Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

Small but strong: A review of the mechanical properties of carbon nanotube–polymer composites

Polymer nanocomposites based on functionalized carbon nanotubes

Recently, polymer nanocomposites reinforced with lower volume fraction of nanoceramics and carbon nanotubes have attracted steadily growing interest due to their peculiar and fascinating properties as well as their unique applications in commercial sectors. The incorporation of nanoceramics such as layered silicate clays, calcium carbonate or silica nanoparticles arranged on the nanometer scale with a high aspect ratio and/or an extremely large surface area into polymers improves their mechanical performances significantly. The properties of nanocomposites depend greatly on the chemistry of polymer matrices, nature of nanofillers, and the way in which they are prepared. The uniform dispersion of nanofillers in the polymer matrices is a general prerequisite for achieving desired mechanical and physical characteristics. In this review article, current development on the processing, structure, and mechanical properties of polymer nanocomposites reinforced with respective layered silicates, ceramic nanoparticles and carbon nanotubes will be addressed. Particular attention is paid on the structure–property relationship of such novel high-performance polymer nanocomposites.

Structural and mechanical properties of polymer nanocomposites

Shape-memory polymers and their composites: Stimulus methods and applications

Physical interactions at carbon nanotube-polymer interface

A new test methodology for evaluating scratch resistance of polymers

Purification and stabilization of colloidal ZnO nanoparticles synthesized from zinc acetate dihydrate and potassium hydroxide in methanol have been performed. Isopropanol and hexane were utilized to achieve the precipitation-redispersion washing procedure in methanol. The results from atomic absorption spectroscopy show that the concentration of K+ cation can be dramatically reduced by washing. X-ray diffraction and transmission electron microscopy results show that zinc layered double hydroxide formed in the ZnO precipitate can be effectively removed through concentrating the unpurified ZnO colloids by solvent evaporation. The purified ZnO nanoparticles can be fully redispersed in methanol, but become unstable with time due to the low concentration of acetate in the colloids. Fortunately, the unstable ZnO methanol colloids are found to become stable after addition of a small amount of hexane. The present study is of particular significance for the preparation of purified colloidal ZnO nanoparticles for device fabrication, functional ZnO coatings and polymer nanocomposite applications.

Purification and stabilization of colloidal ZnO nanoparticles in methanol

The large-scale assembly of asymmetric colloidal particles is used in creating high-performance fibres. A similar concept is extended to the manufacturing of thin films of self-assembled two-dimensional crystal-type materials with enhanced and tunable properties. Here we present a spray-coating method to manufacture thin, flexible and transparent epoxy films containing zirconium phosphate nanoplatelets self-assembled into a lamellar arrangement aligned parallel to the substrate. The self-assembled mesophase of zirconium phosphate nanoplatelets is stabilized by epoxy pre-polymer and exhibits rheology favourable towards large-scale manufacturing. The thermally cured film forms a mechanically robust coating and shows excellent gas barrier properties at both low- and high humidity levels as a result of the highly aligned and overlapping arrangement of nanoplatelets. This work shows that the large-scale ordering of high aspect ratio nanoplatelets is easier to achieve than previously thought and may have implications in the technological applications for similar materials.

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Large-scale self-assembled zirconium phosphate smectic layers via a simple spray-coating process

A systematic study of surface damage exerted by a progressive scratching load is performed on model polypropylene (PP) systems. Mar-scratch and stress-whitening transitions can be readily observed, and the corresponding critical loads determined. Distinctive surface damage features are determined before and after the transitions. The progressive load test enables the scratch hardness values to be obtained using the graphical method, thereby allowing scratch resistance to be accurately quantified and ranked among materials. Visibility of the scratched surface is quantified using a gray level analysis via a flatbed scanner and a commercial image analysis tool. It is found that the onset of scratch visibility can be determined accurately and reproducibly using the custom-built scratcher under progressive loading condition. Exposed talc particles on the surface of talc-filled PP are found to be responsible for the increased light scattering, leading to greatly increased visibility. The observed scratch visibility is also found to be related to the corresponding friction force profiles. Approaches for producing scratch resistant PP are discussed.

Minhao Wong

Papers

Physical interactions at carbon nanotube-polymer interface

A new test methodology for evaluating scratch resistance of polymers

Purification and stabilization of colloidal ZnO nanoparticles in methanol

Large-scale self-assembled zirconium phosphate smectic layers via a simple spray-coating process

Study of surface damage of polypropylene under progressive loading