Peng Zou and Lei Nie contributed to the work equally and should be regarded as co-first authors.
Synthesis, micellization and gelation of temperature-responsive star-shaped block copolymers
Article first published online: 30 JAN 2013
Copyright © 2013 John Wiley & Sons, Ltd.
Polymers for Advanced Technologies
Volume 24, Issue 5, pages 460–465, May 2013
How to Cite
Zou, P., Nie, L., Feng, S. and Suo, J. (2013), Synthesis, micellization and gelation of temperature-responsive star-shaped block copolymers. Polym. Adv. Technol., 24: 460–465. doi: 10.1002/pat.3104
- Issue published online: 16 APR 2013
- Article first published online: 30 JAN 2013
- Manuscript Accepted: 3 DEC 2012
- Manuscript Revised: 29 NOV 2012
- Manuscript Received: 6 JUN 2012
- star-shaped block copolymers;
- sol–gel transition
A series of amphiphilic temperature-responsive star-shaped poly(D,L-lactic-co-glycolic acid)-b-methoxy poly(ethylene glycol) (PLGA-mPEG) block copolymers with different arm numbers were synthesized via the arm-first method. Gel permeation chromatography data confirmed that star-shaped PLGA-mPEG copolymers had narrow polydispersity index, indicating the successful formation of star-shaped block copolymers. Indirectly, the 1H NMR spectra in two kinds of solvents and dye solubilization method had confirmed the formation of core-shell micelles. Further, core-shell micelles with sizes of about 30–50 nm were directly observed by transmission electron microscopy. Subsequently, the micellar sizes and distributions as a function of concentrations and temperature were measured. At various copolymer concentrations, individual micelles with size of 20–40 nm and grouped micelles with size of 600–700 nm were found. Micellar mechanism of star-shaped block copolymers in aqueous solution was simultaneously discussed. In addition, sol–gel transition of star-shaped block copolymers in water was also investigated via the inverting test method. The critical gel temperature (CGT) and critical gel concentration (CGC) values of two-arm, three-arm and four-arm copolymer solutions were markedly higher than ones of one-arm copolymer. Moreover, the same CGC values of copolymer solution with different molecular weight and the same arm composition were ~15 wt %, and CGT values increased from ~38 to ~47°C with increasing arm numbers. Finally, the temperature-dependent micellar packing gelation mechanism of star-shaped block copolymer was schematically illustrated. Copyright © 2013 John Wiley & Sons, Ltd.