Nanoporous materials from ordered polylactide-containing block copolymer templates

This thesis describes our efforts in preparing ordered nanoporous polymer monoliths from polylactide-containing block copolymers. The viability of this method was demonstrated by the successful preparation of nanoporous polystyrene monoliths from polystyrene-polylactide (PS-PLA) diblock copolymers that form hexagonally packed nanocylinders of PLA in a PS matrix. A morphological diagram for the PS-PLA system was developed to determine the parameters (molecular weight and composition) in which the equilibrium morphologies existed. The preparative strategy for creating nanoporous frameworks involved macroscale alignment of the cylindrical morphology through shear flow followed by hydrolytic removal of the degradable PLA component. The pore size and shape were found to replicate that of the template and a narrow pore size distribution was observed. The pore walls were also decorated with accessible hydroxyl functionalities.; The strategy of using a degradable PLA component to make ordered nanoporous monoliths was extended to the bicontinuous gyroid (G) morphology. As in the preparation of nanoporous materials from cylinder-forming PS-PLA, much of the effort in this system was devoted to identifying the G morphology. G was found to exist in a small compositional window at low molecular weights in PS-PLA binary blends. The PLA domains were chemically etched to yield a nanoporous material; however, the size and shape of the voids were not templated by the structure of the precursor.; We also explored the use of polyisoprene-PS-PLA triblock copolymers as a route to ordered nanoporous monoliths. The morphological behavior of a low molecular weight PI-PS-PLA system was systematically studied along the f _PI ≈ f_PS isopleth. The multicontinuous morphology, core-shell gyroid, was identified. Higher molecular weight systems were also prepared and characterized. The removal of the PLA component from these materials proved to be challenging.