Soft Self-Assembled Mechanoelectrical Transducer Films from Conductive Microgel Waterborne Dispersions.

The present study aims in the developing of new soft transducers based on sophisticated stimuli-responsive microgels that exhibit spontaneous self-assembly forming cohesive films with conductive and mechanoelectrical properties. For that, oligo(ethylene glycol)-based stimuli-responsive microgels have been synthesized using bio-inspired catechol cross-linkers by one-step batch precipitation polymerization in aqueous media. Then, 3,4-ethylene dioxyyhiophene (EDOT) has been directly polymerized onto stimuli-responsive microgels using catechol groups as the unique dopant. PEDOT location is dependent on the cross-linking density of microgel particles and EDOT amount used. Moreover, the spontaneous cohesive film formation ability of the waterborne dispersion after evaporation at soft application temperature is demonstrated. The films obtained present conductivity and enhanced mechanoelectrical properties triggered by simple finger compression. Both properties are function of the cross-linking density of the microgel seed particles and PEDOT amount incorporated. In addition, to obtain maximum electrical potential generated and the possibility to amplify it, several films in series were demonstrated to be efficient. The present material can be a potential candidate for biomedical, cosmetic, and bioelectronic applications.

Electrode-modified block copoly-ionic liquid boosting the CO2 reduction toward CO in water-based media.

Coupling polymer and ionic liquids with electrodes for catalysis is a promising tool for optimization of electrocatalytic CO2 reduction reaction (CO2RR). Here, block copolymer ionic liquids BCPILs were synthesized via controlled radical polymerization and nucleophilic post-substitution to introduce imidazole moieties. We show that, thanks to these PIL functionalities, the BCPIL/Re@HPC/GDL electrode can keep the selectivity toward CO when a higher amount of water is present in the electrolyte than the raw Re@HPC/GDL system. Our results help to understand the development of solid-state ionic liquids for enhanced CO2RR in water-based electrolyte.

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

Bioinspired honeycomb-like porous films with switchable properties have drawn much attention recently owing to their potential application in scenarios in which the conversion between two opposite properties is required. Herein, the CO2-gas-triggered ON/OFF switching wettability of biocompatible polylactic acid (PLA) honeycomb porous films is fabricated. Highly ordered porous films with diameters between 2.0 and 2.8 µm are separately prepared from complexes of nonresponsive PLA and a CO2-sensitive melamine derivative [N2,N4,N6-tris(3-(dimethylamino)propyl)-1,3,5-triazine-2,4,6-triamine, MET] via the breath figure method. The hydrophilic CO2-sensitive groups can be precisely arranged in the pore's inner surface and/or top surface of the films by simply changing the PLA/MET ratio. The sensitive groups in the pore's inner surface act as a switch triggered by CO2 gas controlling water to enter the pores or not, thus resulting in ON/OFF switching wettability. The largest response of the water contact angle of honeycomb films reaches 35°, from 100 to 65°, leading to an obvious hydrophobic-hydrophilic conversion. The improved surface wettability enhances the interaction between the cell and honeycomb film surface, thus resulting in a better cell attachment. Such smart properties accompanying the biocompatible polymer and biological gas trigger facilitate possible biomedical and bioengineering applications in the future for these films.

Bio-Inspired Silica Films Combining Block Copolymers Self-Assembly and Soft Chemistry: Paving the Way toward Artificial Exosqueleton of Seawater Diatoms.

This review is in line with the principles of bio-inspiration and biomimicry in order to envisage a softer and more environmentally friendly chemistry. Here, the source of inspiration is a microalga from the oceans with the ability to build an exoskeleton of silica under ambient conditions. Following this model, this review is interested in different ways of creating porous silica films with a hierarchical porosity similar to diatoms. For this purpose, polymeric/hybrid/inorganic films structured in honeycomb using the breath figure method are reported. This versatile and easy to implement method based on the principle of rapid evaporation of a solvent in a humid atmosphere is widely used in the formation of structured films with micron-sized pores. In addition to this, the self-assembly of copolymer at the nanoscale can be addressed to obtain a hierarchically structured film. Following this structuration step, the degradation of a sacrificial block is then described from the most energy-intensive to soft process, allowing an added nanoporosity to the micron porosity of the BF method. Finally, hierarchical porous silica films are described using the sol-gel process, which is known as a soft chemistry process.

