Poly(vinyl alcohol-co-vinyl acetate) complex formation with anionic surfactants particle size of nanogels and their disaggregation with sodium dodecyl sulfate

Colloidal aggregates, the so-called “pseudo-micelles” or nanogels, in view of their size in the nanometer range, are present in aqueous solution of vinyl alcohol-vinyl acetate copolymers (PVA) as a consequence of hydrophobic interaction between acetate sequences. The characteristics of PVAs, which are of interest as polymeric emulsifiers in suspension polymerization, were examined by dynamic light scattering (DLS). Different samples of average hydrolysis degrees (DH¯) from 73 to 88 mol% were studied. These nanogels corresponding to volume fractions up to 30% and in the size range of 30–40 nm, could be disaggregated by complex formation with sodium dodecyl sulfate (SDS). The evolution of the particle size was determined as a function of SDS concentration and temperature. Relative small amounts of SDS, typically 1–5% with respect to PVA, induce the disaggregation of the nanogels. By complex formation, the cloud point of PVA is shifted to higher temperatures, which are adjustable by the SDS concentration.