In the preparation of polymer/clay nanocomposites, organoclay plays an important role in lipophilizing and dispersing the clay into less polar polymer matrixes. Organic modifiers of various chain lengths were examined in different types of clays, smectite, montmorillonite (MMT), and mica, to prepare their corresponding organoclays. The layered structure and gallery spacing of organoclays and polylactide (PLA) nanocomposites shows that, with a modifier of the same chain length, the gallery spacing of the organoclay was largest for mica and smallest for smectite because of the higher ion-exchange capacity of mica and physical jamming of the modifier due to a restricted conformation at the core part of the clay of larger size. The increment of the modulus in a smectite nanocomposite, compared to that of PLA, is higher than MMT or mica nanocomposite due to better dispersion in a smectite system for the same clay loading. Being a well-dispersed system, smectite nanocomposites have better gas barrier properties than the MMT or mica systems, which are larger in size but stacked in nature in their nanocomposites. A new idea for obtaining porous ceramic material from layered silicate/polymer nanocomposites by burning is unveiled using various clays and the mechanism of their formation is elucidated.

Understanding the structure-property relationship in polymer/layered silicate nanocomposites is of fundamental importance in designing materials with desired properties. To understand these relations in the case of poly(butylene succinate) (PBS)/organically modified layered silicate (OMLS) nanocomposites, we studied the rheological properties of these materials in detail, because the rheological behavior of polymer/OMLS nanocomposites is strongly influenced by their nanostructure and the interfacial characteristics. For this reason, a series of PBS/OMLS nanocomposites were prepared using a simple melt intercalation technique. Two different types of OMLS, montmorillonite (mmt) modified with octadecylammonium chloride and saponite (sap) modified with quaternary hexadecyl tri-nbutylphosphonium bromide, were used for the nanocomposite preparations. The structure of nanocomposites in the nanometer scale was characterized using wide-angle X-ray diffraction (WAXD) analyses and transmission electron microscopy (TEM) observations. A flocculated structure has a strong effect on mechanical properties (both in solid and melts) and various other materials properties.

Cover:The picture on the cover shows the structure and dynamic mechanical properties of neat poly(butylene succinate-co-adipate) and its nanocomposites with organically modified montmorillonite. Further can be found in the article by S. Sinha Ray, M. Bousmina,* and K. Okamoto on page 759.

A series of new poly(butylene succinate) (PBS)/layered silicate nanocomposites were prepared successfully by simple melt extrusion of PBS and organically modified layered silicates (OMLS). Three different types of OMLS were used for the preparation of nanocomposites: two functionalized ammonium salts modified montmorillonite and a phosphonium salt modified saponite. The structure of the nanocomposites in the nanometer scale was characterized with wide‐angle X‐ray diffraction and transmission electron microscopic observations. With three different types of layered silicates modified with three different types of surfactants, the effect of OMLS in nanocomposites was investigated by focusing on four major aspects: structural analysis, materials properties, melt rheological behavior, and biodegradability. Interestingly, all these nanocomposites exhibited concurrent improvements of material properties when compared with pure PBS. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3160–3172, 2003