首先以辛酸亚锡为催化剂, 消旋丙交酯(D,L-LA)与壳聚糖(CS)为原料, 在超临界二氧化碳(scCO2)中合成了以PDLLA为基体、CS--g--PDLLA共聚物为填充相的共混体系, 然后通过scCO2萃取/致孔技术原位构建了CS--g--PDLLA/PDLLA多孔支架材料。对共聚物的结构与性能、PDLLA的分子量进行了表征, 对多孔支架的结构形态进行观察, 并对支架材料的孔隙率进行测定。结果表明, 以scCO2为反应介质, 成功合成了PDLLA均聚物和CS--g--PDLLA共聚物，同时, 通过改变原料比、反应温度和时间能在一定程度上调控共聚物的组成与PDLLA的分子量以及产率。CS--g--PDLLA/PDLLA多孔支架材料的孔洞分布均匀, 孔洞连通性较好, 孔内壁具有非常独特的长沟壑形微观结构, 且CS--g--PDLLA填充相与PDLLA基体的相容性良好; 减压速率和处理温度对多孔支架的结构形态有一定影响。
Poly(D,L-lactide) (PDLLA) and chitosan--graft--poly(D,L-lactide) (CS--g--PDLLA) copolymer were synthesized firstly in supercritical carbon dioxide (scCO2) using D,L-lactide and chitosan as raw materials and tin (II) 2--ethylhexanoate as catalyst. Then, CS--g--PDLLA/PDLLA porous scaffolds were prepared in-situ by scCO2 extraction/pore forming technologies. The structure and properties of the graft copolymers and the molecular weight of PDLLA were characterized. The porous structure morphology of the scaffolds was observed and the porosity of the scaffolds was measured. The results showed that PDLLA and CS--g--PDLLA were synthesised successfully in scCO2 fluid, and the structure of the graft copolymer, the molecular weight and yield of PDLLA can be adjusted by controlling the feeding ratio, reaction temperature and time. Uniformly distributed and highly interconnected pore structures with a unique long gully type microstructure were formed in the CS--g--PDLLA/PDLLA scaffolds, and the compatibility of CS--g--PDLLA with PDLLA was good. Moreover, the depressurization rate and temperature have effects on the structure morphology of the porous scaffolds.
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