CN102675520A - Method for preparing poly(vinylidene fluoride-trichloroethylene) or poly(vinylidene fluoride-chlorotrifluoroethylene-trichloroethylene) - Google Patents

Abstract

The method for preparing poly(vinylidene fluoride-trifluoroethylene) or poly(vinylidene fluoride-trifluoroethylene-trifluoroethylene), adding poly(vinylidene fluoride-trifluoroethylene) to a three-necked bottle and simultaneously adding solvent , after the poly(vinylidene fluoride-chlorotrifluoroethylene) is fully dissolved, add a reducing agent, and continue to stir and react at room temperature for 16-24 hours; pour the obtained solution into a beaker filled with hydrochloric acid at pH=3, and stir After 1 hour, the polymer was precipitated, and the obtained polymer was repeatedly washed with methanol until white, and vacuum-dried to constant weight at no higher than 60°C to obtain the target product. The present invention uses poly(vinylidene fluoride-chlorotrifluoroethylene) One-step synthesis of poly(vinylidene fluoride-trifluoroethylene) or poly(vinylidene fluoride-chlorotrifluoroethylene-trifluoroethylene) as a raw material, the method is simple and easy to control, and the reaction system used has low cost and is harmless to the human body and The advantages of environmental friendliness, and the reducing agent can be easily removed from the polymer.

Description

Process for preparing poly(vinylidene fluoride-trifluoroethylene) or poly(vinylidene fluoride-chlorotrifluoroethylene-trifluoroethylene)

technical field

The invention relates to a new hydrogenation reduction reaction method of fluorine-containing polymers, in particular to a method for preparing poly(vinylidene fluoride-trifluoroethylene) by reduction of poly(vinylidene fluoride-trifluoroethylene) P(VDF-CTFE) P(VDF-TrFE) or poly(vinylidene fluoride-chlorotrifluoroethylene-trifluoroethylene)P(VDF-CTFE-TrFE) method. the

Background technique

Polyvinylidene fluoride (PVDF) and its copolymer with trifluoroethylene (P(VDF-TrFE)) have excellent dielectric, ferroelectric, piezoelectric and other properties. Since it was reported in the 1900s, PVDF and its copolymers have been widely used in electrical insulation, microelectronic devices, sensors and other fields. In order to realize the application of such materials in energy storage capacitors, in 1998, Professor QM Zhang of Pennsylvania State University used the electron radiation method (Science.1998, 280, 2101-2104.), in P(VDF-TrFE) crystal The introduction of defects in the structure not only greatly increases the dielectric constant of the polymer at room temperature, but also effectively improves its DE curve, making it transform into a paraelectric at room temperature, increasing its energy storage density at room temperature while reducing energy loss . In 2002, Professor TCMike Chung of Pennsylvania State University adopted the method of introducing a third monomer (such as CTFE, chlorodifluoroethylene (CDFE)) into the P(VDF-TrFE) copolymer, which basically did not reduce the crystallinity of the polymer. Under the premise of appropriately reducing the crystal size, and transforming the long-sequence TTTT configuration of P(VDF-TrFE) into a TTTG structure, it was found that the room temperature dielectric constant of the new trimer can be as high as 100 (Macromolecules 2002, 35, 7678-7684.). The latest research that the applicant has participated in shows that the energy storage density of the terpolymer can be as high as 12J/ ^cm3 under the electric field of 500MV/m (Macromolecules.2007, 40, 783-85; Macromolecules.2007, 40, 9391-97; US Pat, No.541781; US Pat, No.0081195A1), making this type of polymer the darling of new high-density capacitors.

