Role of electrolytes in the preparation of nanoparticles via the emulsion polymerization of vinyl pivalate

By controlling both the kind of ion and the ionic strength of electrolytes in an emulsion polymerization system of vinyl pivalate containing about 1% sodium lauryl sulfate as a surfactant, nanoparticles of polyvinylpivalate having a diameter of about 25 nm were successfully prepared. The use of high concentrations of lithium chloride and lithium sulfate (∼1.0 mol L−1) prevented the nanoparticles from aggregating and produced nanoparticles sizes of 25–50 nm. Ammonium acetate and sodium acetate, on the other hand, accelerated the aggregate of the nanoparticles. These phenomena were examined in detail and found to be similar to the Hofmeister phenomena and the combination rule proposed by Craig et al.

The 15-nm particles of PVPi were the main products. Aggregates of the particles having a diameter of ∼80 nm were formed by the aggregate of ∼15-nm particles.Figure optionsDownload as PowerPoint slide