PREPARATION AND CHARACTERIZATION OF A HOMOBIFUNCTIONAL SILICONE-RUBBER MEMBRANE GRAFTED WITH ACRYLIC-ACID VIA PLASMA-INDUCED GRAFT-COPOLYMERIZATION

Polyacrylic acid (PAA) was grafted onto the surface of silicone rubber membrane (SR) by plasma-induced graft copolymerization (PIP). Ar-plas ma was used to activate the surface of SR. Also, a determination was m ade of the influences of plasma treatment power, pressure, time, graft ed copolymerization reaction time, and monomer concentration on polyme rization yield. The surface properties of SR were measured by ATR-FTIR , ESCA, and SIMS. In those analyses, the elemental composition and dif ferent carbon bindings on the surface of SR were examined by ESCA with the amount of O1s/C1s being approximately 0.7 at 60 s by Ar-plasma tr eatment (60 W, 200 mtorr). The peroxide group introduced on SR was mea sured via 1,1-diphenyl-2-picryhydrazyl (DPPH). The optimum amount of p eroxide groups was 6.85 x 10(-8) mol/cm(2) at 60 s of Ar-plasma treatm ent. The peroxide group (33D peak) was introduced onto the surface of SR by negative spectra of SIMS analysis after SR treatment by Ar-plasm a. An increase was obtained in grafted polymerization yield with a reg ion of 5 to 50% (v/v) of acrylic acid aqueous solution. Both sites of polyacrylic acid were detected after staining by toluidine blue O. Tha t is, a homobifunctional membrane was developed via this surface modif ication method. (C) 1996 John Wiley & Sons, Inc.