiloxane:

the purified polyborosiloxane was again dissolved in chloroform, tetramethylmethanediamine was added in an N/B ratio of 0.5: 1, and the mixture was stirred in a sealed state at 25 ℃ for 3 hours. Then spin-evaporating at 25 deg.C to remove a large amount of solvent, and drying in vacuum oven at 25 deg.C for 24 hr. The hydrolysis resistant polyborosiloxane is obtained.

The nitrogen content was 415ppm, and the linear frequency sweep test gave the polyborosiloxane a modulus of elasticity of 146555Pa and a relaxation time of 4.0s.

Example 2

S1, preparing polyborosiloxane with high boron content and high polybasic borate content:

mixing the end-dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 300cst at 25 ℃ and boric acid which is ground, sieved and dried according to the molar ratio of hydroxyl (boric acid: silicone oil) of 1:1, and reacting for 48 hours at 120 ℃. And directly transferring the reacted polyborosiloxane to a vacuum oven, controlling the vacuum degree within the range specified above, and carrying out vacuum reaction for 12h at 120 ℃ to obtain a crude product of the polyborosiloxane. The crude product was dissolved in chloroform, filtered to remove unreacted boric acid, and the filtrate was subjected to rotary evaporation to remove the solvent, and then dried in a vacuum oven at 60 ℃ for 24 hours. Purified polyborosiloxane was obtained.

The boron content was 726ppm, the tribasic borate content was 50.5%, and the dibasic borate content was 37.3%.

S2, preparing hydrolysis-resistant borosiloxane:

the purified polyborosiloxane was again dissolved in chloroform, diethylamine and bis (3-aminopropyl) -terminated polydimethylsiloxane (in which the molar ratio of N in diethylamine to N in bis (3-aminopropyl) -terminated polydimethylsiloxane was 1:1 and the number average molecular weight of bis (3-aminopropyl) -terminated polydimethylsiloxane was 3000 g/mol) were added in an N/B ratio of 1, and stirred in a sealed state at 25 ℃ for 3 hours. Then spin-evaporating at 25 deg.C to remove a large amount of solvent, and drying in vacuum oven at 25 deg.C for 24 hr. The hydrolysis resistant polyborosiloxane is obtained.

The nitrogen content was 649ppm, and the linear frequency sweep test gave the polyborosiloxane a modulus of elasticity of 48850Pa and a relaxation time of 2.2s.

Example 3

S1, preparing polyborosiloxane with high boron content and high polybasic borate content: same as example 1

Mixing the end-dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 60cst at 25 ℃ and boric acid which is ground, sieved and dried according to the molar ratio of hydroxyl (boric acid: silicone oil) of 1:1, and reacting for 48 hours at 120 ℃. And directly transferring the reacted polyborosiloxane to a vacuum oven, controlling the vacuum degree within the range specified above, and carrying out vacuum reaction for 12 hours at 120 ℃ to obtain a crude polyborosiloxane product. The crude product was dissolved in chloroform, filtered to remove unreacted boric acid, and the filtrate was subjected to rotary evaporation to remove the solvent, and then dried in a vacuum oven at 60 ℃ for 24 hours. Purified polyborosiloxane was obtained.

The boron content is 1117ppm, the ternary borate content is 53.7 percent, and the binary borate content is 34.8 percent.

S2, preparing hydrolysis-resistant borosiloxane:

the purified polyborosiloxane was again dissolved in chloroform, triethylamine was added in an N/B ratio of 0.7: 1, and the mixture was stirred in a sealed state at 25 ℃ for 3 hours. Then spin-evaporating at 25 deg.C to remove a large amount of solvent, and drying in vacuum oven at 25 deg.C for 24 hr. The hydrolysis resistant polyborosiloxane is obtained.

The nitrogen content was 715ppm, and the linear frequency sweep test gave the polyborosiloxane an elastic modulus of 116800Pa and a relaxation time of 3.5s.

