Preparation And Application Of Polystyrene Based Functional Microspheres

Polymer microspheres have excellent properties,and have a wide range of applications in chemical,medical,electronic and architectural fields.With the development of the times,the performance requirements of building materials are gradually improved,including mechanical properties,thermal insulation and weather resistance.In this paper,polystyrene microspheres with different functional groups,silica/polystyrene organic-inorganic composite microspheres and polystyrene hollow microspheres were prepared,and their applications in concrete and coating were studied.Firstly,soap free emulsion polymerization was used to prepare polystyrene microspheres P?St-co-Na SS?with carboxyl group P?St-co-MAA?,amide group P?St-co-AM?and sulfonic acid on the surface by introducing functional monomers.The effects of the amount of functional monomers on the polymerization,the particle size and morphology of microspheres and the content of surface functional groups were studied.The results show that when the amount of functional monomers is 3-9 mol%of the total amount of monomers,it is conducive to the stability of the polymerization system,the improvement of the polymerization rate and the final conversion rate of monomers,and the polymer microspheres with good monodispersity are obtained.With the increase of the amount of functional monomers,the size of microspheres decreased,and the content of functional groups on the surface increased.Polystyrene microspheres with different functional groups on the surface were coated by nano-SiO₂ sol.The effects of the amount of SiO₂ sol and the functional groups on the preparation of composite microspheres were studied,and the composite microspheres were applied to cement hydration.With the increase of SiO₂sol content,the particle size of the SiO₂/P?St-co-MAA?microspheres remained almost the same,all of them kept good dispersion,and the coverage of SiO₂increased.When the SiO₂ sol content was 4 g,the coverage was 5.15%.The exothermic curve of cement hydration after the doping of the microspheres was 0.6 h earlier than that of nano-SiO₂ particles.The coating rate of SiO₂ to P?St-co-Na SS?is less than that of P?St-co-MAA?,so P?St-co-AM?microspheres can not be coated.P?St-co-MAA-co-BA-co-MMA?was treated by alkali and acid to obtain hollow microspheres,which were used in reflective coating.With the increase of nuclear monomer dropping time,the conversion rate of nuclear emulsion polymerization and the PDI of nuclear microspheres first increased and then decreased.With the increase of the molar ratio of alkali to acid,the diameter of microspheres increased.The polymer hollow microspheres with the diameter of 289.4 nm can be obtained by controlling the dropping time of monomer for 2 h and the molar ratio of alkali to acid for 1.75:1.The thermal conductivity of the coating decreased with the addition of hollow polymer microspheres,but the brightness,tensile strength and glossiness of the coating did not change significantly.When the amount of polymer hollow microspheres was 10 wt%of the coating formulation,the thermal conductivity of the coating decreased to 0.124 W/mK.