When a pH-triggered nanopatterned shape transition drives the wettability of a hierarchically self-organized film: A bio-inspired effect of "sea Anemone".

HYPOTHESIS: Hierarchically structured surfaces including sensitive materials presents the advantage to exalt wettability variation due to the combination of micro structure effect directed by Cassie Baxter and/or Wenzel behaviour which is tuned by the surface energy variation of sensitive polymer films. EXPERIMENTS: Herein is reported the synthesis and the hierarchical structuration of a pH sensitive diblock copolymer P(S-stat-MMA)-b-P4VP with a pH-sensitive Poly 4-vinylpyridine P4VP block. Applying the Breath Figure method casting (minute time scale process), this diblock copolymer allows to obtain a micro porous honeycomb film while a wall nano-structuration due to self-assembly of diblock copolymer is observed. FINDINGS: The pH-triggered wettability is studied and correlated with the morphology evolution of P4VP nano-domains investigated by AFM in a liquid cell. Indeed, a nano-dots to nano-rings/donuts transition is highlighted when decreasing the pH below the pKa of the P4VP. This nano "sea Anemone" shape transition induces the macroscopic changes of the wettability of a hierarchically self-organized honeycomb film, explained by the protonation of P4VP chains inducing electrostatic repulsion and then hydrophilic surface.

Reactive nano-patterns in triple structured bio-inspired honeycomb films as a clickable platform.

A hierarchically structured platform was obtained from directed self-assembly of a poly(styrene)-b-poly(4-vinylbenzylchloride) (PS-b-PVBC) block copolymer (BCP) during breath figure (BF) templating. The BF process using a water/ethanol atmosphere gave a unique double porosity in which hexagonally arranged micron-sized pores were encircled by a secondary population of smaller, nano-sized pores. A third level of structuration was simultaneously introduced between the pores by BCP self-assembly to form out-of-the-plane nano-cylinders, offering a film with an unprecedented triple structure, which could be used as a reactive platform. Indeed the surface nano-domains of VBC were exploited as reactive nano-patterns for site-specific chemical functionalization.

Hierarchically organized honeycomb films through block copolymer directed self-assembly in "breath figure" templating and soft microwave-triggered annealing.

Hierarchically organized polymer films are produced with a high level of order from the combination of block copolymer nanophase segregation, "breath figure" methodology and microwave irradiation. A block copolymer based on poly(methyl methacrylate) and poly(n-butylacrylate) featuring cylindrical nanopatterns is involved in the "breath figure" process to create a microporous honeycomb structure. These films are submitted to microwave annealing to enhance the degree of ordering of the nano-segregation without the destruction of the honeycomb microstructure, which is not possible by classical thermal or solvent annealing. Ellipsometry, optical and atomic force microscopy are used to study three key parameters; the substrate nature, the film thickness and the microwave irradiation power. The silicon wafer is the substrate of choice to efficiently act as the heating transfer element and 60 seconds at 10 watts are enough to nicely order the 1 µm thick copolymer films. These conditions are eventually applied on hierarchically organized polymer films to obtain a hexagonal array of 100 nm deep holes within a matrix of perpendicularly aligned nano-cylinders.

Highly Ordered Nanoring Arrays Formed by Templated Si-Containing Triblock Terpolymer Thin Films.

Laterally ordered nanorings with a periodicity of 38 nm are produced from the directed self-assembly of poly(1,1-dimethylsilacyclobutane)-block-polystyrene-block-poly(methyl methacrylate) thin films on topographically patterned substrates. Such nanoscale arrays with vertically oriented rings are highly desired in technological applications including memory using magnetic recording, metamaterial, waveguide, etc.