Example 4

S1, preparing polyborosiloxane with high boron content and high polybasic borate content: same as example 2

Mixing the end-dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 300cst at 25 ℃ and boric acid which is ground, sieved and dried according to the molar ratio of hydroxyl (boric acid: silicone oil) of 1:1, and reacting for 48 hours at 120 ℃. And directly transferring the reacted polyborosiloxane to a vacuum oven, controlling the vacuum degree within the range specified above, and carrying out vacuum reaction for 12h at 120 ℃ to obtain a crude product of the polyborosiloxane. The crude product is dissolved in chloroform, filtered to remove unreacted boric acid, and then the filtrate is subjected to rotary evaporation to remove the solvent and is dried in a vacuum oven for 24 hours at 60 ℃. Purified polyborosiloxane was obtained.

The boron content is 726ppm, the ternary borate content is 50.5%, and the binary borate content is 37.3%.

S2, preparing hydrolysis-resistant borosiloxane:

the purified polyborosiloxane was again dissolved in chloroform, bis (3-aminopropyl) -terminated polydimethylsiloxane (number average molecular weight 3000 g/mol) was added in an N/B ratio of 0.9: 1, and stirred in a sealed state at 25 ℃ for 3 hours. Then spin-evaporating at 25 deg.C to remove a large amount of solvent, and drying in vacuum oven at 25 deg.C for 24 hr. The hydrolysis resistant polyborosiloxane is obtained.

The nitrogen content was 602ppm, and the elastic modulus of the above polyborosiloxane was 22725Pa and the relaxation time was 1.4s by a linear frequency sweep test.

Example 5

S1, preparing polyborosiloxane with high boron content and high polybasic borate content:

mixing the end-dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 1000cst at 25 ℃ and boric acid which is ground, sieved and dried according to the molar ratio of hydroxyl (boric acid: silicone oil) of 1:1, and reacting for 48 hours at 120 ℃. And directly transferring the reacted polyborosiloxane to a vacuum oven, controlling the vacuum degree within the range specified above, and carrying out vacuum reaction for 12h at 120 ℃ to obtain a crude product of the polyborosiloxane. The crude product is dissolved in chloroform, filtered to remove unreacted boric acid, and then the filtrate is subjected to rotary evaporation to remove the solvent and is dried in a vacuum oven for 24 hours at 60 ℃. Purified polyborosiloxane was obtained.

The boron content is 529ppm, the ternary borate content is 50.4%, and the binary borate content is 40.1%.

S2, preparing hydrolysis-resistant borosiloxane:

the purified polyborosiloxane was again dissolved in chloroform, bis (3-aminopropyl) -terminated polydimethylsiloxane (number average molecular weight 4000 g/mol) was added in an N/B ratio of 0.3:1, and stirred in a sealed state at 25 ℃ for 3 hours. Then, a large amount of the solvent was removed by rotary evaporation at 25 ℃ and dried in a vacuum oven at 25 ℃ for 24 hours. The hydrolysis resistant polyborosiloxane is obtained.

The nitrogen content was 146ppm, and the linear frequency sweep test gave the polyborosiloxane an elastic modulus of 37845Pa and a relaxation time of 1.0s.

Example 6

S1, preparing polyborosiloxane with high boron content and high polybasic borate content: same as example 5

The terminal dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 1000cst at 25 ℃ and the boric acid which is ground, sieved and dried are mixed according to the molar ratio of hydroxyl (boric acid: silicone oil) of 1:1 and reacted for 48 hours at 120 ℃. And directly transferring the reacted polyborosiloxane to a vacuum oven, controlling the vacuum degree within the range specified above, and carrying out vacuum reaction for 12h at 120 ℃ to obtain a crude product of the polyborosiloxane. The crude product is dissolved in chloroform, filtered to remove unreacted boric acid, and then the filtrate is subjected to rotary evaporation to remove the solvent and is dried in a vacuum oven for 24 hours at 60 ℃. Purified polyborosiloxane was obtained.

