CBET-EPSRC Molecular Engineering of Inhibitors to Self-Assembly: Fundamental structure informing in silico design
Lead Research Organisation:
Imperial College London
Department Name: Chemical Engineering
Abstract
Polyaromatic hydrocarbons (PAHs) are complex organic molecules which have the unique trait of including in their molecular structure more than one carbon rings. Everyday examples include naphthalene and some household solvents, however they are more common as chemical feedstocks and materials. Chemically, these compounds are unique both in terms of the physical properties and in terms of the way they interact with other compounds. PAHs have a strong propensity to self-associate, which must be either carefully controlled to obtain optimum material properties or appropriately inhibited to avoid unwarranted behaviour. The crux of the matter is that the association of PAHs in mixtures of organic solvents is central to a diverse range of contemporary engineering challenges including the fabrication of organic photovoltaics, design of high-performance discotic liquid crystals, and prevention of petroleum asphaltene aggregation and fouling.
The problem faced by us is that the association of PAH's is misunderstood. It is a complex problem that involves not only the chemical nature of the molecules but the collective behaviour of molecules forming solid structures from solution. We are uniquely placed to study this problem, as we will obtain detailed information from X-ray and neutron experiments, where high energy beams scatter off pairs and clusters of these molecules giving us direct information on the type, shape and size of the clusters formed. In parallel, we will study these systems through molecular simulations, where we solve by numerical methods the time evolution of a model of the fluid at the level of the atoms forming the molecules. These simulations intimately depend on the description of the intermolecular forces, which we will validate against the scattering experiments.
The disordered (as opposed to crystalline) multiscale structure of petroleum asphaltenes (aromatic aggregates of 4-8 molecules and diffuse clusters of radii ~5-20 nm) will serve as a benchmark case. Their association is driven by a collection of interactions, including, but possibly not limited to, a) phase separation due to the large difference in average molecular size between molecules and the surrounding solvents, b) enhanced interactions between the cores of the PAH cores that form a significant part of the molecules and c) polar interactions arising from the presence of heteroatoms (S, N, O, etc.). Of these three contributions, the latter is much less studied and is the focus of this study.
In a final stage of our integrated approach we will consider coarse-grained simulations, where molecules are modelled by larger units (of several atoms each). This strategy, which we will fine tune to our rigorous experiments and fine-grained simulations, will allow us to perform extremely large simulations and explore time scales that are relevant to the association of PAH's. Our ultimate objective is to develop a set of guidelines that could inform the computer design of inhibitors to self-assembly. This will open an incredibly powerful research area where one could envision engineering molecules on a computer to satisfy industrial requirements.
The problem faced by us is that the association of PAH's is misunderstood. It is a complex problem that involves not only the chemical nature of the molecules but the collective behaviour of molecules forming solid structures from solution. We are uniquely placed to study this problem, as we will obtain detailed information from X-ray and neutron experiments, where high energy beams scatter off pairs and clusters of these molecules giving us direct information on the type, shape and size of the clusters formed. In parallel, we will study these systems through molecular simulations, where we solve by numerical methods the time evolution of a model of the fluid at the level of the atoms forming the molecules. These simulations intimately depend on the description of the intermolecular forces, which we will validate against the scattering experiments.
The disordered (as opposed to crystalline) multiscale structure of petroleum asphaltenes (aromatic aggregates of 4-8 molecules and diffuse clusters of radii ~5-20 nm) will serve as a benchmark case. Their association is driven by a collection of interactions, including, but possibly not limited to, a) phase separation due to the large difference in average molecular size between molecules and the surrounding solvents, b) enhanced interactions between the cores of the PAH cores that form a significant part of the molecules and c) polar interactions arising from the presence of heteroatoms (S, N, O, etc.). Of these three contributions, the latter is much less studied and is the focus of this study.
In a final stage of our integrated approach we will consider coarse-grained simulations, where molecules are modelled by larger units (of several atoms each). This strategy, which we will fine tune to our rigorous experiments and fine-grained simulations, will allow us to perform extremely large simulations and explore time scales that are relevant to the association of PAH's. Our ultimate objective is to develop a set of guidelines that could inform the computer design of inhibitors to self-assembly. This will open an incredibly powerful research area where one could envision engineering molecules on a computer to satisfy industrial requirements.
Planned Impact
This proposal is very timely, as it is fully in line with these perceived high-priority needs and most importantly aligns with EPSRC's Energy Efficiency portfolio. It will immediately benefit the energy industry, but has potential to impact UK competitiveness and its results will be academically relevant.
The choice of asphaltenes as a prototypical associating system stems from its topical nature in the energy industry and as such the possibility of providing guidelines towards the design of asphaltene deposition inhibitors is key. The single blockage of a production pipe by asphaltenes can cause losses of over 70M$ per incident, hence the prospect of being able to intelligently design inhibitors (as opposed to the empirical trial-and-error search) is appealing. A large energy company such as BP, which actively supports this proposal, sees this project as a chance to enhance their international competitiveness in the area of energy efficiency.
