超声辐照乳液聚合制备聚丙烯酸正丁酯空心微球

PBA HOLLOW MICROSPHERES PREPARED THROUGH ULTRASONICALLY INITIATED ENCAPSULATION EMULSION POLYMERIZATION

利用超声辐照引发包覆乳液聚合制备了聚丙烯酸正丁酯(PBA)空心微球.TEM和DLS结果显示,空心微球粒径均一,壳层厚度均匀.FTIR结果显示,壳-核物质间以物理吸附相结合,没有形成化学键.同时,利用TEM和DLS研究了空心微球的形成机理,阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)在CMC浓度以下首先吸附在纳米SiO2粒子表面形成双层结构,然后丙烯酸正丁酯(BA)单体增溶进入CTAB层间,在超声辐照引发、分散作用下包覆聚合形成均一的PBA-SiO2壳-核粒子,再利用HF溶液去除无机核,得到PBA空心微球.

An efficient, clean and simple preparation method of polymer hollow microspheres was provided. Ultrasonic irradiation was applied to prepare hollow polymer mierospheres, 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 SiO2 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-admieelles. And then, the hydrophobic SiO2 surface favored the adsorption of a hydrophobic monomer butyl acrylate （BA）-adsolubilization. As a result of the ultrasonically initiated polymerization, SiO2 particles were embedded by PBA, resulting in PBA-SiO2 core-shell particles-polymerization. The PBA hollow microspheres were obtained by etching the inorganic SiO2 cores in a hydrofluoric （HF） aqueous solution. And the conversion rate of BA monomer reached 88.8 % in 30 min.