Designing a photocatalytic and self-renewed g-C3N4 nanosheet/poly-Schiff base composite coating towards long-term biofouling resistance.

Inhibiting the adhesion and growth of marine microorganisms through photocatalysis is a potentially efficient and environmentally friendly antifouling strategy. However, the undesired "shading effect" caused by resin coatings and microbial deposition reduces the utilization of the catalysts and leads to a failure in the antifouling active substance on the coating surface. Here, we successfully developed a composite coating (DPC-x) combining g-C3N4 nanosheet (g-C-NS) photocatalysts with degradable green poly-Schiff base resins, which integrates the dual functions of enhanced dynamic self-renewal and photocatalytic antibacterial activities towards long-term anti-biofouling. The controllable and complete degradability of the poly-Schiff base polymer chains and the self-renewal mechanism of the DPC-x coating exposed the internal g-C-NS, which provided a constant stream of photocatalytic reactive interfaces for 100% utilization and release of the photocatalysts. g-C-NS were homogeneously dispersed in the degradable resin coating, significantly enhancing and adjusting the self-renewal rate of the poly-Schiff base resin coating in visible light. The degradation reaction rate of DPC-0.2 (20 wt% g-C-NS) was 40 times that of DPC, thus improving the capabilities of surface self-renewal and fouling-release. Due to the synergistic antifouling mechanism of the efficient antibacterial properties and the enhanced degradation/self-renewal, the antimicrobial rates of DPC and DPC-0.2 were 94.58% and 99.31% in the dark, and 98.2% and 99.87% in visible light. DPC-x has excellent all-weather antimicrobial efficacy and could offer a new perspective on eco-friendly marine antifouling strategies.

Thermomechanically Resilient Polyionic Elastomers with Enhanced Anti-Icing Performances.

Anti-icing gels inhibit ice formation and accretion; however, current iterations face prevalent drawbacks such as poor strength, weak substrate adhesion, and limited anti-icing properties. Herein, we propose a novel approach to address these challenges by developing a thermomechanical robust polyionic elastomer (PIE) with enhanced anti-icing properties. The PIE surface exhibits an icing delay time up to 5400 s and remains frost-free after exposure to -10 °C for 3.5 h, attributed to the inhibitory effect on ice formation by ions from ILs and the polyelectrolyte network. Moreover, the PIE exhibits remarkable anti-icing durability, with ice adhesion strengths below 35 kPa after undergoing 30 icing/deicing cycle tests at -20 °C. Following sandpaper abrasion (300 cycles), scratching, and heat treatment (100 °C, 16 h), the adhesion strength remains ca. 20 kPa, highlighting its resilience under various thermal and mechanical conditions. This exceptional durability is attributed to the low volatility of the IL and the robust ionic interactions within the PIE network. Furthermore, the PIE demonstrates favorable self-healing properties and strong substrate adhesion in both low-temperature and ambient environments, facilitated by the abundance of hydrogen bonds and electrostatic forces within PIE. This work presents an innovative approach to developing high-performance, durable, and robust anti-icing materials with potential implications across various fields.

Multi-stimulus Response Behavior of Biomimetic Autocrine Waxy Materials for Potential Self-Constructing Surface Microstructures.

Many functions of terrestrial plant leaves rely on the regenerable epidermal wax layer. Biomimetic autocrine waxy materials (AWMs) inspired by renewable epidermal waxes are attracting increasing attention. However, the growth properties of the wax layer remain unclear, limiting the development of this promising material. This work focuses on the stimulated growth characteristics and microstructural regulation methods of the waxy layers. It is found that the wax layers exhibit a corresponding behavior of changing their surface micromorphology under force, heat, solvents, and other stimuli during the self-growth process, and as a result of which, various types of fine surface microstructures such as grids, rings, stripes, pattern copying, and printing can be self-built on their surfaces. The composition of the surface autocrine wax layer changes with the autocrine time, and this finding may be useful for the separation and purification of alkane mixtures. In addition, the surface wax layer possesses the ability to self-heal and strengthen itself at the damage site after being stimulated by injury, similar to the damage-response behavior of a bark surface. Such multi-stimulus response behavior described here provides a platform for the discovery of more functional materials and microstructural self-construction techniques and can also serve as a basis for their applications.

Engineering the interface in graphene oxide/epoxy composites using bio-based epoxy-graphene oxide nanomaterial to achieve superior anticorrosion performance.

The protective performance of graphene/polymer composite coatings largely depends on the interface design in resin matrix. Herein, we report the synthesis of bio-based cardanol epoxy modified graphene oxide (GODN) nanomaterial and its application in epoxy coatings for the achievement of fine interface toward high performance anticorrosion composite coatings. The chemical composition of prepared GODN nanomaterial was investigated by FTIR, Raman and XPS spectra, respectively. The presence of cardanol epoxy attached on GO surface promotes the formation of chemical bonds between GO and epoxy resin, providing strong interfacial interaction and enhanced adhesion. Electrochemical results revealed that the GODN1%/EP composite coating exhibits high impedance (4.38 × 108 Ω cm2) even after 45 days immersion. Compared with pure EP coating, the localized corrosion reaction of GODN1%/EP coating can be inhibited under defected interface. The enhanced protective performance of GODN/EP composite coating was attributed to two aspects: (1) the impermeable GO greatly suppressed the penetration of aggressive ions and (2) the attached cardanol epoxy chains effectively improved the interfacial interaction and thus inhibited the crack propagation.

Incorporation of electroconductive carbon fibers to achieve enhanced anti-corrosion performance of zinc rich coatings.

Zinc rich epoxy (ZRE) coatings can provide sacrificial anode protection for metal substrate. Electrically conductive fillers can be added into ZRE coatings to create electroconductive network and improve the utilization of zinc particles. Inspired by the structure of reinforced concrete, in this work, carbon fibers with a length of 2 mm, 5 mm, and 10 mm were used as electrically conductive fillers to drive more zinc particle into electrically conductive paths and to provide coatings with better mechanical properties. Without agglomeration, ZRE-10 can achieve an efficient protection for copper substrate up to 50 days in 3.5 wt% NaCl solution, much longer than that of ZRE coating. Moreover, the fraction of water absorbed by ZRE-10 is 14%, which for ZRE is 20%, and the adhesion strength of ZRE-10 increased by 65% compared with that of ZRE. All tests in this work can prove a remarkably enhanced anticorrosion performance and mechanical properties of ZRE coatings achieved by addition of longer carbon fibers.