Synthesis, Characterization and Properties of Chain Terminated Polyhedral Oligomeric Silsesquioxane-Functionalized Perfluorocyclobutyl Aryl Ether Copolymers (Postprint)

摘要

A new class of perfluorocyclobutyl (PFCB) polymers covalently functionalized with polyhedral oligomeric silsesquioxnes (POSS) is presented. Three discreetly functionalized POSS monomers possessing thermally reactive trifluorovinyl aryl ethers (TFVE) were prepared in good yields. The POSS TFVE monomers were prepared by initial corner capping of cyclopentyl (-C5H9), iso- butyl (-CH2CH(CH3)2), or trifluoropropyl (-CH2CH2CF3) functionalized POSS trisilanols with acetoxyethyltrichlorsilane followed by sequential acid- catalyzed deprotection and coupling with 4-(trifluorovinyloxy)benzoic acid. TFVE functionalized POSS monomers were thermally polymerized with 4,4'-bis(4-trifluor ovinyloxy)biphenyl or 2,2-bis(4-trifluorovinylo xybiphenyl)-1,1,1,3,3,3- hexafluoropropane monomers via a condensate-free, 2+2 step-growth polymerization. The polymerization afforded solution processable PFCB polymers with POSS macromers installed on the polymer chain ends. POSS monomers and their corresponding copolymers were characterized by 1H, 13C, 19F, and 29Si NMR, GPC, ATR-FTIR, and elemental combustion analysis. GPC trace analysis showed agreeable number-average molecular weight for various weight percent of iso- butyl and trifluoropropyl chain terminated POSS PFCB copolymers. DSC analysis showed the introduction of increasing POSSweight percent in the endcapped PFCB copolymers lowers glass transition temperatures as high as 31 deg C. On the other hand, the trifluoropropylPOSS endcapped PFCB polymer glass transition temperature was unaffected when copolymerized with the more fluorinated 2,2- bis(4-trifluorovinylo xybiphenyl)-1,1, 1,3,3,3-hexafluoropropane monomer.