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Method for protecting amino end groups in polybenzimidazole high-molecular material

A technology of polybenzimidazole and polymer materials, which is applied in the field of protection of terminal amino groups, can solve the problems affecting the stability and service life of materials, and achieve the effect of high yield and easy reaction

Inactive Publication Date: 2010-07-07
SHANDONG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] Studies have found that the two adjacent terminal amino groups are easily oxidized under high temperature and oxidative conditions, thereby degrading the polymer molecule from one end, which affects the stability and service life of this type of material

Method used

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  • Method for protecting amino end groups in polybenzimidazole high-molecular material
  • Method for protecting amino end groups in polybenzimidazole high-molecular material
  • Method for protecting amino end groups in polybenzimidazole high-molecular material

Examples

Experimental program
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Effect test

Embodiment 1

[0053] The reaction equation is as follows:

[0054]

[0055] In the formula: (1) is polybenzimidazole; (2) is urea; (3) is PBI with protected amino groups (that is, polymers that generate terminal benzimidazolones)

[0056] In a 250mL four-neck flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel, add polybenzimidazole (15g), urea (18-28g), and 70mL of dimethylacetamide to be protected successively, and stir heating. Stir under the protection of nitrogen, heat the oil bath to 100°C~108°C, add 95% sulfuric acid dropwise, keep the pH value of the reaction solution between 5~6, and react at 100°C~180°C. And add 4.5g urea every 1h, continue to react for 6h, slowly pour the reaction mixture into water to spin, and wash with deionized water for 3~5 times. The solid polymer was pulverized and washed three times with deionized water, and filtered to obtain PBI (light yellow or brown powder) with protected amino groups.

Embodiment 2

[0057] [Example 2] Microwave-assisted solid-phase synthesis

[0058] Microwave-assisted solid-phase synthesis was used. In a three-necked flask equipped with a condenser tube and inert gas protection, add the polybenzimidazole to be protected, urea, water and concentrated sulfuric acid (the amount added is the same as in Example 1), first feed the protective gas nitrogen for 10min, and then Microwave intermittent heating reaction, every heating 3mim, intermittent 10min, after the temperature drops, add 5g of urea. Respond intermittently for 6 to 8 times. The reaction solution was slowly poured into water for spinning. Other processing methods are with embodiment 1.

Embodiment 3

[0060] With the method of embodiment 1, just change urea into equimolar substituted urea, thiourea, substituted thiourea and can obtain other protected situations in the general formula.

[0061] Polybenzimidazole can be of any structure, but the amount of urea added in the reaction process of PBI with different structures is different. For example, the amount of urea required for general long-chain PBI is 2 to 4 times that of its terminal amino group. And hyperbranched PBI has a large amount of terminal amino groups, so the amount of urea should be more. The amount of urea is 2 to 5 times that of its terminal amino group. If the quality of PBI is used as a benchmark, the amount of urea used in hyperbranched PBI is 5 to 10 times that of chained PBI.

[0062] The solvent can be selected from dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone and the like.

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Abstract

The invention relates to a method for protecting amino end groups in polybenzimidazole high-molecular material. The method is characterized in that under the protection of nitrogen and the effect of catalyst, polybenzimidazole reacts with protective agent and solvent, wherein the protective agent is carbamide, thiocarbamide or carbamidine compound, and the solvent is dimethylacetylamide, dimethyl sulfoxide or N-methylpyrrolidone. The method can ensure that the amino end groups can form a stable structure, so that the amino end groups cannot be reduced as amino groups.

Description

technical field [0001] The invention relates to a method for protecting terminal amino groups in polybenzimidazole polymer materials. Background technique [0002] Polybenzimidazole (PBI) first appeared in the US patent in 1959. The aromatic PBI polymer was reported by H.Vogel in 1961. The American Hoechst Celanese company put PBI film products on the US market in 1988. A polymer containing benzimidazole repeating units in the main chain of the PBI polymer, which is a yellow to tan amorphous powder. The glass transition temperature of aromatic polybenzimidazole is 480°C, basically no weight loss below 500°C in nitrogen, and the highest decomposition temperature exceeds 600°C. Excellent low temperature performance, not brittle at -196°C. The tensile strength of the PBI film is 110MPa, the tensile modulus is 2.65GPa, and the elongation is 11%. PBI is nonflammable in air and burns slowly in oxygen. It can resist strong acid, strong alkali and organic solvent, and it is the ...

Claims

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Application Information

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IPC IPC(8): C08G73/18
Inventor 李忠芳王素文董飞龙于先进
Owner SHANDONG UNIV OF TECH
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