Synthesis, characterization and reversible transport of thermo-sensitive carboxyl methyl dextran/poly (N-isopropylacrylamide) hydrogel

A thermo-sensitive hydrogel based on a copolymer of carboxyl methyl dextran (CM-dextran) and poly(N-isopropylacrylamide)-NH2 (PNIPAAm-NH2) has been synthesised using 1-Ethyl-(3-3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). FTIR spectra supported the formation of gel network. The responsive properties of the hydrogels were characterized in terms of structural changes using SEM, and the effect of temperature on their balance of hydrophobicity using turbidity measurements. Composite pore filled membranes formed by impregnating glass fiber filters disc with the polymer mixture prior to gelation were used to determine the transport changes in response to temperature, using riboflavin (MW: 376), reactive red 120 (MW: 1470) and lysozyme (MW: 14300). Clear correlation was found between changes in morphology, turbidity and hydrogel transport as the temperature was increased from 24 to 37 °C. The transport profile of reactive red 120 through hydrogel composite membrane with thermal cycling shows the transport of reactive red 120 acted as reversible change in response to temperature.