Synthesis method of polyfluorosiloxane with low byproduct content

Abstract

The invention belongs to the technical field of polyfluorosiloxane synthesis, and provides a low-by-product polyfluorosiloxane controllable synthesis method which comprises the following steps: carrying out anionic ring opening polymerization on D3F by adopting a binary organic catalytic system, weakening the strong nucleophilicity of an active center based on hydrogen-bond interaction and steric effect, and inhibiting the occurrence of chain back-biting side reaction, so as to obtain the low-by-product polyfluorosiloxane. The polyfluorosiloxane with low content of by-product DnF (n is greater than or equal to 4), controllable structure and narrow molecular weight distribution is prepared. The polyfluorosiloxane with low byproduct content is catalyzed by the binary organic catalyst, the synthesis method is simple, the operation is convenient, the reaction condition is mild, the catalyst has good stability, large-scale production is easy, and further development of the polyfluorosiloxane in the field of high-end and harsh oil-resistant sealing materials can be promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of polyfluorosilicone synthesis, and particularly relates to a method for synthesizing polyfluorosilicone with low by-product content. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Polyfluorosilicone, due to its unique trifluoropropyl group in the side chain and the Si-O-Si structure in the main chain, gives fluorosilicone materials excellent solvent resistance, low surface energy, electrical insulation and high chemical stability. It has shown broad application prospects in anti-fouling coatings, anti-adhesion materials, microelectronic packaging, biomedicine and aerospace. In recent years, researchers have obtained functionalized polyfluorosilicone with a defined structural composition through chain end design and segment composition optimization. This has enhanced the mechanical strength and surface properties of the material, and further endowed the material with high and low temperature resistance and low dielectric properties, making it play an important role in high-performance sealants, self-lubricating coatings, high-temperature resistant elastomers, low dielectric constant materials and super-hydrophobic surfaces. However, the strong electron-withdrawing effect of the trifluoropropyl group means that the synthesis of polyfluorosilicone is still restricted by the catalytic system, resulting in serious backbiting side reactions and a high content of low-molecular-weight by-products.

[0004] Traditional acid-base catalytic systems, such as sodium hydroxide, potassium hydroxide, trifluoromethanesulfonic acid, and tetrakis(pentafluorophenyl)boronic acid, are susceptible to the electron-withdrawing effect of the trifluoropropyl substituent, which accelerates the nucleophilic attack rate of the anion on the more positively charged silicon atom and enhances the interaction ability of the cation with the more electronegative oxygen atom, resulting in higher ring-opening activity and the inability to control the degree of polymerization reaction. More importantly, the probability of side reactions (chain backbiting) increases, generating cyclic byproducts (D n F, n≥4), the molecular weight of the polymer product decreases, the molecular weight distribution broadens, and the productive rate is only 10-20%. In order to solve the above problems, scientific researchers use organic lithium compounds as initiators to carry out anionic ring-opening polymerization of D3F and have achieved certain results, but such catalysts are sensitive to moisture and easily deactivated. There are studies that trifluoropropylmethylcyclotrisiloxane, water and carbon-based solid catalysts are carried out ring-opening polymerization, and the catalyst is easy to remove and the hydroxy fluorosilicone oil with stable viscosity is obtained, but the reaction temperature of this catalytic system is high and the reaction time is long. There are studies that trifluoropropylmethylcyclotrisiloxane, water, alkaline catalyst and reaction stabilizer are carried out polymerization reaction, and the product viscosity is easily controlled, the by-product content is small, and the hydroxyl-terminated polyfluorosiloxane with high target product productive rate is obtained, but the polymer prepared by inorganic base catalyst system is prone to "bite-back" phenomenon, and the polymer molecular weight is unstable.

