Morphology Control And Self-assembly Of Dimpled Non-spherical Polymer Particles

Due to the asymmetry of the geometric shape,van der Waals force,charge distribution,curvature,and so on,non-spherical particles exhibit excellent physical and chemical properties.Thus,non-spherical particles are widely used in the fields of photonic crystals,special coatings,biomedicine and construction of new materials.In this paper,dimpled non-spherical particles are synthesized by seed dispersion polymerization,and the morphology of the particles is precisely controlled.The formation mechanism of dimpled non-spherical particles is proposed based on the experimental results.After that,the self-assembly behavior of dimpled non-spherical particles was also studied.(1)Spherical polystyrene particles were prepared by One-step dispersion polymerization.Dispersion polymerization is divided into two stages,polystyrene(PS)spheres with different particle sizes were prepared by adjusting the amount of styrene(St)in stage ? and stage ?.When the mass ratio of stage ? and stage ? of St is 20/0,the diameter of the prepared spherical particles is 2.5 ?m.When the mass ratio of stage ? and stage ? of St is 15/5,the diameter of the prepared spherical particles is 3?m.When the mass ratio of stage ? and stage ? of St is 5/15,the diameter of the prepared spherical particles is 6 ?m.(2)The dimpled non-spherical polymer particles were prepared by seed dispersion polymerization.PS spheres with a diameter of 3 ?m are used as seeds,and the morphology of dimpled non-spherical particles can be precisely controlled by adjusting the temperature,media polarity,reaction time,oscillation rate,the amount of monomer and swelling agent.When the mass ratio of methanol to water is 9.5/2,the reaction temperature is 60?,the reaction time is 24 h,the amount of monomer is0.15 g,and the amount of swelling reagent decane is 1.25 g,dimpled tetrahedron particles with regular geometric shapes are prepared.When the amount of monomer is increased,the concave surface of the dimpled tetrahedron particle deepens.When the polarity of the medium is reduced,the amount of swelling reagent is reduced,or the reaction temperature is lowered,the dimples on the particle surface will become smaller and the number of dimples will increase.When the reaction temperature or the polarity of the medium is increased,the oscillating rate or the reaction time is increased,the particle morphology changes to a disc shape.When the oscillation rate is very low,single-concave non-spherical particles are prepared.(3)Self-assembly of dimpled non-spherical polymer particles.Dimpled non-spherical particles and spherical particles are assembled via depletion interaction force and centrifugal force.The effects of centrifugation times,particle size,concentration of PEO and particles on the assembly of dimpled non-spherical particles were studied.When spherical particles and dimpled non-spherical particles have a high degree of curvature matching,increasing the number of centrifugations or concentration of particles,the self-assembly efficiency become higher.When the concentration of PEO is 1 g/L for the self-assembly of dimpled tetrahedron particles with spherical particles,the self-assembly efficiency is highest.