Bubble Seeding Nanocavities
| Autor: | Joost Duvigneau, Shanqiu Liu, G. Julius Vancso, Sida Yin |
|---|---|
| Přispěvatelé: | Materials Science and Technology of Polymers |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Thermogravimetric analysis
Materials science Nanocellular materials Scanning electron microscope Nucleation UT-Hybrid-D General Physics and Astronomy Nanoparticle 02 engineering and technology 010402 general chemistry 01 natural sciences CO capillary condensation Article chemistry.chemical_compound Core-shell nanoparticles Blowing agent General Materials Science CO2 capillary condensation Coalescence (physics) chemistry.chemical_classification Polydimethylsiloxane General Engineering Polymer 021001 nanoscience & nanotechnology core−shell nanoparticles 0104 chemical sciences Nanocavity chemistry Chemical engineering Polymer foam 0210 nano-technology |
| Zdroj: | ACS nano, 14(2), 1623-1634. American Chemical Society ACS Nano |
| ISSN: | 1936-0851 |
| DOI: | 10.1021/acsnano.9b06837 |
| Popis: | We describe a successful strategy to substantially enhance cell nucleation efficiency in polymer foams by using designer nanoparticles as nucleating agents. Bare and poly(dimethylsilane) (PDMS)-grafted raspberry-like silica nanoparticles with diameters ranging from ∼80 nm to ∼200 nm were synthesized and utilized as highly efficient cell nucleators in CO2-blown nanocellular polymethyl methacrylate (PMMA) foams. The successful synthesis of core–shell nanoparticles was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller measurements, and transmission electron microscopy. The cell size and cell density of the obtained PMMA micro- and nanocellular foams were determined by scanning electron microscopy. The results show that increased surface roughness enhances the nucleation efficiency of the designer silica particles. This effect is ascribed to a decreased nucleation free energy for foam cell nucleation in the nanocavities at the melt–nucleator interface. For PDMS grafted raspberry-like silica nanoparticles with diameters of 155 and 200 nm, multiple cell nucleation events were observed. These hybrid particles had nucleation efficiencies of 3.7 and 6.2, respectively. The surprising increase in nucleation efficiency to above unity is ascribed to the significant increase in CO2 absorption and capillary condensation in the corresponding PMMA during saturation. This increase results in the presence of large amounts of the physical blowing agent close to energetically favorable nucleation points. Additionally, it is shown that as a consequence of cell coalescence, the increased number of foam cells is rapidly reduced during the first seconds of foaming. Hence, the design of highly efficient nucleating particles, as well as careful selection of foam matrix materials, seems to be of pivotal importance for obtaining polymer cellular materials with cell dimensions at the nanoscale. These findings contribute to the fabrication of polymer foams with high thermal insulation capacity and have relevance in general to the area of cellular materials. |
| Databáze: | OpenAIRE |
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