Modified Soap-free Emulsion Method For Preparing Polystyrene Nanoparticles With Controllable Morphology

In the past few decades,the research on non-spherical polymer particles has developed rapidly and has become a research focus in the polymer field.Non-spherical polymer particles have unique advantages and irreplaceable functions in the field of new materials,special photonic crystals,and self-assembly and identification due to their unique physical and chemical properties.Therefore,it is extremely important to explore its preparation method and morphological control.This paper takes polystyrene particles as an example,and mainly explores three aspects:First,monodispersed PS nanospheres were prepared by an improved soap-free emulsion polymerization method,which broke the problems of uneven polymerization and harsh reaction conditions in traditional soap-free emulsions.The prepared particles had high monodispersity and could be left for a long time.Using dynamic light scattering?DLS?characterization methods to detect the data,through the adjustment of the amount of styrene monomer and ethanol,the particle size of monodisperse PS microspheres was adjusted from 100 nm to 350 nm.At the same time,this method was extended to other small molecule alcohol systems,and the effects of different alcohol systems on the formation of PS microspheres were explored.Experiments have observed that as the relative molecular mass of the alcohol used increases,the resulting PS particle size increases.These experiments laid the foundation for the subsequent control of non-spherical morphology.Second,it can control the morphology of PS particles by changing the volume of the initiator solution of KPS and NaHSO₃ added to a constant volume of styrene/water/alcohol monomer mixture.In the styrene/water/ethanol system,through this The experimental method obtained spherical,raspberry-like,hollow flower-shaped PS nanoparticles in turn,and further discussed the formation mechanism.At the same time,the prepared PS particles were used to coat the film to realize the coating from hydrophilic to hydrophobic.change.In this experiment,the PS particles obtained in other small molecule alcohol systems were also discussed,which increased the scope of application of the experimental method.In the experiment,transmission electron microscope?TEM?and scanning electron microscope?SEM?were used to characterize the morphology of the prepared PS particles.The differences in the roughness and particle size of the particles were measured by atomic force probe microscope?AFM?and DLS,respectively.Characterized.Third,based on the principle that the degree of polymerization of the outer wall of the particles obtained during the polymerization of styrene in this system is higher than that of the interior,PS nanoparticles with adjustable hollow structure size were prepared by the dilution method and the dialysis method.When the reaction emulsions of different polymerization times are diluted to the same multiple,single collapsed hollow PS particles are obtained.When the reaction emulsions of the same polymerization time are diluted to different multiples,double collapsed PS particles are found at low polymerization time and high dilution multiples.Solid PS microspheres are obtained at high polymerization times and high dilution times.At the same time,the relevant mechanism was further explored.At the same time,the morphology of the experiment was characterized by TEM and SEM,and the mechanism of the experiment was explored by surface tension meter.