Generally, polymers containing TrFE units are obtained by directly copolymerizing several monomers such as VDF, TrFE, CTFE, etc. according to a certain ratio, but due to the difference in the reactivity ratio of the monomers, the composition of the polymer is different. Uniformity; at the same time, due to the high cost of TrFE monomer preparation and transportation, the cost of polymers prepared by this method remains high, much higher than PVDF. Therefore, in 2006, T.C.Mike Chung et al reported the preparation of trimers by hydrogenation of P(VDF-CTFE), using tributyltin hydride to convert the Cl atom in CTFE into H under the catalysis of azobisisobutyronitrile atoms, thereby preparing TrFE units (Macromolecules. 2006, 39, 4268-71; Macromolecules, 2006, 39, 6962; J. Am. Chem. Soc. 2006, 128, 8120). The preparation of terpolymer by this method has the advantages of easy composition control, simple method, and low cost. Although the performance of the obtained polymer is different from that of the direct terpolymer due to the different introduction methods of monomers, its high cost performance makes it Still has a very good application prospect (Polymer, 2009, 50, 707-715). However, in this method, tributyltin hydride, a highly toxic reagent, is used, and its product tributyltin chloride is also highly toxic, and in order to remove trace traces of tin oxide residues in the polymer, only more toxic reagents can be used. Potassium fluoride reacts with it, and these toxic reagents are very harmful to operators and the environment, so they need to be improved urgently. In recent years, our research group has also found that the low-valent salt of the transition metal Cu can be complexed with the corresponding nitrogen-containing ligands to generate macromolecular free radicals in the solution of P(VDF-CTFE) under appropriate conditions. The chain transfer reaction of molecular radicals to the solvent can realize the preparation of copolymers containing TrFE monomers (Chem. Commun., 2011, 47, 4544-4546; Chinese invention patent, application number: 200910024186.3). Compared with the previous hydrogenation system, this system has greatly improved both in terms of controllability and environmental friendliness. However, copper salts are difficult to remove in the polymer, and at the same time, the use of nitrogen-containing ligands is also easy. Causes elimination degradation of fluoropolymers. the

Contents of the invention

In order to overcome the defects of the existing hydrogenation reduction technology, the object of the present invention is to provide a kind of preparation poly(vinylidene fluoride-trifluoroethylene) or poly(vinylidene fluoride-trifluoroethylene) by reduction of poly(vinylidene fluoride-chlorotrifluoroethylene) The method of chlorofluoroethylene-trifluoroethylene) has the advantages of simple operation and easy control, and the adopted reaction system has the advantages of low cost, friendly to human body and environment, and the reducing agent is easy to be removed from the polymer. the

In order to achieve the above object, technical scheme of the present invention is achieved in that:

A method for preparing poly(vinylidene fluoride-trifluoroethylene) or poly(vinylidene fluoride-trifluorochloroethylene-trifluoroethylene) by reduction of poly(vinylidene fluoride-trifluoroethylene-trifluoroethylene), comprising the following steps:

Step 1. In the there-necked flask, add poly(vinylidene fluoride-chlorotrifluoroethylene) P(VDF-CTFE) and simultaneously add solvent, poly(vinylidene fluoride-chlorotrifluoroethylene) P(VDF-CTFE) and solvent The mass ratio is 0.1:100～40:100. After the poly(vinylidene fluoride-chlorotrifluoroethylene)P(VDF-CTFE) is fully dissolved, a reducing agent is added. The specific amount of reducing agent added depends on the amount of hydrogenation required. After the reductant is dissolved by magnetic stirring, continue to stir and react at room temperature for 16-24 hours;

The molar ratio of active ingredients in the reducing agent to Cl atoms in poly(vinylidene fluoride-chlorotrifluorovinyl)P(VDF-CTFE) is 1.5:1-4:1, and the reducing agent mentioned below refers to the effective reducing agent;

The reducing agent is an alkali metal or alkaline earth metal hydride or a strong organic reducing agent, including: LiH, NaH, LiAlH ₄ , CaH ₂ , lithium trimethoxy aluminum hydride, borohydride exchange resin/Ni(OAc) ₂ , Sodium borohydride, red aluminum, zinc, SnCl ₂ , trisilane, (Me ₃ Si) ₃ SiH-NaBH ₄ , SmI ₂ -THF-HMPA, Et ₃ SiH diethyl phosphate-Et ₃ N, [(Me ₂ N ) ₃ P], metal carbonyl compounds such as Fe(CO) ₅ or organotin hydride RnSnH _4-n ;

