Preparation and Properties of PED-TDI Polyurethane-Modified Silicone Coatings

To explore the influence mechanisms of polyurethane soft segments on modified silicone coatings, a series of modified coatings was prepared by introducing different contents of hydroxypropyl-terminated polydimethylsiloxane (PDMS2200) into the soft segment of polyurethane. ATR-FTIR, NMR, CLSM, AFM, contact angle measurement, the tensile test, bacterial adhesion, and the benthic diatom adhesion test were used to investigate the structure, morphology, roughness, degree of microphase separation, surface energy, tensile properties, and antifouling properties of the modified coatings. The results show that PDMS2200 could aggravate the microphase separation of the modified coatings, increase the surface-free energy, and reduce its elastic modulus; when the microphase separation exceeded a certain degree, increasing PDMS2200 would decrease the tensile properties. The PED-TDI polyurethane-modified silicone coating prepared with the formula of PU-Si17 had the best tensile properties and antifouling properties among all modified coatings.

Facile Preparation of Robust Superhydrophobic/Superoleophilic TiO2-Decorated Polyvinyl Alcohol Sponge for Efficient Oil/Water Separation

Oily wastewater and oil spills pose a threat to the environment and human health, and porous sponge materials are highly desired for oil/water separation. Herein, we design a new superhydrophobic/superoleophilic TiO₂-decorated polyvinyl alcohol (PVA) sponge material for efficient oil/water separation. The TiO₂-PVA sponge is obtained by firmly anchoring TiO₂ nanoparticles onto the skeleton surface of pristine PVA sponge via the cross-linking reactions between TiO₂ nanoparticles and H₃BO₃ and KH550, followed by the chemical modification of 1H,1H,2H,2H-perfluorodecyltrichlorosilane. The as-prepared TiO₂-PVA sponge shows a high water contact angle of 157° (a sliding angle of 5.5°) and an oil contact angle of ∼0°, showing excellent superhydrophobicity and superoleophilicity. The TiO₂-PVA sponge exhibits excellent chemical stability, thermal stability, and mechanical durability in terms of immersing it in the corrosive solutions and solvents, boiling it in water, and the sandpaper abrasion test. Moreover, the as-prepared TiO₂-PVA sponge possesses excellent absorption capacity of oils or organic solvents ranging from 4.3 to 13.6 times its own weight. More importantly, the as-prepared TiO₂-PVA sponge can separate carbon tetrachloride from the oil-water mixture with a separation efficiency of 97.8% with the aid of gravity and maintains a separation efficiency of 96.5% even after 15 cyclic oil/water separation processes. Therefore, the rationally designed superhydrophobic/superoleophilic TiO₂-PVA sponge shows great potential in practical applications of dealing with oily wastewater and oil spills.

Kill-Resist-Renew Trinity: Hyperbranched Polymer with Self-Regenerating Attack and Defense for Antifouling Coatings

Traditional antifouling coatings are generally based on a single antifouling mechanism, which can hardly meet the needs of different occasions. Here, a single "kill-resist-renew trinity" polymeric coating integrating fouling killing, resistance, and releasing functions is reported. To achieve the design, a novel monomer-tertiary carboxybetaine ester acrylate with the antifouling group N-(2,4,6-trichlorophenyl)maleimide (TCB-TCPM) is synthesized and copolymerized with methacrylic anhydride via reversible addition-fragmentation chain transfer polymerization yielding a degradable hyperbranched polymer. Such a polymer at the surface/seawater is able to hydrolyze and degrade to short segments forming a dynamic surface (releasing). The hydrolysis of TCB-TCPM generates the antifouling groups TCPM (killing) and zwitterionic groups (resistance). Such a polymeric coating exhibits a controllable degradation rate, which increases with the degrees of branching. The antibacterial assay demonstrates that the antifouling ability arise from the synergistic effect of "attacking" and "defending". This study provides a new strategy to solve the challenging problem of marine biofouling.

Polymers with Hemiaminal Ether Linkages for pH-Responsive Antibacterial Materials

Antibacterial materials containing biocides suffer from the fact that biocides are usually quickly released and hence display a limited antibacterial ability over a long period of time. To overcome this problem, the antibacterial agent 6-chloropurine is conjugated to a monomer via a hemiaminal ether linkage. The functional monomer is then reacted with a urethane acrylate by photopolymerization to yield thin polymer coatings. The release of the antibacterial agent from the coatings is sustained due to the slow kinetics of the hydrolysis of the hemiaminal ether linkage. Antibacterial performance is achieved against S. aureus and E. coli bacteria. This simple strategy can be applied for the rapid preparation of antibacterial coatings on various substrates and other applications such as antifouling or anticorrosion coatings.

