PHOTOCONTROLLED GATING BY POLYMER BRUSHES GRAFTED ON POROUS-GLASS FILTER

Polymethacrylate-containing spiropyran was grafted on a glass filter t o control permeation of organic liquid by photoirradiation. The glass filter was at first coupled with octadecyldimethyl-N,N-diethylaminosil ane and next subjected to glow-discharge treatment for graft copolymer ization of spiropyran-substrated methyl methacrylate (SPMA), beta-meth acryloylethyl)-3,3-dimethylindoline-2,2'- spiro-6'-nitrospirobenzopyra n, and methyl methacrylate (MMA). The surface modifications were monit ored by X-ray photoelectron spectroscopy. The surface wettability was altered by these treatments. An SPMA/MMA copolymer in toluene was solu ble under irradiation of ultraviolet light but was insoluble under irr adiation of visible light, while the copolymer was soluble in N,N-dime thylformamide (DMF) irrespective of photoirradiation. Toluene permeati on through a glass filter grafted with SPMA/MMA copolymer increased by ultraviolet-light irradiation, and decreased by visible-light irradia tion. DMF permeation did not depend on the photoirradiation. These res ults demonstrated that the permeation of organic liquid through a glas s filter can be controlled by the solubility, i.e., the extension/cont raction of polymer chains grafted on the surface.