Fabrication of Regularly Patterned Microporous Films by Self‐Organization of an Amphiphilic Liquid‐Crystalline Diblock Copolymer in a Dry Environment

Abstract

An amphiphilic LCBC PEO‐b‐PAz consisting of flexible PEO as a hydrophilic block and poly(methacrylic acid) containing an azobenzene moiety in side chain as a hydrophobic LC segment was synthesized and used to fabricated microporous films by spin‐coating method under a dry environment. With the help of a small amount of water, well‐arranged ellipsoidal micropores embedded in a LC matrix were obtained and the pore size is in the range of several tens µm of water. The influence of water content and rotational speed was studied in detail. It was found that regularly patterned microporous films can be prepared with certain water content, and the pore size can be easily tailored through changing the rotational speed. The obtained microporous structures showed good thermal and photo stability.

Breath Figure: A Nature-Inspired Preparation Method for Ordered Porous Films

“…A liquid-crystalline (LC) diblock copolymer, poly(ethylene oxide)-b-poly(azobenzene-modified methacrylic acid) (PEO-b-PAz, 30), was also used to prepare BFA films by spin-coating method. 239 Fluoride BCPs are a group of unique polymers with high thermal stability and chemical inertness and low dielectric constants and surface energy. 240 Johnston and Korgel et al prepared PEO-b-PFOMA (2) and used it to prepare BFA films.…”

“…They attributed these differences to the smaller thickness of the polymer solution on the water surface. A liquid-crystalline (LC) diblock copolymer, poly­(ethylene oxide)- b -poly­(azobenzene-modified methacrylic acid) (PEO- b -PAz, 30 ), was also used to prepare BFA films by spin-coating method …”

Azobenzene-Containing Materials for Hologram

“…In LC block copolymers with well-defined structures, microphase separation often occurs because of the inherent immiscibility of the different blocks, resulted in diverse of nanostructures like nanospheres and nanocylinders (Yu et al, 2006a(Yu et al, , 2006b(Yu et al, , 2007d(Yu et al, , 2007e, 2009bChen et al, 2010b). Generally, the phase-segregated nano domains are far smaller than the wavelength of the visible light (Yu et al, 2007b(Yu et al, , 2007c, making it possible to get rid of the scattering effect.…”

Photoresponsive Block Copolymers Containing Azobenzenes and Other Chromophores

“…With an amphiphilic PRBC consisting of a flexible PEO segment as a hydrophilic part and poly(methacrylate) containing an AZ moiety in side chain as a hydrophobic one, well-arranged ellipsoidal micropores embedded in an LC matrix were fabricated by spin coating under a dry environment ( Figure 23 ) [ 125 ]. The formation process of the microporous films consisted of the following steps: Firstly, the PRBC was dissolved in tetrahydrofuran (THF), a good solvent for both segments.…”

“…With the help of small amount water, the obtained pore size was controlled in a range of several-ten microns [ 125 ]. Then the influence of water content and rotational speed was studied in detail.…”