In situ intercalative polymerization is an environmentally-friendly process to produce polymer-clay nanocomposites with good clay dispersion. In this work, quaternary ammonium salts with tertiary amine groups were synthesized to modify clay as catalytically active modifiers for polyurethanes. Polyol dispersions with the catalyst-modified vermiculites were prepared by ultrasonication and examined by X-ray scattering and rheology. In the polyurethane elastomers synthesized from the above dispersions in a solvent-free process, X-ray scattering showed that the clay was highly intercalated/exfoliated without noticeable peaks for d < 9 nm, and TEM images revealed that the local dispersion of clay sheets was affected by the structure of the modifier. Addition of the modified clay to the polyurethane elastomers had only a small effect on the phase separation between hard and soft segments as deduced from DSC, FT-IR and DMA results. Thermo-mechanical and barrier properties of the composites were evaluated, and with one modifier, the nanocomposites showed a 390% increase in tensile modulus at 25 °C and a 40% reduction in CO 2 permeability at a loading of 5.3 wt% of catalyst-modified clay.
Bibliographical noteFunding Information:
The authors thank Huntsman Polyurethanes for providing financial support, and Dr. Conny Nijs and Dr. Qiang Lan from Huntsman for valuable discussions. Parts of this work were carried out at the University of Minnesota Characterization Facility, which receives partial support from the NSF through the NNIN program, and at the College of Science and Engineering Polymer Characterization Facility, University of Minnesota, which has received capital equipment funding from the NSF through the MRSEC. Jeffol ® and Suprasec ® are registered trademarks of Huntsman LLC and affiliates thereof in one or more, but not all countries.
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- Polymer-clay nanocomposite