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Chulikavit N, Huynh T, Khatibi A, Das R, Kandare E. Thermal degradation and flame spread characteristics of epoxy polymer composites incorporating mycelium. Sci Rep 2023; 13:17812. [PMID: 37857694 PMCID: PMC10587079 DOI: 10.1038/s41598-023-45097-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 10/16/2023] [Indexed: 10/21/2023] Open
Abstract
Although bioderived flame retardants are environmentally sustainable and less toxic, their impact on the thermal stability and flammability of polymers remains poorly understood. In this study, we assessed the influence of mycelium on the thermal stability and flame spread characteristics of epoxy through thermogravimetric analysis, Fourier transform infrared spectroscopy, the UL94 flammability test, and scanning electron microscopy. We observed a decrease in the maximum mass loss rate temperature when mycelium was incorporated into epoxy, indicating an earlier onset of thermal degradation. The inclusion of mycelium increased char yields above 418 °C due to mycelium's inherent char-forming ability. However, mycelium did not alter the thermal degradation pathway of epoxy. Furthermore, according to the UL94 test results, the incorporation of mycelium reduced the flame spread rate compared to that of neat epoxy. These findings contribute to our understanding of the interaction between bioderived flame retardants and polymers paving the way for the development of more sustainable fireproofing materials.
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Affiliation(s)
| | - Tien Huynh
- School of Science, RMIT University, Bundoora, VIC, 3083, Australia
| | - Akbar Khatibi
- School of Engineering, RMIT University, Bundoora, VIC, 3083, Australia
| | - Raj Das
- School of Engineering, RMIT University, Bundoora, VIC, 3083, Australia
| | - Everson Kandare
- School of Engineering, RMIT University, Bundoora, VIC, 3083, Australia.
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Gaigeot MP. Some opinions on MD-based vibrational spectroscopy of gas phase molecules and their assembly: An overview of what has been achieved and where to go. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 260:119864. [PMID: 34052762 DOI: 10.1016/j.saa.2021.119864] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 04/13/2021] [Accepted: 04/18/2021] [Indexed: 06/12/2023]
Abstract
We hereby review molecular dynamics simulations for anharmonic gas phase spectroscopy and provide some of our opinions of where the field is heading. With these new directions, the theoretical IR/Raman spectroscopy of large (bio)-molecular systems will be more easily achievable over longer time-scale MD trajectories for an increase in accuracy of the MD-IR and MD-Raman calculated spectra. With the new directions presented here, the high throughput 'decoding' of experimental IR/Raman spectra into 3D-structures should thus be possible, hence advancing e.g. the field of MS-IR for structural characterization by spectroscopy. We also review the assignment of vibrational spectra in terms of anharmonic molecular modes from the MD trajectories, and especially introduce our recent developments based on Graph Theory algorithms. Graph Theory algorithmic is also introduced in this review for the identification of the molecular 3D-structures sampled over MD trajectories.
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Affiliation(s)
- Marie-Pierre Gaigeot
- Université Paris-Saclay, Univ Evry, CNRS, LAMBE UMR8587, 91025 Evry-Courcouronnes, France.
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Wagner JP, McDonald DC, Colley JE, Franke PR, Duncan MA. Infrared spectroscopy of the protonated HCl dimer and trimer. J Chem Phys 2021; 155:134302. [PMID: 34624978 DOI: 10.1063/5.0065477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The protonated HCl dimer and trimer complexes were prepared by pulsed discharges in supersonic expansions of helium or argon doped with HCl and hydrogen. The ions were mass selected in a reflectron time-of-flight spectrometer and investigated with photodissociation spectroscopy in the IR and near-IR regions. Anharmonic vibrational frequencies were computed with VPT2 at the MP2/cc-pVTZ level of theory. The Cl-H stretching fundamentals and overtones were measured in addition to stretch-torsion combinations. VPT2 theory at this level confirms the proton-bound structure of the dimer complex and provides a reasonably good description of the anharmonic vibrations in this system. The trimer has a HCl-HClH+-ClH structure in which a central chloronium ion is solvated by two HCl molecules via hydrogen bonding. VPT2 reproduces anharmonic frequencies for this system, including several combinations involving core ion Cl-H stretches, but fails to describe the relative band intensities.
