Hydrosilation-Cured Poly(dimethylsiloxane) Networks: Intrinsic Contact Angles via Dynamic Contact Angle Analysis

Abstract

A method for measuring intrinsic advancing (θadv) and receding (θrec) water contact angles is reported for hydrosilylation-cured poly(dimethylsiloxane) network coatings that are analogues of biomedical materials. Static and dynamic contact angle (DCA) methods were used to evaluate coatings prepared from commercial divinyl-terminated poly(dimethylsiloxane) (C-DVPDMS) and synthesized low polydispersity divinyl-terminated poly(dimethylsiloxane) (N-DVPDMS). DCA measurements showed that coatings prepared with both C-DVPDMS and N-DVPDMS contaminated the water surface during analysis. For ambient temperature cure, the rate of contamination was C-DVPDMS > N-DVPDMS. Methods for acquiring intrinsic contact angles on the PDMS coatings include using a large surface area reservoir or changing the water reservoir between DCA cycles. Intrinsic contact angles for hydrosilylation-cured PDMS coatings are as follows: θadv, 118°, θrec 83°; after contamination of the water surface the contact angles change to θadv, 108°, θrec 87°.