Dielectric investigation of metal-organic framework/polymer mixed matrix membranes for triboelectric nanogenerator devices
2Faculty of Materials Science and Applied Chemistry, Institute of Materials and Surface Engineering, Riga Technical University, Riga, Latvia
3Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
There is a strong interest to study the contact electrification (CE) properties of various materials to design triboelectric nanogenerator (TENG) devices with better efficiencies. Recently UIO-66 metal-organic frameworks (MOFs) with various linker modifications were identified as promising filler materials in mixed matrix membranes (MMM) for TENG devices [1]. Such composites allow preservation of the original excellent properties and low preparation cost of polymers while the addition of functional fillers can effectively improve triboelectric properties of the membranes [2,3]. Energy harvesting is mainly affected by charge-inducing ability (surface properties) and charge-trapping capability (dielectric property) of triboelectric materials. MOFs contain metallic and organic counterparts thus different CE mechanisms may coexist. In this study we have focused on broadband dielectric properties of several selected polyether block amide (PEBA)/UIO-66 mixed matrix membranes aiming at investigation of dynamic processes and filler/matrix interaction in these composites.
PEBA-based nanocomposite films were prepared with 1, 2 and 5 wt% UIO-66 and modified UIO-66-NH2 concentrations. Dielectric properties of these MMM were measured in 150 K – 360 K ant 1 Hz – 1MHz frequency range using computer controlled ModuLab XM MTS impedance measurement system with MTS Femto Ammeter module for low current measurements and compared with the response of vanilla polyether block amide sample. This allowed us to identify the influence of the filler/matrix interaction on the glass transition and melting/crystallization relaxations of polyether (PE) and polyamide (PA) segments. Incorporation of UIO-66 crystallites increases glass transition temperature in PEBA matrix. On further heating Maxwell-Wagner relaxation process of interfacial polarization resulting from the existence of well separated phases involving ionic charge carriers was observed. Modification of UIO-66 linkers with -NH2 groups showed much stronger MOF-polymer interaction and increase in dielectric permittivity as compared with pure UIO-66 MMM.
[1] Y.-M. Wang, Nanotechnology 33 (2022) 065402, https://doi.org/10.1088/1361-6528/ac32f8
[2] A. Šutka Adv. Mater. Technol. 2022, 2200162, DOI: 10.1002/admt.202200162
[3] Y. Hu, Macromol. Mater. Eng. 2021, 306, 2100128, DOI: 10.1002/mame.202100128
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