Adhesion study at the interface of a PDMS-elastomer and borosilicate glass-slide: effect of modulus and thickness of the elastomer.

Adhesion control at the interface of two surfaces is crucial in many applications. Examples are the design of micro and nanodevices such as microfluidic devices, biochips, and electronic sensors. Adhesion at the interface of two materials can be controlled by various methods, such as chemical treatment on the surface of the materials, modification of the surface texture of the materials, and change of the mechanical properties of the materials. The main idea of this study is to control the adhesion by changing the mechanical properties (modulus) of the polydimethylsiloxane (PDMS) elastomer. We vary the modulus of the PDMS elastomer by changing mixing ratio (w/w) of the silicone elastomer base and its curing agent (Sylgard 184, Dow Corning). Our study also includes the effect of the thickness of the PDMS elastomer sheet on its adhesion behavior. Adhesion measurements at the interface of the borosilicate glass slide and different PDMS elastomer specimens were performed using a wedge test. This method inserts a glass coverslip at the interface to create a wedge. We observe a significant decrease in the work of adhesion and an increase in equilibrium crack length with an increase in elastic-modulus and thickness of the PDMS elastomer samples. We present and discuss the effect of modulus and specimen-thickness on the adhesion behavior of the PDMS elastomer against a glass slide.