Abstract
Two calixarene derivatives (2a, 2b) have been synthesized and used as macro,initiators to prepare starshaped poly(ε,caprolactone)s (SPCLs) via controlled ringopening polymerization of ε,caprolactone in the presence of yttrium tris(2,6,di,tert,butyl,4,methylphenolate) [Y (DBMP)3]. The molecular weight of SPCLs was characterized by end group 1H,NMR analyses and size,exclusion chromatography (SEC). The results indicate that SPCLs based on a calix[4]arene derivative (2a) are well,defined four,arm star polymers with reasonably narrow molecular weight distributions in the given molecular weight range,while SPCLs based on a calix[6]arene derivative (2b) are star polymers with not so defined structures. Differential scanning calorimetry (DSC) analyses suggest that the maximal melting point, the crystallization temperature and the degree of crystallinity of SPCLs increases with the increasing molecular weight and are lower than those of the liner poly(ε,caprolactone) (LPCL) counterpart. Furthermore,polarized optical microscopy (POM) indicates that SPCL exhibits irregular spherulites with poor morphology and slower crystallization rate, whereas LPCL shows fast crystallization rate and good spherulitic morphology.
基金项目
国家自然科学基金(20434020)
国家重点基础研究发展计划(973计划)(G2005CB623802)
浙江省科技厅科技计划(2006A-1001-17)
NETL
NSTL
万方数据