Departments of Chemistry, Biochemistry and Molecular Biology, and Physics , The Pennsylvania State University , University Park , State College , Pennsylvania 16802 , United States.
ACS Appl Mater Interfaces. 2019 Jan 30;11(4):4568-4577. doi: 10.1021/acsami.8b17907. Epub 2019 Jan 18.
During evaporative self-assembly of colloidal crystal films, spherical l-arginine-stabilized silica colloids adapt to different close-packed geometries by faceting and forming bridge connections with their nearest neighbors. We systematically studied the morphological changes of 37 and 138 nm diameter colloids during evaporative assembly and compared them to 65 nm Stöber silica colloids prepared without l-arginine. Colloidal crystal films were grown from particles that had been dialyzed against water or l-arginine, and tetraethyl orthosilicate (TEOS) and/or l-arginine were added to solutions during colloidal film growth. Solid-state Si NMR spectra showed the presence of l-arginine and incompletely condensed silica in colloids grown from silica seeds in l-arginine solutions. These colloids were especially susceptible to chemical ripening during the colloidal assembly process, adopting faceted shapes that reflected the packing symmetry of the colloidal crystal films. The addition of l-arginine and TEOS accelerated these shape changes by catalyzing the hydrolysis and olation of silica and by adding a source of silica to the solution, respectively. This chemistry provides a route to single-component and binary colloidal crystals composed of nonspherical silica building blocks.
在胶体晶体膜的蒸发自组装过程中，球形 l-精氨酸稳定的硅溶胶通过表面处理和与最近邻形成桥接连接来适应不同的密堆积几何形状。我们系统地研究了 37nm 和 138nm 直径胶体在蒸发组装过程中的形态变化，并将其与没有 l-精氨酸的 65nm Stöber 硅溶胶进行了比较。胶体晶体膜是由经过水或 l-精氨酸透析的颗粒生长而成的，在胶体膜生长过程中，四乙氧基硅烷（TEOS）和/或 l-精氨酸被添加到溶液中。固态 Si NMR 光谱表明，在 l-精氨酸溶液中用硅种子生长的胶体中存在 l-精氨酸和不完全缩合的硅。这些胶体在胶体组装过程中特别容易受到化学熟化的影响，采用反映胶体晶体膜堆积对称性的有面形状。添加 l-精氨酸和 TEOS 分别通过催化硅的水解和硅烷化以及向溶液中添加硅源来加速这些形状变化。这种化学方法为由非球形硅基块组成的单组分和二元胶体晶体提供了一种途径。
