Nanocomposite type hydrogels (NC gels) were synthesized by in-situ free-radical polymerization of N-substituted acrylamides in the presence of various inorganic clays in water. It was confirmed that, NC gels, formed without using organic crosslinker, exhibited extraordinarily good mechanical properties due to the formation of organic (polymer) / inorganic (clay) networks, in comparison with conventional organic crosslinked hydrogels (OR gels) or gel-like materials prepared from linear polymers (LR gels).The tensile strengths and fracture energies of NC gels were observed to be approximately 10 and 500 times those of corresponding OR gels. NC gels prepared using synthetic swollen hectorites with slightly different compositions exhibited reproducibly good mechanical properties. Also, it was found that the modification of clay by, for example, fluorine substitution and/or the addition of a dispersant such as sodium pyrophosphate had large effect on the mechanical properties of the resulting NC gels. The modulus and strength decreased while elongating to break increased by introducing fluorine into the clay and incorporating the dispersing agent. Furthermore, in the case of clay which did not swell in water, the mechanical properties of the NC gel obtained became very poor and close to those of LR gels. The change in stress-strain curves using different clays and modifications was discussed in terms of the change in crosslinking density in the organic/inorganic network structure model.

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Low-modulus die bonding adhesive films are useful for a chip size/scale package (CSP) which is suitable for compact electronic calculators with higher speed. In particular, to cope with their wide-spreading application of very thin semiconductor wafers and Pb-free solders, the films are expectedly to have both low viscosity in the attaching process and high reliability of bonding in the high temperature reflow process after curing. We studied the phase structure and the property of a new reaction-induced polymer alloy consisting of a low modulus acrylic polymer and a highly heat-resistant epoxy resin. As a result, this alloy film is clarified to have both the high resin flow and superior reflow-crack resistance.

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Nano-composites were prepared from an epoxy resin and organoclay via an intercalation process. Organoclay was prepared by a cation exchange of montmorillonite (MMT) with an intercalation agent such as dodecylamine or 12-aminododecanoic acid. The obtained epoxy/clay nano-composites were studied with regard to phase structure and thermal and mechanical properties. Observation with transmission electron microscopy (TEM) revealed that the organoclay having a wider interlayer space had higher dispersibility. Tan δ curve of the nano-composites prepared from MMT treated with 12-aminododecanoic acid was observed remarkably shifting to a high temperature region. This may result from increasing transition energy due to the formation of covalent bond between the clay and epoxy resin.

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The effect of SiO₂ nano-particles was investigated on the thermal property of epoxy composites including SiO₂, by examining the effect of OH groups, the amount of which was noticed. Results were as follows : high Tg and high elastic modulus appeared by adding the nano-particles of SiO₂. As compared with epoxy composites used SiO₂ without free-type OH, Tg of that with free-type OH increased by 5°C, and elastic modulus improved by 2.5 times at elevated temperatures above Tg. Therefore, the improvement on the thermal resistance of epoxy composites is possible by controlling the amount of OH groups.

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Nano-technology for fabrication of semiconductor devices is based on the miniaturization technique, that is referred to as “top-down nanotechnology.” In organic and polymeric materials, on the other hand, bottom-up approaches for constructing nanoscale-structures in organic molecular assemblies have been of interest. In this review, there is described the development of soft nano-devices based on polymer nano-sheet assemblies which are prepared using mainly, Langmuir-Blodgett technique. There are also described various functions incorporated into the polymer sheets such as a photofunction, a nano-coating, and a hybrid with nano-particles, as well as soft nano-devices based on their integrated assemblies are also described.

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In the field of a polymer composite material, nanocomposite materials have drawn attention as a new type of composite in recent years. New research and development of nanocomposites have been started and entered the market one after another. The physical properties and functions, which are obtained by nanocomposite technology, have dramatically improved dramatically compared with conventional glass fibers and old inorganic fillers. In this paper, a polymer-nanocomposite is described focusing on the polymer/clay nanocomposite, of attracting attention industrially.

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