PBA HOLLOW MICROSPHERES PREPARED THROUGH ULTRASONICALLY INITIATED ENCAPSULATION EMULSION POLYMERIZATION

Abstract

An efficient,clean and simple preparation method of polymer hollow microspheres was provided.Ultrasonic irradiation was applied to prepare hollow polymer microspheres,which provided multi-functions of intensive dispersion,agitation,emulsification and initiation.As a result,poly(butyl acrylate)(PBA)hollow microspheres were prepared by ultrasonically initiated encapsulation emulsion polymerization.The structure and size distribution of the obtained products were investigated by transmission electron microscopy(TEM),dynamic light scattering(DLS) and Fourier transform infrared spectroscopy(FTIR).The results showed that PBA hollow microspheres had quite uniform size and even shell thickness.PBA shell was adsorbed on the surface of SiO_2 core by strong physical interaction.Furthermore,the formation mechanism of PBA hollow microspheres was studied.The results suggested that the adsorbed cationic surfactant cetyltrimethylammonium bromide(CTAB) formed a local bilayer structure with a lower layer of head groups adsorbed on the substrate surface and an upper layer of head groups in contact with solution-admicelles.And then,the hydrophobic SiO_2 surface favored the adsorption of a hydrophobic monomer butyl acrylate(BA)-adsolubilization.As a result of the ultrasonically initiated polymerization,SiO_2 particles were embedded by PBA,resulting in PBA-SiO_2 core-shell particles-polymerization.The PBA hollow microspheres were obtained by etching the inorganic SiO_2 cores in a hydrofluoric(HF) aqueous solution.And the conversion rate of BA monomer reached 88.8% in 30 min.