UV-nanoparticles: Photopolymerized polymer colloids from aqueous dispersions of acrylated oligomers

Polymer colloids are usually prepared using thermally activated polymerization. Photo-induced techniques for the preparation of polymerized or crosslinked colloids have seldom been reported in the literature and to our knowledge none has found real application in industry. Here, we introduce a new approach to form insoluble crosslinked colloidal particles by in situ photopolymerization starting from aqueous dispersions of auto-dispersible acrylated oligomers originally developed for water-based UV-coating applications. Of particular interest is the relatively high rate at which particle polymerization takes place even in highly opaque conditions e.g. with particle loadings of more than 20 w/w% and particle sizes ranging from 40 up to 500 nm. In this paper, the preparation process is demonstrated with an immersion-type batch photoreactor and the properties of this new family of organic colloids are highlighted. Furthermore, we report the preparation of submicron sized containers by loading a hydrophobic compound (i.e. n-hexadecane) within a water-dispersible urethane acrylate shell followed by solidification of the container wall using radical photopolymerization with a suitable photoinitiator. The thermal and colloidal characteristics of these novel capsules are discussed in some detail and the potential application as nanoscaled phase-change material is highlighted.

Publication year:2014