The production of monoliths containing aligned nano-pores by selective etching of a poly(styrene)/poly(lactide) block copolymer (P(S- b -LA) is examined. Small angle X-ray scattering (SAXS) is employed to characterize block copolymer (BCP) phase structure and orientation, and is used to observe the progress of poly(lactide) (PLA) hydrolysis through a section 5mm long. Orientation is found to be good, and complete etching of the PLA phase is observed and confirmed by weight loss. Diffusion of hydroxide ions through etched pores is tested using a diffusion cell, and found to obey the qualitative behaviour expected in a porous membrane. Breakthrough times are shown to be extended by the requirement of surface wetting. It is confirmed that nanoporous monoliths can be made from block copolymers, suggesting potential applications in membrane and chromatography applications.
- Block copolymers