Thermal stability and bond dissociation energy of fluorinated polymers: A critical evaluation

Giannetti, Enzo

doi:10.1016/j.jfluchem.2005.01.008

Cited by 48 publications

(30 citation statements)

References 42 publications

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“…For example, BDE values are used to predict relative reaction rates using well-established Evans-Polanyi-type correlations with bond strengths in radical hydrogen atom abstractions 2 . BDEs also provide insight into thermodynamically accessible reaction mechanisms for a given compound, and their calculation is often the first step in characterizing dominant pathways in combustion 3 , polymer synthesis 4 and thermal stability 5,6 , lignin depolymerization 7 , drug metabolism [8][9][10] , explosives 11 , organic synthesis planning 12,13 , and other applications to energy-related materials 14 .…”

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confidence: 99%

Prediction of organic homolytic bond dissociation enthalpies at near chemical accuracy with sub-second computational cost

et al. 2020

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Bond dissociation enthalpies (BDEs) of organic molecules play a fundamental role in determining chemical reactivity and selectivity. However, BDE computations at sufficiently high levels of quantum mechanical theory require substantial computing resources. In this paper, we develop a machine learning model capable of accurately predicting BDEs for organic molecules in a fraction of a second. We perform automated density functional theory (DFT) calculations at the M06-2X/def2-TZVP level of theory for 42,577 small organic molecules, resulting in 290,664 BDEs. A graph neural network trained on a subset of these results achieves a mean absolute error of 0.58 kcal mol −1 (vs DFT) for BDEs of unseen molecules. We further demonstrate the model on two applications: first, we rapidly and accurately predict major sites of hydrogen abstraction in the metabolism of drug-like molecules, and second, we determine the dominant molecular fragmentation pathways during soot formation.

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confidence: 99%

Prediction of organic homolytic bond dissociation enthalpies at near chemical accuracy with sub-second computational cost

et al. 2020

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“…Colliding an excited‐state BSBCz with another excited‐state BSBCz would result in the formation of higher molecular‐weight degradation byproducts through the creation of new chemical bonds between the molecules. This would be initiated by the dissociation of π bonds for the stilbene units of BSBCz because π bonds are weaker than σ bonds . Therefore, films degraded at high excitation >200 mW cm −2 contain not only lower molecular‐weight byproducts but also higher molecular‐weight byproducts working as exciton quenchers for BSBCz.…”

Section: Resultsmentioning

confidence: 99%

Degradation Mechanism and Stability Improvement Strategy for an Organic Laser Gain Material 4,4′‐Bis[(N‐carbazole)styryl]biphenyl (BSBCz)

Matsushima

Yoshida

Inada

et al. 2019

Adv Funct Materials

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The organic material 4,4′‐bis[(N‐carbazole)styryl]biphenyl (BSBCz) is an excellent gain medium for laser devices. However, BSBCz laser output quickly degrades during photoexcitation, which is an issue that must be overcome before it can be used for practical applications. In this study, the photodegradation mechanisms of BSBCz are investigated with the aim of enhancing its excited‐state stability. The photodegradation of BSBCz is attributed to instability of the triplet excited states that would occasionally decompose into other species. This decomposition reduces absorption and introduces exciton quenchers. Incorporating the triplet managing material 9,10‐di(naphtha‐2‐yl)anthracene (ADN) into BSBCz films greatly improves photoluminescence and amplified spontaneous emission stability because of the effective removal of the unstable triplets by ADN. This triplet managing method makes it possible to increase operational stability for BSBCz‐based organic light‐emitting diodes. Therefore, these results will contribute toward the fabrication of stable optically and electrically pumped organic laser diodes.

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“…In general, the thermal stability of a molecule depends on the strength of the bond present in the molecule. 67 The lower thermal stability of Py-Br is possibly due to the presence of weak C–Br bond as compared to C–C, C–O, and C–H bonds (present in other molecules). Meanwhile, the corresponding glass transition temperatures ( T g ) were determined from DSC to be 155 and 202 °C for Py-03 and Py-Br ( Figure S2e,h ), respectively; however, no clear T g was observed for Py-MeO and Py-Me .…”

Section: Resultsmentioning

confidence: 99%

Functional Pyrene–Pyridine-Integrated Hole-Transporting Materials for Solution-Processed OLEDs with Reduced Efficiency Roll-Off

et al. 2021

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A series of new functional pyridine-appended pyrene derivatives, viz., 2,6-diphenyl-4-(pyren-1-yl)pyridine ( Py-03 ), 2,6-bis(4-methoxyphenyl)-4-(pyren-1-yl)pyridine ( Py-MeO ), 4-(pyren-1-yl)-2,6-di- p -tolylpyridine ( Py-Me ), and 2,6-bis(4-bromophenyl)-4-(pyren-1-yl)pyridine ( Py-Br ) were designed, developed, and studied as the hole-transporting materials (HTMs) for organic light-emitting diode (OLED) application. The crystal structures of two molecules revealed to have a large dihedral angle between the pyrene and pyridine units, indicating poor π-electronic communication between them due to ineffective orbital overlap across the pyrene–pyridine systems as the two p-orbitals of pivotal atoms are twisted at 66.80° and 68.75° angles to each other in Py-03 and Py-Me , respectively. The influence of variedly functionalized pyridine units on the electro-optical properties and device performance of the present integrated system for OLED application was investigated. All of the materials have suitable HOMO values (5.6 eV) for hole injection by closely matching the HOMOs of indium tin oxide (ITO) and the light-emitting layer. All of the synthesized molecules have suitable triplet energies, glass transition temperatures, and melting temperatures, which are highly desirable for good HTMs. The pyrene–pyridine-based devices demonstrated stable performance with low-efficiency roll-off. The device with Py-Br as HTM showed a maximum luminance of 17300 cd/m 2 with a maximum current efficiency of 22.4 cd/A and an EQE of 9% at 3500 cd/m 2 with 7% roll-off from 1000 to 10 000 cd/m 2 . Also, the devices with Py-Me and Py-03 showed performance roll-up while moving from 1000 to 10 000 cd/m 2 .

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Thermal stability and bond dissociation energy of fluorinated polymers: A critical evaluation

Cited by 48 publications

References 42 publications

Prediction of organic homolytic bond dissociation enthalpies at near chemical accuracy with sub-second computational cost

Prediction of organic homolytic bond dissociation enthalpies at near chemical accuracy with sub-second computational cost

Degradation Mechanism and Stability Improvement Strategy for an Organic Laser Gain Material 4,4′‐Bis[(N‐carbazole)styryl]biphenyl (BSBCz)

Functional Pyrene–Pyridine-Integrated Hole-Transporting Materials for Solution-Processed OLEDs with Reduced Efficiency Roll-Off

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