A novel hard coating with a non-leaching, self-enriched amphiphilic telomer has been developed, which exhibits excellent robustness, fouling release and fouling resistance.

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...

Silicone elastomer is one of the ecofriendly fouling release materials. However, it suffers from poor fouling resistant performance during idle periods. We developed a silicone elastomer with self-stratifying, nonleaching amphiphilic side chains by grafting telomer of dodecafluoroheptyl methacrylate (DFMA), poly­(ethylene glycol) methyl ether methacrylate (PEGMA), and 3-mercaptopropyl trimethoxysilane (KH590) to bis-silanol terminated silicone. The amphiphilic telomer can be self-enriched on the surface during coating formation because the fluorocarbon segment with low surface energy is incompatible with silicone. Meanwhile, the telomer with KH590 can cross-link to silicone so that it is nonleaching. Such modified silicone elastomer has a low surface energy and low elastic modulus close to the unmodified one because most of the amphiphilic telomers are on the surface, so the former as a coating still has excellent fouling release performance. Moreover, it has remarkable fouling resistance toward marine bacterial biofilm and diatoms under a suitable molar ratio of DFMA and PEGMA (GF1P2). Such a modified silicone elastomer is expected to find application to inhibit marine biofouling.

Silicone elastomer-based fouling release coatings have been gaining increased attention in marine antibiofouling. However, the lack of fouling resistance limits their application. Introducing a zwitterionic polymer into silicone enhances its fouling resistance, but their incompatibility makes this challenging. In this work, a silicone elastomer with zwitterionic pendant chains has been prepared by grafting a telomer of tertiary carboxybetaine dodecafluoroheptyl ester ethyl acrylate (TCBF) and 3-mercaptopropyltriethoxysilane to the bis-silanol-terminated poly(dimethylsiloxane) (PDMS). The fluorocarbon groups drive the telomer onto the surface in the film formation process, while the TCBF groups hydrolyze and generate zwitterions on the surface, which is confirmed by attenuated total reflection infrared spectra analysis and water contact angle measurements. Bioassays using marine bacteria (Pseudomonas sp.) and diatoms (Navicula incerta) demonstrate that the antifouling efficacy is improved as the telomer content increases. The bacteria and diatom adhesion decreases by 95 and 81%, respectively, for the PDMS with 30 wt % telomer compared with the unmodified PDMS control. Meanwhile, the fouling release performance of PDMS is maintained with a pseudobarnacle removal strength of ∼0.1 MPa. This work provides a facile way to fabricate efficient silicone-based antifouling coatings.