The boron content is 529ppm, the ternary borate content is 50.4%, and the binary borate content is 40.1%.

S2, preparing hydrolysis-resistant borosiloxane:

the purified polyborosiloxane was again dissolved in chloroform, tetramethylmethanediamine was added in an N/B ratio of 1:1, and the mixture was stirred in a sealed state at 25 ℃ for 3 hours. Then spin-evaporating at 25 deg.C to remove a large amount of solvent, and drying in vacuum oven at 25 deg.C for 24 hr. The hydrolysis resistant polyborosiloxane is obtained.

The nitrogen content was 498ppm, the modulus of elasticity of the polyborosiloxane was 11650Pa and the relaxation time was 0.8s, as determined by a linear frequency sweep test.

Comparative example 1: step S1 is performed without vacuum reaction, and step S2 is performed without vacuum reaction

S1, preparing polyborosiloxane:

mixing the end-dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 60cst at 25 ℃ and the boric acid which is ground, sieved and dried according to the molar ratio of hydroxyl (boric acid: silicone oil) of 1:1, and reacting for 48 hours at 120 ℃. The obtained product was dissolved in chloroform, filtered to remove unreacted boric acid, and then the filtrate was subjected to rotary evaporation to remove the solvent, followed by drying in a vacuum oven at 60 ℃ for 24 hours. Purified polyborosiloxane was obtained.

The boron content is 763ppm, the ternary borate content is 40.7%, and the binary borate content is 25.9%. The elastic modulus of the polyborosiloxane is 107060Pa and the relaxation time is 0.9s by a linear frequency scanning test.

Comparative example 2: step S2 is not performed

S1, preparing polyborosiloxane: same as example 1

Mixing the end-dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 60cst at 25 ℃ and boric acid which is ground, sieved and dried according to the molar ratio of hydroxyl (boric acid: silicone oil) of 1:1, and reacting for 48 hours at 120 ℃. And directly transferring the reacted polyborosiloxane to a vacuum oven, controlling the vacuum degree within the range specified above, and carrying out vacuum reaction for 12h at 120 ℃ to obtain a crude product of the polyborosiloxane. The crude product was dissolved in chloroform, filtered to remove unreacted boric acid, and the filtrate was subjected to rotary evaporation to remove the solvent, and then dried in a vacuum oven at 60 ℃ for 24 hours. Purified polyborosiloxane was obtained.

The boron content is 1117ppm, the ternary borate content is 53.7 percent, and the binary borate content is 34.8 percent. The linear frequency sweep test gave the polyborosiloxane an elastic modulus of 266600Pa and a relaxation time of 8.4s.

Comparative example 3: no vacuum reaction was performed in step S1

S1, mixing the end-dihydroxy terminated polydimethylsiloxane with the kinematic viscosity of 60cst at 25 ℃ with the boric acid which is ground, sieved and dried according to the hydroxyl molar ratio (boric acid: silicone oil) of 1:1, and reacting for 48 hours at 120 ℃. The obtained product was dissolved in chloroform, filtered to remove unreacted boric acid, and then the filtrate was subjected to rotary evaporation to remove the solvent, followed by drying in a vacuum oven at 60 ℃ for 24 hours. Purified polyborosiloxane was obtained.

The boron content is 763ppm, the ternary borate content is 40.7%, and the binary borate content is 25.9%.

S2, dissolving the purified polyborosiloxane into chloroform again, adding tetramethylmethanediamine according to the N/B ratio of 0.5: 1, and stirring for 3 hours at 25 ℃ in a sealed state. Then spin-evaporating at 25 deg.C to remove a large amount of solvent, and drying in vacuum oven at 25 deg.C for 24 hr to obtain polyborosiloxane.

The nitrogen content was 322ppm. The elastic modulus of the above-mentioned polyborosiloxane was 87750Pa and the relaxation time was 0.4s by a linear frequency sweep test.