[0005] In recent years, a variety of bulky organic catalysts, such as organophosphazene catalysts, guanidine catalysts, and binary organic catalysts, have been used for the anionic ring-opening polymerization of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, methylphenylcyclosiloxane, diphenylcyclosiloxane, ethylcyclosiloxane, or various cyclic lactones to synthesize polymers with narrow molecular weight distributions, precise structures, and few byproducts. Therefore, a new catalytic system suitable for trimethyltrifluoropropylcyclotrisiloxane was developed to inhibit backbiting side reactions, reduce byproduct content, and achieve precise control of polyfluorosilicone synthesis, promoting its further development in the field of high-end, demanding, oil-resistant sealing materials. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a method for synthesizing polyfluorosilicone with low by-product content. The present invention uses a binary organic catalytic system to perform anionic ring-opening polymerization on D3F, and based on the hydrogen bonding and steric effect, weakens the strong nucleophilicity of the active center, inhibits the occurrence of chain backbiting side reactions, and prepares the by-product D n Polyfluorosilicone with low F (n ≥ 4) content, controllable structure and narrow molecular weight distribution.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention provides a method for synthesizing polyfluorosilicone with low by-product content, comprising:

[0009] In an inert atmosphere, a co-catalyst, an organic non-nucleophilic strong base and benzyl alcohol are uniformly mixed, and then D3F is added to carry out anionic ring-opening polymerization to obtain a polyfluorosiloxane with low by-product content;

[0010] Wherein, the co-catalyst is a hydrogen bond donor.

[0011] The second aspect of the present invention provides a polyfluorosilicone with low by-product content prepared by the above method.

[0012] The third aspect of the present invention provides the use of the above-mentioned low-byproduct content polyfluorosilicone in antifouling coatings, anti-adhesion materials, microelectronic packaging, biomedicine and aerospace fields.

[0013] Beneficial effects of the present invention

[0014] (1) The low by-product content polyfluorosiloxane of the present invention is catalyzed by a binary organic catalyst, and the catalyst synthesis is simple.

[0015] (2) The polyfluorosiloxane with low by-product content of the present invention can react at room temperature and has a high polymerization rate.

[0016] (3) The low by-product content polyfluorosiloxane of the present invention has a low by-product content, controllable molecular weight and distribution, a molecular weight that meets the feed amount, and a clear end group.

[0017] (4) The polymerization reaction conditions of the present invention are simple, the preparation process is simple, environmentally friendly, and easy to scale up production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0019] Figure 1 This is a mechanism diagram for preparing polyfluorosilicone with low by-product content according to Example 1 of the present invention.

[0020] Figure 2 This is the H-NMR spectrum of the organic strong base selected in Experimental Example 1 of the present invention.

[0021] Figure 3 This is the H NMR spectrum of the binary organic catalytic system prepared in Experimental Example 2 of the present invention.

[0022] Figure 4 This is a graph showing the molecular weight-time variation of polyfluorosilicone with low by-product content prepared in Example 1 of the present invention.

[0023] Figure 5 This is a gel permeation chromatogram of the polyfluorosilicone with low by-product content prepared in Example 1 of the present invention.

[0024] Figure 6 This is a graph showing the conversion rate versus time for preparing polyfluorosilicone with low by-product content in Test Example 3 of the present invention.

[0025] Figure 7 This is the NMR silicon spectrum of the polyfluorosiloxane with low by-product content prepared in Example 1 of the present invention.

[0026] Figure 8 This is a graph showing the change in number average molecular weight and theoretical molecular weight of polyfluorosilicone with low by-product content prepared in Example 2 of the present invention.

[0027] Figure 9 This is a gel permeation chromatogram of the polyfluorosilicone with low by-product content prepared in Example 2 of the present invention.

[0028] Figure 10 This is a gel permeation chromatogram of the polyfluorosilicone with low by-product content prepared in Example 3 of the present invention.

[0029] Figure 11 This is the H NMR spectrum of triphenyl-terminated polyfluorosiloxane prepared in Example 4 of the present invention.

[0030] Figure 12 This is a graph showing the molecular weight-time variation of polyfluorosilicone prepared in Example 5 of the present invention.

[0031] Figure 13 This is a gel permeation chromatogram of polyfluorosilicone prepared in Example 5 of the present invention.

[0032] Figure 14 This is the NMR silicon spectrum of polyfluorosiloxane prepared in Example 5 of the present invention.

[0033] Figure 15 This is a graph showing the molecular weight-time variation of polyfluorosilicone prepared in Example 6 of the present invention.

