Nanostructured coupling agents for multifunctional composites

Nanoengineered composite materials, in which one or more of the composite constituents (e.g., matrix, fibers, laminates) is nanostructured and possesses enhanced and functional properties, represent a potentially enabling technology for a wide range of DoD and civilian applications. For example; future aerospace and electronic systems will demand materials with elements of integrated "functionality" such as thermal management, in addition to excellent mechanical and electrical properties, dimensional stability, low outgassing, and electromagnetic shielding. However, there are significant challenges related to the synthesis and processing of these "multiscale" composites that must be addressed in order to exploit the true potential that nanotechnology holds for composites. The interface plays a significant role in the behavior of traditional and nanoscale composites. This is the region in the vicinity of the particle in which the polymer properties are altered as compared to the bulk. Research found on traditional polymer matrix composites contains a significant body of knowledge on how to control the fiber-resin interface by changing the chemistry of the filler surfaces. Understanding of nanocomposite interfaces is even more critical than that of traditional composites because it represents a much larger volume fraction. Furthermore, the number of interfaces increases in a multiscale composite, further complicating the issue. We have recently developed nanostructured coupling agents designed to couple micron-scale reinforcements to the composite matrix. Scanning electron microscopy and Raman spectroscopy show evidence of carbon nanotubes deposited onto the carbon fibers. X-ray photoelectron spectroscopy provides possible evidence of a covalent link between the carbon nanotubes and the carbon fibers.