Silicone-Based Fouling-Release Coatings for Marine Antifouling

Marine biofouling profoundly influences marine industries and activities. It slows the speed and increases the fuel consumption of ships, corrodes offshore platforms, and blocks seawater pipelines. The most effective and economical antifouling approach uses coatings. Fouling-release coatings (FRCs) with low surface free energy and high elasticity weakly adhere to marine organisms, so they can be readily removed by the water shear force. FRCs have attracted increasing interest because they are biocide-free and hence ecofriendly. However, traditional silicone-based FRCs have weak adhesion to substrates, low mechanical strength, and low fouling resistance, limiting their applications. In recent years, many attempts have been made to improve their mechanical properties and fouling resistance. This review deals with the progress in the construction of high-performance silicone-based fouling-release surfaces.

Contact-active antibacterial polyethylene foils via atmospheric air plasma induced polymerisation of quaternary ammonium salts

Polyethylene (PE) foils were modified with potent contact-active antibacterial quaternary ammonium salts (QAS) by an atmospheric air plasma activation step, followed by graft-polymerisation of vinylbenzyltrimethylammonium chloride (VBTAC) monomers. The presented approach uses a cost efficient air plasma activation and subsequent radical polymerisation in highly concentrated aqueous monomer solutions to generate efficient antibacterial materials. The obtained contact-active poly-VBTAC modified PE foils feature a homogeneous and 300 nm thick polymer layer with a high charge density of approximately 10¹⁶ N⁺/cm². The antibacterial properties were evaluated against Gram-negative (P. aeruginosa, E. coli) and Gram-positive (S. aureus, S. epidermidis) bacteria. The materials showed strong antibacterial activity by eradicating all the inoculated bacteria with bacterial challenges of 10⁴ to 10⁵ CFU/cm² and good reductions even at maximum challenge (10⁸ CFU/cm²). We have confirmed contact-activity by an agar diffusion assay. The obtained materials are therefore highly attractive for applications, for example, in packaging and are a contribution to an ecomic and green antimicrobial management without release of biocides to the environment.

Polymerization-Induced Phase Segregation and Self-Assembly of Siloxane Additives to Provide Thermoset Coatings with a Defined Surface Topology and Biocidal and Self-Cleaning Properties

In this work, we report on the incorporation of a siloxane copolymer additive, poly((2-phenylethyl) methylsiloxane)-co(1-phenylethyl) methylsiloxane)-co-dimethylsiloxane), which is fully soluble at room temperature, in a rapid-cure thermoset polyester coating formulation. The additive undergoes polymerization-induced phase segregation (PIPS) to self-assemble on the coating surface as discrete discoid nanofeatures during the resin cure process. Moreover, the copolymer facilitates surface co-segregation of titanium dioxide pigment microparticulate present in the coating. Depending on the composition, the coatings can display persistent superhydrophobicity and self-cleaning properties and, surprisingly, the titanium dioxide pigmented coatings that include the siloxane copolymer additive display high levels of antibacterial performance against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria. This antibacterial performance is believed to be associated with the unique surface topology of these coatings, which comprise stimuli-responsive discoid nanofeatures. This paper provides details of the surface morphology of the coatings and how these relates to the antimicrobial properties of the coating.

Preparation and properties of gelatin hydrolysate modified with polysiloxane quaternary ammonium salts

PSiQAEp-GH polymers were synthesized by the reaction of gelatin hydrolysate (GH) and polysiloxane quaternary ammonium salts containing epoxy group (PSiQAEp) with different molecular weight from 3147 to 12996. The results of FTIR, ¹H NMR and ¹³C NMR showed that the reaction occurred between primary amino group of arginine in GH and epoxy of PSiQAEp. The XRD and DSC studies showed that the degree of short-range order of PSiQAEp-GH reduced and its glass transition temperature (Tg) lowered more than 10 °C compared with GH. The determinations of moisture absorption and contact angle (CA) indicated that the hydrophobility of PSiQAEp-GH was better than GH. The tests of inhibitory zone and minimum bactericidal concentration (MBC) illustrated that the PSiQAEp-GHs exhibited excellent antibacterial activity, and the antibacterial activity depended on both the chemical structure of PSiQAEp-GHs and the biological structure of the bacteria.

Dual-functional anticoagulant and antibacterial blend coatings based on gemini quaternary ammonium salt waterborne polyurethane and heparin

A simple design of the dual-functional anticoagulant and antibacterial blend coatings with controlled release of heparin.

Development of high performance dental resin composites with outstanding antibacterial activity, high mechanical properties and low polymerization shrinkage based on a SiO2 hybridized tetrapod-like zinc oxide whisker with CC bonds

Novel dental resin composites with outstanding antibacterial activity, high mechanical properties and low polymerization shrinkage were fabricated with SiO₂ hybridized tetrapod-like zinc oxide whiskers, and the origin behind was revealed.

Steam treatment of a hollow lithium phosphate catalyst: enhancing carbon deposition resistance and improving the catalytic performance of propylene oxide rearrangement

The reaction mechanism of propylene oxide rearrangement on a hollow lithium phosphate catalyst in the presence of steam.

Investigating into the liquid oxygen compatibility of a modified epoxy resin containing silicon/phosphorus and its mechanical behavior at cryogenic temperature

A 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative (DOPO–TVS) was synthesized through a reaction between DOPO and triethoxyvinylsilane (TVS).