Described solvent is the good solvent of fluoropolymer, comprises THF, dioxane, N, N-dimethylformamide, N, N-dimethylacetamide or dimethyl sulfoxide;

Step 2, pour the final solution obtained in step 1 into a beaker filled with hydrochloric acid of pH=3, the volume ratio of hydrochloric acid to the solution obtained in step 1 is not less than 5: 1, after stirring for 1 hour, the polymer is precipitated, and the The obtained polymer is repeatedly washed with methanol until white, and vacuum-dried to constant weight at no higher than 60° C. to obtain the target product. the

The reaction temperature condition when stirring is continued in the step 1 is 0-80°C. the

The reaction temperature condition when the stirring is continued in the step 1 is preferably 20-50° C., if the temperature is too low, the reaction proceeds slowly; if the temperature is too high, the reaction is too fast, and side reactions are prone to occur. the

The present invention uses tetrahydrofuran as a solvent, a metal compound containing hydrogen as a reducing agent, and poly(vinylidene fluoride-chlorotrifluoroethylene) P(VDF-CTFE) as a raw material to synthesize poly(vinylidene fluoride-trifluoroethylene) in one step. )P(VDF-TrFE) or poly(vinylidene fluoride-chlorotrifluoroethylene-trifluoroethylene)P(VDF-CTFE-TrFE), the method is simple and easy to control, and the reaction system used has low cost and is harmless to the human body and The advantages of environmental friendliness, and the reducing agent can be easily removed from the polymer. the

Description of drawings

Figure 1 is the DSC curve of the polymer before and after hydrogenation. the

Fig. 2 is the ¹⁹ F-NMR curves of the polymer before and after hydrogenation.

Fig. 3 is the ¹ H-NMR curves of the polymer before and after hydrogenation.

Detailed ways

Embodiment one

A method for preparing poly(vinylidene fluoride-chlorotrifluoroethylene-trifluoroethylene) by poly(vinylidene fluoride-chlorotrifluoroethylene) reduction, comprising the following steps:

Step 1. In the three-necked flask, add poly(vinylidene fluoride-chlorotrifluoroethylene) P(VDF-CTFE), the molar composition is VDF/CTFE=80:20, and add solvent at the same time, poly(vinylidene fluoride-trifluoroethylene) P(VDF-CTFE) The mass ratio of chlorofluoroethylene) P(VDF-CTFE) to solvent is 4.5:100. After the poly(vinylidene fluoride-trifluorochloroethylene)P(VDF-CTFE) is fully dissolved, a reducing agent is added, and the reducing agent and poly (Vinylidene fluoride-chlorotrifluoroethylene)P(VDF-CTFE)The molar ratio of Cl atoms is 3.4:1, after the reductant is dissolved by magnetic stirring, continue to stir and react at room temperature for 20 hours;

Described solvent is tetrahydrofuran;

The reducing agent is LiAlH ₄ ;

Step 2: Pour the final solution obtained in step 1 into a beaker filled with hydrochloric acid of pH=3. The volume ratio of hydrochloric acid to the solution obtained in step 1 is 5: 1. After stirring for 1 hour, the polymer is precipitated, and the obtained The polymer was repeatedly washed with methanol until white, and vacuum-dried to constant weight at 60° C. to obtain the target product. the

The molar composition of the polymer as measured by NMR is VDF/TrFE/CTFE=80:18:2. the

The products correspond to the red curves in Figures 1, 2, and 3. The characteristic peaks of the product in the DSC of Figure 1 and the nuclear magnetic fluorine spectrum ( ¹⁹ F-NMR) of Figure 3 can confirm that the CTFE unit is indeed converted into a TrFE unit, and the molar composition of the product is calculated from the curve of the nuclear magnetic hydrogen spectrum ( ¹ H-NMR) in Figure 2 get.