[0034] Figure 16 This is a gel permeation chromatogram of polyfluorosilicone prepared in Example 6 of the present invention.

[0035] Figure 17 This is the NMR silicon spectrum of polyfluorosiloxane prepared in Example 6 of the present invention.

[0036] Figure 18 This is a graph showing the molecular weight-time variation of polyfluorosilicone prepared in Example 7 of the present invention.

[0037] Figure 19 This is a gel permeation chromatogram of polyfluorosilicone prepared in Example 7 of the present invention.

[0038] Figure 20 This is the NMR silicon spectrum of polyfluorosiloxane prepared in Example 7 of the present invention.

[0039] Figure 21 This is a graph showing the change in number average molecular weight and theoretical molecular weight of polyfluorosilicone prepared in Example 8 of the present invention.

[0040] Figure 22 This is a gel permeation chromatogram of polyfluorosilicone prepared in Example 8 of the present invention.

[0041] Figure 23 This is the H NMR spectrum of methyl vinyl terminated polyfluorosiloxane prepared in Example 9 of the present invention.

[0042] Figure 24 This is the H NMR spectrum of methyl vinyl terminated polyfluorosiloxane prepared in Example 10 of the present invention.

[0043] Figure 25 This is the H-NMR spectrum of the symmetrical polyfluorosiloxane prepared in Example 11 of the present invention.

[0044] Figure 26 This is a graph showing the molecular weight-time variation of polyfluorosilicone prepared in Comparative Example 1 of the present invention.

[0045] Figure 27It is the gel permeation chromatogram of polyfluorosilicone prepared in Comparative Example 1 of the present invention.

[0046] Figure 28 This is a graph showing the molecular weight-time variation of polyfluorosilicone prepared in Comparative Example 2 of the present invention.

[0047] Figure 29 It is the gel permeation chromatogram of polyfluorosilicone prepared in Comparative Example 2 of the present invention.

[0048] Figure 30 This is a molecular weight-time variation diagram of polyfluorosilicone prepared in Comparative Example 3 of the present invention.

[0049] Figure 31 It is the gel permeation chromatogram of polyfluorosilicone prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0050] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0051] A method for synthesizing polyfluorosilicone with low by-product content comprises: adding a co-catalyst with hydrogen bond donor properties, an organic non-nucleophilic strong base, and benzyl alcohol (BnOH) into a dry Schlenk tube under a nitrogen environment; stirring at room temperature; adding D3F into the system to carry out anionic ring-opening polymerization; and terminating the reaction to obtain polyfluorosilicone with low by-product content.

[0052] Furthermore, the binary organic catalytic system consists of an organic non-nucleophilic strong base and a co-catalyst with hydrogen bond donor properties.

[0053] Different base catalysts affect the efficiency of the polymerization reaction and the frequency of side reactions. Therefore, the present invention studies and screens base catalysts. Preferably, the multiple organic non-nucleophilic strong bases are selected from at least one of lithium tert-butoxide (tBuOLi), lithium hexamethyldisilazane (LiHMDS), sodium hexamethyldisilazane (NaHMDS), and potassium hexamethyldisilazane (KHMDS). The main function is to deprotonate the co-catalyst in the binary catalytic system. It has the structure shown in formula (I):

[0054]

[0055] More preferably, the organic non-nucleophilic strong base is NaHMDS.

[0056] The structure of the hydrogen bond donor has a great influence on the effect of the co-catalyst. Therefore, the present invention studies and screens hydrogen bond donors. Preferably, the hydrogen bond donors are indolecarbazole (ICZ), tris[3,5-bis(trifluoromethyl)phenylthioureaethyl]amine (trithiourea, TTU), 1-[3,5-bis(trifluoromethyl)phenyl]-3-cyclohexylthiourea (TU-1), 1,3-bis[3,5-bis(trifluoromethyl)phenyl]thiourea (TU-2) and 1-cyclohexyl-3-phenyl-2-thiourea (TU-3), which are used as Bronsted bases to control the nucleophilicity of the active center. It has the structure shown in formula (II):

[0057]

[0058] Among them, ICZ has a large aromatic ring conjugated system, which can generate cation-π interactions with the metal cations of the catalyst.