Comparative example 4: with other amine compounds

S1, preparing polyborosiloxane: same as example 4

The end-dihydroxy terminated polydimethylsiloxane with a kinematic viscosity of 300cst at 25 ℃ and the boric acid which is ground, sieved and dried are mixed according to a molar ratio of hydroxyl (boric acid: silicone oil) of 1:1 and reacted for 48 hours at 120 ℃. And directly transferring the reacted polyborosiloxane to a vacuum oven, controlling the vacuum degree within the range specified above, and carrying out vacuum reaction for 12 hours at 120 ℃ to obtain a crude polyborosiloxane product. The crude product was dissolved in chloroform, filtered to remove unreacted boric acid, and the filtrate was subjected to rotary evaporation to remove the solvent, and then dried in a vacuum oven at 60 ℃ for 24 hours. Purified polyborosiloxane was obtained.

The boron content was 726ppm, the tribasic borate content was 50.5%, and the dibasic borate content was 37.3%.

S2, preparing a polyborosiloxane/amine compound:

the purified polyborosiloxane was again dissolved in chloroform, 1, 12-diaminododecane was added in an N/B ratio of 0.9: 1, and the mixture was stirred in a sealed state at 25 ℃ for 3 hours. Then spin-evaporating at 25 deg.C to remove a large amount of solvent, and drying in vacuum oven at 25 deg.C for 24 hr. As a result, it was not possible to remove uncomplexed 1, 12-diaminododecane, and it was observed that 1, 12-diaminododecane had a significant phase separation from the polyborosiloxane, and no effective B: N coordination was formed.

See table 1 for a summary of individual preparation conditions and product specification characteristics for examples 1-6 and comparative examples 1-3.

Table 1: summary of individual preparation conditions and product specification characteristics for examples 1-6 and comparative examples 1-3

Example 7: product testing

1. Test one

The products obtained in examples 1 to 6 and comparative examples 1 to 3 were subjected to characterization of the structure after soaking in water:

the polyborosiloxane is subjected to chemical bond breakage in hydrolysis, and B on a chain can be detached in the form of boric acid and dissolved in water, so that the boron content of a sample after soaking in water can be reduced. The hydrolysis degree of the polyborosiloxane is characterized by the change of the boron content in the sample after ICP detection and nuclear magnetic detection of the boric acid content in water. The samples were subjected to soaking for 1, 3, 6, 12, and 24 hours, and the boron content of the samples was measured at different soaking times, and the results are shown in table 2, in which the change of the boric acid content with soaking time of example 1 and comparative example 1 is shown in fig. 1.

Table 2: boron content of the products of examples 1-6 and comparative examples 1-3 as a function of soak time

Note: the 0h sample represents the original sample when not bubbled. The samples of comparative examples 1-4 were soaked in water for 24 hours and the products were not gelled and could not be tested for boron content and were therefore designated as ND. The boron falling rate of the original sample is not less than the boron content of the original sample (the boron content of the sample after soaking in water for a certain time)/the boron content of the original sample is multiplied by 100 percent.

As can be seen from the test results in Table 2, the boron content of each sample gradually decreased with increasing soaking time, indicating that the hydrolysis gradually increased. Compared with comparative examples 1-4, the boric acid shedding ratio of the samples of examples 1-6 is obviously reduced after the samples are soaked in water for 12 hours; moreover, after soaking in water for 24h, the samples of examples 1-6 still maintain the gel state, the boric acid shedding ratio is still low, while the samples of comparative examples 1-4 are not gelled and basically disintegrated; as demonstrated above, the hydrolysis resistance was significantly improved in the samples of examples 1 to 6 as compared with those of comparative examples 1 to 4.

