Adhesion of PDMS substrates assisted by Plasma Graft Polymerization

Abstract

Transparent polymers have great potential when applied toward flexible devices as encapsulation or substrate materials in the fields of electronics, optics, biology, and so on because of their low costs and lightweight. The use of polymeric materials in bonding technology is indispensable due to the practicality of these materials. In general, polymer bonding can be achieved through the use of interlayer‐like adhesives or through direct bonds such as ultrasonic or thermocompression bonding. Polydimethylsiloxane (PDMS) joints were achieved by surface modification via oxygen‐argon plasma. Plasma treatment at various plasma power levels (150, 200, 250, and 300 W) was conducted on the PDMS surface with the modified surfaces being analyzed via contact angle measurement and X‐ray photoelectron spectroscopy. Plasma‐activated PDMS films were bonded without adhesives at 160 °C, which did not lead to deformation. The bond strength of the plasma‐activated PDMS was measured using a T‐peel test prior to and after bending cycles, and the optical transmittance of the specimens was also measured. The fractured surface was investigated via optical microscopy and scanning electron microscopy following adhesion testing. The experimental results revealed that the bond strength of PDMS was proportional to the employed plasma power level. The bond strength of PDMS decreased by approximately 10.8% after 100 000 bending cycles, indicating that plasma polymerization‐assisted direct bonding could function as a versatile bonding method for polymeric materials. Copyright © 2016 John Wiley & Sons, Ltd.