Realizing Ultrapurified Poly(vinyl alcohol) with High Insulation and Transparency by Ecofriendly Supercritical Assisted Elimination of Sodium-Associated Impurities

Poly(vinyl alcohol) (PVA) emerges as a promising sustainable material for environmentally friendly electronics, because of its biodegradable and biocompatible properties. Unfortunately, PVA suffers from problems associated with large leakage current, poor stability, and insufficient transparency. Impurities, particularly those related to sodium, are the major cause of the poor electric-optical characteristics when PVA acts as dielectric layer or substrate. However, removal of sodium-associated impurities has been one of the daunting challenges. Here, an ecofriendly supercritical carbon dioxide (SCCO 2 )-assisted hydration (SAH) strategy is introduced to eliminate the deep-seated sodium-related impurities. Ultrapurified PVA is obtained with outstanding insulation and high transmittance via a room-temperature SAH process, resulting in a 100-fold reduction in leakage, better stability, and up to 98% transparency in PVA-based devices. The SAH approach, which can effectively utilize and recycle CO 2, offers competitive advantages in developing entirely ecofriendly processes and devices, as well as a viable avenue to improve biocompatible materials and electronics.