First separation and characterization of cis and trans 1,2-bisaryloxy perfluorocyclobutanes

4-Bromotrifluorovinyloxybenzene (4-Br-TFVE) undergoes cyclodimerization upon heating at 150 °C affording cis and trans isomers of 1,2-bis(4-bromophenoxy)hexafluorocylcobutane. Stereoisomers were separated by selective crystallization, confirmed by single crystal X-ray, and further characterized by NMR. Remarkable difference in the solid state structures include aryl to aryl dihedral angles of 12° for the trans isomer and 88° for the cis isomer. Polymers containing roughly equal amounts of cis and trans fused perfluorocyclobutyl (PFCB) rings should be expected to have low crystallinity due to the marked difference in the two unit cells as is observed.     

Novel fluorinated poly(aryl ether)s derived from 1,2-bis(4-(4-fluorobenzoyl)phenoxy)-hexafluorocyclobutane

Two novel poly(aryl ether)s were prepared from 1,2-bis(4-(4-fluorobenzoyl)-phenoxy)-hexafluorocyclobutane and aromatic bisphenols by the aromatic nucleophilic substitution reaction in a polar aprotic solvent. These polymers have good thermal stability up to 341 °C with 10% weight loss in inert atmosphere and good solubility in common organic solvents such as THF, DMAc, DMF and DMSO.     

Synthesis of novel aromatic ether polymers containing perfluorocyclobutyl and triazole units via click chemistry

The synthesis and characterization of a novel class of linear aromatic ether polymers containing perfluorocyclobutyl and triazole unites is described. These polymers were prepared from the click chemistry (the copper-catalyzed Huisgen's 1,3-dipolar cycloaddition) of new monomer 1,2-bis(4-azidomethylphenoxy) perfluorocyclobutane and bisethynyl compounds.     

含全氟环丁烷环可溶性聚酰亚胺的合成与表征

以乙酰氨基苯酚为原料,经过BrCF2CF2Br氟烷基化、Zn催化脱卤、热环化二聚,以及水解去保护,合成了一种含全氟环丁烷环的二胺单体1,2,3,3,4,4-六氟-1,2-双[4-(氨基)苯氧基]环丁烷.用该单体分别与酯环二酐双环[2·2·1]辛烷-2,3,5,6-四羧基2,3,5,6-二酐(BHDA)、芳香性二酐3,3′,4,4′-联苯四酸二酐(BPDA)和3,3′,4,4′-二苯酮四酸二酐(BTDA)通过“一步法”制备了3种新型含全氟环丁烷环聚酰亚胺.通过粘度测试、溶解性实验、FT-IR、热失重分析(TGA)和差热扫描量热(DSC)分析等手段,对所合成的聚酰亚胺的结构与性能进行了表征.结果显示该类聚酰亚胺可溶于大多数常用极性有机溶剂,热分解温度高于480℃,其中两种聚合物玻璃化温度低于150℃,表明含全氟环丁烷环聚酰亚胺具有良好的溶解性和可加工性.     

Sulfonated poly(fluorenyl ether) membranes containing perfluorocyclobutane groups for fuel cell applications

This paper describes the preparation and electrochemical properties of new proton conducting polymer membranes, sulfonated poly(fluorenyl ether) membrane-containing perfluorocyclobutane (PFCB) moieties for fuel cell applications. The sulfonated polymers were prepared via thermal cyclodimerization of 9,9-bis(4-trifluorovinyloxyphenyl)fluorene and subsequent post-sulfonation using chlorosulfonic acid (CSA) as a sulfonating agent. The post-sulfonation reaction was carried out by changing the molar ratio of CSA/repeating unit of the polymer at room temperature for 5 h and the resulting sulfonated polymers showed different degrees of sulfonation (DS) and ion exchange capacities (IEC). With the increment of CSA content, the DS, IEC and water uptake of the sulfonated polymer membranes increased. Their proton conductivity was investigated as a function of temperature. The polymer membrane with an IEC value of 1.86 mmol/g showed a water content of 25% similar to Nafion-115's but showed higher proton conductivity than Nafion-115 over the temperature 25–80 °C. The polymer membrane with lower water uptake and higher IEC showed similar proton conductivity and methanol permeability to Nafion-115. These results confirmed that the sulfonated poly(fluorenyl ether)-containing PFCB groups could be a promising material for fuel cell membranes.