Molecular dynamics simulations on adhesion energy of PDMS-silica interface caused by molecular structures and temperature

Polydimethylsiloxane (PDMS)-silica interface commonly exists in adhesion system such as wall-climbing robots. In order to develop PDMS materials with excellent adhesion properties, it is necessary to understand their adhesion mechanism. Available studies on the adhesion performance of PDMS are mainly focused on the fabrication of microstructures. The adhesion energy of PDMS molecular structure on silica interface is rarely addressed. Therefore, present study investigates the adhesion at nanoscale by establishing a molecular model of the PDMS-silica interface. The molecular dynamics simulations and the Bell model are employed to evaluate the effects of chain length and typical terminal group (methyl group, hydroxyl group, and hydrogen group) of PDMS and temperature on the adhesion characteristics. The results demonstrate that the PDMS with 30 repeat units presents the highest adhesion energy but temperature is the factor that causes the greatest proportional change in the adhesion energy of the PDMS-silica interface. Rising the temperature of system in a certain range, the molecular weight or polarity of PDMS terminal group is beneficial for adhesion energy improvement as well. These results are important guidelines for the development, design and application of PDMS materials.