Polycyanurates <i>via</i> Molecular Dynamics: <i>In Situ</i> Crosslinking from Di(Cyanate Ester) Resins and Model Validation through Comparison to Experiment

Moore, Levi M. J.; Redeker, Neil D.; Browning, Andrea; Sanders, Jeffrey M.; Ghiassi, Kamran B.

doi:10.1021/acs.macromol.1c00207

Cited by 10 publications

(12 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After thermally quenching the system, the final temperature of the amorphous F8BT production simulations (350 K) is below the glass transition temperature observed to occur at T g ≃ 478 K. This value is significantly higher than the T g = 398 K reported experimentally. 34 Discrepancies between T g values calculated by experiment and computer simulation are commonplace, 35 with differences of the magnitude observed in this work attributable primarily to force field effects, 36 while the thermal quenching rate also makes a contribution. 37,38 At T < T g , each F8BT chain is kinetically trapped in a single conformation in the metastable (nonequilibrium) amorphous phase, unlike the single chains studied in solution.…”

Section: Resultsmentioning

confidence: 83%

Conformational Heterogeneity and Interchain Percolation Revealed in an Amorphous Conjugated Polymer

et al. 2022

View full text Add to dashboard Cite

Conjugated polymers are employed in a variety of application areas due to their bright fluorescence and strong biocompatibility. However, understanding the structure of amorphous conjugated polymers on the nanoscale is extremely challenging compared to their related crystalline phases. Using a bespoke classical force field, we study amorphous poly(9,9-di- n -octylfluorene- alt -benzothiadiazole) (F8BT) with molecular dynamics simulations to investigate the role that its nanoscale structure plays in controlling its emergent (and all-important) optical properties. Notably, we show that a giant percolating cluster exists within amorphous F8BT, which has ramifications in understanding the nature of interchain species that drive the quantum yield reduction and bathochromic shift observed in conjugated polymer-based devices and nanostructures. We also show that distinct conformations can be unravelled from within the disordered structure of amorphous F8BT using a two-stage machine learning protocol, highlighting a link between molecular conformation and ring stacking propensity. This work provides predictive understanding by which to enhance the optical properties of next-generation conjugated polymer-based devices and materials by rational, simulation-led design principles.

show abstract

Section: Resultsmentioning

confidence: 83%

Conformational Heterogeneity and Interchain Percolation Revealed in an Amorphous Conjugated Polymer

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Due to the fact that the ordinate of the RDF curve represents the normalized probability density and the value of g(r) will eventually approach 1, it can be considered that only very weak interaction exists between C20 and DGEBA or between DGEBA and alkyl chains of D12. 17 On the contrary, the interaction between DGEBA and the main chains of D12 is relatively strong due to the lowest r value (5.9−7.5 Å) and relatively high g(r) value (4.5−8.4) for all the EP DA-X systems listed in Table 2. The above facts are easy to understand because the huge polarity difference between DGEBA and C20 or the alkyl side chains of D12 can be the driving force for alkyl chains in C20 or D12 to stay away from the DGEBA molecules, leading to the very weak interaction between DGEBA and C20 or between DGEBA and the alkyl chains of D12.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…However, all the values of g ( r ) for the first peak that existed in Figure (d) and (f) are very low (<2). Due to the fact that the ordinate of the RDF curve represents the normalized probability density and the value of g ( r ) will eventually approach 1, it can be considered that only very weak interaction exists between C20 and DGEBA or between DGEBA and alkyl chains of D12 . On the contrary, the interaction between DGEBA and the main chains of D12 is relatively strong due to the lowest r value (5.9–7.5 Å) and relatively high g ( r ) value (4.5–8.4) for all the EP DA‑X systems listed in Table .…”