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Affiliation(s)
- J Philipp Wagner
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, USA
| | - David C McDonald
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, USA
| | - Jason E Colley
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, USA
| | - Peter R Franke
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, USA
| | - Michael A Duncan
- Department of Chemistry, University of Georgia, 140 Cedar Street, Athens, Georgia 30602, USA
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Leicht D, Rittgers BM, Douberly GE, Wagner JP, McDonald DC, Mauney DT, Tsuge M, Lee YP, Duncan MA. Infrared spectroscopy of H+(CO)2 in the gas phase and in para-hydrogen matrices. J Chem Phys 2020; 153:084305. [DOI: 10.1063/5.0019731] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Daniel Leicht
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | | | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - J. Philipp Wagner
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - David C. McDonald
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Daniel T. Mauney
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Masashi Tsuge
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Yuan-Pern Lee
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
- Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu 30010, Taiwan
- Institute of Atomic and Molecular Sciences Academia Sinica, Taipei 10617, Taiwan
| | - Michael A. Duncan
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
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de Souza GLC, Peterson KA. Probing the ionization potentials of the formaldehyde dimer. J Chem Phys 2020; 152:194305. [PMID: 33687222 DOI: 10.1063/5.0009658] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In this work, we present a computational investigation on the ionization potentials (IPs) of the formaldehyde dimer, (H2CO)2. Twelve lowest lying IPs (corresponding to the entire valence orbitals) for both C2h and Cs symmetry conformers have been computed at the coupled cluster level of theory using large correlation consistent basis sets with extrapolation to the complete basis set limit and consideration of core electron correlation effects. Specifically, the equation-of-motion ionization potential coupled-cluster with single and double (EOMIP-CCSD) excitations method with the aug-cc-pVXZ and aug-cc-pCVXZ (X = T, Q, and 5) basis sets combined with the Feller-Peterson-Dixon approach was employed, as well as CCSD with perturbative triples [CCSD(T)] with the aug-cc-pVTZ basis sets. In general, excellent agreement was observed from the comparison between the results obtained through the use of these approaches. In addition, the IPs for the formaldehyde monomer were also obtained using such methodologies and the results compared with existing experimental data; excellent agreement was also observed in this case. To the best of our knowledge, this work represents the first of its kind to determine the IPs for all these systems using a high level theory approach and is presented to motivate experimental investigations, e.g., studies involving photoionization, particularly for the formaldehyde dimer. The equilibrium binding energy of the C2h dimer is calculated in this work at the CCSD(T)/aug-cc-pVTZ level of theory to be -4.71 kcal/mol. At this same level of theory, the equilibrium isomerization energy between C2h and Cs conformers is 0.76 kcal/mol (Cs conformer being more stable).
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Affiliation(s)
- Gabriel L C de Souza
- Departamento de Química, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso 78060-900, Brazil
| | - Kirk A Peterson
- Department of Chemistry, Washington State University, Pullman, Washington 99164, USA
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Franke PR, Duncan MA, Douberly GE. Infrared photodissociation spectroscopy and anharmonic vibrational study of the HO 4 + molecular ion. J Chem Phys 2020; 152:174309. [PMID: 32384862 DOI: 10.1063/5.0005975] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular cations of HO4 + and DO4 + are produced in a supersonic expansion. They are mass-selected, and infrared photodissociation spectra of these species are measured with the aid of argon-tagging. Although previous theoretical studies have modeled these systems as proton-bound dimers of molecular oxygen, infrared spectra have free OH stretching bands, suggesting other isomeric structures. As a consequence, we undertook extensive computational studies. Our conformer search used a composite method based on an economical combination of single- and multi-reference theories. Several conformers were located on the quintet, triplet, and singlet surfaces, spanning in energy of only a few thousand wavenumbers. Most of the singlet and triplet conformers have pronounced multiconfigurational character. Previously unidentified covalent-like structures (H-O-O-O-O) on the singlet and triplet surfaces likely represent the global minima. In our experiments, HO4 + is formed in a relatively hot environment, and similar experiments have been shown capable of producing multiple conformers in low-lying electronic states. None of the predicted HO4 + isomers can be ruled out a priori based on energetic arguments. We interpret our argon-tagged spectra with Second-Order Vibrational Perturbation Theory with Resonances (VPT2+K). The presence of one or more covalent-like isomers is the only reasonable explanation for the spectral features observed.
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Affiliation(s)
- Peter R Franke
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Michael A Duncan
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Gary E Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
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Tan JA, Kuo JL. A theoretical study on the infrared signatures of proton-bound rare gas dimers (Rg-H +-Rg), Rg = {Ne, Ar, Kr, and Xe}. J Chem Phys 2019; 150:124305. [PMID: 30927880 DOI: 10.1063/1.5090031] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The infrared spectrum of proton-bound rare gas dimers has been extensively studied via matrix isolation spectroscopy. However, little attention has been paid on their spectrum in the gas phase. Most of the Rg2H+ has not been detected outside the matrix environment. Recently, ArnH+ (n = 3-7) has been first detected in the gas-phase [D. C. McDonald et al., J. Chem. Phys. 145, 231101 (2016)]. In that work, anharmonic theory can reproduce the observed vibrational structure. In this paper, we extend the existing theory to examine the vibrational signatures of Rg2H+, Rg = {Ne, Ar, Kr, and Xe}. The successive binding of Rg to H+ was investigated through the calculation of stepwise formation energies. It was found that this binding is anti-cooperative. High-level full-dimensional potential energy surfaces at the CCSD(T)/aug-cc-pVQZ//MP2/aug-cc-pVQZ were constructed and used in the anharmonic calculation via discrete variable representation. We found that the potential coupling between the symmetric and asymmetric Rg-H+ stretch (ν1 and ν3 respectively) causes a series of bright n1ν1 + ν3 progressions. From Ne2H+ to Xe2H+, an enhancement of intensities for these bands was observed.
