Photopatterning of PDMS Films: Challenging the Reaction between Benzophenone and Silicone Functional Groups

Direct photopatterning of PDMS (Polydimethylsiloxane) through benzophenone photo-inhibition has received great interest in recent years. Indeed, the simplicity and versatility of this technique allows for easy processing of micro-canals, or local control of PDMS mechanical properties. Surprisingly, however, the chemical reactions between silicone hydride and/or silicone vinyl groups and benzophenone have only been assessed through qualitative methods (e.g., Attenuated total reflection fourier transform infrared). In this communication, the previously proposed reaction pathways are challenged, using nuclear magnetic resonance (NMR) spectroscopy and size exclusion chromatography (SEC) monitoring. A different mechanism depicting the role of benzophenone irradiation on the polyaddition reaction of silicone formulations is proposed, and a simplified procedure involving aromatic solvent is finally disclosed.

Automated summary

This communication challenges the previously proposed reaction pathways for photopatterning of PDMS via benzophenone photo-inhibition, and proposes a new mechanism based on nuclear magnetic resonance and size exclusion chromatography. A simplified procedure involving aromatic solvent is finally disclosed.