New eco-friendly coating to propel ocean economy

A novel marine antifouling coating, developed by a research team from South China University of Technology, has achieved large-scale applications in various fields including shipbuilding and maintenance, as well as wave energy power generation platforms, undersea data centers and marine ranches.

According to Zhang Guangzhao, a professor with the university's School of Materials Science and Engineering, the coating plays an increasingly important role in promoting and accelerating the high-quality development of the ocean economy.

Unlike traditional products that rely heavily on toxic biocidal substances to repel organisms, the innovative coating inhibits marine biofouling adhesion and colonization via dynamic regeneration of the coating surface, said Zhang, who leads the marine science and engineering research team. The coating is primarily formulated with controllably degradable polymer materials, including polyester-polyurethane and polyester-polyacrylate.

In marine environments, seawater gradually hydrolyzes the ester groups within the material, triggering steady and controllable layer-by-layer degradation, creating a self-renewing surface that prevents fouling organisms — marine species such as algae and barnacles — from forming stable attachments, thereby delivering durable and highly efficient antifouling performance.

"The coating adopts fully controllable degradable polymer structures, which break down into harmless small molecules in seawater and completely avoid microplastic accumulation," Zhang explained.

To further optimize antifouling efficacy, Zhang's team incorporates natural-product-based antifouling ingredients into the polymer system, practicing an eco-innovative development philosophy of "derive from the ocean, apply to the ocean", he said. "Compared with conventional coatings, this new formulation eliminates the use of heavy-metal biocides, features an environmentally compatible system and produces no adverse impacts on marine ecosystems," he added.

Observations showed that each time fouling organisms attempted to anchor themselves, the constantly renewing substrate subtly changed in real time, making stable bio-attachment impossible.

By precisely tuning the surface regeneration rate of degradable polymers, Zhang's team achieved long-term ecologically benign antifouling effects suitable for widespread marine engineering applications.

Conventional resins adopted in marine equipment antifouling coatings are non-degradable, posing potential microplastic pollution risks. In addition, such coatings release high levels of heavy-metal antifouling biocides, severely disrupting marine ecosystems.

According to Zhang, marine biofouling remains a global bottleneck restricting marine economic development and ecological governance. Barnacles, algae and oysters readily adhere to submerged structures such as ship hulls, propellers and marine ranch cages. As biofouling accumulates and thickens over time, the additional weight can reach tens of kilograms per square meter in extreme cases. Often referred to as "marine psoriasis", biofouling significantly increases vessel resistance and fuel consumption, pushing up operational costs across the marine industry. It also accelerates equipment corrosion and shortens service lifespans.

For decades, China lacked independent intellectual property rights and core manufacturing technologies for high-end polymer resins. As a result, the domestic marine antifouling coating market has long been dominated by foreign suppliers, with 95 percent of the domestic market reliant on imports. This technical gap has long constrained the upgrade and development of China's marine equipment industry.

Official data shows that marine biofouling causes nearly $50 billion in economic losses worldwide annually, while China accounts for around $15 billion of the total losses, said Zhang. Zhang's research team has partnered with multiple domestic enterprises to scale up production of the newly developed eco-friendly marine coating to meet rising market demand.

Currently, the annual production capacity of the new coating stands at 5,000 to 6,000 metric tons. It has been widely applied in ocean-going shipping, marine energy facilities, offshore communication infrastructure and marine ranches.

Key domestic end-users include COSCO Shipping, China State Shipbuilding Corporation, China National Offshore Oil Corporation and LESSO, a global manufacturer of piping and building materials.

Contact the writers at zhengcaixiong@chinadaily.com.cn