[0059] More preferably, the hydrogen bond donor is trithiourea (TTU), which can form a hexavalent hydrogen bond with the benzyl alcohol oxygen anion and the active silanol chain end, better control its nucleophilicity, and reduce the occurrence of backbiting reaction.

[0060] The ratio of each raw material will affect the efficiency of the polymerization reaction and the frequency of side reactions. Therefore, the present invention studies and screens the ratio of the raw materials. Preferably, the molar ratio of NaHMDS, TTU, BnOH and D3F is 1: (1-10): (1-40): (10-800), more preferably 1: (1-5): (1-20): (10-500), and further preferably 1: (1-3): (1-10): (10-200).

[0061] In some embodiments, the polymerization reaction is carried out at room temperature.

[0062] The polymerization reaction time affects the efficiency of the polymerization reaction and the frequency of side reactions. Therefore, the present invention studies and screens the polymerization reaction time, and the polymerization reaction time is 8-480 min; more preferably, it is 30-240 min.

[0063] Furthermore, a preferred embodiment of the method for synthesizing polyfluorosilicone with low by-product content comprises the following steps:

[0064] Under a nitrogen environment, TTU, NaHMDS and BnOH are added to a dry Schlenk tube, stirred at room temperature, and then D3F is added, maintaining the molar ratio of NaHMDS, TTU, BnOH and D3F at 1:(1-3):(1-10):(10-200), to carry out anionic ring-opening polymerization, and then terminate the reaction to obtain polyfluorosilicone with low by-product content.

[0065] In some embodiments, a capping agent is further added during the synthesis process.

[0066] The type of end-capping agent affects the production efficiency and quality of the end-functionalized polyfluorosilicone. Therefore, the present invention studies and screens the types of end-capping agents. Preferably, the end-capping agent is selected from at least one of triphenylchlorosilane, dimethyldichlorosilane, and vinyldimethylchlorosilane to form the end-functionalized polyfluorosilicone.

[0067] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0068] In the following test examples, each test method adopts the common method in the industry, and this application will not make any special explanations for this.

[0069] Example 1

[0070] Under nitrogen, (0.48 g, 0.5 mmol) TTU, (500 μL, 0.5 mmol) NaHMDS, and (0.16 g, 1.5 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 min, (10.55 g, 22.5 mmol) D3F was added to carry out anionic ring-opening polymerization, and then the reaction was terminated.

[0071] Example 2

[0072] Under nitrogen, (0.48 g, 0.5 mmol) TTU, (500 μL, 0.5 mmol) NaHMDS, and (0.16 g, 1.5 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 min, (14.06 g, 30 mmol) D3F was added to carry out anionic ring-opening polymerization, and then the reaction was terminated.

[0073] Example 3

[0074] Under nitrogen, (0.48 g, 0.5 mmol) TTU, (500 μL, 0.5 mmol) NaHMDS, and (0.16 g, 1.5 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 minutes, (10.55 g, 22.5 mmol) D3F was added to initiate anionic ring-opening polymerization. After 60 minutes of polymerization, (10.55 g, 22.5 mmol) D3F was added to initiate anionic ring-opening polymerization. Polymerization continued for 120 minutes before termination.

[0075] Example 4

[0076] Under nitrogen, (0.48 g, 0.5 mmol) TTU, (500 μL, 0.5 mmol) NaHMDS, and (0.16 g, 1.5 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 minutes, (10.55 g, 22.5 mmol) D3F was added for anionic ring-opening polymerization, which was then terminated. After the D3F polymerization reached the desired molecular weight, triphenylsilyl chloride was added as an end-capping agent and the reaction continued to yield the final polymer.

[0077] Example 5

[0078] Under nitrogen, (0.13 g, 0.5 mmol) ICZ, (500 μL, 0.5 mmol) NaHMDS, and (0.22 g, 2 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 minutes, (23.43 g, 0.05 mol) D3F was added to initiate anionic ring-opening polymerization. Samples were collected at various times during the 90-minute polymerization, and the experiment was terminated.

