Department of Chemistry, Renmin University of China, Beijing 100872, China.
Langmuir. 2011 Dec 6;27(23):14240-7. doi: 10.1021/la2030632. Epub 2011 Nov 2.
We apply the concept of wettability transition to manipulate the morphology and entrapment of polymer nanostructures inside cylindrical nanopores of anodic aluminum oxide (AAO) membranes. When AAO/polystyrene (PS) hybrids, i.e., AAO/PS nanorods or AAO/PS nanotubes, are immersed into a polyethylene glycol (PEG) reservoir above the glass transition temperature of PS, a wettability transition from wetting to nonwetting of PS can be triggered due to the invasion of the more wettable PEG melt. The wettability transition enables us to develop a nondestructive method to entrap hemispherically capped nanorods inside nanopores. Moreover, we can obtain single nanorods with the desired aspect ratio by further dissolving the AAO template, in contrast to the drawbacks of nonuniformity or destructiveness from the conventional ultrasonication method. In the case of AAO/PS nanotubes, the wettability transition induced dewetting of PS nanotube walls results in the disconnection and entrapment of nonwetting PS domains (i.e., nanospheres, nanocapsules, or capped nanorods). Moreover, PEG is then washed to recover the pristine wettability of PS on the alumina surface; further annealing of the PS nanospheres inside AAO nanopores under vacuum can generate some unique nanostructures, particularly semicylindrical nanorods.
我们应用润湿性转变的概念来操纵聚合物纳米结构在阳极氧化铝（AAO）膜的圆柱纳米孔内的形态和捕获。当 AAO/聚苯乙烯（PS）杂化物，即 AAO/PS 纳米棒或 AAO/PS 纳米管，浸入到高于 PS 的玻璃化转变温度的聚乙二醇（PEG）储层中时，由于更润湿性的 PEG 熔体的侵入，可以触发 PS 从润湿到不润湿的润湿性转变。润湿性转变使我们能够开发一种非破坏性的方法来捕获纳米孔内具有半球形帽的纳米棒。此外，我们可以通过进一步溶解 AAO 模板获得具有所需纵横比的单根纳米棒，与传统超声法的不均匀性或破坏性的缺点形成对比。在 AAO/PS 纳米管的情况下，PS 纳米管壁的润湿性转变诱导的去湿导致不润湿 PS 域（即纳米球、纳米胶囊或帽状纳米棒）的断开和捕获。此外，然后可以洗去 PEG 以恢复氧化铝表面上 PS 的原始润湿性；在真空下对 AAO 纳米孔内的 PS 纳米球进行进一步退火可以产生一些独特的纳米结构，特别是半圆柱形纳米棒。
