| Abstract: | A solvent-soluble polybiphenylene with a single hetero atom in the chain (a bridged polybiphenylene) was prepared according to the synthetic procedure for a solvent-soluble poly(4,4′-biphenylene). In addition, a related copolymer was similarly prepared by the addition of the MMA monomer in the reaction system. The thermal properties and viscosity behavior of each product were influenced by the hetero atom, especially by the introduction of MMA component in the chain. Each viscosity curve (ηsp/c vs. c) shows an anomalous peak at a specific concentration (0.3–0.002 g/100 ml DMF), depending upon the atomic group. The ηsp/c value for each homopolymer was not over 0.1 except in the neighborhood of the anomalous peak, while those for copolymers became 3–4 times larger than values for corresponding homopolymers. It is obvious that the viscosity of each copolymer increases due to an increase in flexibility due to introduction of the MMA units in the chain, since little difference in molecular weights is found between homopolymers (16,000–15,000) and copolymers (10,000–12,000). |
