(181u) Porous Thin Films Via Physicochemical-Selective Initiated Chemical Vapor Deposition (iCVD)

Development of scalable methods for fabrication of porous and chemically heterogeneous thin films with precise control over their physical properties can open a new venue in many important applications especially membrane-based separation and purification technologies. Here, we introduce a simple method to fabricate thin film composite membranes through area-selective initiated chemical vapor deposition (iCVD) which gives us precise control over thickness, pore size, and porosity of produced the films. Our method uses physicochemical templates to impose area-selective deposition during the iCVD process. We study different conditions for the physicochemical inhibition of film deposition to estimate the effective time constant for growth inhibition. We achieved control over spacing between the pores, pore diameter, and thickness of the films at the submicron resolution on planar surfaces (e.g., Si wafer). The chemical and physical properties of the porous films were analyzed through scanning electron microscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Furthermore, we extended our method to 3-Dimensional (3D) substrates and created composite membranes by selective deposition of hydrophobic fluoropolymers on hydrophilic supports. We successfully tested the membranes in direct contact membrane distillation process where a stable averaged flux of 24±3 kg m^-2 h^-1 and 100% salt rejection was observed over 2 hours of experiment.