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Title: Porous polymeric microparticles foamed with supercritical CO2 as scattering white pigments
Author(s): Borgmann, Luisa Maren
Johnsen, Siegbert
Santos de Oliveira, Cristine
Martins de Souza e Silva, Juliana
Li, Juan
Kirchlechner, ChristophLook up in the Integrated Authority File of the German National Library
Gomard, Guillaume
Wiegand-Tripp, GabrieleLook up in the Integrated Authority File of the German National Library
Hölscher, HendrikLook up in the Integrated Authority File of the German National Library
Issue Date: 2023
Type: Article
Language: English
Abstract: Nowadays, titanium dioxide (TiO2) is the most commercially relevant white pigment. Nonetheless, it is widely criticized due to its energy-intensive extraction and costly disposal of harmful by-products. Furthermore, recent studies discuss its potential harm for the environment and the human health. Environment-friendly strategies for the replacement of TiO2 as a white pigment can be inspired from nature. Here whiteness often originates from broadband light scattering air cavities embedded in materials with refractive indices much lower than that of TiO2. Such natural prototypes can be mimicked by introducing air-filled nano-scale cavities into commonly used polymers. Here, we demonstrate the foaming of initially transparent poly(methyl methacrylate) (PMMA) microspheres with non-toxic, inert, supercritical CO2. The properties of the foamed, white polymeric pigments with light scattering nano-pores are evaluated as possible replacement for TiO2 pigments. For that, the inner foam structure of the particles was imaged by phase-contrast x-ray nano-computed tomography (nano-CT), the optical properties were evaluated via spectroscopic measurements, and the mechanical stability was examined by micro compression experiments. Adding a diffusion barrier surrounding the PMMA particles during foaming allows to extend the foaming process towards smaller particles. Finally, we present a basic white paint prototype as exemplary application.
Open Access: Open access publication
License: (CC BY 4.0) Creative Commons Attribution 4.0(CC BY 4.0) Creative Commons Attribution 4.0
Journal Title: Bioinspiration & biomimetics
Publisher: Inst. of Physics
Publisher Place: London
Volume: 18
Issue: 2
Original Publication: 10.1088/1748-3190/acb899
Appears in Collections:Open Access Publikationen der MLU

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