聚乳酸蜂窝状多孔膜的形成与控制

以单一组分聚L-乳酸(PLLA)为成膜材料,利用水辅助法制备了聚乳酸(PLLA)蜂窝状多孔膜.利用扫描电镜(SEM)和原子力显微镜(AFM)观察多孔膜形貌.研究溶剂、溶液浓度、环境温度和湿度等因素对所成多孔膜结构的影响.实验结果表明,高湿度环境和具有一定浓度的聚合物溶液是制备蜂窝状多孔膜的必要条件.溶剂的挥发性是形成规整蜂窝状孔结构的关键因素.环境相对湿度由43%增加到91%,PLLA多孔膜的孔径由(1.75±0.24)μm增加到(11.50±1.43)μm,且孔呈现六边形的蜂窝状结构.扫描电镜断面和AFM表明:膜表面形成了深度约为1.8μm的单层孔结构.通过控制溶液浓度、环境温度和湿度等因素来控制膜的表面形貌及其所成蜂窝状孔的大小.最佳的成膜条件为溶剂CH2Cl2,湿度75%RH,温度34℃,浓度3 wt%.讨论了蜂窝状多孔膜的形成机理.

FABRICATION AND CONTROL OF POLYLACTIDE HONEYCOMB POROUS FILMS BY BREATH FIGURE METHOD

A well-ordered honeycomb structure of single component polylactide(PLLA) films was prepared via breath figure method.Their pore structure and morphology were characterized by scanning electron microscopy(SEM) and atomic force microscopy(AFM).The effect of factors,such as solvent type,PLLA concentration,temperature,relative humidity and spreading volume,on the pore patterns was investigated.The results showed that high humidity and optimal PLLA concentrations were necessary for preparing the honeycomb porous PLLA films.Compared to CHCl3,CH2Cl2 with higher vapor pressure favored the formation of more regular honeycomb porous structure.The pore size of PLLA films increased from(1.75±0.24) μm to(11.50±1.43) μm with increasing relative humidity from 43% to 91%.Instead of the formation of three-dimensional honeycomb pore structure,a single layer pores with depth of ca.1.8 μm was formed on the film surface.The optimum preparation conditions for the honeycomb structured PLLA films were:solvent CH2Cl2,relative humidity 75%,temperature 34℃,spreading volume 80 μL and PLLA concentration 3 wt%.A possible mechanism was proposed.Due to the homeycomb porous structure,this special PLLA films would be in favor of cell adhesion and growth.Thus they are expected to be a very promising tissue engineering scaffold.