The work addresses a long-standing weakness of conventional fouling-release coatings, which are typically based on polydimethylsiloxane, or PDMS. Silicone elastomers are prized for their low surface energy and low elastic modulus, which weakens the adhesion of barnacles and other hard foulers so that they slough off when a vessel moves through the water. The catch is that this mechanism depends on hydrodynamic shear: a ship at cruising speed sheds fouling effectively, but a hull sitting idle in a warm harbor, or a stationary aquaculture structure, offers no such assistance. Under static conditions, fouling-release silicones perform poorly, which is precisely why researchers have been trying to add fouling-resistance functions, such as hydrophilic surfaces that repel proteins and microbes before they ever attach.

The most straightforward way to make a silicone surface hydrophilic is to blend in or graft hydrophilic polymers, but this approach has historically been undermined by two failure modes. First, small hydrophilic molecules and loosely bound polymer chains simply leach out into seawater over time, depleting the surface of its antifouling function and raising environmental concerns. Second, the interface itself is unstable: because PDMS is strongly hydrophobic, hydrophilic components buried in the bulk tend to migrate away from the surface, or the surface composition drifts unpredictably as the coating ages in water. Amphiphilic surfaces, which combine hydrophilic and hydrophobic chemical groups in the same material, promise both fouling resistance and fouling release, but only if the amphiphilic character can be preserved at the interface for the long term.

The Chinese team’s answer is an additive they call PFV, chemically poly(FMA-co-NVP-co-TPS), a copolymer that unites three functional building blocks. The fluorinated methacrylate, FMA, contributes low-surface-energy fluorinated segments that reinforce the fouling-release character of the silicone matrix. N-vinylpyrrolidone, NVP, provides hydrophilic PVP segments that attract water molecules and form a stable hydration layer at the interface, a molecular cushion that makes it energetically unfavorable for proteins to adsorb and for bacteria and diatoms to settle. The third component, TPS, serves as the chemical anchor: it allows the additive to be covalently incorporated into the cross-linked PDMS network during curing, which is the key to making the system non-leaching.

That covalent incorporation matters enormously. Because PFV is tethered to the silicone network rather than merely blended into it, the hydrophilic PVP segments cannot wash away into the ocean, solving the leaching problem that has plagued simpler formulations. At the same time, the additive is designed to be amphiphilic enough that, during the curing process, it spontaneously segregates toward the air-facing surface of the coating. This surface segregation is the elegant trick of the design: instead of requiring elaborate surface-grafting chemistry or post-treatment, the material does the work of enriching the interface with functional groups on its own, driven by thermodynamics as the elastomer cross-links.

To test whether the amphiphilic architecture was genuinely necessary, the researchers prepared comparison coatings containing only the hydrophilic segments, poly(NVP-co-TPS) or PNT, or only the hydrophobic fluorinated segments, poly(FMA-co-TPS) or PFT. The results were unambiguous: coatings containing the full amphiphilic additive PFV outperformed both single-character alternatives. The synergy appears to arise from the complementary roles of the two segment types. The hydrophilic PVP segments at the surface generate the hydration layer that inhibits protein adsorption and blocks the initial attachment of bacteria and diatoms, while the fluorinated and silicone-rich hydrophobic character maintains the low surface energy that weakens the adhesion of anything that does manage to settle. Neither function alone reproduced the combined performance.

Perhaps the most practically important finding of the study is that the additive concentration is not a case of more is better. The coatings showed outstanding antifouling performance only within a defined loading window of 10 to 30 weight percent PFV. Below that range, there is simply not enough additive segregating to the surface to build a continuous, effective hydration layer. Above it, the excess amphiphilic material presumably disrupts the silicone network, degrading the mechanical and surface properties that make PDMS an effective fouling-release substrate in the first place. Within the window, however, the balance is right, and the optimized formulation containing 20 weight percent PFV achieved inhibition of more than 90 percent of bacterial and diatom attachment, a striking figure for a coating that contains no biocides at all.

The environmental significance of that last point is hard to overstate. Traditional antifouling paints have relied on toxic biocides, most famously tributyltin until its global ban, and copper-based compounds remain widespread despite growing evidence of harm to non-target marine organisms. Regulatory pressure on biocidal coatings continues to intensify worldwide, which has driven a broad research effort toward physically based antifouling strategies: zwitterionic and PVP-based hydration layers, amphiphilic co-networks, liquid-infused slippery surfaces, self-polishing polymers, and bioinspired topographies. The PFV approach fits squarely into this movement toward environmentally sustainable, non-toxic silicone-based coatings, and the demonstration that a single covalently anchored additive can deliver both fouling resistance and fouling release makes it attractive from a manufacturing standpoint, since it can in principle be dropped into existing PDMS coating formulations.

The concept of a critical concentration for amphiphilic antifouling performance echoes earlier findings in the field, including work on surface-enriched non-leaching amphiphilic side chains in silicone elastomers and studies of how the extent of amphiphilicity governs fouling-release behavior. What the new study adds is a systematic demonstration, using matched hydrophilic-only and hydrophobic-only controls, that the surface-segregating amphiphilic additive concept delivers superior performance within a quantitatively defined loading window, along with evidence of durability in the optimized formulation. By defining the 10 to 30 weight percent window and identifying 20 weight percent as the optimum, the researchers have given coating formulators a concrete design rule rather than a vague direction.

For the shipping industry, aquaculture operators, and anyone maintaining submerged infrastructure, the implications are tangible. A durable, non-leaching, biocide-free silicone coating that resists bacterial and diatom settlement even under static conditions could extend the intervals between hull cleanings and dry-docking, cut fuel consumption caused by fouling drag, and reduce the environmental footprint of maritime operations. The work also offers broader guidance for designing surface-segregating additive systems in other polymeric materials, from membranes to biomedical devices, wherever the challenge is the same: keeping a functional, chemically stable interface intact against the relentless pull of the surrounding environment. As the authors note, their findings provide a roadmap for designing environmentally sustainable silicone-based antifouling coatings, and with biofouling estimated to cost the global shipping industry billions of dollars annually, that roadmap is likely to attract considerable attention.

Subject of Research: Surface-segregating amphiphilic additives in PDMS-based antifouling coatings

Article Title: Surface-segregating amphiphilic additives: a critical loading window for effective antifouling coatings

Article References: Lu, G., Huang, L., Wei, Y., Wang, J., & Wu, J. (2026). Surface-segregating amphiphilic additives: a critical loading window for effective antifouling coatings. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13718-4

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13718-4

Keywords: antifouling coatings, amphiphilic polymers, PDMS, surface segregation, PVP hydration layer, fouling release, marine biofouling, non-leaching additives, polymer chemistry, bacterial attachment, diatom adhesion, environmentally sustainable coatings