Nanocellular polymers are a new type of cellular materials which are defined as organic materials with cell sizes in the nanometric range. The reduction of the cell size to the nanoscale strongly influences the physical properties of the cellular polymer providing unexpected and improved properties compared to conventional cellular polymers or microcellular polymers. In particular, these novel materials, structurally comparable to silica aerogels but based on a polymer matrix, have better mechanical properties than microcellular polymers, could have thermal conductivities well below those of the best thermal insulators currently in the market. Moreover, the polymer matrix properties can be modified by the molecular confinement of the polymer chains inside the cell walls and struts due the low thicknesses of these elements. In addition, when the materials are produced with an open cell structure they could be used as selective filters or in catalysis applications. Finally, it has been proved recently that these materials, when cell sizes are below 50 nm, can be transparent. This unique combination of properties, not reached for any material, makes these new light weight polymers promising for a significant amount of applications in strategic market sectors such as automotive, aeronautic, renewable energies, construction, filtration, thermal insulation, etc.
However, the production of these materials is not a simple task. Very high nucleation densities are needed (higher than 1014cells/cm3). In addition, no coalescence or coarsening are needed to have a nanocellular polymer with a significant expansion ratio.
In the last few years, research on this topic has been intense and the progress in creating ways to produce nanocellular polymers with controlled cell sizes, open or closed cell structures and low densities has been significant. This keynote lecture will review the recent approaches that has permitted to produce improved nanocellular polymers using the gas dissolution foaming technology.