Swelling Behavior of pH-Sensitive Hydrogels Containing Degradable Poly(1,3-dioxolane) Segments

pH-sensitive hydrogels were obtained by radical copolymerization of telechelic poly(1,3-dioxolane) (PDXLDA) with acrylic acid (AA). The copolymer networks of Poly(AA-block-DXL) showed pH sensitivity due to –COOH groups. They were insoluble in any solvents, but swelled in water or good solvents. The swelling behavior in both water and organic solvents is composition -dependent. The property that the hydrogel can swell in both water and organic solvents can be explained by a microphase-separated bicontinuous structure. The networks containing polyacetal segments (polyDXL) can be decrosslinked under acidic condition due to the low ceiling temperature of polyDXL. The networks structure, swelling behavior and degradation were characterized by Fourier transform infrared, differential scanning calorimetry, GC-MS analysis and swelling data.