Tuning Surface\nProperties of PLA for Capturing Nonpolar\nCompounds from Water

In the available literature, the surface wettability\nof polylactic\nacid (PLA), a compostable polymer, has been tuned for oil capture\nby employing multistep processes and incorporating non-biodegradable\nmaterials. Such processes are complicated to scale up for industrial\nproduction, and the addition of multiple components reduces the compostability\nof PLA. In this work, we report on the surface wettability tuning\nof PLA by an easily scalable, solvent-induced recrystallization process,\ntermed Dip-Dip-Dry (DDD), without adding any other materials into\nPLA. The increase in crystallinity by DDD treatment increases the\nintramolecular coupling interaction of C=O and C–O groups in\nPLA, thus reducing the polar component of surface energy to zero,\nrendering it nonpolar. Surface-modified PLA selectively captures non-polar\ncompounds from water mixtures: discs uptake 0.11 g of oil/g of PLA\nand 0.06 g of diesel/g of PLA and powders uptake 2.6 g of oil/g of\nPLA. The selective oil capture capacity of surface-modified PLA is\nalso confirmed in real world conditions by testing them in acidic,\nbasic, and salt water–oil mixtures. The oil-saturated PLA can\nbe regenerated by washing in isopropanol. The durability of this material\nwas tested by exposing it to DI water and simulated seawater for more\nthan 30 days. Hence, this work proposes DDD treated PLA as an industrially\nscalable sustainable material for non-polar compound capture that\nprevents secondary pollution.