TY - CHAP

T1 - STUDY OF TRANSPORT PROPERTIES OF SOLUTIONS WITH INVERSE PREMICELLAR AGGREGATES VIA MOLECULAR DYNAMICS SIMULATIONS

AU - Polovinkin, M.S.

AU - Volkov, N.A.

AU - Adzhemyan, L.Ts.

AU - Shchekin, A.K.

N1 - Conference code: 23

PY - 2022/8

Y1 - 2022/8

N2 - Surfactants in non-polar solvents can form reverse micelles. In this work, we report results of the study of transport properties of the solution of nonionic surfactant C12E4 in heptane. For all considered systems, we performed all-atom molecular dynamics simulations in NPT statistical ensemble. The all-atom models were created using the CGenFF 4.4 force field [1]. To find the viscosities of colloid systems via molecular dynamics simulations, one can employ the StokesEinstein formula [2,3]. Palmer proposed an alternative method [4] based on the calculation of autocorrelation functions of the momentum. We used Palmer’s method implemented in GROMACS 2020.1 package [5] to find the viscosities of one-component liquids (water, pentane, heptane, decane) and two-component systems consisting of hydrocarbon (heptane) and a C12E4 aggregate. In particular, viscosities of the systems containing inverse premicellar aggregates with 2, 4, 8, 16 and 25 C12E4 molecules were estimated. Our results for one-component systems are consistent with previous works of other authors. For water systems, the agreement with the results of the molecular dynamics simulation in [6] was observed. The results of the viscosity calculation for pentane matched well those from [7]. For the system containing decane, the agreement with the experimental data from [8] was observed. For the systems containing inverse micelles, we also used the Stokes-Einstein formula to estimate the viscosities. The StokesEinstein formula relates the viscosity of the liquid media with the size of a spherical particle in it and the particle’s diffusion coefficient. The in-house programs were used to analyze the obtained molecular dynamics trajectories and to calculate the average radii of inverse premicellar aggregates and their diffusion coefficients. Thus, the dependence of viscosity on the total surfactant concentration was obtained by two different methods.

AB - Surfactants in non-polar solvents can form reverse micelles. In this work, we report results of the study of transport properties of the solution of nonionic surfactant C12E4 in heptane. For all considered systems, we performed all-atom molecular dynamics simulations in NPT statistical ensemble. The all-atom models were created using the CGenFF 4.4 force field [1]. To find the viscosities of colloid systems via molecular dynamics simulations, one can employ the StokesEinstein formula [2,3]. Palmer proposed an alternative method [4] based on the calculation of autocorrelation functions of the momentum. We used Palmer’s method implemented in GROMACS 2020.1 package [5] to find the viscosities of one-component liquids (water, pentane, heptane, decane) and two-component systems consisting of hydrocarbon (heptane) and a C12E4 aggregate. In particular, viscosities of the systems containing inverse premicellar aggregates with 2, 4, 8, 16 and 25 C12E4 molecules were estimated. Our results for one-component systems are consistent with previous works of other authors. For water systems, the agreement with the results of the molecular dynamics simulation in [6] was observed. The results of the viscosity calculation for pentane matched well those from [7]. For the system containing decane, the agreement with the experimental data from [8] was observed. For the systems containing inverse micelles, we also used the Stokes-Einstein formula to estimate the viscosities. The StokesEinstein formula relates the viscosity of the liquid media with the size of a spherical particle in it and the particle’s diffusion coefficient. The in-house programs were used to analyze the obtained molecular dynamics trajectories and to calculate the average radii of inverse premicellar aggregates and their diffusion coefficients. Thus, the dependence of viscosity on the total surfactant concentration was obtained by two different methods.

KW - Viscosity

KW - Diffusion

KW - Micelles

KW - Molecular Dynamics

KW - Aggregation

KW - Surfactants

M3 - Conference abstracts

SP - 289

BT - XXIII International Conference on Chemical Thermodynamics in Russia, RCCT-2022 August 22-26, 2022, Kazan, Russia: Abstracts.

PB - Казанский Федеральный университет

CY - Kazan

Y2 - 22 August 2022 through 27 August 2022

ER -