Specifically, the method comprises the following steps: examples 1-6 showed overall better hydrolysis resistance, with example 5 showing slightly higher boric acid release than the other examples, mainly due to the fact that the N/B ratio of the bis (3-aminopropyl) terminated polydimethylsiloxane blend in examples is 0.3, the blending ratio is low, there are cases where B: N cannot coordinate effectively, and at the same time, the hydrolysis degree of example 5 is slightly worse than the other examples, due to the fact that the molecular weight of the bis (3-aminopropyl) terminated polydimethylsiloxane is high, only one of the two coordination sites is coordinated with B, and the dynamic B: N coordination bond content in the sample is low. Comparative example 1 is a polyborosiloxane with medium boron content, ternary borate and binary borate, and is not blended with amine compounds, the boron content is reduced seriously only after 1 hour of soaking water, and the hydrolysis speed is far faster than that of example 1. Comparative example 2 is a high boron, tribasic and dibasic borate containing polyborosiloxane, but not blended with amine compounds; comparative example 3 is a medium boron, tribasic borate and dibasic borate containing polyborosiloxane, blended with amine compounds; compared with the comparative example 1, the comparative example 2 and the comparative example 3 only adopt a hydrolysis resistance measure and can also improve the hydrolysis resistance of the polyborosiloxane to a certain extent, which shows that the boron content, the contents of the tribasic boric acid ester and the dibasic boric acid ester are improved to a certain extent, and the polyborosiloxane is blended with a micromolecular organic substance or a high molecular polymer containing primary amine, secondary amine or tertiary amine respectively to improve the hydrolysis resistance. In comparative example 4, in which 1, 12-diaminododecane was used in combination with polyborosiloxane, hydrolysis resistance was not significantly improved since excess 1, 12-diaminododecane was not removed and phase separation from polyborosiloxane occurred.

The change of the boric acid content (nuclear magnetic characterization) of the example 1 and the comparative example 1 along with the water soaking time is shown in figure 1, and it can be seen that the boric acid content increases along with the water soaking time, the boric acid content in the water in the comparative example 1 within 1h is greatly increased, and the severe hydrolysis occurs. The boric acid content in the water of the example 1 is relatively low, which proves that the hydrolysis-resistant polyborosiloxane can remarkably improve the hydrolysis resistance of the polyborosiloxane.

2. Test two

The polyborosiloxane products obtained in examples 1 to 6 and comparative examples 1 to 3 were subjected to a small bubble water forming test:

a3 mL glass vial was used as a container, about 0.25g of the sample was placed on the bottom of the vial, about 1.5mL of ultrapure water was added, the morphology of the sample in the vial was recorded by photographing 1, 3, 6, 12, 24 hours after soaking in water, and the time until the polyborosiloxane gel product started to gel was recorded. The test results are shown in Table 3, in which the morphology of the samples of example 1 and comparative examples 1-3 at different soaking times is shown in FIG. 2.

Table 3: polyborosiloxane gel failure time in the example and comparative example Vial formation experiments

Sample (I)	Polyborosiloxane non-gel time (h)
		Example 1	34
Example 2	36
		Example 3	34
Example 4	32
		Example 5	26
Example 6	36
		Comparative example 1	14
Comparative example 2	22
		Comparative example 3	16
Comparative example 4	18

As can be seen from the test results, the polyborosiloxanes obtained in examples 1 to 6 remained in gel form after being soaked in the vials for 12 hours; of these, examples 1-4,6 also remained in gel form after 24h of soaking, and example 5 did not gel right from the start. The product of comparative example 1 could not maintain the gel form even after soaking in water for 12h, indicating that severe hydrolysis had occurred and that it could not be used normally in any application. Comparative example 2 and comparative example 3 have an increased time for maintaining the gel form compared to comparative example 1 due to the fact that only one anti-hydrolysis measure was taken, but no gel was formed at all when the water was soaked for 24 hours. The above results demonstrate that examples 1-6 of the present invention significantly improve the hydrolysis resistance of polyborosiloxane.

