A Study of Glow Discharge Polymerization as a Means of Preparing Composite Reverse Osmosis Membranes with Ultrathin Skin

摘要

Polymer thin film formation by glow discharge in organic vapors (glow discharge polymerization, or plasma polymerization (PP) from a monomer (3.g., styrene) produces polymers which are considerably different from those formed from the same monomer by conventional polymerization. Such plama polymers form highly branched and crosslinked networks, excellent adhesion of a thin deposit to the substrate in glow discharge from low pressure plasma, are completely amorphous, and without macroscopic pinholes. Hence, an ideal composite reverse osmosis (RO) membrane can be prepared by PP using the proper porous substrate and PP conditions. Reproducibility and continuous operation feasibility, semi-continuous PP using hollow fibers was examined using a special constructed tandem reactor. Factors influencing continuous PP and variation of resultant RO membrane characteristics as a function of reaction time were investigated. While further improvement in the maximum salt rejection (90%) should be possible, the obtained water flux was exceptionally good. Allylamine plasma polymers produced had high chemical stability under extreme conditions of pH and in free chlorine oxidizing environments, superior to commercial RO membranes. Grafting acrylic acid onto the membrane surface improved its desalination characteristics. Further, PP can be used in continuous operation with very good reproducibility.