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Semi-interpenetrated polyvinyl alcohol polymer networks (SIPNs) were prepared by integrating various charged components into polyvinyl alcohol polymer. Contact angle measurement, attenuated total reflection Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and tensile tests were used to characterize the physicochemical properties of the prepared SIPNs. To investigate the contribution of charges to marine antifouling, the adhesion behaviors of green algae Dunaliella tertiolecta and diatoms Navicula sp. in the laboratory and of the actual marine animals in field test were studied for biofouling assays. The results suggest that less algae accumulation densities are observed for neutral-, anionic-, and zwitterionic-component-integrated SIPNs. However, for the cationic SIPNs, despite the hydration shell induced by the ion-dipole interaction, the resistance to biofouling largely depends on the amount of cationic component because of the possible favorable electrostatic attraction between the cationic groups in SIPNs and the negatively charged algae. Considering that the preparation of novel nontoxic antifouling coating is a long-standing and cosmopolitan industrial challenge, the SIPNs may provide a useful reference for marine antifouling and some other relevant fields.

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The optical window is a key part of a sensor specially used for oceanographic detection, but it is often severely affected by marine biofouling and oil pollution, resulting in reduced transparency and lifespan. Hydrogel, as a hydrophilic polymer network, has excellent antifouling effects with good transparency, but it is difficult to adhere to substrates, which greatly limits its practical applications. To solve the above problem, a transparent Janus hydrogel wet adhesive was prepared through modifying poly­(vinyl alcohol)/glycerol–tannic acid/Cu2+ (PVA/Gly-TA/Cu2+) hydrogel with the underwater adhesive poly­(dopamine methacrylamide-co-methoxyethyl acrylate) (P­(DMA-co-MEA)) via the coordination effect between Cu2+ and catechol. Even when coated with adhesive, the sample still retained good transmittance. The presence of Cu2+ endowed the hydrogel with better tensile strength and, at the same time, can improve the adhesion of the hydrogel to the substrate through the coordination effect with the adhesive. The tensile stress of Janus hydrogels can even reach 4.4 MPa, and the adhesion strength of the obtained Janus hydrogel can reach about 14 kPa in seawater. Furthermore, the Cu-rich Janus hydrogel presented a significant inhibitory effect on the growth of surface algae. The oil contact angle of the Janus hydrogel was as high as 148° underwater. After the hydrogel was reswollen, there were lower algae densities on the surfaces of the hydrogel and little change in transparency. Considering the above properties, this novel Janus hydrogel is anticipated to be a promising protective material to solve the marine pollution problem confronting optical equipment.

Shear thickening is a general process crucial for many processed products ranging from food and personal care to pharmaceuticals. Theoretical calculations and mathematical simulations of hydrodynamic interactions and granular-like contacts have proved that contact forces between suspended particles dominate the rheological characteristic of colloidal suspensions. However, relevant experimental studies are very rare. This study was conducted to reveal the influence of nanoparticle (NP) interactions on the rheological behavior of shear-thickening fluids (STFs) by changing the colloidal surface chemistries. Silica NPs with various surface chemical compositions are fabricated and used to prepare dense suspensions. Rheological experiments are conducted to determine the influence of NP interactions on corresponding dense suspension systems. The results suggest that the surface chemistries of silica NPs determine the rheological behavior of dense suspensions, including shear-thickening behavior, onset stress, critical volume fraction, and jamming volume fraction. This study provides useful reference for designing effective STFs and regulating their characteristics.

2-Hydroxyethyl methacrylate polymer brushes with various grafting densities and chain lengths were prepared through surface-initiated atom transfer radical polymerization. X-ray photoelectron spectra, ellipsometry measurement, contact angle measurement, and atom force microscope were used to characterize the prepared polymer brush. The biofouling assays of polymer brush were investigated by adhesion of Dunaliella tertiolecta, Navcular sp., and Bovine Serum Albumin protein and by static marine immersion field test. Besides, hydroxyl and sulfonate-terminated self-assembled monolayers, anionic charged 3-sulfopropyl methacrylate potassium salt polymer brush were prepared for comparison. Results suggest that the settlement of microorganisms can be largely reduced by polymer with enough polymer chain length and grafting density. More importantly, static immersion field tests indicate that hydrophilic polymer film with enough hydration layer thickness is necessary for long-term marine antifouling application. This comprehensive investigation is of great importance to understanding their influence on the adhesion of marine microorganism.