Synthesis And Performance Of Nano-sized Hollow Opaque Polymer Particles

Opaque polymer is a kind of hollow polymer microsphere, which has excellent opacifying performances because of the refractive index difference between the shell polymer and the internal substance with small molecular weight, such as air or water. This opaque polymer also has many other excellent characters such as deformation performance, good stability and light specific gravity. Many kinds of opaque polymers can be obtained by changing the composition of the shell, the size of particles and holes or the kinds of internal substance. In this paper, the preparation and characterization of P(acrylate-styrene) opaque polymer hollow microspheres was studied. The parameters that affect the structure and performance of opaque polymer were discussed and the control of configurations and sizes was also described.Firstly seeded emulsion polymerization was adopted to prepare the core-shell polymer emulsion which is hydrophilic in core and hydrophobic in shell. The core contained some amounts of monomer with carboxyl groups. Then alkali was used to swell the core-shell polymer in some conditions and opaque polymer hollow microspheres were obtained after cooling. The average diameters of opaque polymer particles were controllable between 0.2-0.8 μm and the percentage of hollow part reached about to 50%.With the objective of obtaining stable, uniform-size and clear structured core-shell polymer, the effect of polymerization technics, dosages and feeding methods of comonomers and emulsifiers, amounts of MAA in core and shell, dosages of cross linkers in core and shell, ratio of the core monomers to shell ones, kind of alkali, initial pH, swelling time and swelling temperature for the sizes, morphologies and volume expansions of opaque polymer hollow particles were investigated. Appropriate polymerization technics, dosages and feeding methods of reactants and conditions of alkali swelling were confirmed. The morphologies and particle sizes of hollow latex particles were characterized by TEM and SEM.The way of controlling the morphologies and particle sizes of opaque polymer hollow particles was described by summarizing the above experiments and analyzing the mechanism of forming hollow particles. After comparing opaque polymer particles obtained from our experiments with HIQUE 280S sold in themorphologies and particle sizes, the former's size was more uniform and controllable.