NER: Creation of Polymeric Nanofoams Based on Retrograde Vitrification

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This award supports a research project aimed at exploring novel process strategies to develop closed-cell polymer foams that have cell sizes in the range of nanometers. The idea of creating nano-scaled cells in polymeric materials is exciting and largely unexplored. Due to the unique structures, nanofoams are expected to have many properties that are superior to those of existing materials, such as a much higher strength-to-weight ratio. In addition, nanofoams would provide novel functional materials that could be tailored for the needed properties, for example, thermal conductivity, dielectric constant, acoustic and damping coefficients. Nanofoams have the potential to be used for any applications where foamed polymers are currently used, with the benefit of further material savings and improved performance. These novel materials will find a wide range of applications in construction, packaging, motor vehicle, microelectronics, and household products.This research will explore the creation of nanofoams from the PMMA-CO2 system using a solid-state foaming method. The retrograde vitrification phenomenon will be employed to increase the gas diffusivity and solubility. Both conventional solid-state foaming techniques and the stress induced bubble nucleation method will be explored to develop the nanofoaming process. A low temperature and high pressure vessel will be designed and instrumented. Gas solubility and diffusivity will be measured. Properties of the new nanofoam materials, such as the morphology, mechanical properties, and dielectric properties, will be characterized in this research.