May 27, 2017

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Polymer/Zirconium Tungstate Nanocomposites

A section view of ZrW2O8 crystal structure composed of zirconium oxide octahedra connected to tungsten oxide tetrahedra through shared oxygen atoms.

Zirconium tungstate (ZrW2O8) is a ceramic material that exhibits strong and isotropic negative thermal expansion (NTE) behavior over a broad temperature range (from 0.3 to 1050 K). Due to this unique property, ZrW2O8 can be integrated into various matrix materials to produce composites with controllable coefficient of thermal expansion (CTE). Such composites materials can be used in a wide range of applications including high precision optical mirrors, microelectronic devices, and aerospace engineering.

The study of polymer nanocomposites reinforced by nano-sized ZrW2O8 particles is especially attractive for two major reasons.  First, nanoparticles have higher surface area than micron-sized materials, which allows composites with superior properties at lower loadings.  Second, the negative thermal expansivity of nano-scale ZrW2O8 is more pronounced than the bulk ZrW2O8.

In our research, ZrW2O8 nanoparticles with various morphologies synthesized from hydrothermal synthesis followed by specific surface treatments are used to reinforce different types of epoxy and polyurethane resins.  Application are being explored in conformal coatings for encapsulation of microelectronic devices and as the matrix in carbon fiber reinforced aerospace composites to improve thermal stability and mechanical performance.

Three types of synthesized ZrW2O8 nanoparticles with different morphologies and CTE values

People Involved

Hongchao Wu, Yuzhan Li, Michael Kessler