Hollow-Particle Latexes: Preparation And Properties

The control of the morphology of latex particles has been an intensive area of research in emulsion polymer science. The preparation of hollow-particle latexes has contributed many fundamental insights into the synthesis and the development of structure in particles. Due to a void within a latex particle, the hollow particles with inefficient opacity enhance the performance of industrial coatings and potentially are useful in other technologies such as micro-encapsulation and controlled release.The preparation and properties of hollow-particle latexes had been researched in this paper. The core-shell polymer particles of Poly(methyl acrylic acid-buthyl acrylate-methyl methacrylate) / Poly(styrene-acrylonitrile) with different core-shell weight ratios were synthesized by seeded emulsion polymerization. The hollow particles were obtained by stepwise alkali-acid treatments. The diameters and their distributions of latexes were determined by TEM, and the morphology was also characterized by TEM. It was found that during the seed forming stage, the amount of the sodium dodecylbenzene sulfonate (SDBS) dosage was 0.5% (wt) of total monomer and the monomer mixture was fed in one batch. During the core forming stage, MAA was used as carboxylic co-monomer, and AN used was 2.5% (wt) of total monomer, and the monomer mixture was fed in a starved feeding fashion to ensure the polymerization stability. When the particles formed with core-shell morphology as precursors of the end-hollow particles, the hollows had already appeared in the particles before swelling. During the swelling treatment stage, the morphology of hollow polymer particles after neutralization depended on core-shell weight ratio as well as the conditions such as base type, temperature, swelling agent, and emulsion pH. The hollow particles with maximum hollow volume of nearly 30% were obtained at the value of core-shell weight ratio equal to 1/10.0, and the ratio of swelling agent MEK to core-shell polymer by weight was 1.50/1. The mechanism of the hollows formation and the hollows distortion was also studied.The release behavior of toluene from hollow particles was examined after toluene was taken into the hollow by solution penetration. There existed the possibility that they were used as drug reserve and release materials. In addition, it was studied that the mechanics properties of acrylate latexes and water-borne polyurethane separately blending with hollow particles were influenced by the hollow particles. The results were not ideal.