School of Chemical and Biological Engineering, Interdisciplinary Program in Nano-Science & Technology, and Center for Functional Polymer Thin Films, Seoul National University, San 56-1, Shilim-dong, Kwanak-gu, Seoul 151-744, Korea.
ACS Appl Mater Interfaces. 2009 Apr;1(4):913-20. doi: 10.1021/am900026s.
The morphological changes from tubules to large hollow spheres to (micelle-sized) small hollow-spherical silica were realized by polystyrene-block-poly(vinylpyridine) (PS-b-PVP) block copolymer micelle templates by controlling the intermolecular interactions with the corona chains. PS-b-PVP with weak intermolecular interactions among PVP corona chains yields the coexistence of tubules, large hollow spheres, and small hollow spheres. The coexistence of the three phases arises from the direct aggregation of block copolymer micelles during hydrolytic condensation of a silica precursor (tetraethylorthosilicate), as evidenced by transmission electron microscopy. When the degree of intermolecular interactions within the PVP corona blocks is increased by a change in either the degree of quaternization of the PVP blocks or the dielectric constant of the medium, small hollow spherical silica, with size equivalent to the block copolymer micelles, were solely obtained. We believe that this morphological change is due to the fact that the dipole-dipole interactions among quaternized PVP blocks physically cross-link the PVP coronas in micelles resisting the curvature change during the silica condensation.
通过控制与冠链的分子间相互作用，聚苯乙烯-嵌段-聚（乙烯基吡啶）（PS-b-PVP）嵌段共聚物胶束模板实现了从管状到大型中空球体再到（胶束大小的）中空小球体的形态变化。具有弱 PVP 冠链分子间相互作用的 PS-b-PVP 会产生管状、大型中空球体和小型中空球体共存的情况。这三种相的共存源于在二氧化硅前体（正硅酸乙酯）的水解缩合过程中，嵌段共聚物胶束的直接聚集，这一点通过透射电子显微镜得到了证明。当 PVP 冠链中的分子间相互作用程度通过改变 PVP 链的季铵化程度或介质的介电常数而增加时，仅获得与嵌段共聚物胶束尺寸相当的小型中空球形二氧化硅。我们认为这种形态变化是由于季铵化 PVP 链之间的偶极-偶极相互作用在物理上交联了胶束中的 PVP 冠，从而在二氧化硅缩合过程中抵抗曲率变化。
