Free Standing Dry and Stable Nanoporous Polymer Films Made through Mechanical Deformation

A new straight forward approach to create nanoporous polymer membranes with well defined average pore diameters is presented. The method is based on fast mechanical deformation of highly entangled polymer films at high temperatures and a subsequent quench far below the glass transition temperature Tg. The process is first designed generally by simulation and then verified for the example of polystyrene films. The methodology does not need any chemical processing, supporting substrate, or self assembly process and is solely based on polymer inherent entanglement effects. Pore diameters are of the order of ten polymer reptation tube diameters. The resulting membranes are stable over months at ambient conditions and display remarkable elastic properties. Free standing, stable nanoporous membranes made of highly entangled polymers are created solely by applying a biaxial deformation at high temperature and a subsequent quench below the glass transition temperature. Porous structures, as observed from simulation and experiment, are governed by polymer chains extending beyond the pore diameters and display remarkable new elastic properties.