Control of particle morphology and film structures of carboxylated poly (n butylacrylate)/poly (methyl methacrylate) composite latex particles

Soft Core–Hard Shell Silicone Hybrid Nanoparticles Synthesized by Miniemulsion Polymerization: Effect of Silicone Content and Crosslinking on Latex Film Properties

Composite nanoparticles consisting of ‘soft’ silicone oil and ‘hard’ polyacrylate with core–shell morphology were obtained by a one-step synthesis via the miniemulsion process. Various parameters, i.e. the viscosity and amount of the silicone, the surfactant content, the (co)monomers affecting the particle size and morphology were studied. With an optimum hydrophilicity of the polymer shell, composite particles possessing a well-defined core–shell morphology were obtained as determined by transmission electron microscopy. The fully encapsulated silicone oil (40 wt-%) in a slightly crosslinked polyacrylate shell showed good film formation as revealed by atomic force microscopy. The ability to highly confine silicone oil in the composite film could clearly be evaluated from contact angle measurements. By finely changing the crosslink concentration in the polymeric shell, tunable hydrophobic properties of films cast from silicone core–polyacrylate shell latexes could be achieved. In addition, the high thermal resistance and excellent water-resistant properties of the film were shown by thermal gravimetric analysis and water swelling determination. These composite latexes are presented as new alternatives for practical utility in waterborne coatings.

The morphology of submicronsized core–shell latex particles: An electron microscopy study

The core-shell structure of a range of acrylic-acrylic latexes has been investigated by combining different specimen preparation methods with transmission electron microscopy (TEM), dark-field scanning transmission electron microscopy (DSTEM) and low-voltage scanning electron microscopy (LV-SEM), including the first reported use of LV-SEM to observe composite latex particles at ambient and subambient temperatures. Spin-coating of liquid latex dispersions directly onto TEM grids or SEM stubs is shown to be a relatively straightforward mean of avoiding film formation during specimen preparation. In conjunction with double staining techniques, it has been found to be particularly convenient for characterizing the fine structure of particles with diameters down to below 100 nm.