| abstract |
The present invention relates to a method of forming defect-free ultrathin film composite membranes by the photochemical synthesis of an ultrathin polymer film on the surface of a microporous support membrane. In one particular embodiment, the method entails placing a support membrane on a filter paper which is saturated with a solution of the desired monomer(s). The solution then wicks to the top of the membrane, covering the surface with a thin solution film, where it is subjected to irradiation by ultraviolet (UV) light to initiate the polymerization of the ultrathin polymer film. The rate of polymerization can be enhanced by adding a photoinitiator to the gas phase above the membrane or into solution with the monomer or monomers to induce radical polymerization. The method results in a defect-free ultrathin composite membrane. In addition, to minimize photon penetration depth and confine the polymerization predominantly to the membrane surface, the incident at which the UV light strikes the membrane surface is kept at an acute angle. The ultrathin film composite membranes can be used in a vast number of chemical separation processes, bioreactors and sensors, energy conversion and drug delivery systems. |