Photomanipulated Architecture and Patterning of Azopolymer Array.

Here reported is the approach to prepare the tunable 3D architecture and patterning through photoinduced orientation of azopolymer. The hemispherical PAzoMA array can be transformed into spindlelike, flat ellipsoidlike, thick spindlelike, near-hexagon, near-quadrangle, and near-rhombus arrays while being exposed to linearly polarized light (LPL). The size and alignment of the arrays can be precisely controlled by manipulating the irradiation time. Furthermore, complex 3D architectures of the PAzoMA array are readily fabricated through secondary irradiation along different direction. This technique is promising for functionalized surfaces and photonic devices.

Deterministic Reshaping of Breath Figure Arrays by Directional Photomanipulation.

The fabrication of desired structures is one of the most urgent topics in current research on porous polymer films. Herein, directional photomanipulation in conjunction with breath figure processing has been demonstrated for the preparation of porous polymeric films with finely tunable pore shape and size. Because of the photoinduced directional mass migration of azobenzene units upon vertical incident linearly polarized light (LPL) irradiation, round pores on honeycomb films can be reshaped into multifarious shapes including rectangle, rhombus, dumbbell, line, and so forth. In addition, slantwise LPL irradiation produces unique asymmetrical structure inside the pores oriented along the polarized direction. On the other hand, circularly polarized light (CPL) irradiation affords manipulation of the wall thickness without changing the pore shape. This versatile directional photomanipulation method can be implemented to large-area and high-throughput reshaping processes, which paves the way to a number of promising applications such as a flexible etching mask for patterning.

Breath Figure in Reactive Vapor: A New Route to Nanopore Array.

A breath figure (BF)-inspired method for preparing ordered porous films has attracted more and more attention because of its simplicity, low cost, and easy implementation. However, it remains a challenge to use this method to fabricate nanoscale porous structures without designed polymer architecture and auxiliary. Herein, we first report a facile method to fabricate BF arrays with nanopores (nanoBFAs) in reactive vapor. Depending on the chemical reaction between the formic acid (FA) droplet template and the polyvinylpyridine (PVP) segments in copolymer, we successfully create nanoBFAs by casting a PVP-containing copolymer solution in CS2 in FA vapor. The condensed FA droplets can be instantly fixed by the PVP composition, and thus the growth and the aggregation of adjacent droplets are effectively restricted. Eventually, nanoBFAs are achieved in wide range solution concentration. In addition, binary porous structures with both nano- and microscale topology can be formed by using a FA/water mixed vapor with a one-step BF process. The produced nanoBFA films exhibit excellent antireflection performance with 0.5% reflectance, which is well-preserved even after hydrophobic treatment. This modified BF technique not only facilitates the elucidation of BFA formation mechanism but also opens a new way of fabricating nanoporous structures, which may have potential applications in electronic and optical devices.

Nanoring Arrays on Fe Coated Substrate: Formation and Guidance for the Growth of Hierarchical CNTs.

In this article, we report the formation of nanoring structures on Fe coated substrate and their application in guiding the growth of carbon nanotube (CNT) patterns with hierarchical structures. The formation of nanorings involves the etching of polystyrene (PS) monolayer colloidal crystals (MCCs) under reactive ion etching (RIE), and the redeposition and cross-linkage of the active degradation products at the contact line between the MCCs and the substrate. After washing out the MCCs, insoluble nanorings with hexagonal order on the substrate are developed. The RIE process can control the morphology of the nanorings, as well as the distribution of the Fe element on the substrate; thus, a continuous Fe layer and separated Fe discs on the substrate are created on substrate after washing, depending on the etching time and the shield of MCCs. The surviving Fe element can work as the catalyst to initiate the in situ growth of aligned CNTs in the following chemical vapor deposition (CVD) process, while the Fe element underneath the nanorings keep its inactivity. Eventually, CNT patterns with hierarchical structures are formed. One level originates from the surviving Fe layer; the other level is templated from the nanoring structures, which cause the blank area in the CNT bundles.