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Polymer composites based on organically modified phyllosilicates (organoclay) and poly(ethylene-co-vinyl acetate) (EVA) were prepared by melt processing to study their combustion behavior. Their degrees of dispersion and intercalation spacings as determined by transmission electron microscopy (TEM) and X-ray diffraction (XRD) were typical of either a microcomposite or an exfoliated nanocomposite, depending on the type of organoclay. Combustion experiments showed that the microcomposite burns in the same way as pure EVA, whereas the heat release is reduced by 70−80% when nanocomposites with low silicate loadings (2−5%) are burned, because a protective charred ceramic surface layer is formed as a result of reassembly of the clay layers and catalyzed charring of the polymer. A chemical mechanism for this charring is proposed.

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SummaryCyclodextrin-based nanosponges, which are proposed as a new nanosized delivery system, are innovative cross-linked cyclodextrin polymers nanostructured within a three-dimensional network. This type of cyclodextrin polymer can form porous insoluble nanoparticles with a crystalline or amorphous structure and spherical shape or swelling properties. The polarity and dimension of the polymer mesh can be easily tuned by varying the type of cross-linker and degree of cross-linking. Nanosponge functionalisation for site-specific targeting can be achieved by conjugating various ligands on their surface. They are a safe and biodegradable material with negligible toxicity on cell cultures and are well-tolerated after injection in mice. Cyclodextrin-based nanosponges can form complexes with different types of lipophilic or hydrophilic molecules. The release of the entrapped molecules can be varied by modifying the structure to achieve prolonged release kinetics or a faster release. The nanosponges could be used to improve the aqueous solubility of poorly water-soluble molecules, protect degradable substances, obtain sustained delivery systems or design innovative drug carriers for nanomedicine.

Nanocomposites of polypropylene-graft-maleic anhydride with organically modified clays have been prepared and characterized by X-ray diffraction and transmission electron microscopy. Their combustion behavior has been evaluated using oxygen consumption cone calorimetry. Synergy is observed between the nanocomposite formed and conventional vapor phase fire retardants, such as the combination of decabromodiphenyloxide and antimony oxide. The presence of bromine and antimony does not affect the heat release rate curves of the virgin polymer.

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