Nanocellular or nanoporous polymers are biphasic materials consisting of a polymeric solid matrix and a gaseous phase at the nanometric scale. The presence of such small pores results in confinement effects in both phases. On the one hand, air molecules are restricted within the nanometric pores, while polymer chains are confined within the solid nanostructure. This confinement has been shown to reduce the thermal conductivity, enhance the mechanical strength, and modify optical properties compared to conventional cellular polymers with larger pores, and even to the solid polymer itself [1].

This study presents recent results linking the polymer configuration in the solid phase and the physical properties of the porous material. In addition, effects related to the fabrication process (gas dissolution foaming with CO2) and their role in tailoring the resulting nanostructure are considered. First, thermal conductivity is analyzed by quantifying the contribution of the solid phase in a collection of nanocellular polymers based on polystyrene (PS) and polymethylmethacrylate (PMMA) with variable pore sizes from the micro to the nanoscale. Results and trends are discussed, revealing marked differences between these nanoporous systems in comparison with conventional polymer foams. Second, impact and tensile mechanical properties are evaluated for micro- and nanocellular polyetherimide (PEI). The process-induced modifications suffered by the polymer and their influence on the final properties of the materials as a function of the pore size are presented and discussed.

Overall, the results presented establish clear relations between polymer nanostructure and thermal and mechanical performance, identifying key structural and processing parameters governing the behavior of thermoplastic nanocellular polymers.

References

1. J. Martin-de Leon, V. Bernardo, M. A. Rodriguez-Perez, Nanocellular Polymers: From Microscale to Nanoscale, 2023, De Gruyter

Acknowledgments

All the authors acknowledge financial support from grant PID2024-157392OB-I00 funded by MICIU/AEI/ 10.13039/501100011033 and, by “ERDF/EU” and grant PDC2025-165502-I00 funded by MICIU/AEI/ 10.13039/501100011033 and, by the “European Union NextGenerationEU/PRTR”.