Highly exfoliated poly(ε-caprolactone)/organomontmorillonite nanocomposites prepared byin situ polymerization

Modified Polymer Surfaces: Thin Films of Silicate Composites via Polycaprolactone Melt Fusion

Polymer/layered silicate composites have gained huge attention in terms of research and industrial applications. Traditional nanocomposites contain particles regularly dispersed in a polymer matrix. In this work, a strategy for the formation of a composite thin film on the surface of a polycaprolactone (PCL) matrix was developed. In addition to the polymer, the composite layer was composed of the particles of saponite (Sap) modified with alkylammonium cations and functionalized with methylene blue. The connection between the phases of modified Sap and polymer was achieved by fusing the chains of molten polymer into the Sap film. The thickness of the film of several μm was confirmed using electron microscopy and X-ray tomography. Surfaces of precursors and composite materials were analyzed in terms of structure, composition, and surface properties. The penetration of polymer chains into the silicate, thus joining the phases, was confirmed by chemometric analysis of spectral data and changes in some properties upon PCL melting. Ultimately, this study was devoted to the spectral properties and photoactivity of methylene blue present in the ternary composite films. The results provide directions for future research aimed at the development of composite materials with photosensitizing, photodisinfection, and antimicrobial surfaces.

The Influence of Melt-Mixing Conditions and State of Dispersion on Crystallisation, Rheology and Mechanical Properties of PCL/Sepiolite Nanocomposites

It is generally accepted that the benefit of anisotropic nanofiller addition is strongly dependent on the state of the dispersion of these fillers in a polymer matrix. In this paper the influence of melt-compounding conditions on the dispersion of a needle-like clay, i. e. sepiolite, in poly(∊-caprolactone) (PCL) is investigated. The crystallisation behavior as well as the rheological and mechanical properties of PCL/sepiolite nanocomposites with filler contents up to 5 wt.% are studied. By changing the screw speed during melt-mixing in a micro-compounder, the state of dispersion was varied, with the higher speed leading to better dispersion and breakdown of the sepiolite agglomerates or bundles. Rheometry showed that better dispersed nanocomposites displayed an increase in viscosity due to network formation at slightly higher filler loadings. Likewise, better dispersed composites showed a modest increase in crystallisation temperature at low filler content, accompanied by a decrease in both nucleation efficiency and degree of crystallisation at higher loadings. Better dispersed nanocomposite systems also showed superior mechanical properties, particularly at higher filler loadings. However, overall the reinforcing efficiency of sepiolite in all nanocomposites was relatively low. This was mainly a consequence of the relatively low filler aspect ratio and the simultaneous breakup of sepiolite needles together with a breakdown of bundles during compounding.

A novel tin-based imidazolium-modified montmorillonite catalyst for the preparation of poly(butylene terephthalate)-based nanocomposites using in situ entropically-driven ring-opening polymerization

A novel alkylimidazolium salt incorporating a 2,2-di-n-butyl[1,3,2]dioxastannolane moiety was synthesized and characterized.

Insight into the Broad Field of Polymer Nanocomposites: From Carbon Nanotubes to Clay Nanoplatelets, via Metal Nanoparticles

Highly ordered polymer nanocomposites are complex materials that display a rich morphological behavior owing to variations in composition, structure, and properties on a nanometer length scale. Metal-polymer nanocomposite materials are becoming more popular for applications requiring low cost, high metal surface areas. Catalytic systems seem to be the most prevalent application for a wide range of metals used in polymer nanocomposites, particularly for metals like Pt, Ni, Co, and Au, with known catalytic activities. On the other hand, among the most frequently utilized techniques to prepare polymer/CNT and/or polymer/clay nanocomposites are approaches like melt mixing, solution casting, electrospinning and solid-state shear pulverization. Additionally, some of the current and potential applications of polymer/CNT and/or polymer/clay nanocomposites include photovoltaic devices, optical switches, electromagnetic interference (EMI) shielding, aerospace and automotive materials, packaging, adhesives and coatings. This extensive review covers a broad range of articles, typically from high impact-factor journals, on most of the polymer-nanocomposites known to date: polymer/carbon nanotubes, polymer/metal nanospheres, and polymer/clay nanoplatelets composites. The various types of nanocomposites are described form the preparation stages to performance and applications. Comparisons of the various types of nanocomposites are conducted and conclusions are formulated.