Synthesis of hollow inorganic nano-particles templated by polymeric micelles with core-shell-corona structure and their applications

我们尝试在水溶液中以具有核-壳-冠结构的聚合物胶束为模板合成无机中空纳米粒子。我们从二氧化硅纳米颗粒开始。以聚苯乙烯-b-2-乙烯基吡啶-b-环氧乙烷（PS-PVP-PEO）为模板，四甲氧基硅烷（TMOS）为前驱体，制备了模板胶束。通过溶胶-凝胶反应将二氧化硅沉积在PVP壳层中。在通过煅烧从聚合物-二氧化硅杂化粒子中去除模板聚合物后，我们获得了中空二氧化硅纳米粒子。发现所获得的中空二氧化硅纳米粒子具有球形结构，具有窄的空隙体积和壳厚度分布。此外，我们试图控制中空二氧化硅的结构参数，即，通过改变PS链长来改变空隙体积，通过改变二氧化硅前体的量来改变壁厚。正如预期的那样，所获得的中空二氧化硅的空隙体积有规律地随着PS链长的增加而增加，并且壁厚随着前体浓度的增加而增加。据我们所知，这是第一次成功地在几纳米尺度上对中空二氧化硅的空腔尺寸和壁厚进行微调的研究，我们的方法的显著特点是在二氧化硅合成过程中共聚物的每个嵌段都有自己的功能;（i）PS嵌段形成胶束的核，作为中空二氧化硅中空隙空间的模板，（ii）PVP嵌段形成壳，作为TMOS的溶胶-凝胶反应的反应场，（iii）PEO形成电晕以稳定聚合物/SiO2中间体杂化物.我们的方法似乎是一个综合性的方法，即它可以应用于其他无机材料，并且可以使用不同的三嵌段共聚物胶束作为模板.

We tried to synthesize inorganic hollow nano-particles by templating a polymeric micelle with a core-shell-corona structure in aqueous solutions. We started with silica nano-particles. The template micelle was prepared from poly (styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-PVP-PEO), and the precursor employed is tetramethoxysilane (TMOS). Silica was deposited in a domain of PVP shell by sol-gel reaction. After removing the template polymer from the polymer-silica hybrid particles by calcinations, we obtained hollow silica nanoparticles. The obtained hollow silica nanoparticles were found to have a spherical structure with narrow distributions of void volume and shell thickness.Furthermore, we tried to control the structural parameters of the hollow silica; i.e., the void volumes by changing the PS chain length, and the wall thickness by changing the amount of the silica precursor. As expected, the void volume of the obtained hollow silica regularly increased with the increase in the PS chain length, and the wall thickness increased with the increase in the concentration of the precursor. To the best of our knowledge, this is the first study in which the cavity size and wall thickness of the hollow silica were successfully fine-tuned on a scale of several nanometers.The significant feature of our method is that each block of the copolymer has its own function during the silica synthesis ; (i) the PS block forms the core of the micelle to be a template of the void space in the hollow silica, (ii) the PVP block forms the shell to be a reaction field of the sol-gel reaction of TMOS, and (iii) PEO forms the corona to stabilize the polymer/silica intermediate hybrids.Our method seems to be a comprehensive one; that is, it can be applied to the other inorganic materials and different triblock copolymer micelles can be used as a template.