SiO_(2)空心球及SiO_(2)/TiO_(2)复合空心球的制备与性能研究

Preparation and Properties of SiO_(2) Hollow Spheres and SiO_(2)/TiO_(2) Composite Hollow Spheres

空心球材料是一种理想的保温结构,其极大降低了表观密度和空气对流换热,增加了热反射,降低了热导系数。因此,空心球材料在建筑、涂料、装潢等领域有着较大的应用前景。采用模板法以聚苯乙烯微球为模板,制备了纳米级SiO_(2)空心球,再以此SiO_(2)空心球为模板,采用包裹沉淀法制备了SiO_(2)/TiO_(2)复合空心球。结果显示:SiO_(2)空心球粒径为150 nm左右,球壳厚度小于10 nm;SiO_(2)/TiO_(2)复合空心球粒径为150 nm左右,球壳厚度约为20 nm,TiO_(2)主要存在于球壳表面。SiO_(2)空心球的太阳光反射率可达80%,导热系数在0.050 W·m^(-1)·K^(-1)~0.054 W·m^(-1)·K^(-1)之间。SiO_(2)/TiO_(2)复合空心球的太阳光反射率在可见-近红外波段可达90%,可见光波段可达95%,导热系数在0.050 W·m^(-1)·K^(-1)~0.052 W·m^(-1)·K^(-1)之间。

Materials in the form of hollow spheres are ideal candidates for thermal insulation,because they exhibit various characteristics,such as low apparent density,low air convection heat transfer,large heat reflection and low thermal conductivity.Therefore,hollow spheres have a great application prospect in the fields of architecture,coating,decoration and so on.Nano-sized SiO_(2) hollow spheres were prepared by using polystyrene microspheres as template,from which SiO_(2)/TiO_(2) composite hollow spheres were obtained by using a precipitation coating method.The SiO_(2) hollow spheres had an average diameter of about 150 nm and a shell thickness of less than 10 nm,while the diameter of the SiO_(2)/TiO_(2) composite hollow spheres was about 150 nm and the shell thickness was about 20 nm,in which TiO_(2) was mainly present on surface of the shell.Solar reflectance of the SiO_(2) hollow spheres reached 80%,with thermal conductivities of 0.050 W·m^(-1)·K^(-1)~0.054 W·m^(-1)·K^(-1).Solar reflectance of the SiO_(2)/TiO_(2) composite hollow spheres was 90%over the visible-near infrared band and 95% in the visible band,with thermal conductivities of 0.050 W·m^(-1)·K^(-1)~0.052 W·m^(-1)·K^(-1).