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Synthesis of Autofluorescent Phenanthrene Microparticles via Emulsification: A Useful Synthetic Mimic for Polycyclic Aromatic Hydrocarbon-Based Cosmic Dust

Chan, Derek, Wills, Jess, Tandy, Jon D., Burchell, Mark J., Wozniakiewicz, Penelope J., Alesbrook, L.S., Armes, Steven P. (2023) Synthesis of Autofluorescent Phenanthrene Microparticles via Emulsification: A Useful Synthetic Mimic for Polycyclic Aromatic Hydrocarbon-Based Cosmic Dust. ACS Applied Materials & Interfaces, 15 (46). pp. 54039-54049. ISSN 1944-8244. (doi:10.1021/acsami.3c08585) (KAR id:104107)

Abstract

Phenanthrene is the simplest example of a polycyclic aromatic hydrocarbon (PAH). Herein, we exploit its relatively low melting point (101 °C) to prepare microparticles from molten phenanthrene droplets by conducting high-shear homogenization in a 3:1 water/ethylene glycol mixture at 105 °C using poly(N-vinylpyrrolidone) as a non-ionic polymeric emulsifier. Scanning electron microscopy studies confirm that this protocol produces polydisperse phenanthrene microparticles with a spherical morphology: laser diffraction studies indicate a volume-average diameter of 25 ± 21 μm. Such projectiles are fired into an aluminum foil target at 1.87 km s−1 using a two-stage light gas gun. Interestingly, the autofluorescence exhibited by phenanthrene aids analysis of the resulting impact craters. More specifically, it enables assessment of the spatial distribution of any surviving phenanthrene in the vicinity of each crater. Furthermore, these phenanthrene microparticles can be coated with an ultrathin overlayer of polypyrrole, which reduces their autofluorescence. In principle, such core−shell microparticles should be useful for assessing the extent of thermal ablation that is likely to occur when they are fired into aerogel targets. Accordingly, polypyrrole-coated microparticles were fired into an aerogel target at 2.07 km s−1. Intact microparticles were identified at the end of carrot tracks and their relatively weak autofluorescence suggests that thermal ablation during aerogel capture did not completely remove the polypyrrole overlayer. Thus, these new core−shell microparticles appear to be useful model projectiles for assessing the extent of thermal processing that can occur in such experiments, which have implications for the capture of intact PAH-based dust grains originating from cometary tails or from plumes emanating from icy satellites (e.g., Enceladus) in future space missions.

Item Type: Article
DOI/Identification number: 10.1021/acsami.3c08585
Additional information: For the purpose of open access, the author(s) has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising.
Uncontrolled keywords: phenanthrene, polycyclic aromatic hydrocarbons, polypyrrole, cosmic dust, synthetic mimics, emulsification
Subjects: Q Science > QB Astronomy > QB651 Planets, Minor
Q Science > QC Physics
Q Science > QD Chemistry
Divisions: Divisions > Division of Natural Sciences > Physics and Astronomy
Divisions > Division of Natural Sciences > Chemistry and Forensics
Funders: Leverhulme Trust (https://ror.org/012mzw131)
Engineering and Physical Sciences Research Council (https://ror.org/0439y7842)
Science and Technology Facilities Council (https://ror.org/057g20z61)
Depositing User: Jon Tandy
Date Deposited: 28 Nov 2023 17:28 UTC
Last Modified: 12 Dec 2023 11:54 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/104107 (The current URI for this page, for reference purposes)

University of Kent Author Information

Wills, Jess.

Creator's ORCID:
CReDIT Contributor Roles:

Tandy, Jon D..

Creator's ORCID: https://orcid.org/0000-0002-0772-9182
CReDIT Contributor Roles:

Burchell, Mark J..

Creator's ORCID: https://orcid.org/0000-0002-2680-8943
CReDIT Contributor Roles:

Wozniakiewicz, Penelope J..

Creator's ORCID: https://orcid.org/0000-0002-1441-4883
CReDIT Contributor Roles:

Alesbrook, L.S..

Creator's ORCID: https://orcid.org/0000-0001-9892-281X
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