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Affiliation(s)
- Jake A Tan
- Institute of Atomic and Molecular Sciences, Academia Sinica, No. 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan
| | - Jer-Lai Kuo
- Institute of Atomic and Molecular Sciences, Academia Sinica, No. 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan
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Galimberti DR, Bougueroua S, Mahé J, Tommasini M, Rijs AM, Gaigeot MP. Conformational assignment of gas phase peptides and their H-bonded complexes using far-IR/THz: IR-UV ion dip experiment, DFT-MD spectroscopy, and graph theory for mode assignment. Faraday Discuss 2019; 217:67-97. [DOI: 10.1039/c8fd00211h] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Graph theory based vibrational modes as new entities for vibrational THz spectroscopy.
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Affiliation(s)
| | | | - Jérôme Mahé
- LAMBE UMR8587
- Univ Evry
- Université Paris-Saclay
- CNRS
- 91025 Evry
| | - Matteo Tommasini
- Department of Chemistry, Materials, Chemical Engineering “G. Natta” Politecnico di Milano
- 20133 Milano
- Italy
| | - Anouk M. Rijs
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
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Eckhardt AK, Wende RC, Schreiner PR. 1,3-Dioxolane-4-ol Hemiacetal Stores Formaldehyde and Glycolaldehyde in the Gas-Phase. J Am Chem Soc 2018; 140:12333-12336. [PMID: 30187747 DOI: 10.1021/jacs.8b07480] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the spontaneous gas-phase formation of 1,3-dioxolane-4-ol, a mixed hemiacetal resulting from the addition of glycolaldehyde to formaldehyde. It was spectroscopically characterized by matching matrix IR spectra with coupled cluster computations. The formation of the hemiacetal must be surface-catalyzed owing to the very high computed reaction barrier of 39.8 kcal mol-1. The reaction barrier is lowered by almost 20 kcal mol-1 when a single water molecule acts as a proton shuttle in a favorable six-membered transition state. We characterized the hemiacetal in solution via NMR spectroscopy and followed its decomposition into its constituents within a few hours; it also dissociates upon contact with water. Sugars form in the presence of Ca(OH)2, in line with formose-type reactivity. 1,3-Dioxolane-4-ol may be considered a storage form for formaldehyde and glycolaldehyde that is rather stable in the gas-phase.
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Affiliation(s)
- André K Eckhardt
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Raffael C Wende
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
| | - Peter R Schreiner
- Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany
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Wagner JP, McDonald DC, Duncan MA. Spectroscopy of Proton Coordination with Ethylenediamine. J Phys Chem A 2018; 122:5168-5176. [PMID: 29771517 DOI: 10.1021/acs.jpca.8b03592] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protonated ethylenediamine monomer, dimer, and trimer were produced in the gas phase by an electrical discharge/supersonic expansion of argon seeded with ethylenediamine (C2H8N2, en) vapor. Infrared spectra of these ions were measured in the region from 1000 to 4000 cm-1 using laser photodissociation and argon tagging. Computations at the CBS-QB3 level were performed to explore possible isomers and understand the infrared spectra. The protonated monomer exhibits a gauche conformation and an intramolecular hydrogen bond. Its parallel shared proton vibration occurs as a broad band around 2785 cm-1, despite the formally equivalent proton affinities of the two amino groups involved, which usually leads to low frequency bands. The barrier to intramolecular proton transfer is 2.2 kcal mol-1 and does not vanish upon addition of the zero-point energy, unlike the related protonated ammonia dimer. The structure of the dimer is formed by chelation of the monomer's NH3+ group, thereby localizing the excess proton and increasing the frequency of the intramolecular shared proton vibration to 3157 cm-1. Other highly fluxional dimer structures with facile intermolecular proton transfer and concomitant structural reorganization were computed to lie within 2 kcal mol-1 of the experimentally observed structure. The spectrum of the trimer is rather diffuse, and a clear assignment is not possible. However, an isomer with an intramolecular proton transfer like that of the monomer is most consistent with the experimental spectrum.
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Affiliation(s)
- J Philipp Wagner
- Department of Chemistry , University of Georgia , 140 Cedar Street , Athens , Georgia 30602 , United States
| | - David C McDonald
- Department of Chemistry , University of Georgia , 140 Cedar Street , Athens , Georgia 30602 , United States
| | - Michael A Duncan
- Department of Chemistry , University of Georgia , 140 Cedar Street , Athens , Georgia 30602 , United States
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