Gelation of aqueous solutions of diblock copolymers of ethylene oxide and D,L-lactide

✍ Scribed by Siriporn Tanodekaew; John Godward; Frank Heatley; Colin Booth

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 527 KB
• Volume: 198
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1997.021981105

✦ Synopsis

The thermally-reversible gelation of aqueous solutions of diblock copolymers of ethylene oxide (E) and tw-lactide (L), E42L12, E3*L16, E39L20, E41L26. E7,LI4 and E77L26, has been studied using gelation temperature measurements, polarised light microscopy and NMR spectroscopy. The solutions showed a high temperature gel-sol boundary but no low temperature gel-sol boundary. Polarised light microscopy showed that the gel phase was isotropic, and the dependence of sol-gel temperature on concentration suggested that the micelles were prolate ellipsoidal, rather then spherical. NMR spectroscopy showed that below ca. 60 "C, the L block in the micelle core became highly restricted. It is tentatively suggested that this is due to the L blocks forming an ordered structure, thus explaining the absence of a low temperature gel-sol boundary.