[0079] Example 6

[0080] Under nitrogen, (0.48 g, 0.5 mmol) TTU, (500 μL, 0.5 mmol) LiHMDS, and (0.16 g, 1.5 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 min, (14.06 g, 30 mmol) D3F was added to carry out anionic ring-opening polymerization, and the reaction was terminated.

[0081] Example 7

[0082] Under nitrogen, (0.48 g, 0.5 mmol) TTU, (500 μL, 0.5 mmol) KHMDS, and (0.16 g, 1.5 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 min, (14.06 g, 30 mmol) D3F was added to carry out anionic ring-opening polymerization, and then the reaction was terminated.

[0083] Example 8

[0084] Under nitrogen, (0.13 g, 0.5 mmol) ICZ, (500 μL, 0.5 mmol) NaHMDS, and (0.22 g, 2 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 min, (46.86 g, 0.1 mol) D3F was added to carry out anionic ring-opening polymerization, and the reaction was terminated.

[0085] Example 9

[0086] Under nitrogen, (0.48 g, 0.5 mmol) TTU, (500 μL, 0.5 mmol) NaHMDS, and (0.16 g, 1.5 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 minutes, (10.55 g, 22.5 mmol) D3F was added for anionic ring-opening polymerization, which was then terminated. After the D3F polymerization reached the desired molecular weight, dimethylvinylsilyl chloride was added as an end-capping agent and the reaction continued to yield the final polymer.

[0087] Example 10

[0088] Under nitrogen, (0.13 g, 0.5 mmol) ICZ, (500 μL, 0.5 mmol) NaHMDS, and (0.22 g, 2 mmol) BnOH were added to a dry Schlenk tube. After stirring at room temperature for 10 min, (23.43 g, 0.05 mol) D3F was added to carry out anionic ring-opening polymerization. After the D3F polymerization reached the desired molecular weight, dimethylvinylchlorosilane was added as a capping agent, and the reaction was continued to obtain the final polymer product.

[0089] Example 11

[0090] Under nitrogen, (0.13 g, 0.5 mmol) ICZ, (500 μL, 0.5 mmol) NaHMDS, and (0.22 g, 2 mmol) methanol were added to a dry Schlenk tube. After stirring at room temperature for 10 min, (10.55 g, 22.5 mmol) D3F was added to carry out anionic ring-opening polymerization. After the D3F polymerization reached the desired molecular weight, dimethyldichlorosilane was added as a capping agent, and the reaction was continued to obtain the final polymer product.

[0091] Comparative Example 1

[0092] The difference from Example 1 is that no co-catalyst TTU is added.

[0093] Comparative Example 2

[0094] The difference from Example 6 is that no co-catalyst TTU is added.

[0095] Comparative Example 3

[0096] The difference from Example 7 is that no co-catalyst TTU is added.

[0097] Test Example 1

[0098] ICZ, tBuOLi:ICZ=1:1, NaHMDS:ICZ=1:1, tBuOLi:ICZ:BnOH=1:1:1, NaHMDS:ICZ:BnOH=1:1:1 and BnOH were dissolved in deuterated DMSO for H NMR spectrum testing.

[0099] Test Example 2

[0100] TTU, NaHMDS:TTU=1:1, NaHMDS:TTU:BnOH=1:1:1, BnOH and NaHMDS:BnOH=1:1 were dissolved in deuterated DMSO for H NMR spectrum testing.

[0101] Test Example 3

[0102] The samples obtained at different times in Example 1 were dissolved in deuterated chloroform and subjected to H-NMR spectrum testing.

[0103] Performance Testing

[0104] 1) Example 1: Mechanism diagram for preparing polyfluorosilicone with low by-product content, as shown in Figure 1 shown.

[0105] 2) Experimental Example 1 Select the H NMR spectrum of an organic strong base, such as Figure 2 As shown. Figure 2 In the present study, NaHMDS was determined to be an organic non-nucleophilic strong base based on the size of the hydroxyl group shift of BnOH.

[0106] 3) The H NMR spectrum of the binary organic catalytic system prepared in Experimental Example 2 is as follows: Figure 3 As shown. Figure 3 In this work, TTU was deprotonated by NaHMDS to form its sodium salt, which then initiated the benzyl alcohol.