On a broader scale, the methods designed here will provide unparallel support to the UK neutron source. The recently completed second target station (TS2) at STFC is optimized for long wavelength neutrons for the study of larger scale structures within materials. The Near and InterMediate Range Order Diffractometer (NIMROD) on TS2 uses this broad spectrum of neutron wavelengths, with wide and small angle detectors to provide a unique Q-range allowing simultaneous determination of atomistic and mesoscale structure within disordered materials. These capabilities are unique to the UK and we strive to obtain the maximum profit from their availability. An underlying theme of this proposal is the development of methods for comparison (and refinement) of CG simulations to this type of experimental scattering data. NIMROD provided an uncommonly large Q-range, which will allow the extension of "traditional" EPSR approaches (which use atomistic simulation), to coarse-graining modelling. Such a capability does not have a mirror either in the EU or the US, posing a significant advantage in the continuous advancement in measurement science, protocols, and standards. The development of these capabilities is crucial if emerging materials are to be developed to meet the challenges of new technologies, the risks of changing requirements, and the opportunities of potential markets that are ahead. Furthermore, it is an opportunity to tailor the knowledge to the current and future UK needs.
On a more fundamental scale, the general principles and procedures that stem our proposed work; on hand the benchmarking and development of force fields relevant to larger polycondensed molecules and on the other the development of procedures to analyse and understand the results from scattering experiments; are of general interest to many collateral disciplines.
The choice of asphaltenes as a prototypical associating system stems from its topical nature in the energy industry and as such the possibility of providing guidelines towards the design of asphaltene deposition inhibitors is key. The single blockage of a production pipe by asphaltenes can cause losses of over 70M$ per incident, hence the prospect of being able to intelligently design inhibitors (as opposed to the empirical trial-and-error search) is appealing. A large energy company such as BP, which actively supports this proposal, sees this project as a chance to enhance their international competitiveness in the area of energy efficiency.
On a broader scale, the methods designed here will provide unparallel support to the UK neutron source. The recently completed second target station (TS2) at STFC is optimized for long wavelength neutrons for the study of larger scale structures within materials. The Near and InterMediate Range Order Diffractometer (NIMROD) on TS2 uses this broad spectrum of neutron wavelengths, with wide and small angle detectors to provide a unique Q-range allowing simultaneous determination of atomistic and mesoscale structure within disordered materials. These capabilities are unique to the UK and we strive to obtain the maximum profit from their availability. An underlying theme of this proposal is the development of methods for comparison (and refinement) of CG simulations to this type of experimental scattering data. NIMROD provided an uncommonly large Q-range, which will allow the extension of "traditional" EPSR approaches (which use atomistic simulation), to coarse-graining modelling. Such a capability does not have a mirror either in the EU or the US, posing a significant advantage in the continuous advancement in measurement science, protocols, and standards. The development of these capabilities is crucial if emerging materials are to be developed to meet the challenges of new technologies, the risks of changing requirements, and the opportunities of potential markets that are ahead. Furthermore, it is an opportunity to tailor the knowledge to the current and future UK needs.
On a more fundamental scale, the general principles and procedures that stem our proposed work; on hand the benchmarking and development of force fields relevant to larger polycondensed molecules and on the other the development of procedures to analyse and understand the results from scattering experiments; are of general interest to many collateral disciplines.
Publications
Aasen A
(2019)
Equation of state and force fields for Feynman-Hibbs-corrected Mie fluids. I. Application to pure helium, neon, hydrogen, and deuterium
in The Journal of Chemical Physics
Aasen A
(2020)
Equation of state and force fields for Feynman-Hibbs-corrected Mie fluids. II. Application to mixtures of helium, neon, hydrogen, and deuterium.
in The Journal of chemical physics
Alonso G
(2020)
Probing the Interfacial Behavior of Type IIIa Binary Mixtures Along the Three-Phase Line Employing Molecular Thermodynamics.
in Molecules (Basel, Switzerland)
Cárdenas H
(2019)
Extension of the SAFT-VR-Mie equation of state for adsorption
in Journal of Molecular Liquids
Fayaz-Torshizi M
(2021)
Coarse-grained molecular dynamics study of the self-assembly of polyphilic bolaamphiphiles using the SAFT-? Mie force field
in Molecular Systems Design & Engineering
Fayaz-Torshizi M
(2021)
Coarse-Grained Molecular Simulation of Polymers Supported by the Use of the SAFT-?$\gamma$ Mie Equation of State
in Macromolecular Theory and Simulations
Headen T
(2019)
Predicting Asphaltene Aggregate Structure from Molecular Dynamics Simulation: Comparison to Neutron Total Scattering Data
in Energy & Fuels
Jiménez-Serratos G
(2019)
Extension of the effective solid-fluid Steele potential for Mie force fields
in Molecular Physics
Mejía A
(2021)
SGTPy: A Python Code for Calculating the Interfacial Properties of Fluids Based on the Square Gradient Theory Using the SAFT-VR Mie Equation of State.
in Journal of chemical information and modeling
Description | We have developed novel ways or relating the results from small angle neutron scattering experiments to the outputs of computer simulations. This allows, on one hand to validate force fields and computer models directly against experimental data. By doing so, one increases the confidence of the predictive capabilities of the in-silico data which in turn allows us to explore a wider ranger of systems and conditions ( as computer simulations are much quicker and cheaper than synchrotron experiments). On the other hand, simulations can be now be used to understand the underlying physics of the scattering results, providing insights for the interpretation of scattering experiments. |
Exploitation Route | The programs developed are open source and the methodologies are in the process of being published. The results will be showcased to the community in a CECAM workshop ( March 2020 ) |
Sectors | Chemicals,Energy,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology |
Description | CECAM workshop |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | A CECAM workshop on " Combining multi-scale simulation and scattering for structural analysis of complex systems" with participation of > 30 researchers from US/EU/UK where we presented the research outcomes and methodologies from this grant |
Year(s) Of Engagement Activity | 2020 |
URL | https://www.cecam.org/workshop1698/ |