Enhancing hydrophilicity of PDMS surfaces through graphene oxide deposition

This study presents a simple approach to modify the wettability of polydimethylsiloxane (PDMS) using graphene oxide (GO). The proposed method involves a series of steps including O₂ plasma treatment, APTES functionalization, GO deposition, and substrate washing and drying. The presence of a GO film on the PDMS surface was confirmed by SEM, AFM, FTIR, and GO reduction using HI acid. The GO film significantly improved the water wettability of the PDMS substrates, as evidenced by a drop in water contact angle from 112° to 40°. Over the course of time, the contact angle increases to reach a value of almost 70° after 4 days before finally settling at a steady value of 82° after 9 days. Once this value was reached, no further changes were observed in the contact angle. Even with the increase in the contact angle, the proposed method shows an enhancement in the hydrophilicity of the PDMS of almost 35°. This treatment improved also the wettability of the PDMS under an oil medium where a dispensed water droplet attaches on the GO-coated PDMS surface. The versatility of this method lies in its ability to tune the wettability of PDMS, making it suitable for a diverse range of applications. For instance, it can be used to create flexible hydrophilic membranes for efficient oil/water separation or to fabricate hydrophilic microfluidic chips for biological purposes. Overall, this study offers a simple and effective approach for altering the surface properties of PDMS, expanding its potential for a wide range of applications.