Fluorinated Poly(substituted methylene)s Prepared by Pd-Initiated Polymerization of Fluorine-Containing Alkyl and Phenyl Diazoacetates: Their Unique Solubility and Postpolymerization Modification

Pd-initiated polymerization of fluorine (F) containing alkyl and phenyl diazoacetates is described. Polymerization of 2,2,2-trifluoroethyl diazoacetate [Et(CF3)-DA] with pi-allylPdCl afforded a C-C main chain polymer bearing a 2,2,2-trifluoroethoxycarbonyl group on each main chain carbon atom. The polymer showed upper critical solution temperature (UCST)-type phase separation in multiple common organic solvents with differing polarities. Although homopolymerization of 3,3,4,4,5,5,6,6,6-nonafluorohexyl diazoacetate [Hex(C4F9)DA] with a higher fluorine content yielded an insoluble product, copolymerization of Hex(C4F9)DA with non-fluorinated ethyl diazoacetate (EDA) proceeded homogeneously to give a soluble F-containing copolymer. Polymerization of a series of F-containing phenyl diazoacetates was also conducted with the same initiator, giving poly[(F-containing aryloxycarbonyl)methylene]s, which showed significant solubility differences depending on the substitution pattern of F atoms on the phenyl ring. Efficient postpolymerization modification of poly[(F-containing aryloxycarbonyl)methylene]s was achieved with a primary amine, affording a polymer with both a five-membered cyclic imide structure and an N-alkylcarbamoyl group in its side chains.