Thermogelling multiblock poloxamer aqueous solutions with closed-loop sol-gel-sol transitions upon increasing pH

A multiblock poloxamer (MBP) with carboxylic acid was designed and the gelation characteristics were investigated as a function of pH and temperature. The synthetic route of the MBP showed that two moles of carboxylic acid groups were generated by one mole of terephthalic anhydride in the coupling reactions. The increased hydrophilicity of the ionized carboxylic acid groups solubilized the MBP at pH 7.4. The results show that the viscosity of the gel steadily increases as the pH increases from pH 2-8 at the same concentration.