| 학회 | 한국고분자학회 |
| 학술대회 | 2005년 봄 (04/14 ~ 04/15, 전경련회관) |
| 권호 | 30권 1호, p.16 |
| 발표분야 | 나노구조형 고분자 분광분석 |
| 제목 | Cooperative Chain Mobility of Hyperbranched Poly(ε-caprolactone)s with Nanoscopic Architectural Variation Characterized by Photon Correlation Spectroscopy |
| 초록 | Photon correlation spectroscopy (PCS) has been extensively utilized to study molecular dynamics in both the concentrated polymer solution and the bulk amorphous polymers due to its wide frequency capability, rapid measurement time, and high sensitivity.1 Molecular motions of the polymeric materials characterized by PCS are associated with either the local segmental relaxation near and above Tg due to the microscale fluctuation of the density or the cooperative chain diffusion due to the fluctuation of the concentration.2,3 However, in case of characterizing the segmental motion, the PCS technique requires a sample of good optical quality, and thus it is not immediately applicable to any bulk polymers. In the present study, the cooperative chain mobility of the hyperbranched poly(ε-caprolactone)s (HPCLs) as well as that of the linear poly(ε-caprolactone) (LPCL) in their concentrated solutions in tetrahydrofuran (Cpolymer=1.0 g/mL) were systematically characterized using PCS technique. The results were interpreted in conjunction with the nanoscopic architectural characteristics of the HPCLs that are the different lengths of the linear segments and the different branching structures. The HPCLs were synthesized to incorporate the different lengths of the linear segments consisting of 5, 10, and 20 ε-caprolactone units on their backbone chains, and thereby referred to as HPCL–5, –10, and –20, respectively. The relative degrees of branching (DB) of the HPCLs, which is obtained by branching ratio values, were found to be in the order of HPCL–5 ＞ –10 ＞ –20. From the narrow distribution of relaxation times and q2-dependence of relaxation rates, it was verified that the relaxation processes concerned in this study were due to the concentration fluctuations caused by cooperative chain diffusion. The correlation times, τc’s, and the corresponding apparent activation energies, Ea’s, which provide a direct evaluation for the molecular mobility, were determined by non-linear curve fittings of measured correlation functions with Kohlrausch-Williams-Watts (KWW) equation (Eq. 1 and 2)4,5 and by the Arrhenius fits of temperature dependences of τc’s (Eq. 3), respectively. ＜Eq. 1＞ ＜Eq. 2＞ |
| 저자 | 최정수, 곽승엽 |
| 소속 | 서울대 |
| 키워드 | Hyperbranched polymer; photon correlation motion; cooperative chain mobility |