Section: Resultsmentioning

confidence: 99%

“…have been proposed, the fractured surfaces studied by SEM can provide only an indirect way to correlate the microstructure and mechanical properties, overlooking some key pieces of information especially like those associated with the microscopic structure of the epoxy cross-linking network. Fortunately, atomistic molecular dynamics (MD) simulation, which can provide insightful information on the atomic scale that it is hard for experimental methods to provide, has played an important role in predicting the T g , modulus, volume shrinkage, density, frictional sliding resistance, and water absorption , of the polymer composites. However, most of the MD simulation research is focused on the simplest epoxy cross-linking network (containing only epoxy resin and curing agent) or the interfacial characteristics between epoxy resin and other components such as carbon fiber, graphene, CNTs, silica, etc.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Directly Using Paraffin as the Toughening Agent of Epoxy Composites: An Experimental and Molecular Dynamics Simulation Study

Chen

Cheng

et al. 2023

Langmuir

View full text Add to dashboard Cite

It is still a challenge in studying the toughening mechanism by well combining the experimental and atomistic molecular dynamics (MD) simulation study. This article directly introduced eicosane (C20, model compound of paraffin) into the epoxy matrix (DGEBA) by using a special epoxy resin with alkyl side chains (D12) as a compatibilizer, which was synthesized through thiol−ene click chemistry. The toughening mechanism of the ternary DGEBA/D12/C20 (EP DA-X ) systems was systematically investigated by experimental and MD simulation methods. Though C20 can be well dispersed in the curing mixture, the huge polarity difference between C20 and DGEBA can be the driving force for C20 to stay away from DGEBA, demonstrating the self-assembly effect of C20 around the alkyl side chains of D12 because of the good compatibility of D12 and C20. The soft alkyl chains of D12 and C20 as well as the self-assembly effect of C20 around the D12 molecules can simultaneously improve the strength, modulus, and toughness of the EP DA-2.5 system. This article not only provides a brand new toughening strategy by directly using nonfunctional alkyl derivatives as the toughening agent of epoxy composites with superior mechanical properties but also provides a systematic MD simulation method to evaluate whether there is the interaction or not and the strength of interaction between different molecular chains so as to provide a theoretical basis for the cause of the microphase separation structure and related toughening mechanism in cross-linking networks on the atomic and molecular levels.

show abstract

“…These thermosetting polymers occupy a niche area between high-glass-transition-temperature bismaleimides and tetrafunctional epoxy resins [ 2 ]. In this respect, they have been utilized for applications such as filament wound Carbon-Fiber-Reinforced Polymers (CFRPs) in heat shields used for atmospheric reentry and airframes [ 3 ]. The combination of high performance with good processability is a unique asset of polycyanurates compared to alternative high-temperature thermosetting resins.…”

Section: Introductionmentioning

confidence: 99%

A Molecular Dynamics Study of Cyanate Ester Monomer Melt Properties

et al. 2022

Self Cite

View full text Add to dashboard Cite

The objective of this work was to computationally predict the melting temperature and melt properties of thermosetting monomers used in aerospace applications. In this study, we applied an existing voids method by Solca. to examine four cyanate ester monomers with a wide range of melting temperatures. Voids were introduced into some simulations by removal of molecules from lattice positions to lower the free-energy barrier to melting to directly simulate the transition from a stable crystal to amorphous solid and capture the melting temperature. We validated model predictions by comparing melting temperature against previously reported literature values. Additionally, the torsion and orientational order parameters were used to examine the monomers’ freedom of motion to investigate structure–property relationships. Ultimately, the voids method provided reasonable estimates of melting temperature while the torsion and order parameter analysis provided insight into sources of the differing melt properties between the thermosetting monomers. As a whole, the results shed light on how freedom of molecular motions in the monomer melt state may affect melting temperature and can be utilized to inspire the development of thermosetting monomers with optimal monomer melt properties for demanding applications.

show abstract

Polycyanurates via Molecular Dynamics: In Situ Crosslinking from Di(Cyanate Ester) Resins and Model Validation through Comparison to Experiment

Cited by 10 publications

References 31 publications

Conformational Heterogeneity and Interchain Percolation Revealed in an Amorphous Conjugated Polymer

Conformational Heterogeneity and Interchain Percolation Revealed in an Amorphous Conjugated Polymer

Directly Using Paraffin as the Toughening Agent of Epoxy Composites: An Experimental and Molecular Dynamics Simulation Study

A Molecular Dynamics Study of Cyanate Ester Monomer Melt Properties

Contact Info

Product

Resources

About