Preparation and characterization of a homobifunctional silicone rubber membrane grafted with acrylic acid via plasma-induced graft copolymerization

Abstract

Polyacrylic acid (PAA) was grafted onto the surface of silicone rubber membrane (SR) by plasma‐induced graft copolymerization (PIP). Ar‐plasma was used to activate the surface of SR. Also, a determination was made of the influences of plasma treatment power, pressure, time, grafted copolymerization reaction time, and monomer concentration on polymerization yield. The surface properties of SR were measured by ATR‐FTIR, ESCA, and SIMS. In those analyses, the elemental composition and different 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 treatment (60 W, 200 mtorr). The peroxide group introduced on SR was measured via 1,1‐diphenyl‐2‐picryhydrazyl (DPPH). The optimum amount of peroxide groups was 6.85 × 10−8 mol/cm2 at 60 s of Ar‐plasma treatment. The peroxide group (33D peak) was introduced onto the surface of SR by negative spectra of SIMS analysis after SR treatment by Ar‐plasma. An increase was obtained in grafted polymerization yield with a region of 5 to 50% (v/v) of acrylic acid aqueous solution. Both sites of polyacrylic acid were detected after staining by toluidine blue O. That is, a homobifunctional membrane was developed via this surface modification method. © 1996 John Wiley & Sons, Inc.

Surface modification of polymethyl methacrylate intraocular lenses with the mixture of acrylic acid and acrylamide via plasma‐induced graft copolymerization

“…In contrast to other studies on graft polymerization using a direct plasma technique, our work showed peroxide groups could be efficient initiators of graft polymerization on the plasma‐treated surfaces 7. Several investigations have revealed that application of DPPH is highly effective for determining the amount of peroxide groups on the activated polymer surface 7–9. The number of peroxide groups increases with the increase in plasma treatment time, reaching a plateau at treatment times of 20, 40, and 50 s under 30, 20, and 10 W of power, respectively, and decreases thereafter (Figure 1).…”

“…Clearly, longer Ar plasma exposure does not guarantee high peroxide formation. It should be noted that low peroxide concentrations at long plasma exposures were not due to direct decomposition of the formed peroxide by the plasma because the plasma exposure was carried out in an atmosphere containing only the Ar gas, which should result in no peroxide formation 7–9. Thus, the peroxides must have been produced during the exposure of the samples to oxygen atmosphere after the plasma treatment, as proposed by Suzuki and colleagues 7…”

Simultaneous graft copolymerization of 2‐hydroxyethyl methacrylate and acrylic acid onto polydimethylsiloxane surfaces using a two‐step plasma treatment

“…The analysis of experimental data indicates that the grafted amount has decreased after passing a maximum at 35 s (60 W). The previous studies have shown that the peroxide groups act as initiators in plasma‐induced graft copolymerization 12, 17, 28, 34. According to our results, the changes of the grafted amount as a function of the pretreatment time directly depend on those of the peroxides concentration (Figs.…”

Surface Modification of Castor Oil‐Based Polyurethane by Polyacrylic Acid Graft using a Two‐Step Plasma Treatment for Biomedical Applications

“…According to our results, as shown in Fig. 25,26 The reasons for plasma pretreatment of the films before grafting are: In other words, this occurrence could be accounted by the produced peroxides that were partially converted into inactive species and not as free radicals into after prolonged plasma pretreatment times.…”