中文摘要：

制备异氰酸酯基封端的一系列生物降解型交联剂，研究了反应条件对产物的影响．进一步使用此生物降解交联剂制备了交联壳聚糖多孔材料，研究了所得材料的性能．结果表明，当反应温度为70℃，反应时间为3h，投料比为2．2：1时，交联剂中N00的质量分数为4．64％，浓度为50％的THF溶液粘度为500MPa·s，其性能适宜交联壳聚糖．随着-NCo／-NH2摩尔比的增加，交联壳聚糖多孔材料表面形貌呈现出从开孔结构逐渐过渡为闭孔结构的状态，保水率基本为未交联材料的3倍，其最大拉伸强度和弹性模量均有较大提高，最大为0．17GPa和1．4GPa．新型交联剂由于具有可降解的PEG～b-PLA链段，不仅保证了交联壳聚糖的降解性能，改善其亲水性，也提高了材料的力学性能．

英文摘要：

A novel biodegradable cross-linker was synthesized from 4,4-tolyene diisocyanate （4,4- MDI） and poly （lactic acid）-poly （ethylene glycol）-poly （lactic acid） （PLA-PEG-PLA） oligomer inter- mediate. The molecular mass of oligomer was measured by GPC. Chemical structures of oligomer and cross-linker were characterized by FT-IR and ^1H MNR. The results showed the best reaction condition was 70 ℃, 3 h and feed molar ratio 2.2：1, under the conditions of which it came out 4.64% of NCO, and 500 MPa.s of the solution viscosity （50% solid content in THF）. Thermal cross-linking of chitosan as cast, dried films was investigated by varying the -NCO/-NH2 ratio from 0.0 to 0.8. The tests showed that chitosan was cross-linked in a concentration-dependent manner under 60 ℃ for 24 h. With -NCO/- NH2 ratio increasing, its morphological microstructure was converted from opening pores to closing pores, water-uptake rate was tripled in cross-linked chitosan than in uncross-linked, the most tensile strength went up to 0.17 GPa, and elastic modulus to 1.4 GPa. The cross-linker with degradable PEG-b-PLA segments can retain the degradable property of cross-linked chitosan, and improve its hydrophilic and mechanical properties.