Design of Mesoporous Materials with Controlled Porosity and Functionality from Nanostructured Diblock Copolymers

摘要

Porous polymeric materials have recently attracted considerable attention due to their established and potential applications in many areas, including advanced filtration or separation techniques, heterogeneous catalysis and template-assisted synthesis of nanoobjects. However, it is still a key challenge to prepare mesoporous organic materials with tunable morphology (pore size and pore size distribution) and functionality, while maintaining good mechanical properties and high chemical stability of the matrices. The synthesis of mesoporous polymeric structures can be accomplished by a variety of approaches such as template-oriented routes, e.g. supramolecular self-assembly, or selective degradation of Interpenetrating Polymer Networks (IPNs). A smart route relies on the synthesis of block copolymer precursors, which are known to self- organize into distinct well-ordered morphologies, followed by the selective removal of one of the blocks. The block copolymer approach provides an excellent way to design mesoporous materials in a membrane form, with a high level of control over the porosity and the surface functionality of the pores. In the present work, we report on the fabrication of functionalized (meso)porous polystyrene membranes obtained from diblock copolymers of polystyrene and poly(D,L-lactide) (PS-b-PLA) with a functional group (such as COOH or NH2) at the junction between both blocks. A cylindrical morphology (PLA cylinders in PS matrix) is aimed for the polymer precursors, which can be achieved by the proper selection of the copolymer composition and a good control over the polymerization conditions. The PLA block is then selectively removed either by base or acidic hydrolysis, leaving behind the porous PS membrane with functional groups located along the walls of the channels.