Controlled Syntheses of Poly(phenylene ethynylene)s with Regiochemically-Tuned Optical Band Gaps and Ordered Morphologies

A series of well-defined poly(phenylene ethynylene)s (PPEs) comprised of para- and/or meta-substituted monomers was synthesized and characterized. With use of a modified catalyst transfer method, the requisite polymerization reactions were found to proceed in a chain growth manner which enabled control over polymer molecular weight while maintaining a low polydispersity. In addition, varying the monomer feed ratio afforded copolymers with tunable regiochemistry and consequent electronic properties. The methodology was found to be general and successfully combined with an isocyanide polymerization reaction to prepare the respective diblock copolymers. With use of differential scanning calorimetry in conjunction with atomic force microscopy, the copolymers were found to adopt ordered, phase-separated morphologies in the solid state.