MACROCYCLES. 9. SMECTIC MULTIBLOCK COPOLYESTERS VIA MACROCYCLIC POLYMERIZATION OF δ-VALEROLACTONE AND ε-CAPROLACTONE

Using 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP) as cyclic initiator 1:1 copolymerizations of e-caprolactone (e-CL) and δ-valerolactone (δ-VC) were conducted in bulk at 80°C. A nearly equimolar incorporation and a random sequence were found by NMR spectroscopy and crystallization below 20°C was detected by DSC measurements. In a second series of experiments, the in situ formed macrocyclic copolyesters were reacted with an excess of sebacoyl chloride and after addition of silylated 4,4′,-dihydroxybiphenyl copolycondensations were performed in bulk at 230°C. These copolycondensations proceeded satisfactorily without significant transesterification and despite a biphasic character of the melt. This biphasic character resulted from the formation of a smectic LC-phase by the 4,4′-dioxybiphenyl sebacate blocks. For comparison a homopolyester was prepared from sebacoyl chloride and silylated 4,4′-dihydroxybiphenyl. The thermal properties of this homopolyester and of the LC-blocks in the copolyester were nearly i...