Preferential Nanoreinforcement in Block-Polymeric Polyurethane Results in Dramatic Thermomechanical Enhancement

摘要

Since the development of Nylon-6/Montmorillonite composites in the late 1980s by Toyota Research Labs [4], polymer-clay nanocomposites have attracted much attention. At small volume fractions, well-dispersed clay can significantly increase the strength, heat distortion temperature, barrier properties, flame retardance, and dimensional stability of a polymer. Therefore, these inexpensive, low-density, composite materials are ideal candidates for numerous applications, including vehicular structural parts, food packaging, and electronic components. The challenge in developing polymer/clay nanocomposites is fully dispersing and exfoliating inorganic, hydrophilic clay within organic and often hydrophobic polymer matrices. We have overcome this challenge by developing a novel solvent exchange approach to exfoliate nanoparticles in water-insoluble polymers. We have used this procedure to exfoliate a commercial clay (Laponite) in polyurethane and develop a nanocomposite system that exhibits dramatic thermomechanical enhancement.