| 초록 |
Hyperbranched poly(ε-caprolactone)s (HPCLs) were synthesized to incorporate different lengths of linear segments consisted of 5, 10, and 20 ε-caprolactone (ε-CL) units, accordingly named as HPCL-5, -10, and -20, respectively. End-group analyses were performed on 1H NMR spectra of the three HPCLs, which provided information about the average number of ε-CL units incorporated in the AB2 macromonomers and thus the average number of AB2 macromonomers incorporated in the resulting HPCLs. Consequently, the absolute values of molecular weight (MW) for the HPCLs were calculated. SEC-MALLS was employed to measure absolute MW and MWD of HPCLs, of which data were in good agreement with those from 1H NMR end-group analyses. From SAXS, the radii of gyration of the HPCLs and their linear counterpart, poly(ε-CL) (LPCL) were determined from the initial slope of 1/I(q) vs. q curves, fit by Zimm scattering function. The ratio of mean-square radius of gyration of each HPCL to that of LPCL, termed as branching ratio, resulted in the relative degree of branching (DB) for individual HPCLs. As the length of linear segments decreased, the more highly branched polymers were obtained, i.e., in the order of HPCL-5, 10, and 20 from higher to lower DB. The Tm of HPCLs was lower than that of LPCL, and decreased with increase in the DB, while Td10 of HPCLs was shown to be higher than that of LPCL, becoming higher as the DB increased. |
