Browse

Phase Transition of the PLGA-g-PEG Copolymer Aqueous Solutions

Cited 62 time in Web of Science Cited 61 time in Scopus
Authors
Jeong, Byeongmoon; Windisch, Charles F. Jr.; Park, Moon Jeong; Sohn, Youn Soo; Gutowska, Anna; Char, Kookheon
Issue Date
2003-08-22
Publisher
American Chemical Society
Citation
J. Phys. Chem. B 2003, 107, 10032
Abstract
The aqueous solution of poly(lactic acid-co-glycolic acid)-g-poly(ethylene glycol) becomes a gel as the temperature increases. The sol-to-gel transition temperature can be controlled from 15 to 45 °C by varying the number of poly(ethylene glycol) grafts and the composition of the polymer. In addition, hysteresis between heating and cooling cycles could be controlled by adding poly(ethylene glycol) with different molecular weights as an additive. To prove the hypothesis of micellar aggregation for the sol-to-gel transition and the change in hydration status for the gel-to-sol transition, several experiments were performed. Small-angle neutron scattering and Raman spectroscopy sensitively detected the sol-to-gel transition, because it involves aggregation of the scattering particle of micelles. IR and 13C NMR showed that little change in hydration status is involved during the sol-to-gel transition, whereas significant change in hydration status is involved in the gel-to-sol transition. The intrinsic viscosity of the PEG showed that more significant dehydration can occur when PEG is attached to the hydrophobic group. On the basis of the experiments above, PEG dehydration is the major driving force for the phase change of the PLGA-g-PEG aqueous solution. At the sol-to-gel transition temperature, partial dehydration of the PEG induces the micellar aggregation while keeping the core−shell structure. However, at the gel-to-sol transition, dehydration of the PEG is so significant that the core−shell structure is broken and macroscopic phase separation occurs. These phenomena were associated with changes in the carbonyl stretching and ether bending modes in the IR spectra.
ISSN
1520-6106 (print)
1520-5207 (online)
Language
English
URI
http://hdl.handle.net/10371/5807
DOI
https://doi.org/10.1021/jp027339n
Files in This Item:
There are no files associated with this item.
Appears in Collections:
College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Chemical and Biological Engineering (화학생물공학부)Journal Papers (저널논문_화학생물공학부)
  • mendeley

Items in S-Space are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse