High Performance Elastomeric Nanocomposites via Solvent Exchange Processing

Liff, S.M., Kumar, N. and McKinley, G.H.,

Nat. Mat., (2007), in press.

The incorporation of nanoparticles into engineering thermoplastics affords engineers an
opportunity to synthesize polymer nanocomposites that potentially rival the most dvanced
materials in nature. Development of these materials is difficult since thermodynamic and
kinetic barriers inhibit the dispersal of inorganic, often hydrophilic nanoparticles in hydrophobic polymer matrices. Using a new solvent exchange approach we preferentially nanoreinforce the hard micro-domains of thermoplastic elastomers with smectic clay of similar characteristic dimensions. The strong adhesion between the clay and the hard micro-domains coupled with the formation of a percolative network not only stiffens and toughens, but increases the heat distortion temperature of the material and induces reversible thermotropic liquid-crystalline transitions. The discotic clay platelets induce morphological ordering over a range of length scales that results in significant thermomechanical enhancement and expands high temperature applications. Merging block-copolymer processing techniques with this method for nanoparticle preferential-ordering facilitates the development of new, hierarchically-ordered materials.