Confined Crystallization Behaviors of Cross-linked Comb-like Copolymers

Cross-linked PEG-based copolymers were obtained via synthesis of polyethylene glycol （PEG） and methoxy polyethylene glycol （MPEG） by the bridging and/or cross-linking agent of 2,4-tolylene diisocyanate （TDI） and/or hexamethylene-l,6-diisocyanate homopolymer （HDI trimer）. The effects on the crystallization behaviors of the samples could be found with the changes in molecular weight of MC-PEG and molecular weight of SC-PEG in certain cross-linked density. It is revealed that the samples appear not to crystallize when the molecular weight of MC-PEG and SC-PEG are 1000 g/mol or less than that. The samples begin to crystallize when the molecular weight of either MC-PEG or SC-PEG reaches 2000 g/mol. The crystallinity of crystallized MC-PEG decreases with the increasing molecular weight of uncrystallized SC-PEG and the crystallinity of crystallized SC-PEG declines with the rise of molecular weight of uncrystallizable MC-PEG. The chains of SC-PEG （M_n = 2000 g/mol） can fold and align easilier than those of MC-PEG （M_n = 2000 g/mol）, when the content of PEG is the same.