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- Tsourtou, Flora D., et al.
(författare)
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Molecular Dynamics Simulation of Amorphous Poly(3-hexylthiophene)
- 2020
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 53:18, s. 7810-7824
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Tidskriftsartikel (refereegranskat)abstract
- Molecular dynamics (MD) simulations are employed to study the effect of chain length and temperature on the density and conformational properties of regioregular poly(3-hexylthiophene), also denoted as RR-P3HT, in its pure amorphous phase. First, several widely used all-atom force fields (FFs) currently available in the literature are evaluated by comparing their predictions for the density, mean-square chain end-to-end distance, mean-square chain radius-of-gyration, and persistence length of RR-P3HT oligomers at temperatures above their melting point with the limited available experimental data in the literature. Then, with one of the most promising from these FFs, we extend the MD simulations to higher-chain-length P3HT systems (containing up to 150 monomers per chain) at various temperatures. The MD results indicate that the density and persistence length of amorphous P3HT increase slightly with chain length approaching limiting asymptotic values equal to 0.788 +/- 0.003 g cm(-3) and 21 +/- 0.4 angstrom, respectively, at temperature T = 700 K and pressure P = 1 atm. This is attributed to excess chain end free volume effects that are significant at low molecular weights. On the contrary, the effective conjugation length, which is found to become larger than the persistence length only above a certain molecular weight, shows a stronger dependence on chain length. Both of these characteristic lengths are found to increase with decreasing temperature due to the increasing relative population of planar (cis and trans) conformational states of the inter-ring torsion angle. The probability distribution of the maximum length of conjugated segments along a P3HT chain coincides with the theoretical distribution of a longest run of "heads" in a coin-flip experiment. Our MD results suggest that short-chain-length RR-P3HT chains in their bulk amorphous phase are semiflexible but, as their molecular weight increases, they adopt more and more random coil conformations, especially at higher temperatures.
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| 2. |
- Porter, Richard T. J., et al.
(författare)
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Techno-economic assessment of CO2 quality effect on its storage and transport : CO(2)QUEST An overview of aims, objectives and main findings
- 2016
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 54, s. 662-681
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides an overview of the aims, objectives and the main findings of the CO(2)QUEST FP7 collaborative project, funded by the European Commission and designed to address the fundamentally important and urgent issues regarding the impact of the typical impurities in CO2 streams captured from fossil fuel power plants and other CO2 intensive industries on their safe and economic pipeline transportation and storage. The main features and results recorded from some of the unique test facilities constructed as part of the project are presented. These include an extensively instrumented realistic-scale test pipeline for conducting pipeline rupture and dispersion tests in China, an injection test facility in France to study the mobility of trace metallic elements contained in a CO2 stream following injection near a shallow-water qualifier and fluid/rock interactions and well integrity experiments conducted using a fully instrumented deep-well CO2/impurities injection test facility in Israel. The above, along with the various unique mathematical models developed, provide the fundamentally important tools needed to define impurity tolerance levels, mixing protocols and control measures for pipeline networks and storage infrastructure, thus contributing to the development of relevant standards for the safe design and economic operation of CCS.
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