Because of their high mechanical strength, Carbon nanotubes (CNTs) are being considered as nanoscale fibers to enhance the performance of polymer composite materials. These polymer-CNT composite materials can be used for micron scale devices with designed mechanical properties and smart polymer coating to protect materials under extreme physical conditions. To explore these possibilities it is important to develop a detailed atomic scale understanding of the mechanical coupling between polymer matrix and embedded nanotubes. In this work we study the thermal and mechanical properties of polymer-CNT composite using molecular dynamics (MD) simulations. The thermal expansions of CNT composites are found to increase above glass transition temperatures, due to the increase of the exclude volume of the embedded CNT; and its thermal motions (both Brownian motions and phonon vibrations) is found to effect the thermal properties of polymer matrix. Our MD studies show that Van der Waals potentials can contribute to the enhancement of the modulus of CNT composites. MD simulations also show that polymer can be chemically bonded to CNT. We will discuss the resulting mechanical coupling between the CNTs and polymer matrix to develop efficient nano-composite materials.
The Lab for Advanced Materials, Stanford University
McCullough Building, Rm 327, 476 Lomita Mall
Stanford, CA 94305-4045 USA