Thermoreversible gelation of methylcellulose and pluronics in water.
Date of Issue2007
School of Mechanical and Aerospace Engineering
The thermoreversible gelation of methylcellulose (MC) and Pruronics [polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PEO-PPO)] in aqueous solutions have been systematically studied. The effects of temperature, polymer molecular weight (Mw), surfactant (sodium dodecyl sulphate, SDS), and magnetic field on the thermoreversible gelation of aqueous solutions of MC have been examined. It is found that the thermoreversibility of the aqueous solutions of MC is independent of Mw. SDS is observed to alter the gelation temperatures: at SDS concentrations below 6 mM the gelation occurs earlier, while at higher concentrations of SDS the gelation is delayed. SDS also alters the pattern of gelation when its concentration is greater than 8 mM. Furthermore, the binding interactions between MC and SDS, studied by isothermal titration calorimetry, are found to be strongly affected by temperature. The effects of a PPO-PEO-PPO triblock copolymer (25R4) on the thermoreversible micellization and gelation of F108 have been investigated. It is observed that 25R4 could participate in the micellization and lower the critical micellization temperature (CMT) of F108, but delays the gelation F108 significantly at high 25R4/F108 molar ratios.
Nanyang Technological University