New polyphenylene-g-polystyrene and polyphenylene-golystyrene/poly(ε-caprolactone) copolymers by combined controlled polymerization and cross-coupling processes

Abstract

1,4-Dibromo-2-(bromomethyl)benzene and 1,3-dibromo-5-(bromomethyl)benzene were used as initiators in the atom transfer radical polymerization of styrene in conjunction with CuBr/2,2'-bipyridine as a catalyst. The resulting polystyrene (PSt)-based macromonomers, possessing at one end a 2,5-dibromophenylene or 3.5-dibromophenylene moiety, were used in combination with 2,5-dihexylbenzene-1,4-diboronic acid for Suzuki coupling in the presence of Pd(PPh3)(4) as a catalyst or with the system NiCl2/2,2'-bipyridine/triphenylphosphine/Zn for Yamamoto polymerization. Polyphenylenes (PPs) with PSt chains as substitution groups were obtained. The Same macromonomers were used in Yamamoto copolycondensation reactions. in combination with a poly(E-caprolactone) (PCL) macromonomer.. and this resulted in PPS with PSU PCL side chains. The obtained PPs had good solubility properties in common organic solvents at room temperature similar to those of the Starting macromonomers. The new polymers were characterized with H-1 (C-13) NMR, JR, and gel permeation chromatography. The optical properties of the polymers were monitored with UV and fluorescence spectroscopy. The thermal behaviors of the macromonomers and final PPS were investigated with differential scanning calorimetry and compared. The morphology of PP containing PSt and PCL blocks was characterized with atomic force microscopy. and a microphase-separated layered morphology was observed. (C) 2005 Wiley. Periodicals. Inc.