A novel pH—sensitive hydrogel was obtained by copolymerization of telechelic poly(1

3-dioxolane) (PDXL) with acrylic acid (AA)．The synthesis and swelling properties of networks were discussed．The networks can swell in water and organic solvents．It can swell faster and has higher equilibrium swelling degree in water of pH＞7 than in that of pH＜7．It is due to the easier ionization of—COOH groups in basic solution．In addition to the pH sensitivity

the hydrogels also have special characteristics：the networks containing polyacetal segments (PDXL) can degrade by acid in different solvents．Degraded residues including DXL and few other heterocycles were determined by IR and GC-MS analysis．The result showed that after degradation

linear PDXL segments were broken and became closed cycles in different ways．The intelligent hydrogel prepared has potentials in biosystems such as intelligent drug release systems．