Hierarchically Porous Polymer Monoliths by Combining Controlled Macro- and Microphase Separation.

Abstract

The ability to tune polymer monolith porosity on multiple length scales is desirable for applications in liquid separations, catalysis, and bioengineering. To this end, we have developed a facile synthetic route to nanoporous polymer monoliths based on controlled polymerization of styrene and divinylbenzene from a poly(lactide) macro-chain transfer agent in the presence of nonreactive poly(ethylene oxide) (PEO). Simple variations in the volume fraction and/or molar mass of PEO lead to either polymerization-induced microphase separation or simultaneous macro- and microphase separation. These processes dictate the resultant morphology and allow for control of the macro- and microstructure of the monoliths. Subsequent selective etching produces monoliths with morphologies that can be tailored from mesoporous, with control over mesopore size, to hierarchically meso- and macroporous, with percolating macropores. This convenient synthetic route to porous polymer monoliths has the potential to be useful in applications where both rapid mass transport and a high surface area are required.