Directed Self‐Assembly in “Breath Figure” Templating of Melamine‐Based Amphiphilic Copolymers: Effect of Hydrophilic End‐Chain on Honeycomb Film Formation and Wetting

Abstract

Amphiphilic copolymers are widely used in the fabrication of hierarchically honeycomb-structured films through a "breath figure" (BF) process because the hydrophilic block plays a key role in stabilising water templating. However, the hydrophilic monomers reported are mainly confined to acrylic acid and its derivatives, which largely limits understanding of the formation of BF arrays and the introduction of additional functions on porous films. The relationship between polymer composition, film microstructure and surface properties are also less documented. Herein, a novel melamine-based hydrophilic moiety, N-[3-({3-[(4,6-bis{[3-(dimethylamino)propyl]amino}-1,3,5-triazin-2yl)amino]propyl}(methyl)amino)propyl]methacrylamide (ANME), was incorporated into polystyrene (PS) chains by combining atom-transfer radical polymerisation and post-modification to afford three well-defined end-functionalised PS-PANME derivatives. These polymers were used to fabricate honeycomb films through the BF technique. Both inner and outer microstructures of the films were characterised by optical microscopy, AFM and SEM. Polymer hydrophilicity is enhanced upon increasing the PANME content, which results in variation of the film microstructure and porosity, and provokes a transition from Cassie-Baxter to Wenzel behaviour. Furthermore, the surface wettability of as-prepared honeycomb films and corresponding pillared films is mainly governed by film morphology, rather than by the properties of the polymers. Knowledge of the relationships between polymer composition and film structure, as well as surface wettability, is beneficial to design and prepare hierarchically porous films with desirable structures and properties.

Large-Scale and Low-Cost Preparation of Ordered Honeycomb-Patterned Film by Solvent Evaporation-Induced Phase Separation Method

“…The lateral capillary force and stable droplets are important factors that control the orderliness of the structure . Therefore, it is a good idea to choose polymers with special structural features, such as block copolymers, comb copolymers, and amphiphilic polymers, because their special structure makes them easier to self-assemble at the interface and prevent the coalescence of droplets. − The addition of nanoparticles or surfactants as stabilizers could improve the stability of droplets to obtain high quality patterned films. It is difficult to develop ordered structures without adding nanoparticles or surfactants to nonpolar linear polymers, since the polymers cannot form envelopes and stabilize the droplets.…”

CO2-Triggered ON/OFF Wettability Switching on Bioinspired Polylactic Acid Porous Films for Controllable Bioadhesion

“…Mammalian cell culture is a key technology to study animal physiological processes and to produce various biopharmaceuticals. − It is well known that both the surface morphology and surface properties affect cell behavior. ,− Rough surfaces with ordered porous structures, that is, honeycomb-patterned PFs, are good substrates for cell attachment and spreading due to the significantly enlarged surface area and channels for cell–cell interaction. ,,,− Previous studies ,,, revealed that honeycomb films with a hydrophilic surface can enhance the interaction between cells and films, leading to better performances for cell culturing. However, most honeycomb films prepared from pure polymers are normally hydrophobic due to the formation mechanism, ,,,, so that they are not suitable to be directly used as scaffolds. Additional treatment, such as UV irradiation, UV–ozone exposure, change of pH or change of temperature, ,,,, were applied to improve film surface wettability before cell culturing.…”

“…8,9,12,45−48 Previous studies 25,35,49,50 revealed that honeycomb films with a hydrophilic surface can enhance the interaction between cells and films, leading to better performances for cell culturing. However, most honeycomb films prepared from pure polymers are normally hydrophobic due to the formation mechanism, 22,31,32,51,52 so that they are not suitable to be directly used as scaffolds. Additional treatment, such as UV irradiation, UV−ozone exposure, change of pH or change of temperature, 12,18,25,49,53 were applied to improve film surface wettability before cell culturing.…”

Self-Assembly of CsPbBr3 Perovskites in Micropatterned Polymeric Surfaces: Toward Luminescent Materials with Self-Cleaning Properties

“…Surfaces patterned by BF mostly consist of polymers, copolymers, blends, or other soft matter compounds. ,, However, some reports show the development of hybrid materials using nanoparticles or metal ion precursors embedded in a high molecular weight polymer matrix. For instance, hybrid films for different functional applications have been prepared using Ag, , Au, Sn, or SiO 2 …”