Surface wettability improvement of silicone elastomers synthesized with water-soluble polyacrylic acid molds

The aim of this work was to evaluate the use of water‐soluble hydrophilic plastic molds for preparing siloxane based random copolymers and for enhancing the surface wettability of resultant polymers, with a view for contact lens manufacture. The random copolymer consisted of silicone monomers and a small amount of N‐vinyl‐2‐pyrrolidone (NVP) along with vinyl acetate and diethyleneglycoldiallylether as a crosslinker. The surface of this copolymer, which faced against a polyacrylic acid (PAA) mold, showed a higher degree of wettability compared to that obtained against a hydrophobic polypropylene (PP) mold. After heating at 80°C for 4 h, the surface of this copolymer became hydrophobic. When it was immersed in water, however, the high degree of surface wettability regained within 30 s, whereas no significant change in wettability was observed for the PP‐facing surface. The results obtained from X‐ray photoelectron spectroscopy indicated that the polar fraction, which is attributed to NVP fractions of the copolymer, concentrated at the vicinity of the PAA facing surface and, in consequence, improved the surface wettability. This surface also showed a dynamic rearrangement of the wettability in response to changes of the surrounding environment. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3786–3789, 2003