Control of Thermogelation Properties of Hydrophobically-Modified Methylcellulose

摘要

Aqueous solutions that undergo reversible thermosensitive gelation around body temperature were developed based on hydrophobically-modi-fied methyl cellulose(HMMC).The approach involved HMMC as the main component of aqueous compositions to provide a system with fast gelling properties,which has not been accomplished with aqueous solutions of unmodified methyl cellulose(MC).MC was modified with the stearyl group as a hydropho-bic modifier by controlling the degree of modification.The gelation rate of aqueous solutions containing identical amounts of HMMC and NaCl increased as the temperature increased.The HMMC solutions gelled at a fixed temperature and concentration range,while the unmodified MC solutions did not show sol-to-gel transition.In addition,HMMC solutions exhibited much faster gelation than MC solutions at given polymer and NaCl concentrations.The HMMC/NaCl solutions exhibited the reversible gel-to-sol transition upon cooling below 25deg C.The rate of sol-to-gel transition at body temperature,and the reversible gel-to-sol transition at room temperature,were modulated by adjusting the concentration of HMMC and NaCl,respectively.The HMMC/ NaCl compositions provided a simple system for accurate control of the thermogelling temperature and the thermogelation rates.