Self-assembled membranes for separation
Separating components in liquids and gases is an important process in a number of fields, including the environmental sciences, medicine, biotechnology and synthetic chemistry. One way to do it is to use a polymer membrane with structured pores and surface chemistry specifically adapted to the task of interest. Certain components pass through and others do not. The focus of the EU-funded project 'Self-assembled polymer membranes' (Selfmem) was to develop novel ultra-thin isoporous membranes with controlled nanostructure based on block copolymer self-assembly. In addition, researchers sought to impose additional functionalities by chemical post-treatment. Applications of interest were water purification, separation of proteins and gases (hydrogen/carbon dioxide) as well as water purification. Self-assembly is an important process by which various molecular and atomic forces of attraction and repulsion cause the formation of suprastructures. Naturally occurring, self-assembled structures include the lipid bilayer cell membrane, DNA and three-dimensional (3D) protein conformations. Selfmem exploited the novel membranes possible via guided self-assembly of synthetic block copolymers from solution into thin films and on top of different inorganic substrates as templates for selective etching of pores. Scientists synthesised both organic (polymeric) and inorganic (silicon-based) ultra-thin membranes (nanoporous silicon membranes (NSiMs)) of controlled and dense porosity and thickness in the nanometre range using self-assembly of block copolymers. The organic membranes are ductile whereas the inorganic membranes are stable under conditions of high temperatures and pressures. Membranes demonstrated very promising filtration properties and post-processing functionalisations opened the door to numerous applications. Micro- and nanofabrication techniques for wafer-scale production of NSiMs were optimised and up-scaled. In addition, NSiMs were integrated into functional fluidic and filtration modules for application to (bio)molecules separation, ultrafiltration or sensing. Complementary investigations were spawned regarding the potential of isoporous membranes in nanotoxicology, drug delivery and diagnostics and the submission of four patents. Results enabled publication of numerous articles in peer-reviewed journals and contributed to the work of six doctoral theses. Selfmem made a significant contribution to understanding and characterisation of nanoporous membranes produced by self-assembly of block copolymers. Uptake by research and industry and continued development will no doubt strengthen the EU position in strategic markets, such as water treatment, molecular biology, and gas purification.
