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

Abstract

Using 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP) as cyclic initiator 1:1 copolymerizations of ε-caprolactone (ε-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 identical indicating the absence of transesterification during the synthesis at 230°C. However, the properties of the LC-phase above 200–210°C did not completely agree with the data reported for the homopolyester in the literature (which are themselves inconsistent).

Keywords:

• Macrocyclic Polymerization
• ε-Caprolactone
• δ-Valerolactone
• Ring-Opening Polymerization
• Multiblock Copolyesters
• Smectic Mesophases

Acknowledgments