Starch nanoparticles produced via ultrasonication as a sustainable stabilizer in Pickering emulsion polymerization
Pickering emulsion polymerizations using starch nanoparticles (SNPs) as the sole stabilizer and persulfate as initiator have been successfully accomplished. The SNPs were prepared in water via high-power ultrasonication without the addition of any chemical reagent. The polymer dispersion stabilized by SNPs proved to be stable for several months, when the SNP content was above 4 wt% relative to the monomer phase. As the SNP loading increased, the particle sizes of the polymer dispersion decreased steadily, confirming the key role of the SNPs in the stabilization process. On the basis of the zeta-potential measurement and change in polymer particle size during emulsion polymerization, a mechanistic aspect of the Pickering emulsion polymerization is proposed. The film-formation properties of the nanocomposite dispersion and the optical properties of the ensuing films are also discussed. It was shown that nanocomposites prepared via the Pickering emulsion route displayed better optical transparency than that obtained by an ex situ mixing route.