Vapor Deposition of Functional Porous Polymer Membranes

The fabrication of porous polymer membranes is currently dominated by solution-phase processing techniques. We recently developed a versatile solventless method to deposit porous polymer membranes. In this paper, we will review the mechanism that governs the fabrication process, the advantages and capabilities of the technique, and potential applications for these membranes. In the fabrication process, low substrate temperatures are used to transition the monomer vapor into solid microstructures which are then polymerized using a thermally cleavable vapor-phase initiator. This paper covers the effect of processing parameters such as time and temperature on the molecular weight distribution of the polymer and the porosity of the membranes. We will discuss several methods for patterning and cross-linking the membranes, and we will demonstrate that asymmetric membranes with varying chemical functionalities and thicknesses can be fabricated. Finally, we will review potential applications for these membranes.