Engineering high mechanical strength and synergistically antibacterial PDMS coatings via a “rivet-like” metal coordination strategy

Polydimethylsiloxane (PDMS) elastomers are widely recognized in marine engineering for their intrinsic low surface energy, which naturally deters biofouling. However, their long-term practical application is often restricted by inherent mechanical weakness and poor physical damage resistance. To overcome these limitations, we engineered a robust polyurea-PDMS elastomer using a “rivet-like” metal coordination strategy. We first synthesized a polyurea backbone utilizing aminopropyl-terminated PDMS, isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI), specifically integrating a Schiff base chain extender (HPA). The subsequent introduction of ZnCl2 drives the formation of a dynamic cross-linked network. Within this system, Zn2+ ions act as molecular “rivets”. Working in tandem with high-density hydrogen bonding, this coordination creates a “reinforced concrete”-like matrix that restricts chain slippage and effectively dissipates strain energy, leading to superior mechanical toughness. Beyond structural reinforcement, the embedded Zn2+ centers function as highly efficient, broad-spectrum biocides. By disrupting bacterial cell membranes through electrostatic adsorption and interfering with algal photosynthesis, the system establishes a dual “physical repulsion–chemical inactivation” defense. Tests demonstrate that our optimized variant, PIHH-Zn2+-4, reaches an impressive tensile strength of 12.03 MPa—vastly outperforming traditional PDMS—along with an elongation at break of 485.77%. This synergistic combination of mechanical durability and active bio-deterrence provides a compelling new paradigm for durable marine protective coatings.