Example two

A method for preparing poly(vinylidene fluoride-chlorotrifluoroethylene-trifluoroethylene) by poly(vinylidene fluoride-chlorotrifluoroethylene) reduction, comprising the following steps:

Step 1. In the three-necked flask, add poly(vinylidene fluoride-trifluoroethylene) P(VDF-CTFE), the molar composition is VDF/CTFE=80:20, and at the same time add solvent, poly(vinylidene fluoride-trifluoroethylene) The mass ratio of chlorofluoroethylene) P(VDF-CTFE) to solvent is 3.6:100. After the poly(vinylidene fluoride-trifluorochloroethylene)P(VDF-CTFE) is fully dissolved, a reducing agent is added, and the reducing agent and poly (Vinylidene fluoride-chlorotrifluoroethylene)P(VDF-CTFE)The molar ratio of Cl atoms is 2.7:1, after the reductant is dissolved by magnetic stirring, continue to stir and react at room temperature for 20 hours;

Described solvent is dimethyl sulfoxide;

The reducing agent is LiAlH ₄ ;

Step 2: Pour the final solution obtained in step 1 into a beaker filled with hydrochloric acid of pH=3. The volume ratio of hydrochloric acid to the solution obtained in step 1 is 5: 1. After stirring for 1 hour, the polymer is precipitated, and the obtained The polymer was repeatedly washed with methanol until white, and vacuum-dried to constant weight at 60° C. to obtain the target product. the

The molar composition of the polymer as measured by NMR is VDF/TrFE/CTFE=80:12:8. the

Embodiment three

A method for preparing poly(vinylidene fluoride-chlorotrifluoroethylene-trifluoroethylene) by poly(vinylidene fluoride-chlorotrifluoroethylene) reduction, comprising the following steps:

Step 1. In the three-necked flask, add poly(vinylidene fluoride-trifluoroethylene) P(VDF-CTFE), the molar composition is VDF/CTFE=80:20, and at the same time add solvent, poly(vinylidene fluoride-trifluoroethylene) The mass ratio of chlorofluoroethylene) P(VDF-CTFE) to solvent is 4.5:100, after poly(vinylidene fluoride-trifluorochloroethylene)P(VDF-CTFE) is fully dissolved, add reducing agent, reducing agent and poly (Vinylidene fluoride-chlorotrifluoroethylene)P(VDF-CTFE)The molar ratio of Cl atoms is 2.2:1, after the reductant is dissolved by magnetic stirring, continue to stir and react at room temperature for 20 hours;

Described solvent is tetrahydrofuran;

The reducing agent is NaBH ₄ ;

Step 2: Pour the final solution obtained in step 1 into a beaker filled with hydrochloric acid of pH=3. The volume ratio of hydrochloric acid to the solution obtained in step 1 is 5: 1. After stirring for 1 hour, the polymer is precipitated, and the obtained The polymer was repeatedly washed with methanol until white, and vacuum-dried to constant weight at 60° C. to obtain the target product. the

The molar composition of the polymer as measured by NMR is VDF/TrFE/CTFE=80:8:12. the

Embodiment four

A method for preparing (vinylidene fluoride-trifluoroethylene) by reduction of poly(vinylidene fluoride-trifluoroethylene), comprising the steps of: poly(vinylidene fluoride-trifluoroethylene)

Step 1. In the three-necked flask, add poly(vinylidene fluoride-chlorotrifluoroethylene) P(VDF-CTFE), and the molar composition of poly(vinylidene fluoride-chlorotrifluoroethylene)P(VDF-CTFE) is VDF/CTFE =80:20, while adding solvent, the mass ratio of poly(vinylidene fluoride-chlorotrifluoroethylene) P(VDF-CTFE) to solvent is 4.5:100. After the poly(vinylidene fluoride-trifluorochloroethylene) P(VDF-CTFE) is fully dissolved, add a reducing agent, the reducing agent and poly(vinylidene fluoride-trifluorochloroethylene) P(VDF-CTFE) in molar Cl atoms The ratio is 4:1, after the reductant is dissolved by magnetic stirring, continue to stir and react at room temperature for 20 hours;

