SiO_2空心球闭孔减反膜的制备及性能研究

Preparation and Properties of Hollow Silica Close Pores Antireflection Coatings

目的在获得光伏/光热用SiO_2减反膜高透过率的同时,提高其抗划伤性能和耐候性。方法以聚丙烯酸(PAA,Mw^3000)为模板制备具有核壳结构的SiO_2,离心水洗去除PAA模板,形成SiO_2空心球,接着将空心球分散于无水乙醇中形成溶胶,然后将该溶胶与酸催化溶胶混合,形成复合溶胶,最后经浸渍提拉成膜、烧结后,在载玻片上制得SiO_2空心球闭孔减反膜。用透射电子显微镜(TEM)和扫描电子显微镜(SEM)分别表征了空心球的微观结构和减反膜的表面形貌,利用紫外-可见分光光度计测试了减反膜的透过率,采用铅笔硬度测试和耐湿热测试(HAST)试验,分别检测了减反膜的抗划伤性能和耐候性。结果 TEM测试结果显示,制备的SiO_2空心球结构完整,壁厚均匀。SEM图显示减反膜表面平坦。当SiO_2空心球溶胶与酸催化溶胶的用量比例为9∶1时,减反膜透过率的峰值为98.1%,抗划伤硬度为5 H,经HAST试验后,其透过率为初始值的98.1%。结论用离心水洗法去除PAA模板制备的空心球比烧结去除模板法的空心占比高,与酸催化溶胶混合后制得的SiO_2空心球减反膜空隙率高、折射率低,从而其透过率得到提高。同时,减反膜闭孔结构使其表面致密平整,比开孔结构减反膜具有更高的抗划伤性能和耐候性,在户外太阳能光伏/光热玻璃表面减反方面具有重要的应用价值。

The work aims to improve the transmittance,scratch resistance and weatherability of SiO2 antireflection coatings used in photovoltaic/optothermal field.The SiO2 with core-shell structure was prepared with polyacrylic acid(PAA,Mw^3000)as template.PAA template was removed by centrifugation washing to form SiO2 hollow spheres.The hollow spheres were dispersed in ethanol to form a sol.Then the sol was mixed with the acid-catalyzed sol to form a composite sol.Finally,the SiO2 hollow sphere antireflection coating was prepared on the slide glass dipping,filming and sintering.The microstructure of the hollow spheres and the surface morphology of the antireflection coatings were characterized by transmission electron microscopy(TEM)and scanning electron microscopy(SEM)respectively.The transmittance of the antireflection coatings was measured by anultroviolet-visible spectrophotometer.The scratch resistance and weatherability of the antireflection coatings were measured through the pencil hardness test and the moisture-heat resistance test(HAST)respectively.TEM measurements showed that the prepared hollow SiO2 hollow spheres had a complete structure with uniform wall thickness.SEM images showed that the antireflection coatings were flat and smooth.When the ratio of SiO2 hollow sphere sol to acid catalyzed sol was 9:1,the peak value of antireflection coating transmittance was 98.1%,the scratch resistance hardness was 5 H,and the attenuation rate of transmittance became 98.1%of the initial value after HAST test.Therefore,hollow spheres prepared by centrifugal washing to remove PAA templates have a higher void ratio than that prepared by the sintering template removal method.The SiO2 hollow spheres antireflection coatings prepared by being mixed with acid-catalyzed sol have high porosity,low refractive index and improved antireflection coatings transmittance.At the same time,the closed pore structure makes antireflective coating flat and smooth,and such a coating has better scratch resistance and weatherability than the coatings with open-cell structure.It has an important application value in the outdoor solar photovoltaic/optothermal antireflection.