NVP接枝壳聚糖水凝胶的合成与溶胀性能

合成了N-乙烯基吡咯烷酮（NVP）接枝壳聚糖（CHI）水凝胶，讨论了NVP/CHI、引发剂、交联剂、聚合温度、乙酸浓度等因素对接枝率及凝胶溶胀性能的影响，NVP∶CHI为6时，接枝率达到300%以上. 溶胀温度、pH值、盐浓度等对凝胶溶胀性能的影响实验表明，凝胶表现出温度敏感性，在40 ℃出现最大平衡溶胀率，并观察到一级相转变;在中性或弱酸性介质中溶胀性能较好;与PVP凝胶相比，NVP接枝CHI凝胶表现出反聚电解质效应. 溶胀动力学研究表明，在溶胀前期，CHI含量较高时，凝胶趋向于非Fick溶胀，说明除了溶剂扩散外，凝胶网络链段弛豫、水分子与凝胶网络间及凝胶高分子链段间相互作用对凝胶溶胀性能的影响至关重要;CHI含量较高时则趋向于Fick溶胀.

Synthesis and swelling behavior of NVP grafted chitosan hydrogel

N-vinyl pyrrolidone(NVP) grafted chitosan(CHI) hydrogels were prepared.The influences of main factors such as mass ratio of NVP∶CHI, initiator content, crosslinking agent content, polymerization temperature and acetic acid concentration on the grafting ratio and swelling property of hydrogels were discussed.Grafting ratio was up to above 300% when mass ratio of NVP to CHI was about 6.The swelling behavior of the hydrogels was studied at different temperatures, pH values and NaCl concentration of swelling mediums.It was found that the swelling ratio of the hydrogels was high when pH value was about 7.Some hydrogels showed temperature sensitivity，had ultimate equilibrium swelling ratio at about 40 ℃ and the first grade phase transition was observed. NVP grafted CHI hydrogels showed anti-polyelectrolyte effect in NaCl solution.The swelling kinetics of hydrogels was investigated with the Fick model.It was suggested from the results that swelling belonged to the non-Fick model when CHI content was above 30% and it was influenced greatly by some other factors such as relaxation, contraction of hydrogel net, interaction between solute molecular and some groups on the polymer net, interaction between polymer chain,except free diffusion of water molecules while swelling belonged to the Fick model when CHI content was lower.