基于F127的原子转移自由基超分子水凝胶的制备及性能

Preparation and Characterization of Supramolecular Structured Hydrogels Using F127 Through Atom Transfer Radical Polymerization

由α-环糊精或2-溴异丁酰溴改性的α-环糊精与溴丙酰溴封端的F127自组装形成的聚准轮烷（PPRs）为大分子引发剂,通过原子转移自由基聚合（ATRP）,以聚乙二醇二丙烯酸酯（PEGDA）为桥键单元,2-甲基丙烯酸羟乙酯（HEMA）为调节剂制备了交联网络可调的热敏性超分子结构水凝胶。红外光谱（FT-IR）、核磁共振（1H-NMR）和X射线衍射（WAXD）对改性和包合物进行了表征。引入α-环糊精降低了凝胶溶胀度,而改性α-环糊精体系可以提高溶胀度。随PEGDA含量的增加,凝胶溶胀度提高,但随HEMA含量增加而降低。在20℃~50℃范围内,引入聚甲基丙烯酸羟乙酯链降低了凝胶的温度响应性,而由改性α-环糊精线穿的PPRs制备的水凝胶显示最好的热敏性和良好的力学强度。水凝胶的热敏性机理是由于共聚物中PPO链段的聚集形成。

Thermosensitive supramolecular hydrogels with tunable crosslinking networks using polypseudo-rotaxanes（PPRs） as macroinitiator,polyethylene glycol diacrylate（PEGDA） as crosslinker and 2-hydroxyethyl methacrylate（HEMA） were prepared by atom transfer radical polymerization（ATRP） in water.PPRs were prepared by supramolecular self-assembly of α-cyclodextrin or 2-bromoisobutyryl bromide modified α-cyclodextrin（α-CD-BIBB） and F127 with bromopropionyl bromide terminated.The products and PPRs were characterized by FT-IR and 1H-NMR.Wide angle X-ray diffraction demonstrates that PPRs have crystal structure.The swelling ratio（SR） decreases with introduction of α-CD,increases with introduction of α-CD-BIBBs.With increase of HEMA concentration,SR decreases,but with increase of PEGDA concentration,SR increases.Between 20 ℃ and 50 ℃,the introduction of PHEMA chains decreases the temperature responsiveness of networks,but the hydrogels prepared with α-CD-BIBBs threading onto the F127 chains show the best thermo-sensitivity and well chemical strength.The thermosensitive mechanism of hydrogels is related to the aggregation of poly（propylene oxide）（PPO） blocks in copolymer.