Abstract
The heat of polymerization for ring-opening polymerization is affected by the following: (1) angle strain, which is very important for the three-and four-membered rings (i.e., those rings that have the greatest angle strain), (2) conformational strain (crowding of eclipsed adjacent hydrogen atoms) and transannular strain (strain and crowding of hydrogen atoms across the ring); and (3) steric effect of side group.