Challenges and perspectives in the nanocellular polymers fieldWednesday (07.10.2020) 09:30 - 10:30 Room 1
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 and 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 thermal insulation, automotive, aeronautic, renewable energies, construction, filtration, electronics, etc.
These materials can be produced by gas dissolution foaming using strategies to reach very high nucleation densities (higher than 1014cells/cm3) and avoiding coalescence or coarsening mechanisms. This approach allows producing parts with significant thickness and excellent properties.
Although the properties of these materials are promising the materials are still far from commercialization due to several challenges in their production. Some of these challenges are related to the density reached during foaming, the presence of microcellular defects in the materials, the presence of bimodal cell size distributions, the difficulties to obtain flat and large panels. etc. In addition, there are other challenges related with their properties, the thermal conductivity by radiation is not known, thermal conductivity by conduction through the solid matrix is high in comparison with silica aerogels, the transparency is, up to some extent, limited, etc. This lecture will review some of these challenges and the perspectives associated to them.