Modification of poly(dimethylsiloxane) as a basis for surface wrinkle formation: Chemical and mechanical characterization

Abstract

In this manuscript, the processes occurring during UV-ozone treatment on polydimethylsiloxane (PDMS) surfaces i.e. formation of a stiff silica-like layer and surface degradation have been studied. While the chemical changes have been evaluated using Confocal Raman Microscopy (CRM) with submicrometer resolution, partial surface degradation occurring during longer ozone treatments have been evidenced both by Optical Profilometry and AFM.Whereas previous studies reported the formation of a thin silica layer of around 20-30nm up to 200 nm depending on the method employed, herein, we demonstrated that in effect a thin rigid layer is formed but instead of a sharp interface predicted by previous reports a gradient depth profile was obtained. CRM evidenced the formation of a 4 µm layer of modified material. By Quantitative Nanomechanical Mapping (QNM) and based on the equations that predict the wrinkle formation, a surface layer thickness of around of 4.5 µm was also determined.

5‐4: Stretchable Oxide TFTs for Wearable Electronics

“…Since UV/O 3 treatment can oxidize the surface of PDMS and form stiff silica-like layer. The elastic modulus of the stiff silica-like layer is reported to increase over ten times compared to the untreated PDMS, while the total thickness is ~5 μm with a gradient depth profile after exposure >90 min [16]. Since the islands are stiffer than the surrounding PDMS regions, the components on the islands is little strained when the sample is macroscopically stretched.…”

“…The PDMS substrate is selectively treated by UV/O 3 to form a stiff silica-like layer on desired surfaces, while the untreated regions remain highly stretchable [16]. The oxide TFTs on the stiff islands can tolerate 50% mechanical stretching and perform well after repeated stretching and relaxing, owning to the reduced strain on these islands [16]. This work provides a promising approach to wearable electronics using oxide TFT technology.…”

“…Here, we report a simple integration of the NP oxide TFTs onto selectively modified polydimethylsiloxane (PDMS) substrate and evaluate the performance of the stretchable devices. The PDMS substrate is selectively treated by UV/O 3 to form a stiff silica-like layer on desired surfaces, while the untreated regions remain highly stretchable [16]. The oxide TFTs on the stiff islands can tolerate 50% mechanical stretching and perform well after repeated stretching and relaxing, owning to the reduced strain on these islands [16].…”

“…The PDMS surface was then covered with a square-shaped mask and exposed in UV/O 3 for 2 h. The mask is to selectively produce exposed areas (3 mm x 3 mm; intervals: 3 mm)) where the UV/O 3 oxidation takes place, and the surrounding areas which are protected by the mask. The surface of PDMS in the exposed region forms a thin stiff silica-like layer with a gradient depth profile, while the unexposed regions remain completely soft [16]. The TFT samples on the thin PI substrate are cut into islands with size of 3 mm x 3 mm using a CO 2 laser, and then transferred to the UV/O 3 treated islands.…”

38‐1: Invited Paper: Stretchable Oxide TFTs with PI/PDMS Substrate

“…The PDMS substrate is selectively treated by UV/O3 to form a stiff silica-like layer on desired surfaces, while the untreated regions remain highly stretchable [15] . The oxide TFTs on the stiff islands can tolerate 50% mechanical stretching and perform well after repeated stretching and relaxing, owning to the reduced strain on these islands [16] . This work provides a promising approach to wearable electronics using oxide TFT backplane.…”