Uniform formation of mesoporous silica shell on micron-sized cores in the presence of hydrocarbon used as a swelling agent
Uniform formation of mesoporous silica shell on micron-sized cores in the presence of hydrocarbon used as a swelling agent
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DOI：
10.1007/s10971-018-4589-y
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发表时间：
2018-03-01
影响因子：
2.5
通讯作者：
Konno, Mikio
中科院分区：
文献类型：
--
作者：
Ishii, Haruyuki;Nara, Mitsunobu;Konno, Mikio
以十六烷基三甲基溴化铵（CTAB）为模板剂，正硅酸乙酯（TEOS）为原料，通过水解缩合反应在低分散性的微米级二氧化硅微球上制备了介孔二氧化硅壳层。在反应中，在存在或不存在非极性烃的情况下，检查适合于均匀形成中孔壳的TEOS的浓度，所述非极性烃用作溶胀剂以扩大CTAB胶束的尺寸。采用分子量低于常规溶胀剂1，3，5-三甲基苯的环己烷（CyH）可以有效地扩大壳中的中孔，均匀地覆盖微米尺寸的球。溶胶-凝胶反应中的核-壳粒子的SEM图像显示，在壳形成的早期阶段观察到核上的网状表面特征，而最终在核上获得均匀的介孔壳。随着溶胀剂CyH扩散到CTAB胶束中的混合时间的延长，介孔壳层厚度的均匀性增加，介孔尺寸增大。[图形]。
Hydrolysis and condensation of tetraethyl orthosilicate (TEOS) with cetyltrimethylammonium bromide (CTAB) used as a template for mesopores were conducted to form mesoporous silica shell onto micron-sized silica spheres with low polydispersity. The concentration of TEOS suitable for uniform formation of the mesoporous shell was examined in the reactions in the presence or absence of nonpolar hydrocarbon that was used as a swelling agent to expand the size of CTAB micelles. Employment of cyclohexane (CyH) with a molecular weight lower than a conventional swelling agent of 1,3,5-trimethylbenzene could effectively expand mesopores in the shell uniformly covering the micron-sized spheres. SEM images of the core-shell particles in the sol-gel reaction reveled that a web-like surface feature on the core was observed in an early stage of shell formation, whereas uniform mesoporous shell was finally obtained on the core. The extension of mixing time for the swelling agent of CyH to be diffused into CTAB micelles resulted in an increase in uniformity in thickness of the mesoporous shell with the large sizes of mesopores.[GRAPHICS].