Thermal gelation of Pluronic F-127 in ethylene glycol as non-aqueous solvent

Abstract

Solutions of Pluronic F-127 in ethylene glycol were prepared at different concentrations (10–25%, w/w), and the behaviour of the samples during heating to 150°C was observed. During heating, the solubility of Pluronic in ethylene glycol increased, but no gel formation was observed. However, gel formation in the sample containing 25% Pluronic F-127 was observed near 50°C during cooling, and all the samples become solid upon cooling to 25°C. Fourier transform infrared spectroscopy, differential scanning calorimetry and optical microscopy were performed to analyse the gel formed by 25% Pluronic F-127 in ethylene glycol, and it was found that the gel formation in ethylene glycol was different from the gel formation of Pluronic in water as the latter gels are crystalline in nature whereas the former are amorphous. Hydrogen bonding was considered to be the main factor behind the gel formation.