Luca Grillo (AMI Polymer Chemistry and Materials): Directional water transport in dense asymmetric membranes

Several natural organisms exploit directional transport as a strategy to retain water. Some species of plants achieve this property by developing a protective membrane called the cuticle, whose main function is regulating water exchange with the environment. Cuticles consist of a polyester matrix mixed with polysaccharides that extend from the internal side and gradually fade in the transversal direction and an external layer of hydrophobic waxes. Inspired by cuticle structure, we developed compositionally asymmetric dense membranes based on a hydrophobic poly(styrene)-block-poly(butadiene)-block-poly(styrene) (SBS) copolymer and hydrophilic polyvinyl alcohol (PVA). The water-induced plasticization of PVA, combined with the asymmetric design, switches the directional water transport when a high relative humidity (RH) gradient is applied. The magnitude of directionality can be tuned by varying the composition and the structure of these bio-inspired membranes, and the switchable feature of the asymmetric water transport may be useful for smart packaging applications in which the take-up or release of moisture is regulated as needed.


Davide Lardani (AMI Polymer Chemistry and Materials): Sensitized triplet-triplet annihilation upconversion: from liquid systems to solid-state materials

First identified in the early 1960s, sensitized triplet-triplet annihilation upconversion (TTA-UC) has emerged as a powerful strategy for converting low-energy photons into higher-energy photons, enabling its use in a wide range of applications, including solar energy conversion, bioimaging, 3D printing, and photocatalysis. Unlike other upconversion techniques, such as second harmonic generation or two-photon absorption, which typically require high-intensity coherent light sources, TTA-UC operates efficiently with non-coherent, low-power-density radiation. These unique characteristics make it particularly well-suited for harnessing and converting diffuse sunlight, paving the way for its integration into solar energy technologies. However, a key challenge that remains open nowadays is transitioning from high-performance liquid-state systems to robust solid-state alternatives that are more practical for industrial applications. In this seminar, Davide Lardani will show an overview of his PhD projects involving liquid and solid-state upconverting systems using different chromophore pairs, named sensitizer and emitter or annihilator.