NaNO<sub>3</sub> as a Removable and Recyclable Dispersant\ntoward High-Purity Polyvinyl Butyral

Polyvinyl butyral (PVB) boasts many\napplications, yet its synthesis\noften suffers from oversizing agglomeration, resulting in limited\nproduct purity and thus large energy consumption and waste emission\nfor purification. This study for the first time demonstrates that\nincorporating NaNO<sub>3</sub> as an additive can prevent the oversizing\nagglomeration to offer high-purity and finely sized PVB products.\nNaNO<sub>3</sub> functions as a removable and recyclable dispersant\nto enable uniform acetalization of poly(vinyl alcohol) with <i>n</i>-butanal in acidic aqueous media at ambient temperatures.\nThe salting-in effect of NaNO<sub>3</sub> diminishes the hydrophobic\ninteraction of <i>n</i>-butanal and polymers, improving\nthe media dispersion and preventing agglomeration runaway. In contrast\nto conventional systems, the NaNO<sub>3</sub>-assisted synthesis at\nambient temperature offers multiple sustainable benefits, including\nsuppression on byproducts, energy conservation, reduction on emission,\nand reusability of the postacetalization medium. This finding offers\na valuable complementary strategy for PVB synthesis and deserves exploration\nin massive production.