Opportunity
Oleophobic coatings, which repel oils, are highly valuable across numerous domestic and industrial sectors, including anti-fouling, anti-icing, chemical protection, and oil transportation. However, existing oleophobic coatings face significant durability challenges. Conventional approaches typically rely on creating micro-nano surface roughness combined with low-surface-energy fluorinated compounds or infusing porous substrates with inert lubricating oils to create slippery interfaces. While these methods offer good oil repellency, they often lack long-term durability because the coatings are susceptible to physical wear, abrasion, or other damage during normal use. Efforts to enhance longevity have focused on improving structural stability or using higher-strength materials, but these do not prevent the loss of oleophobic properties once the coating is physically compromised. Alternative methods utilizing the diffusion of fluorinated small molecules for chemical self-healing can improve environmental resistance to some extent, but they fail when the fluorinated molecules are depleted or when the coating suffers severe physical damage. Therefore, there is a critical unmet need for oleophobic coatings that possess intrinsic self-healing capabilities to autonomously repair physical damage, thereby ensuring long-term performance and reliability in demanding applications.
Technology
This patent addresses the durability problem by inventing a novel supramolecular polymer, designated PDMS-Cat-M, used to create a self-healing oleophobic coating. The core innovation lies in the polymer's dynamic non-covalent dual-crosslinked network, comprising abundant hydrogen bonds and metal-ligand coordination bonds. The polymer is synthesized by first creating a ligand compound (PDMS-Cat) through the copolymerization of dopamine hydrochloride, isophorone diisocyanate, and amino-terminated polydimethylsiloxane (PDMS). This ligand is then coordinated with metal ions (M), such as Zn²⁺, Ca²⁺, Co²⁺, or Fe³⁺, to form the final supramolecular polymer PDMS-Cat-M. The dynamic nature of the hydrogen and coordination bonds allows them to break and re-form under specific conditions (e.g., mild heating at 60-80°C), enabling the coating to repair cuts, scratches, and other physical damage. The oleophobicity is primarily derived from the PDMS chains densely distributed on the coating surface, which minimize interaction with oil droplets, causing them to slide off easily. Furthermore, by simply changing the coordinated metal ion, the optical properties (e.g., color, transparency) and mechanical strength of the coating can be finely tuned without significantly affecting its oil-repellent performance. The coating is prepared via a simple casting method, where a solution of PDMS-Cat-M in tetrahydrofuran is applied to a substrate and dried.
Advantages
- Introduces a self-healing capability for physical damage, significantly enhancing the longevity and durability of oleophobic coatings.
- The coating is fluorine-free, making it potentially more environmentally benign compared to conventional fluorinated coatings.
- Exhibits strong adhesion to various substrate materials.
- Allows for tunable optical (e.g., transparency/color) and mechanical properties by selecting different metal ions for coordination.
- The synthesis and coating preparation processes are relatively simple, scalable, and suitable for potential large-scale production.
- Demonstrates excellent repellency against a wide range of oils, including straight-chain alkanes and vegetable oils, with low contact angle hysteresis.
Applications
- Self-Cleaning Surfaces: For windows, solar panels, building exteriors, and automotive finishes where oil-based stains are a problem.
- Anti-Icing Coatings: For aircraft wings, wind turbines, power lines, and refrigeration systems to prevent ice adhesion.
- Anti-Fouling and Anti-Pollution: For marine vessels, underwater sensors, and industrial equipment exposed to oily environments.
- Chemical Protection: For protective clothing, gloves, laboratory equipment, and containers handling oils or corrosive chemicals.
- Oil Transportation: For coating the interior of pipelines or storage tanks to reduce friction and improve flow efficiency.
- Biomedical Devices: For creating anti-fouling surfaces on medical instruments or implants.
