Method for reducing low-molecular-weight carboxyl-terminated fluorine-containing polymer by hydroboron/diisobutylaluminium hydride reduction system

A technology of diisobutylaluminum hydride and borohydride, which is applied in the field of reduction of low-molecular-weight carboxyl-terminated fluoropolymers, can solve the problems of poor selectivity of reduction reaction, high content of metal ions, and difficulty in post-treatment separation, and achieve selectivity High, high reduction rate, excellent chemical stability effect

Active Publication Date: 2021-10-19
DALIAN MARITIME UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, borohydride reducing systems (such as sodium borohydride / iodine, sodium borohydride / zinc chloride, sodium borohydride / rhenium chloride, sodium borohydride / cerium chloride, sodium borohydride / neodymium chloride, sodium borohydride / Catechol or lithium aluminum hydride, etc.) has poor selectivity for the reduction reaction of low molecular weight fluoropolymers, a large amount of use, high metal ion content, difficult post-treatment separation, and affects application performance
Although lithium aluminum hydride, another strong reducing agent, can effectively reduce carboxyl groups, it can only be dissolved in a small amount of ether solvents such as tetrahydrofuran and diethylene glycol dimethyl ether, which severely limits its scope of application.

Method used

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  • Method for reducing low-molecular-weight carboxyl-terminated fluorine-containing polymer by hydroboron/diisobutylaluminium hydride reduction system
  • Method for reducing low-molecular-weight carboxyl-terminated fluorine-containing polymer by hydroboron/diisobutylaluminium hydride reduction system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] In a three-necked flask, 5 g of low molecular weight carboxyl-terminated fluoropolymer (vinylidene fluoride-hexafluoropropylene copolymer, carboxyl mass percentage content 2.5%, number average molecular weight 3600, carboxyl content is 2.8mmoL) was dissolved in 40mL tetrahydrofuran and Add 5.6mmoL sodium borohydride to 10mL diglyme mixed solution at 0°C under inert gas protection, stir for 1 hour, add 5.6mmoL diisobutylaluminum hydride reducing agent, heat up to 60°C, Stirring was continued for 9h. After the reaction is finished, quench the reaction with hydrochloric acid solution, wash with ethanol, and then wash with deionized water for 3 to 4 times, collect the product and dry it in vacuum at 60°C to constant weight, and determine the low molecular weight carboxyl-terminated fluorine-containing polymer by chemical titration. The material reduction rate is 91%.

[0026] figure 1 It is the infrared spectrogram of the low molecular weight carboxyl-terminated fluorine-...

Embodiment 2

[0029] Prepare and test according to Example 1. The difference is that the amount of reducing agent is different, and the molar ratio of carboxyl group / sodium borohydride / isobutyl aluminum hydride is 1 / 1 / 1. The reaction condition is 60°C for 9 hours, and the reduction rate up to 75%.

Embodiment 3

[0031] Prepare and test according to Example 1. The difference is that the amount of reducing agent is different, and the molar ratio of carboxyl / sodium borohydride / isobutylaluminum hydride is 1 / 4 / 4. The reaction condition is 60°C for 9 hours, and the reduction rate Reached 91%.

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Abstract

The invention discloses a method for reducing a low-molecular-weight carboxyl-terminated fluorine-containing polymer by using a hydroboron / diisobutylaluminium hydride reduction system. According to the method, hydroboron and diisobutylaluminium hydride are compounded to form a reduction system for reducing the low-molecular-weight carboxyl-terminated fluorine-containing polymer, the method has the characteristics of small reducing agent dosage, safe reaction, simple post-treatment process, good selectivity, better reduction effect of a composite system than that of a single system and the like, and the reduction rate is up to 80% or above. The product can be applied as a functional fluorine-containing polymer intermediate, an adhesive, a joint mixture, a coating, a processing compounding agent and the like.

Description

technical field [0001] The invention relates to a method for reducing a low-molecular-weight carboxyl-terminated fluoropolymer with a borohydride / diisobutylaluminum hydride reduction system. Background technique [0002] Due to the stable carbon-fluorine single bond of low molecular weight fluoropolymer (C-F 485kJ mol -1 ) and the shielding effect of fluorine atoms on the main chain make it have more stable chemical properties, and it has fluidity and easy processability, which overcomes the defects of traditional high molecular weight fluoropolymers in terms of processing and molding difficulties. Therefore, low-molecular-weight fluoropolymers are widely used in the fields of aviation, aerospace, automobiles and petrochemicals due to their excellent heat resistance, weather resistance, oil resistance, chemical medium resistance and excellent physical and mechanical properties and electrical properties after curing. It is an indispensable and important material in modern in...

Claims

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Application Information

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IPC IPC(8): C08F8/04C08F214/22C08F214/28C08F214/26C08F216/14
CPCC08F8/04C08F214/22C08F214/28C08F214/222C08F214/262C08F216/1408
Inventor 廖明义常云飞
Owner DALIAN MARITIME UNIVERSITY
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