Adhesion Study of Complementary Rough Surfaces of the PDMS Elastomer

Adhesion between soft elastomers such as polydimethylsiloxane (PDMS) plays a critical role in a wide range of applications, including the fabrication of microfluidic devices, soft robotic components, bioinspired adhesives, flexible electronic sensors, and triboelectric nanogenerators. Adhesion behavior is governed by multiple factors, including the sample preparation, surface energy, mechanical properties such as the elastic modulus, and surface texture or roughness. In this study, we focus specifically on the influence of surface roughness on the adhesion behavior of the PDMS elastomer, with particular attention being paid to a complementary interface with identical roughness. Surface roughness on the PDMS elastomer was introduced during the molding process using sandpapers with grit sizes ranging from <i>N</i> = 120 to <i>N</i> = 2000. The surface roughness of the PDMS elastomer was then characterized by using a stylus profilometer. Interfacial adhesion was evaluated through wedge test experiments, which enabled the analysis of the relationship among the surface roughness, work of adhesion, and equilibrium crack length. We observed nonmonotonic variation in adhesion with roughness. Furthermore, the study also explores the correlation between the real area of contact and the work of adhesion as well as between the dimensionless scan length and the work of adhesion. These results are significant for the design and development of triboelectric nanogenerators.