Synthesis and liquid crystalline properties of new amide-modified poly(1,4-cyclohexanedimethylene terephthalate)

Abstract

New series of cycloaliphatic poly(ester-amide)s, poly(1,4-cyclohexanedime-thyleneterephthalate-co-1,3-cyclohexanedimethylene terephthalamide), were synthesized through solution polymerization route. The compositions of ester/amide units in the copolymers were varied from 0 to 100% by varying the amount of 1,4-cyclohexanedimethanol and 1,3-cyclohexanebis(methylamine) in the feed. The structures of the polymers were confirmed by NMR and FTIR, and the molecular weights were determined by inherent viscosity. The composition analysis by NMR reveals that the reactivity of the diamine toward the acid chlorides is lowered than that of diol, which results in the formation of more ester content in the poly (ester-amides). The thermal analysis indicate that the new poly(ester-amide)s having less than 10 mol % of amide linkages are thermotropic liquid crystalline from 200 to 250 degrees C and a thread like nematic phases are observed under the polarizing microscope. WXRD studies suggest that the liquid crystalline domains promote the nucleation process in the polyester chains and increases the percent crystallinity of the poly(ester-amide)s. The glass transition temperature of the copolymers initially increases with increase in amide units because of the presence of nematic phases and subsequently follows the Flory-Fox behavior.