Tests I and II show that the polyborosiloxane prepared by the invention is completely soaked in water at room temperature, the boric acid shedding ratio is below 18% after soaking in water for 12 hours, the boric acid shedding ratio is below 25% after soaking in water for 14 hours, the polyborosiloxane can still keep a gel shape after 24 hours, and the polyborosiloxane shows better hydrolysis resistance. Meanwhile, as can be seen from table 1, the elastic modulus of the polyborosiloxane prepared by the invention is above 20000Pa, and can reach 20000-400000 Pa; the relaxation time is 1-10 s, and the material shows good mechanical property.

The foregoing examples are included merely to facilitate an understanding of the principles of the invention and their core concepts, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that approximate the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims (9)

1. A preparation method of hydrolysis-resistant polyborosiloxane is characterized by comprising the following steps:

a) The preparation of the polyborosiloxane with high boron content and high polybasic borate content specifically comprises the following steps:

a1 Reacting a terminal bishydroxy-terminated polydimethylsiloxane with boric acid to obtain a primary reactant;

the molar ratio of the boric acid to the hydroxyl in the end-dihydroxy-terminated polydimethylsiloxane is (0.5-1) to 1;

a2 Transferring the primary reactant to a vacuum condition for vacuum reaction to obtain a crude product of the polyborosiloxane;

the temperature of the vacuum reaction is 100-150 ℃, and the time is 8-16 h;

a3 Removing unreacted boric acid from the crude polyborosiloxane product to obtain purified polyborosiloxane;

b) Blending:

blending the purified polyborosiloxane with an amine compound to obtain a hydrolysis-resistant polyborosiloxane;

the amine compound is an alkylamine compound and/or aminoalkyl terminated siloxane;

the alkylamine compound is an alkylamine compound of C4-C6.

2. The method according to claim 1, wherein the terminal bishydroxy terminated polydimethylsiloxane is a bishydroxy terminated polydimethylsiloxane having a kinematic viscosity of 60 to 3000cst at 25 ℃.

3. The method according to claim 1 or 2, wherein in the step b), the amine compound is one or more selected from the group consisting of diethylamine, triethylamine, tetramethylmethanediamine, triethylenediamine and bis (3-aminopropyl) -terminated polydimethylsiloxane.

4. The method according to claim 1, wherein in the step B), the amine compound and the purified polyborosiloxane are blended in a molar ratio of N: B of (0.2-1) to 1.

5. The method of claim 1 or 2, wherein the terminal bishydroxy terminated polydimethylsiloxane is one or more selected from the group consisting of bishydroxy terminated polydimethylsiloxanes having kinematic viscosities of 60cst, 100cst, 300cst, 1000cst, and 3000cst at 25 ℃.

6. The method according to claim 3, wherein the bis (3-aminopropyl) -terminated polydimethylsiloxane has a number-average molecular weight of 1000 to 50000g/mol.

7. The preparation method according to claim 1, wherein the reaction temperature in step a 1) is 80-140 ℃ and the reaction time is 12-48 h.

8. The method according to claim 1, wherein step b) comprises in particular:

dissolving the purified polyborosiloxane in an organic solvent, adding an amine compound for mixing, and then removing the organic solvent to obtain the hydrolysis-resistant polyborosiloxane;

the step a 3) specifically comprises the following steps:

dissolving the crude polyborosiloxane in an organic solvent, carrying out solid-liquid separation, and removing the organic solvent from the obtained separated liquid to obtain purified polyborosiloxane;

in the step a 2), the vacuum degree under the vacuum condition is as follows: the vacuum degree is more than or equal to 0.06MPa and less than 0.1MPa;

the specification of the purified polyborosiloxane obtained in the step a) is as follows: the boron content is more than or equal to 300ppm, the content of the ternary borate unit is 30-60 wt%, and the content of the binary borate unit is 30-50 wt%.

9. A hydrolysis-resistant polyborosiloxane prepared by the preparation method of any one of claims 1 to 8.

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