Atomistic molecular dynamics simulations of the LCST conformational transition in poly(N-vinylcaprolactam) in water.

Autor: Zhelavskyi OS; School of Chemistry, V.N. Karazin Kharkiv National University, 4 Svobody Square, Kharkiv, 61022, Ukraine., Kyrychenko A; School of Chemistry, V.N. Karazin Kharkiv National University, 4 Svobody Square, Kharkiv, 61022, Ukraine. Electronic address: a.v.kyrychenko@karazin.ua.
Jazyk: angličtina
Zdroj: Journal of molecular graphics & modelling [J Mol Graph Model] 2019 Jul; Vol. 90, pp. 51-58. Date of Electronic Publication: 2019 Apr 12.
DOI: 10.1016/j.jmgm.2019.04.004
Abstrakt: Thermoresponsive poly(N-vinylcaprolactam) (PVCL) has received growing interest due to a temperature-induced phase transition, which switches its solubility in aqueous solutions. However, the lower critical solution temperature (LCST) of PVCL is greatly influenced by the molecular weight, morphology and the environment. Therefore, despite of numerous experimental studies of the thermal response of PVCL, a driving force and a molecular origin of conformation transitions in solution remain far less studied. To get a better understanding of the coil-to-globule conformation transition of PVCL in aqueous solution, we examined the structure and conformation dynamics of a single-chain PVCL 30 in a temperature range of 280-360 K by using atomistic molecular dynamics (MD) simulations. The united-atom GROMOS G53a6 force field was re-parameterized and fine-tuned by DFT calculations to reproduce the experimental LCST transition of PVCL. Our MD model reproduces the LCST transition of PVCL 30 to occur within a temperature range of 34.6-38.5°. MD simulation results suggest a significant difference between the hydration state of the carbonyl group of PVCL below and above the LCST threshold. The analysis of the number of hydrogen bonds of PVCL with water molecules demonstrates that dehydration of the polymer plays an important role and drives the temperature-induced polymer collapse. Finally, the developed MD model and FF parameters were successfully tested for large-scale systems, such as mixture PVCL 30 oligomer and single-chain PVCL 816 polymer, respectively.
(Copyright © 2019 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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