Harnessing Liquid-like Self-Lubricated Silicone Interfaces To Catalyze the Breakdown of Biodegradable Plastics

Abstract

Given the demand for plastic products, solving the problem of plastic waste is urgent. To alleviate this, biodegradable plastics are replacing conventional plastics; however, their biodegradation rates are often low. While engineering plastics with low-surface-energy silicon-containing lubricants provide broad liquid repellency, the limited moisture permeability slows biodegradation. A long-standing challenge is to combine the conflicting requirements of waterproofness and breathability within a single platform. Here, for the first time, we propose a new class of self-lubricative, omniphobic, covalently attached liquid coating that harnesses the dual mechanisms of both physical and chemical cross-linking. This coating was achieved by the cohydrolysis and co-condensation of linear polydimethylsiloxane (PDMS) blocks and silicone oil onto noncommercial plastics via a facile, cost-effective, and industrially feasible spray-coating technique. The superior smoothness and the interfacial slippage arising from the synergistic lubrication effects between the PDMS and silicone oil enable a wide range of both polar and nonpolar liquids to slide easily. Diffusion of silicone oil into the porous PDMS skeleton improved the breathability (180 g m^-2 per day) and led to pronounced biodegradation (33% mass loss in 10 weeks). This work provides proof-of-concept data for constructing biodegradable coatings on plastics, which may have significant applications in biomedical settings.

Keywords: biodegradable plastics; bioplastics; breathable coatings; liquid-like coatings; self-lubricative coatings; silicone materials; slippery coatings.