HOLLOW-FIBER MEMBRANES COATED WITH POLYMERIZABLE BICONTINUOUS MICROEMULSIONS

A new method has been successfully employed to prepare hollow-fiber me mbranes by coating and polymerizing bicontinuous microemulsions onto t he internal surfaces of hollow-fiber membranes. The bicontinuous micro emulsion consisting of water, a polymerizable zwitterionic surfactant of acryloyloxyundecyl dimethylammonio acetate, methyl methacrylate, an d 2-hydroxylethyl methacrylate (HEMA) can form a transparent polymer t hin film after polymerization. The hollow-fiber membranes as the suppo rts for microemulsion coatings were fabricated from the spinning solut ion of polyethersulfone/diethylene glycol/N-methyl-2-pyrrolidone. The microemulsion coated hollow-fiber membranes were evaluated by the sepa ration efficiency and the permeation rate of polyethylene glycol (PEG) solutions. The performance of coated membrane on the PEG separation i s strongly dependent on the concentration of HEMA and water in precurs or bicontinuous microemulsions. The pore size of the hollow-fiber memb ranes can be regulated between about 2 to 40 nm by varying the composi tion of precursor bicontinuous microemulsions. The characteristics of the coated membranes is believed to be directly related to the biconti nuous structures of precursor bicontinuous microemulsions. The use of polymerizable bicontinuous microemulsions enable one to better control the microstructures of coated membranes via in situ polymerization.