Described solvent is tetrahydrofuran;

The reducing agent is LiAlH ₄ ;

Step 2, pour the solution obtained at last in step 1 into a beaker filled with hydrochloric acid of pH=3, the volume ratio of hydrochloric acid to the solution obtained in step 2 is 5:1, after stirring for 1 hour, the polymer is precipitated, and the obtained The polymer was repeatedly washed with methanol until white, and vacuum-dried to constant weight at 60° C. to obtain the target product. the

According to NMR, the molar composition of the polymer is VDF/TrFE=80:20. the

The products correspond to the blue curves in Figures 1, 2, and 3. The characteristic peaks of the product in the DSC of Figure 1 and the nuclear magnetic fluorine spectrum ( ¹⁹ F-NMR) of Figure 3 can confirm that the CTFE unit is indeed converted into a TrFE unit, and the molar composition of the product is calculated from the curve of the nuclear magnetic hydrogen spectrum ( ¹ H-NMR) in Figure 2 get.

Embodiment five

A method for preparing poly(vinylidene fluoride-chlorotrifluoroethylene-trifluoroethylene) by poly(vinylidene fluoride-chlorotrifluoroethylene) reduction, comprising the following steps:

Step 1. In the three-necked flask, add poly(vinylidene fluoride-trifluoroethylene) P(VDF-CTFE), the molar composition is VDF/CTFE=80:20, and at the same time add solvent, poly(vinylidene fluoride-trifluoroethylene) The mass ratio of chlorofluoroethylene) P(VDF-CTFE) to solvent is 3.6:100. After the poly(vinylidene fluoride-trifluorochloroethylene)P(VDF-CTFE) is fully dissolved, a reducing agent is added, and the reducing agent and poly (Vinylidene fluoride-chlorotrifluoroethylene)P(VDF-CTFE)The molar ratio of Cl atoms is 2.7:1, after the reductant is dissolved by magnetic stirring, continue to stir and react at room temperature for 20 hours;

Described solvent is dimethyl sulfoxide;

The reducing agent is NaH;

Step 2: Pour the final solution obtained in step 1 into a beaker filled with hydrochloric acid of pH=3. The volume ratio of hydrochloric acid to the solution obtained in step 1 is 5: 1. After stirring for 1 hour, the polymer is precipitated, and the obtained The polymer was repeatedly washed with methanol until white, and vacuum-dried to constant weight at 60° C. to obtain the target product. the

The molar composition of the polymer as measured by NMR is VDF/TrFE/CTFE=80:12:8. Other non-limiting examples are shown in the table below:

Claims (8)

1. prepare the method for gathering (vinylidene-trifluoro-ethylene) or gathering (vinylidene-trifluorochloroethylene-trifluoro-ethylene), it is characterized in that, may further comprise the steps:

Step 1, in there-necked flask; Add and to gather (vinylidene-trifluorochloroethylene) P (VDF-CTFE) and to add solvent simultaneously, the mass ratio that gathers (vinylidene-trifluorochloroethylene) P (VDF-CTFE) and solvent is 0.1:100～40:100, waits to gather (vinylidene-trifluorochloroethylene) P (VDF-CTFE) fully after the dissolving; Add reductive agent; The concrete add-on of reductive agent is decided according to required hydrogenant amount, after to be restored dose of dissolving of magnetic agitation, at room temperature continues stirring reaction 16-24 hour;

Effective constituent is 1.5:1～4:1 with gathering the middle Cl atomic molar ratio of (vinylidene-trifluorochloroethylene) P (VDF-CTFE) in the said reductive agent, and hereinafter mentions that reductive agent all refers to effective reductive agent;

