8. Fibers and soft-matter nanotechnology for photonics and energy
harvesting:
Contact person:
Luana Persano
Arrigo Calzolari
Polymer fibers and nanostructures with features size in the micrometer
and submicrometer range are raising an increasing interest, because of their smart properties
for a wide class of applications, including textiles, microelectromechanical systems, sensors,
filtration membranes, scaffolds for tissue engineering, smart clothes and protective wound
dressing. In this context, we are developing functional nanofibers and nanowires as building
blocks of photonic and energy harvesting devices. The nanostructures are engineered in order
to feature targeted light-emission, light-transport and optical scattering properties, enabling
the realization of cavity-free, random laser systems. In addition, nanogenerators and sensing
devices based on both isolated fibers and dense arrays of fibers, made by piezo-electric
polymers, are being designed to exploit the intrinsic capability of such fibers to generate
voltage output in the direction normal to the applied compressive stress. Electrospinning
technologies, due to the combination of strong stretching forces and high electric fields, allow
the realization of piezoelectric materials in the form of nanofibers and nanowires with
enhanced piezoelectric properties.
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Individual suspended fibers of
poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) generate an open-circuit voltage
under well-defined levels of displacement in the submicroscale. Density functional theory has
been used to calculate the piezoelectric coefficients and the full piezoelectric tensor for
different copolymer configurations. By doping the PVDF-TrFE with light-emitting molecules,
an electromechanical coupling through piezoelectric polymer chains makes the nanofiber
emission sensitive to tensile stress and enables a reversible tuning of the emission of the
embedded organic molecules.
L. Persano, A. Camposeo, A. Terentjevs, F. Della Sala,
E. Fabiano, M. Montinaro, and D. Pisignano, Electrostatic mechanophores in tuneablelight-emitting piezopolymer nanowires, Adv. Mat., 29, 1701031 (2017)
L. Persano, A. Catellani, C. Dagdeviren, Y. Ma, X. Guo, Y. Huang, A. Calzolari, and D.
Pisignano Shear piezoelectricity in
poly(vinylidenefluoride-co-trifluoroethylene): full piezotensor coefficients by molecular
modeling, biaxial transverse response, and use in suspended energy-harvesting
nanostructures, Adv. Mat., 28, 7633 (2016)
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