Preparation of novel polyimide nanocomposites with high mechanical and tribological performance using covalent modified carbon nanotubes via Friedel-Crafts reaction

Preparation of superhydrophobic coatings with excellent durability by synergistic reinforcement of cationic starch and tannic acid

The intrinsic hydrophilicity of sustainable and environmentally friendly biobased materials like starch and its derivatives limits their potential as hydrophobic functional materials. This study presents an eco-friendly and non-toxic method to create coatings with exceptionally high hydrophobicity. Octadecyltrimethoxysilane (ODS) reacts with nano silica (SiO2) through a silane coupling reaction to form superhydrophobic SiO2. The Si-OH groups generated from ODS hydrolysis can undergo a condensation reaction with tannic acid (TA), which is rich in phenolic hydroxyl groups. This enables the hydrophobic silane to bind indirectly with cationic starch (CS), resulting in a stable superhydrophobic CS-based coating. The coating demonstrates significant hydrophobicity (contact angle >170°), excellent UV light transmittance (<4.05 %), self-cleaning properties, prolonged shelf life (over eight months), antibacterial activity, and encapsulation capability. It also shows a separation efficiency exceeding 99 % after 25 oil-water separation cycles and is easily recoverable. The study elucidates the mechanism behind the preparation process and the factors enhancing hydrophobic properties. The research findings suggest that the novel, cost-effective CS/TA/ODS/SiO2 coating offers a scalable solution for superhydrophobic applications and broadens the horizon for green starch use in hydrophobic materials.

Mussel-inspired polydopamine modified mica with enhanced mechanical strength and thermal performance of poly(lactic acid) coating

Polylactic acid (PLA), as a green functional polymer, has been useful in various coating applications. However, due to the low mechanical strength and thermal stability of PLA, it needs to be improved in order to expand its application areas. In this work, a series of polylactic acid (PLA) nanocomposite films were prepared through introducing polydopamine-modified mica (PDA@MICA) as a self-assemble nanofiller to enhance its mechanical and thermal properties. The results demonstrated that PLA/PDA@MICA shows excellent mechanical properties. Tensile tests showed that PLA/PDA@MICA exhibits a 58.3 % increase in tensile strength and a 16.8 % increase in Young's modulus compared to pure PLA. Meanwhile, thermal performance testing shown the introduction of PDA@MICA led to an increase in crystallinities (Xc = 24.78 %). And the thermal decomposition temperature of PLA/PDA@MICA film (374 °C) was slightly higher than that of PLA film (367 °C). The simultaneous improvement of the mechanical and thermal properties was attributed to the formation of hydrogen bonds between PLA and PDA@MICA. In addition, the parallel arrangement of PDA@MICA and PLA macromolecular chains forms a unique "brick and mortar" structure in the coating, which enhances the mechanical properties of PLA/PDA@MICA composite coatings. This study reports a successful approach to simultaneously address the drawbacks of PLA, specifically its low thermal stability and mechanical strength, thereby promoting its widespread application in the coatings industry.

Tribological Properties of Blocky Composites with Carbon Nanotubes

A large amount of primary energy is lost due to friction, and the study of new additive materials to improve friction performance is in line with the concept of low carbon. Carbon nanotubes (CNTs) have advantages in drag reduction and wear resistance with their hollow structure and self-lubricating properties. This review investigated the mechanism of improving friction properties of blocky composites (including polymer, metal, and ceramic-based composites) with CNTs' incorporation. The characteristic tubular structure and the carbon film make low wear rate and friction coefficient on the surface. In addition, the effect of CNTs' aggregation and interfacial bond strength on the wear resistance was analyzed. Within an appropriate concentration range of CNTs, the blocky composites exhibit better wear resistance properties. Based on the differences in drag reduction and wear resistance in different materials and preparation methods, further research directions of CNTs have been suggested.

Synthesis by partial oxygenation of graphite-like carbon nitride (OCN) decorated with oleic diethanolamide borate (ODAB) for oil-based lubricant additives and its tribological properties

ODAB-OCN retaining long-term dispersion stability in an oil environment exhibits excellent tribological properties.

Fabrication of Novel CeO2/GO/CNTs Ternary Nanocomposites with Enhanced Tribological Performance

Increasing demands of multi-functional lubricant materials with well distributed nanoparticles has been generated in the field of oil lubrication. In this study, one-dimensional (1-D) acidified multi-walled carbon nanotubes (CNTs) and two-dimensional (2-D) graphene oxide (GO) sheets were dispersed together under an ultra-sonication condition to form CNTs/GO hybrids and the corresponding CNTs/GO hybrids decorated with uniform zero-dimensional (0-D) cerium oxide (CeO2) nanoparticles were prepared via a facile hydrothermal method. The tribological performance of CeO2/CNTs/GO ternary nanocomposite was systematically investigated using a MS-T3000 ball-on-disk tester. The results demonstrated that CeO2/GO/CNTs nanocomposites can effectively reduce the friction of sliding pairs in paraffin oil. Moreover, the oil with 1 wt% of CeO2/GO/CNTs exhibited the best lubrication properties with the lowest friction coefficient and wear scar diameters (WSD) compared with adding only GO nanosheet, CeO2, and CeO2/CNTs hybrid nanocomposite as lubricant additives. It is concluded that due to the synergistic effect of 0D CeO2, 1D CNTs, and 2D GO during sliding process, a dimensionally mixed CeO2/GO/CNTs nanocomposite exhibits excellent lubricating properties, providing innovative and effective additives for application in the field of lubrication.

Urea modified fluorinated carbon nanotubes: unique self-dispersed characteristic in water and high tribological performance as water-based lubricant additives

UF-CNTs retaining a long-term dispersion stability in aqueous environments exhibit excellent tribological properties.