Described reductive agent is basic metal or alkaline earth metal hydride or strong organic reducing agent, comprising: LiH, NaH, LiAlH ₄, CaH ₂, trimethoxy lithium aluminum hydride, the hydrogen exchange resin/Ni of boron (OAc) ₂, Peng Qinghuana, red aluminium, zinc, SnCl ₂, three silane, (Me ₃Si) ₃SiH-NaBH ₄, SmI ₂-THF-HMPA, Et ₃SiH diethyl phosphoric acid-Et ₃N, [(Me ₂N) ₃P], metal carbonyl such as Fe (CO) ₅Or the hydrogenate RnSnH of organotin _4-n

Said solvent is the good solvent of fluoropolymer, comprises THF, dioxane, N, dinethylformamide, DMAC N,N or DMSO 99.8MIN.;

Step 2, the solution that obtains at last in the step 1 is poured in the beaker of the hydrochloric acid that fills pH=3; The volume ratio of gained solution is not less than 5:1 in hydrochloric acid and the step 1; Stir after 1 hour; Polymkeric substance is separated out, with resulting polymers with the methyl alcohol repetitive scrubbing to white, vacuum-drying to constant weight obtains title product under 60 ℃ of conditions not being higher than.

2. method according to claim 1 is characterized in that, the temperature of reaction condition when continuing to stir in the said step 1 is 0-80 ℃.

3. method according to claim 1 is characterized in that, the temperature of reaction condition when continuing to stir in the said step 1 is 20-50 ℃.

4. method according to claim 1, the reduction preparation gathers (vinylidene-trifluorochloroethylene-trifluoro-ethylene), it is characterized in that, may further comprise the steps:

Step 1, in there-necked flask; Add and gather (vinylidene-trifluorochloroethylene) P (VDF-CTFE), mole consists of VDF/CTFE=80: 20, and add solvent simultaneously; The mass ratio that gathers (vinylidene-trifluorochloroethylene) P (VDF-CTFE) and solvent is 4.5: 100; After waiting to gather the abundant dissolving of (vinylidene-trifluorochloroethylene) P (VDF-CTFE), add reductive agent, reductive agent is 3.4: 1 with gathering the middle Cl atomic molar ratio of (vinylidene-trifluorochloroethylene) P (VDF-CTFE).After to be restored dose of dissolving of magnetic agitation, at room temperature continued stirring reaction 20 hours;

Said solvent is a THF;

Described reductive agent is LiAlH ₄

Step 2, the solution that obtains at last in the step 1 is poured in the beaker of the hydrochloric acid that fills pH=3; The volume ratio of gained solution is 5: 1 in hydrochloric acid and the step 1; Stir after 1 hour; Polymkeric substance is separated out, and resulting polymers is extremely white with the methyl alcohol repetitive scrubbing, and vacuum-drying to constant weight obtains title product under 60 ℃ of conditions.

5. method according to claim 1, the reduction preparation gathers (vinylidene-trifluorochloroethylene-trifluoro-ethylene), it is characterized in that, may further comprise the steps:

Step 1, in there-necked flask; Add and gather (vinylidene-trifluorochloroethylene) P (VDF-CTFE), mole consists of VDF/CTFE=80: 20, and add solvent simultaneously; The mass ratio that gathers (vinylidene-trifluorochloroethylene) P (VDF-CTFE) and solvent is 3.6: 100; After waiting to gather the abundant dissolving of (vinylidene-trifluorochloroethylene) P (VDF-CTFE), add reductive agent, reductive agent is 2.7: 1 with gathering the middle Cl atomic molar ratio of (vinylidene-trifluorochloroethylene) P (VDF-CTFE); After to be restored dose of dissolving of magnetic agitation, at room temperature continued stirring reaction 20 hours;

Said solvent is a DMSO 99.8MIN.;

Described reductive agent is LiAlH ₄

Step 2, the solution that obtains at last in the step 1 is poured in the beaker of the hydrochloric acid that fills pH=3; The volume ratio of gained solution is 5: 1 in hydrochloric acid and the step 1; Stir after 1 hour; Polymkeric substance is separated out, and resulting polymers is extremely white with the methyl alcohol repetitive scrubbing, and vacuum-drying to constant weight obtains title product under 60 ℃ of conditions.

