Shear-activated chemisorption and association of cyclic organic molecules

Bhuiyan, Fakhrul H.; Li, Yu-Sheng; Kim, Seong H.; Martini, Ashlie

doi:10.1039/d2fd00086e

Cited by 7 publications

(9 citation statements)

References 43 publications

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“…23 Relevant to our current investigation, ReaxFF simulations have been used to study the formation of alkylsilane self-assembled monolayers (SAM) on silica 24 and shear-activated oxidative chemisorption and oligomerization of cyclic hydrocarbons on amorphous silica. 25,26 Simulations of the functionalization of crystalline silicon surfaces with alkyl radicals were able to accurately reproduce surface densities measured experimentally. 27 In our previous work, 28 a method to simulate the functionalization of amorphous silica with 9-anthracenyl trimethoxysilane was developed to corroborate the surface density obtained from experimental solution-based depositions with good agreement between experiments and simulations.…”

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confidence: 84%

“…The ReaxFF potential has been shown to accurately describe the geometry, stability, and chemical bonding of conjugate, nonconjugate, and radical-containing compounds . Relevant to our current investigation, ReaxFF simulations have been used to study the formation of alkylsilane self-assembled monolayers (SAM) on silica and shear-activated oxidative chemisorption and oligomerization of cyclic hydrocarbons on amorphous silica. , Simulations of the functionalization of crystalline silicon surfaces with alkyl radicals were able to accurately reproduce surface densities measured experimentally …”

Section: Introductionmentioning

confidence: 91%

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Reactive Simulations of Silica Functionalization with Aromatic Hydrocarbons

Romero Garcia,

Zholdassov,

Braunschweig

et al. 2023

Langmuir

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Reactive molecular dynamics simulations are used to model the covalent functionalization of amorphous silica with aromatic hydrocarbons. Simulations show that the surface density of silanol-terminated phenyl, naphthyl, and anthracenyl molecules is lower than the maximum value calculated based on molecule geometry, and the simulation densities decrease faster with the number of aromatic rings than the geometric densities. The trends are analyzed in terms of the surface–silanol bonding configurations, tilt angles, local conformational ordering, and aggregation of surface-bound molecules under steady-state conditions. Results show that the surface density is affected by both the size and symmetry of the aromatic hydrocarbons. The correlations among bonding, orientation, and surface density identified here may guide the selection or design of molecules for functionalized surfaces.

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confidence: 84%

Section: Introductionmentioning

confidence: 91%

Reactive Simulations of Silica Functionalization with Aromatic Hydrocarbons

Romero Garcia,

Zholdassov,

Braunschweig

et al. 2023

Langmuir

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“…For example, the C–C, C–H, and C–O bond compression/extension energies were compared with corresponding DFT calculations during the reparameterization process until satisfactory agreement was achieved 51 . This force field has been used to study mechanochemical reactions in similar systems, specifically the shear-driven oligomerization of α-pinene 29 , 46 , cyclohexane, methylcyclopentane, and cyclohexene 47 , 48 . Postprocessing of the simulation data was carried out using in-house python scripts and OVITO software 55 .…”

Section: Methodsmentioning

confidence: 99%

“…Our previous research on cyclohexene explored shear-driven oligomerization reactions on stainless steel in inert, oxidizing, and reducing environments, and on hydroxylated silica in inert environment 47 , 48 . These studies showed easier mechanochemical activation during sliding for cyclohexene than for similar molecules such as cyclohexane and methylcyclopentane on both stainless steel and hydroxylated silica.…”

Section: Introductionmentioning

confidence: 99%

“…These studies showed easier mechanochemical activation during sliding for cyclohexene than for similar molecules such as cyclohexane and methylcyclopentane on both stainless steel and hydroxylated silica. Complementary reactive MD simulations revealed the shear-driven reaction pathways and identified the C=C double bond of the cyclohexene molecule as the source of its shear sensitivity 47 . However, the role of molecular deformation in mechanochemical activation within the context of the Bell model was not explored.…”

Section: Introductionmentioning

confidence: 99%

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Shear-activation of mechanochemical reactions through molecular deformation

Bhuiyan,

Li,

Kim

et al. 2024

Sci Rep

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Mechanical stress can directly activate chemical reactions by reducing the reaction energy barrier. A possible mechanism of such mechanochemical activation is structural deformation of the reactant species. However, the effect of deformation on the reaction energetics is unclear, especially, for shear stress-driven reactions. Here, we investigated shear stress-driven oligomerization reactions of cyclohexene on silica using a combination of reactive molecular dynamics simulations and ball-on-flat tribometer experiments. Both simulations and experiments captured an exponential increase in reaction yield with shear stress. Elemental analysis of ball-on-flat reaction products revealed the presence of oxygen in the polymers, a trend corroborated by the simulations, highlighting the critical role of surface oxygen atoms in oligomerization reactions. Structural analysis of the reacting molecules in simulations indicated the reactants were deformed just before a reaction occurred. Quantitative evidence of shear-induced deformation was established by comparing bond lengths in cyclohexene molecules in equilibrium and prior to reactions. Nudged elastic band calculations showed that the deformation had a small effect on the transition state energy but notably increased the reactant state energy, ultimately leading to a reduction in the energy barrier. Finally, a quantitative relationship was developed between molecular deformation and energy barrier reduction by mechanical stress.

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Molecular Structure and Environment Dependence of Shear-Driven Chemical Reactions: Tribopolymerization of Methylcyclopentane, Cyclohexane and Cyclohexene on Stainless Steel

Jang

Bhuiyan

et al. 2023

Tribol Lett

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Tribochemistry, which is another name of mechanochemistry driven by shear, deals with complex and dynamic interfacial processes that can lead to facilitation of surface wear or formation of bene cial tribo lms. For better mechanistic understanding, we investigated the reactivity of tribopolymerization of organic molecules with different internal ring strain energy (methylcyclopentane, cyclohexane, and cyclohexene) on a stainless steel (SS) surface in inert ( N 2 ), oxidizing (O 2 ), and reducing (H 2 ) environments. On the clean SS surface, precursor molecules were found to physisorb with a broad range of molecular orientations. In inert and reducing environments, the strain-free cyclohexane showed the lowest tribochemical activity among the three tested. Compared to the N 2 environment, the tribochemical activity in H 2 was suppressed. In the O 2 environment, only cyclohexene produced tribo lms and methylcyclopentane and cyclohexane did not. When tribo lms were analyzed with Raman spectroscopy, the spectral features of diamond-like carbon (DLC) or amorphous carbon (a-C) were observed due to photochemical degradation of triboproducts. Based on infrared spectroscopy, tribo lms were found to be organic polymers containing oxygenated groups. Whenever polymeric tribro lms were produced, wear volume was suppressed by orders of magnitudes but not completely to zero. These results supported the previously suggested mechanisms which involved surface oxygens as a reactant species of the tribopolymerization process.

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Shear-activated chemisorption and association of cyclic organic molecules

Abstract: tbc

Cited by 7 publications

References 43 publications

Reactive Simulations of Silica Functionalization with Aromatic Hydrocarbons

Reactive Simulations of Silica Functionalization with Aromatic Hydrocarbons

Shear-activation of mechanochemical reactions through molecular deformation

Molecular Structure and Environment Dependence of Shear-Driven Chemical Reactions: Tribopolymerization of Methylcyclopentane, Cyclohexane and Cyclohexene on Stainless Steel

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