“From the nature, for the nature” is an instructive strategy to develop environment-friendly antifouling coatings. In this work, bio-sourced poly­(lactic acid)-based polyurethane with hydrolyzable triisopropylsilyl acrylate (TSA) side groups has been prepared via thiol–ene reaction and polyaddition. Such a polymer exhibits high adhesion strength (∼2.0 MPa) and a controlled degradation rate tuned by varying its soft segment and TSA content. An environment-friendly coating is prepared with the polymer and an eco-friendly antifoulant (butenolide) derived from marine bacteria. Our study shows that butenolide can be released from the coating in continuous manner with a controlled rate as the polymer degrades in seawater. Digital holographic microscopy tracking analysis demonstrates that the coating can effectively inhibit the adhesion of marine bacteria Pseudomonas sp. Marine field test shows that such coating has excellent antifouling ability for more than 3 months.

dynamic surfaces, [4] polymethacrylate bearing ferrocenyl groups, [5] amphiphilic copolymers, [6] liquid-infused slippery surfaces, [7] surface-deforming materials, [8] enzyme containing coatings, [9] and so on. Among them, silicone-based FRCs with excellent fouling release ability have gained considerable attention because it is environment-friendly and has drag reducing ability. [10] The fouling release ability of silicone elastomers arises from its low surface energy and low elastic modulus. [11] The latter makes the elastomer form a physically dynamic surface to which microorganisms weakly adhere. [2b,12] Yet, an external shearing force is needed to detach fouling organisms from the surface of silicone elastomer that cannot resist biofouling in static immersion without strong water flow. Moreover, it was reported that slime consisting of bacteria and diatoms is able to accumulate on silicone surface, and it is difficult to remove even with the help of water jet. [13] Therefore, the fouling resistance of silicone-based FRC needs improving, particularly that on static conditions. Physical addition of antifoulant can improve the antifouling ability of silicone, but the release of antifoulant is usually not consistent since silicone is not erodible in seawater. Moreover, it may affect the metabolism and growth of nontarget marine organisms. Chemically immobilization of biocidal moieties such as organic antifoulant, [14] quaternary ammonium salt, [15] zwitterion, [16] and amphiphile [17] on PDMS elastomer can avoid their release. Yet, most of such biocidal moieties are readily trapped in bulk and cannot fully exert fouling resistance. Moreover, their presence often increases the modulus and swelling of the coating, leading to decreased fouling release and mechanical performances. Enrichment of the grafted biocidal moieties on coating surface can lead to good antifouling performance without undermining the advantages of silicone elastomers. However, it is a challenge because silicone segment tends to cover biocidal moieties during the formation of coating due to its low surface energy.In this study, we have prepared a novel telomer of triclosan acrylate (TA), dodecafluoroheptyl methacrylate (DFMA), and 3-mercaptopropyl trimethoxysilane, where triclosan is a broad spectrum antimicrobial agent. [18] Silicone-based coating is Chemical immobilization of antifoulant groups to polymers is a promising approach to develop ecofriendly antifouling materials with static antifouling ability and a durable efficacy. In this work, telomer of dodecafluoroheptyl methacrylate (DFMA), triclosan acrylate (TA), and 3-mercaptopropyl trimethoxysilane (KH590) is grafted to bis-silanol terminated poly(dimethylsiloxane) (PDMS), yielding a novel self-stratifying silicone coating containing nonleaching antifoulants. X-ray photoelectron spectroscopy (XPS) analysis reveals that the antifoulant groups are enriched on the coating surface due to DFMA migration. Such a modified PDMS coating can significantly inhibit the growth of marine bacteri...

Surface stiffness plays a critical role in bacterial adhesion, but the mechanism is unclear since the bacterial motion before adhesion is overlooked. Herein, the three-dimensional (3D) motions of Escherichia coli and Pseudonomas sp. nov 776 onto poly­(dimethylsiloxane) (PDMS) surfaces with varying stiffness before adhering were monitored by digital holographic microscopy (DHM). As Young’s modulus (E) of the PDMS surface decreases from 278.1 to 3.4 MPa, the adhered E. coli and Pseudonomas sp. decrease in number by 40.4 and 34.9%, respectively. Atomic force microscopy (AFM) measurements show that the adhesion force of bacteria to the surface declines with the decreased surface stiffness. In contrast, a nontumbling mutant of adhered E. coli (HCB1414 with the adaptive function being partially deficient) decreases much less (by 18.4%). On the other hand, the tumble frequency (F t) of E. coli HCB1 and flick frequency (F f) of Pseudomonas sp. increase as the surface stiffness decreases, and the motion bias (B θ) of Pseudomonas sp. also increases. These facts clearly indicate that the bacteria have adapted responses to the surface stiffness. RNA sequencing (RNA-seq) reveals that the downregulated Cph2 and CsrA as well as the upregulated GcvA of swimming E. coli HCB1 in bulk near the softer surface promote the bacterial motility.

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