6. method according to claim 2, the reduction preparation gathers (vinylidene-trifluorochloroethylene-trifluoro-ethylene), it is characterized in that, may further comprise the steps:

Step 1, in there-necked flask; Add and gather (vinylidene-trifluorochloroethylene) P (VDF-CTFE), mole consists of VDF/CTFE=80: 20, and add solvent simultaneously; The mass ratio that gathers (vinylidene-trifluorochloroethylene) P (VDF-CTFE) and solvent is 4.5: 100; After waiting to gather the abundant dissolving of (vinylidene-trifluorochloroethylene) P (VDF-CTFE), add reductive agent, reductive agent is 2.2: 1 with gathering the middle Cl atomic molar ratio of (vinylidene-trifluorochloroethylene) P (VDF-CTFE); After to be restored dose of dissolving of magnetic agitation, at room temperature continued stirring reaction 20 hours;

Said solvent is a THF;

Described reductive agent is NaBH ₄

Step 2, the solution that obtains at last in the step 1 is poured in the beaker of the hydrochloric acid that fills pH=3; The volume ratio of gained solution is 5: 1 in hydrochloric acid and the step 1; Stir after 1 hour; Polymkeric substance is separated out, and resulting polymers is extremely white with the methyl alcohol repetitive scrubbing, and vacuum-drying to constant weight obtains title product under 60 ℃ of conditions.

7. method according to claim 1, (vinylidene-trifluoro-ethylene) is characterized in that, may further comprise the steps:

Step 1, in there-necked flask; Add and gather (vinylidene-trifluorochloroethylene) P (VDF-CTFE); Mole consists of VDF/CTFE=80: 20, and add solvent simultaneously, the mass ratio that gathers (vinylidene-trifluorochloroethylene) P (VDF-CTFE) and solvent is 4.5: 100.After treating that polymkeric substance fully dissolves, add reductive agent, reductive agent is 4: 1 with gathering the middle Cl atomic molar ratio of (vinylidene-trifluorochloroethylene) P (VDF-CTFE), after to be restored dose of dissolving of magnetic agitation, at room temperature continues stirring reaction 20 hours;

Said solvent is a THF;

Described reductive agent is LiAlH ₄

Step 2, the solution that obtains at last in the step 1 is poured in the beaker of the hydrochloric acid that fills pH=3; The volume ratio of gained solution is 5: 1 in hydrochloric acid and the step 2; Stir after 1 hour; Polymkeric substance is separated out, and resulting polymers is extremely white with the methyl alcohol repetitive scrubbing, and vacuum-drying to constant weight obtains title product under 60 ℃ of conditions.

8. method according to claim 1, the reduction preparation gathers (vinylidene-trifluorochloroethylene-trifluoro-ethylene), it is characterized in that, may further comprise the steps:

Step 1, in there-necked flask; Add and gather (vinylidene-trifluorochloroethylene) P (VDF-CTFE), mole consists of VDF/CTFE=80: 20, and add solvent simultaneously; The mass ratio that gathers (vinylidene-trifluorochloroethylene) P (VDF-CTFE) and solvent is 3.6: 100; After waiting to gather the abundant dissolving of (vinylidene-trifluorochloroethylene) P (VDF-CTFE), add reductive agent, reductive agent is 2.7: 1 with gathering the middle Cl atomic molar ratio of (vinylidene-trifluorochloroethylene) P (VDF-CTFE); After to be restored dose of dissolving of magnetic agitation, at room temperature continued stirring reaction 20 hours;

Said solvent is a DMSO 99.8MIN.;

Described reductive agent is NaH;

Step 2, the solution that obtains at last in the step 1 is poured in the beaker of the hydrochloric acid that fills pH=3; The volume ratio of gained solution is 5: 1 in hydrochloric acid and the step 1; Stir after 1 hour; Polymkeric substance is separated out, and resulting polymers is extremely white with the methyl alcohol repetitive scrubbing, and vacuum-drying to constant weight obtains title product under 60 ℃ of conditions.

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