Molecular modelling of ring-opening polymerisation of lactamimide-containing macrocyclic esters

The molecular modelling of anionic (MeO- initiated) and cationic (H+ initia ted) polymerisation of lactamimide-containing macrocyclic esters has been c arried our at PM3 and HF/3-21G levels of theory. It was found that it is st rain release that drives the polymerisation of these macrocycles. Most like ly that entropy gain on the ring-opening can not compensate entropy loss on polymer formation due to the relative rigidity of cyclic molecules. Methan olate initiated anionic polymerisation will not lead to high molecular weig ht product due to the side reactions involving the attack of growing anioni c species at carbonyls of lactamimide moiety, while the cationic polymerisa tion should proceed smoothly provided that polymerisation temperature is le ss than ceiling temperature.