Synthesis And Properties Of Novel Sulfonated Polybenzimidazole Copolymer

At present, polybenzimidazole is a kind of high-performance polymer and is considered as fine-base material of the proton exchange membrane. Since the PBI of proton exchange membrane on acid doped has been reported, polybenzimidazole polymer materials are more and more concerned by people. People have been synthesizing the polybenzimidazole with complementary properties as the proton exchange membrane matrix, by grafting, sulfonation and polymerization.In this thesis, we successfully produced a series of polybenzimidazoles material by taking 3,3',4,4'-tetramino diphenyl sulfone as four amine monomer and a variety of binary acid though solution polycondensation. The structures and properties of polymers are characterized by FT-IR, DSC, TG, WADX etc, and the dissolved performance of polymers are also inspected. The overview of this paper is as follows: 1. In the fourth chapter of this paper, we use 4, 4'-diaminodiphenyl sulfone (DADS) as the raw material to synthesize 3, 3', 4, 4'-tetramino diphenyl sulfone (TADS) though series of reactions such as acetylation, nitration, hydrolysis, neutralization in the system of palladium/carbon. The products are characterized by FT-IR, 1H-NMR, etc. The results show that the products have prospective structure and high purity.2. In the fifth chapter of this paper, we use biphenyl as the raw material to synthesize dicarboxylic acid by acetylation reaction, potassium permanganate oxidation reaction. Dicarboxylic acid is characterized by FT-IR, 1H-NMR, etc. The results show that the product has prospective structure and high purity.The series of new polybenzimidazole with phenoxy, sulfonyl structure are produced by the copolymerization by taking polyphosphoric acid (PPA) as the solvent. And the ternary monomers of the copolymerization are the TADS, dicarboxylic acid and 5-sodium isophthalic acid. The polybenzimidazole resins are characterized by FT-IR, 1H-NMR, TG, DSD, WAXD, etc. The results showed that all the polymers exhibit good thermal stability and have good solubility in organic solvents, such as DMAc, DMSO, and DMF.3. In the sixth chapter of this thesis, we use 2, 2-bis-(4-hydroxyphenyl) hexafluoropropane and p-fluorophenyl cyanide as raw materials though nucleophilic substitution reaction to synthesize 4, 4'-double-[4-(4-cyano-phenoxy) phenyl] hexafluoropropane (HFIBPDDBN) under the conditions of K₂CO₃ and DMF. The product is recrystallised in ethanol-acetone to impurity. And the product is oxidationed by potassium hydroxide, and then is recrystalled in ethanol-water solution and other steps. 4, 4'-double-[4-(4-carboxy-phenoxy) phenyl] hexafluoropropane (HFIBPDDBA) is producted. It is characterized by FT-IR, 1H-NMR, etc. The experimental test patterns show that the product has prospective structure and high purity.The series of new polybenzimidazole resin containing sulfonic group and trifluoromethyl group are producted by the copolymerization by taking polyphosphoric acid (PPA) as the solvent. And the ternary monomers of the copolymerization are the TADS, 5-sodium isophthalic acid and 4, 4'-double-[4-(4 - carboxy-phenoxy) phenyl] hexafluoropropane (HFIBPDDBA) as the third monomer. The polybenzimidazole resins are characterized by FT-IR, 1H-NMR, TG, DSD, WAXD, etc. And we inspected the polymer's dissolved performance. The results show that the thermal decomposition temperatures (Td, 5%) is the lowest to 400℃in nitrogen atmosphere because of methyl of flexible group trifluoro introduced; The temperature is a bit lower than ones without flexible groups. Meanwhile, because of the introduction of trifluoro methyl and sulfonic acid, the dissolution performance of the polymer are improved in a certain extent.4. In the seventh chapter of this thesis, 2,6-bis (4-carboxy-phenoxy) benzonitrile (DCPB) is produced by using hydroxybenzoic acid and 2,6-Fluorobenzonitrile as raw materials under the conditions of K₂CO₃ and DMSO. The dicarboxylic acid obtained above is characterized by FT-IR, 1H-NMR, etc. The results show that the product has prospective structure and high purity.The series of new polybenzimidazole resin containing sulfonic group and cyanide-side group structure are produced by the copolymerization by taking polyphosphoric acid (PPA) as the solvent. And the ternary monomers of the copolymerization are the TADS, 5-sodium isophthalic acid and 2, 6-bis (4-carboxy-phenoxy) benzonitrile (DCPB) as the third monomer. The polybenzimidazole resins are characterized by FT-IR, 1H-NMR, TG, DSD, WAXD, etc. The results show that the copolymer have excellent heat resistance due to the introduction of cyano chemically; the thermal decomposition temperatures (Td, 5%) are at 440℃or more in nitrogen atmosphere; at the same time, the polymer can greatly improve the solubility in organic solvents, such as DMAc, DMSO, and DMF under the introduction of sulfonic acid.