Preparation and characterization of highly elongated polydimethylsiloxane nanosheets

Polydimethylsiloxane (PDMS) is a biocompatible polymer that exhibits high flexibility and heat resistance. PDMS can be rapidly cross-linked at low temperatures by a platinum-catalyzed addition reaction and is used to create nanostructures owing to its high formability. In this study, free-standing PDMS thin films (PDMS nanosheets) were fabricated and characterized. PDMS nanosheets, about 90–2500 nm thick, were prepared using a microgravure coater. The mechanical properties of the PDMS nanosheets depended on the amount of cross-linker added in preparation. For example, a 93-nm-thick PDMS nanosheet showed high flexibility with elongation at break of 338% and Young's modulus of 0.46 MPa. The adhesion strength of the PDMS nanosheets was also dependent on the amount of cross-linker, and the lesser the cross-linker, the higher the adhesion strength. The PDMS nanosheets showed no change in physical properties when annealed at 150°C. Flexible, adhesive, and heat-resistant PDMS nanosheets were demonstrated as a substrate for skin-contact strain sensors and showed resistance changes of 20%–30% in response to skin stretching.