RING STRAIN AND POLYMERIZABILITY OF CYCLIC ESTERS

Ring strain is one of the most important factors affecting the polymer izability of a cyclic monomer. In this work, the ring strains in gamma -butyrolactone, delta-valerolactone and epsilon-caprolactone were infe rred on the basis of infrared and Raman spectroscopy data. The thermod ynamic factors influencing the ability to polymerize of these three la ctones and other cyclic diesters in the glycolide series were studied using molecular modelling methods. The ring strain was observed to inc rease with increasing ring size for the three lactones studied increas ing the thermodynamic scope for these monomers to polymerize. For the glycolide series, ring strain and polymerizability decreased with incr easing substitution on the alpha-carbon. (C) 1998 Elsevier Science Ltd . ALI rights reserved.