Design of 1,3-Cyclohexadiene Polymers Synthesized by the Living Anionic Polymerization and Their Properties

Kimio IMAIZUMI* and Itaru NATORI†

Specialty Chemicals Research and Development Center, Kawasaki Division, Asahi ChemicalIndustry Co., Ltd.; 1-3-1 Yakoh Kawasaki-ku, Kawasaki-shi 210-0863 Japan
† Corporate Research and Development Administration, Groval Technology Section (London), Asahi Chemical Industry Co., Ltd.; 22 the Courtyards, Hatters Lane, Cfoxley Business Park Watford, Herts WDI 8YH, United Kingdom

The organometallic system consisting of alkyllithium and amine as an initiator for the polymerization of 1,3-cyclohexadiene (CHD) was studied. As a specific system consisting of butyllithium(n-BuLi) and N,N,N',N'-tetramethyl-1,2-ethanediamine (TMEDA) was found to be particularly active as an initiator of living anionic polymerization of CHD. Poly(1,3-cyclohexadiene) (PCHD) yielded had high molecular weight with narrow molecular weight dispersity. PCHD had two kind of microstructure in the main chain (1,2-unit and 1,4-unit), the molar ratio of which was determined by measuring 2D-NMR. The glass transition temperature of PCHD was found to rise with an increase in the ratio of 1,2-unit to 1,4-unit. Hydrogenated poly(1,3-cyclohexadiene), as it was called, polycyclohexene showed higher heat resistance and modulus than those of PCHD. The designs of poly(1,3-cyclohexadiene-block-butadiene-block-1,3-cyclohexadiene), P(CHD-block-Bd-block-CHD), triblock copolymers and the effects of microphase structures on the mechanical and thermal properties of several triblock copolymers were also reported. Heat resistance of the completely hydrogenated triblock copolymers was found to be higher than that of the unhydrogenated triblock copolymers, nevertheless lower mechanical strength than those of the unhydrogenated triblock copolymers with the same weight ratio of CHD to butadiene. To clarify the relationship between the higher order structures of those triblock copolymers and their properties, the degree of compatibility between the polycyclohexene (PCHE) block sequence and the poly(ethylene/butylene) (PEB) block sequence was observed and it found to be increased. The micro phase separation structure of those triblock copolymers was considered to become minute by hydrogenation of P(CHD-block-Bd-block-CHD).


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