Antifouling behaviour of pH responsive amphiphilic smart coatings on the basis of charge conversion in the marine environments

In response to complex marine fouling issues, this study developed pH-responsive amphiphilic antifouling coatings (PDHM) synthesized via condensation reactions between protonated zwitterionic-tertiary amine polymers and polydimethylsiloxane (PDMS). These amphiphilic coatings demonstrate pH-responsive surface charge transitions governed by protonation equilibria. Under seawater conditions (pH ∼ 8.3), the PDHM surface exhibits negative charge enrichment, synergizing with a hydrated interfacial layer to impede biofouling adhesion. Subsequent surface acidification induced by colonizing organisms triggers protonation of tertiary amines, converting the surface charge to positive. This transition disrupts fouling organism viability and promotes release under hydrodynamic shear forces. Relative to PDMS, PDHM coatings achieved 99.54 % and 99.59 % reduction in bacterial adhesion ( B. subtilis and P. ruthenica , respectively), alongside a 98.23 % reduction in algal adhesion ( P. ruthenica ). Marine field evaluations in the East China Sea confirmed sustained antifouling efficacy for 180 days. Furthermore, 16S rDNA analysis revealed significantly attenuated biofilm formation and reduced abundance of mobile genetic elements (MGEs) on PDHM surfaces versus PDMS, corroborating its superior antifouling performance. This work establishes a novel methodology for designing smart-responsive marine antifouling coatings.