Liquid crystalline features of optically active poly(methylene-l,3- cyclopentane)

Poly(methylene-1,3-cyclopentane) (PMCP), which is composed with alternating linkage of methylene and 1,3-cyclopentane unit, was synthesized by cyclization polymerization of 1,5-hexadiene (HD) with various metallocene catalysts. The optically active PMCP samples were prepared by cyclization polymerization of HD with an optically active zirconocene catalyst, [(+)-(S,S)-ethylene-1,2- bis(n⁵-4,5,6,7-tetrahydro-1-indenyl)- 1,1'-bi-2-naphtholate], combined with methylaluminoxane (MAO) as a cocatalyst in the presence of triethylaluminum (A1Et₃) as a chain transfer reagent to control the molecular weight in toluene at room temperature. The PMCP samples obtained with the optically active zirconocene catalyst show optical rotation in chloroform solution. The M_nS of the PMCP samples were measured by gel-permeation chromatography and relatively calibrated with standard polystyrene samples. The birefringent texture of PMCP with relatively high molecular weight showed the fingerprint texture indicating cholesteric liquid crystal.