NaNO₃ as a Removable and Recyclable Dispersant toward High-Purity Polyvinyl Butyral

Polyvinyl butyral (PVB) boasts many applications, yet its synthesis often suffers from oversizing agglomeration, resulting in limited product purity and thus large energy consumption and waste emission for purification. This study for the first time demonstrates that incorporating NaNO3 as an additive can prevent the oversizing agglomeration to offer high-purity and finely sized PVB products. NaNO3 functions as a removable and recyclable dispersant to enable uniform acetalization of poly(vinyl alcohol) with n-butanal in acidic aqueous media at ambient temperatures. The salting-in effect of NaNO3 diminishes the hydrophobic interaction of n-butanal and polymers, improving the media dispersion and preventing agglomeration runaway. In contrast to conventional systems, the NaNO3-assisted synthesis at ambient temperature offers multiple sustainable benefits, including suppression on byproducts, energy conservation, reduction on emission, and reusability of the postacetalization medium. This finding offers a valuable complementary strategy for PVB synthesis and deserves exploration in massive production.