Antifouling bio-coatings (marine)

Marine antifouling bio-coatings prevent algae, mussels and barnacles from colonizing ship hulls without relying on the toxic heavy-metal biocides (copper, tributyltin) that dominated the sector for decades and caused lasting damage to port and estuary ecosystems. The leading commercial route is the self-polishing copolymer (SPC), a resin that hydrolyzes slowly and evenly in seawater under hull friction to release a controlled, steady dose of repellent; AkzoNobel’s International brand launched its Intersleek 2120 silicone foul-release coating in June 2026, while Jotun’s Seaquantum Ultra S uses a one-component, chemically hydrolysing silyl-acrylate chemistry for stable self-polishing. Hempel completed the first newbuilding application of its next-generation Hempaguard NB silicone hull coating in 2026, applying it directly during vessel construction in partnership with Maersk and Yangzijiang Shipyard rather than only as an in-service retrofit. Biomimetic surface texturing (shark-skin- and lotus-leaf-inspired micropatterns) and enzymatic barriers that break down the protein “glue” barnacle larvae use to attach are the two fastest-growing biological alternatives to silicone/SPC chemistry, and reduced hull friction from any of these routes can cut a vessel’s hydrodynamic drag enough to lower fuel burn and CO2 emissions.

The key directions of marine antifouling bio-coatings are:

1. Self-polishing copolymers (SPC): resin matrices that hydrolyze at a controlled rate in seawater, continuously renewing a smooth, repellent-releasing surface as the ship moves.
2. Natural bioactive repellents: compounds such as zosteric acid (from seagrass), tannins and chitosan used in place of copper or organotin biocides.
3. Biomimetic surface texturing: micro-patterned surfaces inspired by shark skin or lotus leaves that physically discourage larval settlement without releasing any biocide.
4. Enzymatic antifouling: protease and galactosidase enzymes embedded in the coating that break down the protein adhesive barnacle larvae use to attach to steel.

Sectoral value chain#

[Repellent/Enzyme Screening] ──> [Copolymer Synthesis & Formulation] ──> [Self-Polishing Matrix Production]
                                                                                  │
                                                                          (Airless spray in drydock)
                                                                                  │
                                                                                  ▼
[In-Service Fouling Monitoring] <─── [Hull Coating Application]

Value chain levels#

Cross-cutting technologies of the sector:

• Self-polishing copolymers (SPC): polymer matrices that hydrolyze slowly and evenly under frictional shear in seawater, keeping a fresh, repellent-releasing surface exposed throughout a hull’s service life.
• Enzymatic antifouling barriers: protease and galactosidase enzymes incorporated into the coating that degrade the protein adhesive barnacle larvae use to attach, preventing settlement without a biocide.
• Biomimetic micro-texturing: shark-skin- or lotus-leaf-inspired surface patterns that physically interfere with larval settlement and biofilm formation.

The antifouling bio-coatings stack pairs a biologically derived active ingredient or surface pattern with a durable polymer delivery matrix.

1. Self-polishing copolymer (SPC) matrices:
   • A silyl-acrylate or silicone-based binder hydrolyzes at a controlled rate under seawater flow shear, continuously exposing fresh, repellent-releasing surface as the outer layer wears away.
   • This mechanism is what allows silicone foul-release systems like Intersleek and Seaquantum to maintain performance across multi-year drydocking intervals.
2. Biomimetic surface texturing:
   • Micro-scale surface patterns modeled on shark skin or lotus-leaf micro-roughness physically disrupt the settlement cues that algae spores and barnacle larvae rely on.
   • Because these surfaces work through geometry rather than chemistry, they avoid biocide-release regulatory hurdles entirely.
3. Enzymatic and natural-repellent additives:
   • Protease and galactosidase enzymes embedded in a coating degrade the protein adhesive barnacle larvae secrete, preventing attachment without a toxic biocide.
   • Natural repellents such as zosteric acid (from Zostera marina seagrass) and chitosan provide a biodegradable alternative to copper/organotin biocides.