Unique Isodimorphism of Poly(decamethylene succinate-ran-decamethylene fumarate): Large Pseudoeutectic Region and Fantastic Crystallization/Melting Behavior

摘要

Poly(decamethylene succinate-ran-decamethy-lene fumarate)s (PDSFs) were synthesized, and their structure and crystallization behavior were systematically studied. All polyesters possess high crystallizability irrespective of composition and display the widest pseudoeutectic region that has been reported to date. Nevertheless, both melting point- and crystallization temperature-composition relationships demonstrate PDSFs display off-V-shaped behavior, indicating particular pseudoeutectic behavior. PDSF57 and PDSF37 located in the pseudoeutectic region are studied in detail. DF-rich crystals form first due to the assembly of fumarate-related preordered structure in the PDSF57 me then DS-rich crystals appear through plausible epitaxial crystallization. PDSF37 is proven to be located in the boundary of the pseudoeutectic region. DF-rich ordered structure forms first but cannot crystallize itself, which plays the role of the "soft epitaxial" substrate for DS-rich crystal formation; meanwhile, the DF-rich form crystallizes with the assistance of DS-rich crystals. The particular crystallization process of PDSF37 induces tightly attached structures between the two types of crystals and results in a fantastic and abrupt melting point jump.