[0107] 4) The molecular weight-time variation diagram of the polyfluorosiloxane with low by-product content prepared in Example 1 is as follows: Figure 4 As shown. Figure 4 With the extension of polymerization time, the molecular weight gradually increased, and the molecular weight of the product at 150 min reached a peak of 7327 g / mol, with a PDI of 1.382.

[0108] 5) Gel permeation chromatogram of low by-product content polyfluorosilicone prepared in Example 1, as shown Figure 5 As shown in the figure, the gel permeation chromatograms at different times all show standard single peaks, with uniform and narrow molecular weight distribution.

[0109] 6) Experimental Example 3: Conversion rate-time variation diagram of preparation of polyfluorosiloxane with low by-product content, as shown in FIG. Figure 6 As shown. Figure 6With the extension of time, the molecular weight gradually increased, and the conversion rate reached 99% at 150 min.

[0110] 7) The NMR spectrum of the polyfluorosiloxane with low by-product content prepared in Example 1 is as follows: Figure 7 As shown, at this point, the monomer conversion is complete. The polyfluorosilicone has Si-OH and BnO-Si as terminal groups, and by-products account for 1%.

[0111] 8) Example 2 Preparation of low by-product content polyfluorosiloxane number average molecular weight and theoretical molecular weight change diagram, as shown Figure 8 GPC showed a good linear relationship between molecular weight and feed ratio. As the feed ratio [M]0 / [I]0 increased, the molecular weight of the prepared polyfluorosilicone increased.

[0112] 9) Gel permeation chromatogram of low by-product content polyfluorosilicone prepared in Example 2, as shown in FIG. Figure 9 When [M]0 / [I]0=10-100, the GPC curve is a standard single peak. When [M] / [I]=150, a slight shoulder peak appears at the bottom of the GPC curve, and the molecular weight distribution is greater than 1.5.

[0113] 10) Gel permeation chromatogram of the polyfluorosilicone with low by-product content prepared in Example 3, as shown in FIG. Figure 10 The black dashed line is the gel permeation chromatography curve of the product obtained from the first batch of feed using a batch feeding method; the red solid line is the gel permeation chromatography curve of the product obtained from the second batch of feed (the same amount as the first). The molecular weight of the second product is twice that of the first, proving that the anionic ring-opening polymerization of D3F using NaHMDS-TTU as a catalyst is a living polymerization.

[0114] 11) The H NMR spectra of the blocked polyfluorosiloxane prepared in Examples 4, 9, 10, and 11 are as follows: Figure 11 、 Figure 23-25 The use of end-capping agents to terminate the polymerization improves the stability of the product and introduces multifunctional groups to improve the utilization rate of the product.

[0115] 12) The molecular weight-time variation diagram, gel permeation chromatography and NMR spectra of polyfluorosiloxane prepared in Example 5 are as follows: Figure 12-14 As shown in Figure 2, a polyfluorosiloxane with a molecular weight of 100 nm was obtained after a reaction time of 60 min, which was close to the theoretical molecular weight. When the reaction time was extended to 90 min, the molecular weight decreased and the molecular weight distribution also increased slightly, indicating that a backbiting side reaction occurred after the monomer was fully converted.

[0116] 13) The molecular weight-time variation diagram, gel permeation chromatography and NMR spectra of polyfluorosiloxane prepared in Example 6 are as follows: Figure 15-17As shown in Figure 2, the monomer can be completely polymerized in 40 minutes under the LiHMDS-TTU catalytic system. As the reaction time increases, the samples obtained after 240 minutes are 29 Si NMR test, we get Figure 18 , the by-products obtained accounted for 3%.

[0117] 14) The molecular weight-time variation diagram, gel permeation chromatography and NMR spectra of the polyfluorosilicone prepared in Example 7 are as follows: Figures 18-20 As shown. The molecular weight of the sample is in a clear downward trend from 90min to 240min, and the PDI also gradually increases. The GPC curve measured after 90min will have a shoulder peak phenomenon. 29 SiNMR analysis showed that the by-product accounted for 9%.

