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Study and characterization of open-cell nanocellular pmma/mam thin filmsThursday (08.10.2020) 10:10 - 10:30
One of the most widely used methods to produce micro and nanocellular polymers is the gas dissolution foaming process, usually employing CO2 as a blowing agent. It allows achieving materials with remarkable properties, such as low thermal conductivity and excellent mechanical properties under impacts, using an environmentally-friendly technique without dangerous pollutants. Based on this method, high nucleation ratios (up to 1016 nuclei/cm3), needed to obtain nanocellular polymers, have been obtained by employing extreme conditions of pressure or temperature in homopolymers, such as PMMA , PEI, or PSU.
On the other hand, heterogeneous nucleation has also resulted in an effective technique to produce nanocelullar polymers. Indeed, it has been proved that the addition of a second phase into the polymer allows reducing the energy barrier to form nuclei controlling in this way the nucleation process. Thus, high nucleation ratios could be achieved by using a heterogeneous route. Several types of nanoparticles and block copolymers have been employed as nucleating agents to produce nanocellular polymers at mild conditions, such as triblock copolymer MAM in PMMA matrix. The proper compatibility between both, their self-assembly capability, and their high CO2 absorption capacities makes PMMA/MAM blends versatile and efficient system to produce nanocellular polymers by gas dissolution foaming. However, although it was demonstrated that high MAM contents promote open-cell structures in bulk PMMA matrices, most of the previous research has been focused on closed-cell nanocellular structures.
The aim of this work is the production of open-cell nanocellular thin films, by foaming PMMA blends with high MAM contents. The cellular structure will be optimized by tuning several parameters, such as the saturation conditions, the foaming conditions, the MAM copolymer grade, and the amount of MAM incorporated, always over 50 wt%. The main interest of this work lies in the possibility of overcoming the limitations found on bulk (high thickness) nanocellular open-cell foams, which cannot used on any typical application of open-cell foams. Therefore, the obtained open-cell nanocellular films are expected to have appropriate features for their use in several applications such as filtration, catalysis, gas separation/storage, water treatment, or acoustic insulation.