Synthesis and characterization of pH-sensitive networks containing degradable poly(1,3-dioxolane) segments

pH-sensitive networks were obtained by radical copolymerization of telechellic poly(1,3-dioxolane) (PDXLDA) with acrylic acid (AA). PDXLDA was synthesized by acrylation of the corresponding dihydroxylated polyacetal (polyDXL) with AA in pyridine. The copolymer networks of poly(AA-b-DXL) showed pH sensitivity due to -COOH groups, which are insoluble in any solvents, but can swell in water or good solvents. The swelling behavior is closely related to the solvents and is composition-dependent. The networks containing polyDXL segments can be decrosslinked under acidic conditions due to the low ceiling temperature of polyDXL. After degradation, the linear segments of polyDXL became cycled molecules. The networks' structure, swelling behavior, and degradation were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, GC-MS analysis, and swelling data. This kind of material can be potentially used in biosystems, such as in intelligent drug-delivery systems. (C) 2002 John Wiley & Sons, Inc.