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) mu m to (11.50 +/- 1.43) mu m 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 mu m was formed on the film surface. The optimum preparation conditions for the honeycomb structured PLLA films were: solvent CH2Cl2, relative humidity 75%, temperature 34 degrees C, spreading volume 80 mu L 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.