Synthesis and characterization of segmented copolymers of aromatic polyether sulphone and a thermotropic liquid crystalline polyester

The bulk copolycondensation of α,ω-di(acetoxy) aromatic polyether sulphone (PSU) with chlorohydroquinone diacetate and trans-1,4-cyclohexanedicarboxylic acid to produce segmented copolymers of amorphous PSU and thermotropic liquid crystalline poly(chloro-1,4-phenylene-trans-cyclohexane dicarboxylate) (PCPTCD) is described. For PSU with M̄n = 1400, true block copolymers were formed with PSU segments incorporated into the thermotropic liquid crystalline polyester structure. For PSU with M̄n ≥ 2300, however, the products were not true block copolymers, but rather blends of PSU chain extended by short PCPTCD segments and PCPTCD homopolymer. This result can be explained by an ‘apparent’ molecular weight dependent reactivity of the α,ω-di(acetoxy)PSU chain ends, which is in fact the consequence of the immiscibility of the amorphous and liquid crystalline phases.