Surface modification of inorganic nanoparticles for development of organic–inorganic nanocomposites—A review

The addition of inorganic spherical nanoparticles to polymers allows the modification of the polymers physical properties as well as the implementation of new features in the polymer matrix. This review article covers considerations on special features of inorganic nanoparticles, the most important synthesis methods for ceramic nanoparticles and nanocomposites, nanoparticle surface modification, and composite formation, including drawbacks. Classical nanocomposite properties, as thermomechanical, dielectric, conductive, magnetic, as well as optical properties, will be summarized. Finally, typical existing and potential applications will be shown with the focus on new and innovative applications, like in energy storage systems.

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Polymer-Nanoparticle Composites: From Synthesis to Modern Applications

The fundamental mechanisms of solid lubrication are reviewed with examples from well-known solid lubricants like the transition metal dichalcogenides and diamond-like carbon families of coatings. Solid lubricants are applied either as surface coatings or as fillers in self-lubricating composites. Tribological (friction and wear) contacts with solid lubricant coatings typically result in transfer of a thin layer of material from the surface of the coating to the counterface, commonly known as a transfer film or tribofilm. The wear surfaces can exhibit different chemistry, microstructure, and crystallographic texture from those of the bulk coating due to surface chemical reactions with the surrounding environment. As a result, solid lubricant coatings that give extremely low friction and long wear life in one environment can fail to do so in a different environment. Most solid lubricants exhibit non-Amontonian friction behavior with friction coefficients decreasing with increasing contact stress. The main mechanism responsible for low friction is typically governed by interfacial sliding between the worn coating and the transfer film. Strategies are discussed for the design of novel coating architectures to adapt to varying environments.

Solid lubricants: a review

Superhydrophobicity is a remarkable evolutionary adaption manifested by several natural surfaces. Artificial superhydrophobic coatings with good mechanical robustness, substrate adhesion and chemical robustness have been achieved separately. However, a simultaneous demonstration of these features along with resistance to liquid impalement via high-speed drop/jet impact is challenging. Here, we describe all-organic, flexible superhydrophobic nanocomposite coatings that demonstrate strong mechanical robustness under cyclic tape peels and Taber abrasion, sustain exposure to highly corrosive media, namely aqua regia and sodium hydroxide solutions, and can be applied to surfaces through scalable techniques such as spraying and brushing. In addition, the mechanical flexibility of our coatings enables impalement resistance to high-speed drops and turbulent jets at least up to ~35 m s−1 and a Weber number of ~43,000. With multifaceted robustness and scalability, these coatings should find potential usage in harsh chemical engineering as well as infrastructure, transport vehicles and communication equipment.

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All-organic superhydrophobic coatings with mechanochemical robustness and liquid impalement resistance.

Recent developments on nanocellulose reinforced polymer nanocomposites: A review

http://research.me.udel.edu/~dlburris/papers/JA9.pdf

A low friction and ultra low wear rate PEEK/PTFE composite

Polymer nanocomposites operate in applications where fluid and grease lubricants fail, and have superior tribological performance to traditional polymer composites. Nanoparticle fillers have been a part of notable reductions in the wear rate of the polymer matrix at very low loadings. Despite instances of remarkable wear reductions at unprecedented loadings (3 000 times at 0.5% loading in one case), there is a lack of general agreement within the literature on the mechanisms of wear resistance in these nanocomposites. In addition, results appear to vary widely from study to study with only subtle changes of the filler material or blending technique. The apparent wide variation in tribological results is likely a result of processing and experimental differences. Tribology is inherently complex with no governing laws for dry sliding friction or wear, and the state of the art in polymeric nanocomposites tribology includes many qualitative descriptors of important system parameters, such as particle dispersion, bulk mechanical properties, debris morphology, and transfer film adhesion, morphology, composition, and chemistry. The coupling of inherent tribological complexities with the complicated mechanics of poorly characterized nanocomposites makes interpretation of experimental results and the state of the field extremely difficult. This paper reviews the state of the art in polymeric nanocomposites tribology and highlights the need for more quantitative studies. Examples of such quantitative measurements are given from recent studies, which mostly involve investigation of polytetrafluoroethylene matrix nanocomposites.

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Polymeric Nanocomposites for Tribological Applications

http://research.me.udel.edu/~dlburris/papers/JA8.pdf

Improved wear resistance in alumina-PTFE nanocomposites with irregular shaped nanoparticles

http://research.me.udel.edu/~dlburris/papers/JA32.pdf

Transfer film evolution and its role in promoting ultra-low wear of a PTFE nanocomposite

http://research.me.udel.edu/~dlburris/papers/JA27.pdf

David L. Burris

Papers

A low friction and ultra low wear rate PEEK/PTFE composite

Polymeric Nanocomposites for Tribological Applications

Improved wear resistance in alumina-PTFE nanocomposites with irregular shaped nanoparticles

Transfer film evolution and its role in promoting ultra-low wear of a PTFE nanocomposite

A quantitative method for measuring nanocomposite dispersion