[0118] 15) The number average molecular weight and theoretical molecular weight change diagram and gel permeation chromatogram of polyfluorosilicone prepared in Example 8 are as follows Figure 21-22 As shown in Figure 2, GPC showed a good linear relationship between molecular weight and feed ratio. As the feed ratio [M]0 / [I]0 increased, the molecular weight of the prepared polyfluorosilicone increased, and the difference between the experimental and theoretical molecular weights tended to increase.

[0119] 16) The molecular weight-time variation diagram and gel permeation chromatogram of polyfluorosiloxane prepared in Comparative Example 1 are as follows: Figure 26-Figure 27 Before 30 minutes, the molecular weight of the sample increased steadily until it stabilized, and the PDI remained at around 1.5. After 30 minutes, the molecular weight showed a gradual upward trend, indicating that the catalytic system was not conducive to stabilizing the molecular weight.

[0120] 17) The molecular weight-time variation diagram and gel permeation chromatogram of polyfluorosilicone prepared in Comparative Example 2 are as follows: Figure 28-Figure 29 At around 10 minutes, the sample reached its highest molecular weight, with PDI maintained at around 1.657. After 10 minutes, the molecular weight dropped significantly, indicating that the side reactions in this catalytic system were serious.

[0121] 18) The molecular weight-time variation diagram and gel permeation chromatogram of polyfluorosilicone prepared in Comparative Example 3 are as follows: Figure 30-Figure 31 The first sampling point at 2 min can be considered to be on the molecular weight decreasing trend line, and as time goes by, the molecular weight decreases rapidly, indicating that the side reactions of the catalytic system are serious.

[0122] Table 1

[0123]

[0124]

[0125] Note: “ / ” means: not tested.

[0126] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for synthesizing polyfluorosilicone with low by-product content, characterized in that: include: In an inert atmosphere, a co-catalyst, an organic non-nucleophilic strong base and benzyl alcohol are uniformly mixed, and then D3F is added to carry out anionic ring-opening polymerization to obtain a polyfluorosiloxane with low by-product content; Wherein, the co-catalyst is a hydrogen bond donor.

2. The method for synthesizing polyfluorosilicone with low by-product content according to claim 1, wherein: The hydrogen bond donor is selected from at least one of indolecarbazole, tris[3,5-bis(trifluoromethyl)phenylthioureaethyl]amine, 1-[3,5-bis(trifluoromethyl)phenyl]-3-cyclohexylthiourea, 1,3-bis[3,5-bis(trifluoromethyl)phenyl]thiourea and 1-cyclohexyl-3-phenyl-2-thiourea.

3. The method for synthesizing polyfluorosilicone with low by-product content according to claim 1, wherein: The organic non-nucleophilic strong base is selected from at least one of lithium tert-butoxide, lithium hexamethyldisilazane, sodium hexamethyldisilazane and potassium hexamethyldisilazane.

4. The method for synthesizing polyfluorosilicone with low by-product content according to claim 1, wherein: The molar ratio of the organic non-nucleophilic strong base, the co-catalyst, BnOH and D3F is 1:(1-10):(1-40):(10-800), or 1:(1-5):(1-20):(10-500), or 1:(1-3):(1-10):(10-200).

5. The method for synthesizing polyfluorosilicone with low by-product content according to claim 1, wherein: The polymerization reaction is carried out at room temperature.

6. The method for synthesizing polyfluorosilicone with low by-product content according to claim 1, wherein: The polymerization reaction time is 8-480 min, or 30-240 min.

7. The method for synthesizing polyfluorosilicone with low by-product content according to claim 1, wherein: A capping agent is also added during the synthesis process.

8. The method for synthesizing polyfluorosilicone with low by-product content according to claim 7, wherein: The end-capping agent is selected from at least one of triphenylsilyl chloride, dimethyldichlorosilane, and vinyldimethylchlorosilane.

9. A polyfluorosilicone with low by-product content prepared by the method according to any one of claims 1 to 8.

10. Use of the low-byproduct content polyfluorosilicone according to claim 9 in antifouling coatings, anti-adhesion materials, microelectronic packaging, biomedicine and aerospace fields.

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