Preparation of nanocellular foams from polycarbonate/poly(lactic acid) blend by using supercritical carbon dioxide

Polymer foams with nanoscale cell structure were prepared from polycarbonate (PC)/poly (lactic acid) (PLA) blends. The immiscible blends with PLA as the dispersed phase were foamed through using batch foaming process and CO2 as the physical foaming agent. Nanoscale cells emerged in both PLA domain and PC matrix of blend with 25 wt.% PLA content under an appropriate foaming condition. In the PLA domain, the formation of nanoscale pores was related to the confined foaming, blend and the crystallinity of PLA component. A transition from closed nanoscale cells to open nanoscale cells emerging in the PLA domain was in connection with the foaming condition. In the PC matrix, the cell property of the nanoscale cells was affected by the PLA phase. Moreover, the average cell sizes of nanocellular foams of both phases could be controlled within 40-130 nm by manipulating the size of PLA domain and saturation pressure.