Transparent Janus Hydrogel Wet Adhesive for Underwater Self-Cleaning

Abstract

The optical window is a key part of a sensor specially used for oceanographic detection, but it is often severely affected by marine biofouling and oil pollution, resulting in reduced transparency and lifespan. Hydrogel, as a hydrophilic polymer network, has excellent antifouling effects with good transparency, but it is difficult to adhere to substrates, which greatly limits its practical applications. To solve the above problem, a transparent Janus hydrogel wet adhesive was prepared through modifying poly­(vinyl alcohol)/glycerol–tannic acid/Cu2+ (PVA/Gly-TA/Cu2+) hydrogel with the underwater adhesive poly­(dopamine methacrylamide-co-methoxyethyl acrylate) (P­(DMA-co-MEA)) via the coordination effect between Cu2+ and catechol. Even when coated with adhesive, the sample still retained good transmittance. The presence of Cu2+ endowed the hydrogel with better tensile strength and, at the same time, can improve the adhesion of the hydrogel to the substrate through the coordination effect with the adhesive. The tensile stress of Janus hydrogels can even reach 4.4 MPa, and the adhesion strength of the obtained Janus hydrogel can reach about 14 kPa in seawater. Furthermore, the Cu-rich Janus hydrogel presented a significant inhibitory effect on the growth of surface algae. The oil contact angle of the Janus hydrogel was as high as 148° underwater. After the hydrogel was reswollen, there were lower algae densities on the surfaces of the hydrogel and little change in transparency. Considering the above properties, this novel Janus hydrogel is anticipated to be a promising protective material to solve the marine pollution problem confronting optical equipment.

Bioinspired Self-Adhesive Lubricating Copolymer with Bacteriostatic and Bactericidal Synergistic Effect for Marine Biofouling Prevention

“…2−6 Moreover, it can interfere with normal operation of the sophisticated sensors and instruments. 7 One of the most useful and convenient method for preventing marine biofouling is the introduction of functionalized surface coatings. 8−13 Tributyltin-based coating has been commonly used for marine antifouling because of its well-known advantages of both effective and durable antifouling properties.…”

“…Marine biofouling is the undesirable accumulation of various kinds organisms, such as bacteria, algae, and mollusks, among others, on the wet surfaces of a vessel, infrastructure, or an aquatic instrument, and it has continuously caused a series of great problems and challenges . For example, the unwanted deposition affects the weight of the ship’s hull and causes high hydrodynamic drag force, and therefore, it results in reduced speed and increased fuel and economic consumption. − Moreover, it can interfere with normal operation of the sophisticated sensors and instruments . One of the most useful and convenient method for preventing marine biofouling is the introduction of functionalized surface coatings. − Tributyltin-based coating has been commonly used for marine antifouling because of its well-known advantages of both effective and durable antifouling properties.…”

A Hydrogen Bonds-Crosslinked Hydrogels With Self-Healing and Adhesive Properties for Hemostatic

“…The good adhesion property of the HPC hydrogels is derived from the hydrogen bond between the functional groups, which are the source of cohesion and interfacial interaction. The hydrogen bonds existing in the HPC hydrogels work as crosslinking domains to improve the cohesion strength, while the functional groups on the interface between the hydrogel and the substrate could form hydrogen bonds and increase the interfacial interaction ( Feng et al, 2021 ). Secondly, the soft nature endows the HPC hydrogels with good adaption ability, making it easy to fill the irregular gaps on the surface, thus increasing the contact area and the binding capacity of the hydrogel to the substrate ( Yang and Yuan 2019 ).…”

Surface Coating with Naphthalene Trisulfonate/Hafnium(IV) Complexes: Versatility and Post-Functionalization

“…The development of surface chemistry for endowing appropriate properties onto material surfaces has been of considerable interest in the materials chemistry field because the performance of functional materials is closely affected by their surface properties. − For example, biocompatible surface modification is a prerequisite for applying nano-/micromaterials in vivo . − In this respect, surface modification reagents, which enable the introduction of desired properties onto the surface of any material, are necessary; therefore, significant effort has been devoted to the development of a versatile surface modification reagent in the last decade. − Dopamine and tannic acid are representative molecules for such versatile surface modification. ,,, Both molecules belong to the hydroxybenzene family, which is prone to oxidation and self-assembly under mild aqueous conditions. Immersion of solid substrates in a solution of alkaline dopamine or tannic acid/metal complexes formed a polydopamine or tannic acid/metal complex coating. ,,, After the versatile surface coating properties of dopamine and tannic acid were investigated, follow-up studies have been extensively conducted, focusing on the synthesis of catechol/pyrogallol derivatives. ,− Since the catechol/pyrogallol derivatives consist of hydrophobic aromatic cores and hydrophilic hydroxyls, these molecules can bind to hydrophobic and hydrophilic solid surfaces, thereby coating diverse surfaces. Moreover, these molecules are similar in that they are transformed to large molecules via self-polymerization or metal-mediated multiple coordination bond formation .…”