Permanent superhydrophilic surface modification in microporous polydimethylsiloxane sponge for multi-functional applications

Polydimethylsiloxane (PDMS) is one of the most preferred material in microfluidic device/biomedical applications because of its unique properties. However, improvement in surface wettability of PDMS is highly desired for microfluidic and biomedical applications as its surface is inherently hydrophobic in nature that restricts flow of aqueous fluid or adherence of biomolecules onto its surface. In spite of several surface modification techniques, prompt recurrence of hydrophobic properties is quite typical in PDMS. Here, we demonstrate a facile and a permanent conversion of a hydrophobic PDMS sponge onto a superhydrophilic state. PDMS sponge was prepared using an eco-friendly sugar leaching method and modified by an ultra-thin coating of polyacrylic acid (PAA). The resultant PDMS-PAA hybrid sponge was found to have highly stable and sustained superhydrophilic property for more than 18 months with water absorption efficiency as high as 89%. Valuable applications like, portable pressure pump in a microfluidic device and as a bioactive matrix for microbial cell immobilization for biodegradation of distillery industry effluent treatment has been demonstrated using these surface modified PDMS sponges. (C) 2019 Published by Elsevier Inc.