Inorganic-Organic Silica/PDMS Nanocomposite Antiadhesive Coating with Ultrahigh Hardness and Thermal Stability

Unravelling polysilazanes: Synthesis, structure-property insights and versatile coating applications

The continuous demand for high-performance protective and functional coatings in industrial structures and smart devices necessitates the development of advanced materials with enhanced properties. Polysilazanes, polymers composed of alternating silicon and nitrogen atoms, have emerged as versatile candidates in this realm. Their applications span a wide range of industries, including high-performance coatings, ceramic synthesis, composites, thermally resistant coatings, packaging materials, solar cells, and electromagnetic devices. This review presents a comprehensive analysis of the latest scientific and technological advancements in polysilazane-based coatings, focusing on the diverse applications and underlying mechanisms. Through systematic examination, the review explores various modifications to polysilazane structures and substrates to achieve desired properties, including the integration of functionalized chemicals and nanoparticles. The paper also outlines potential future research directions to further harness the capabilities of polysilazanes in advanced material science.

Self-Adaptive Zwitterionic Polysilazane Coatings with Mechanical Robustness, High Transparency, and Broad-Spectrum Antiadhesion Properties

Antiadhesive coatings have been extensively studied owing to their wide applications in biology, environment, and energy. However, developing a mechanically robust coating with broad-spectrum antiadhesion properties remains challenging. Herein, a novel strategy for preparing hard yet flexible and self-adaptive zwitterionic polysilazane coatings with broad-spectrum antiadhesion properties (anti-biofouling, anti-liquid adhesion, and anti-scaling) is proposed. The coatings are prepared by combining polysilazane with a telomer (FT) consisting of a low-surface-energy fluorine motif and hydrolysis-induced zwitterions. Before Si─OH generation in polysilazane, the fluorine motif drives the zwitterionic precursor to enrich on the surface, generating a zwitterionic layer following pre-hydrolysis. This unique design prevents the coatings from swelling in water, allowing them to adapt to diverse environments. The fluorine motif can orient toward the surface of air, providing anti-liquid adhesion capabilities, whereas the zwitterions orient underwater to endow anti-biofouling, anti-liquid adhesion, and anti-scaling capabilities. The highly cross-linked network toughened by FT contributes to the high hardness (up to 7H) and good flexibility of the coating. The chemical bonding between the coating and substrates ensures their strong adhesion (≈2.06-7.67 MPa). This study contributes to the design of mechanically robust broad-spectrum antiadhesive coatings applicable in marine industries, optical devices, pipeline transportation, and other fields.

Waterborne Liquid-like Coatings with High Transparency, Superior Scratch Resistance, and Antismudge Properties

The aqueous formulation of antismudge coatings is a crucial step for environmental protection and pollution reduction. However, the inferior mechanical durability of waterborne antismudge coatings poses challenges for their practical application. Herein, we developed a fully waterborne antismudge coating with excellent scratch resistance by preparing hyperbranched amine-rich polysiloxane (HySPx) for antismudge ability and epoxy-rich zirconium-based aqueous solution (ZAS) for mechanical performance. The former is obtained by combining SPx, polydimethylsiloxane modified by 3-isocyanatopropyltriethoxysilane (IPTS), with 3-aminopropyltriethoxysilane (KH550), and the latter is synthesized using zirconium propoxide solution (TPOZ) with 3-glycidyloxypropyltrimethoxysilane (KH560). This report investigates the effects of the chain length and content of SPx on the performance of the coating. The results indicate that the coating exhibits optimal comprehensive performance when the molecular weight of polydimethylsiloxane is 4.5 kDa, and the mass fraction of SPx in HySPx is 1.5%. The coating possesses high transparency similar to glass, good adhesion (≈3 MPa) to various substrates, high hardness (8H), flexibility (2.5 mm bending radius), and exceptional antismudge property. More importantly, the coating can still maintain excellent antismudge property even after enduring 400 cycles of abrasion with steel wool. Furthermore, the rapid enrichment of polydimethylsiloxane on the coating surface endows the coating with excellent lubrication ability, allowing most common liquid stains to slide off the coating surface. Moreover, the rewritability of the coating remains stable even after writing traces that have persisted on its surface for several weeks. This coating is anticipated to be utilized for protecting foldable electronic screens, vehicles, and other fields.

Eco-Friendly Sustainable and Responsive High-Performance Benzotriazole-Metal Organic Frameworks/Silica Composite Coating with Active/Passive Corrosion Protection on Copper

Coatings with only passive protection cannot offer long-term anticorrosion on metals. Eco-friendly sustainable and responsive coating for active/passive corrosion protection is desirable to extend the service life of metals. Here, benzotriazole (BTA)-metal organic frameworks (Cu-MOFs, UiO-66) were embedded in silica (SiO2) coating by one-step electrodeposition on copper. Combined with passive capability of MOFs and active protection of BTA inhibitor, the composite coating (BTA-MOF/SiO2) exhibited high and stable corrosion resistance, confirmed by microstructure characterizations and electrochemical tests. As a result, the as-prepared composite coating exhibited superhydrophobicity with a water contact angle of 154.2°. With loading of BTA-MOF in SiO2 coating, the impedance modulus at 0.01 Hz increased by ∼10-fold and the corrosion current density decreased to 3.472 × 10-9 A·cm-2. Immersion and salt spray tests confirmed the long-term protection of the composite coating. The responsive release of BTA inhibitor endows the coating with a responsively anticorrosive behavior. The active-passive ability makes the coating a good candidate for protection on metals used in highly salty environments.

Engineered Sustainable Omniphobic Coatings to Control Liquid Spreading on Food-Contact Materials

The adhesion of sticky liquid foods to a contacting surface can cause many technical challenges. The food manufacturing sector is confronted with many critical issues that can be overcome with long-lasting and highly nonwettable coatings. Nanoengineered biomimetic surfaces with distinct wettability and tunable interfaces have elicited increasing interest for their potential use in addressing a broad variety of scientific and technological applications, such as antifogging, anti-icing, antifouling, antiadhesion, and anticorrosion. Although a large number of nature-inspired surfaces have emerged, food-safe nonwetted surfaces are still in their infancy, and numerous structural design aspects remain unexplored. This Review summarizes the latest scientific research regarding the key principles, fabrication methods, and applications of three important categories of nonwettable surfaces: superhydrophobic, liquid-infused slippery, and re-entrant structured surfaces. The Review is particularly focused on new insights into the antiwetting mechanisms of these nanopatterned structures and discovering efficient platform methodologies to guide their rational design when in contact with food materials. A detailed description of the current opportunities, challenges, and future scale-up possibilities of these nanoengineered surfaces in the food industry is also provided.