Stability of Newton black films under mechanical stretch--a molecular dynamics study.
The stability of Newton black films (NBFs) under lateral mechanical stretch was investigated by nonequilibrium molecular dynamics (NEMD) simulations using force field parameters validated by accurate prediction of surface tensions. The applied strains accelerated film ruptures, enabling efficient measurements of the critical thicknesses of the films. Two representative surfactants, sodium dodecyl sulfate (SDS) for ionic surfactant and pentaethylene glycol monododecyl ether (C12EO5H) for nonionic surfactant, were investigated and compared. The predicted critical thickness of C12EO5H-coated film is smaller than that of the SDS-coated film, which is consistent with previously reported experimental observations. Our simulation results show that while the two surfactant-coated films exhibit similar dynamic properties attributed to the Marangoni-Gibbs effect, their surface structural characteristics are quite different. Consequently the two films demonstrate distinct rupture mechanisms in which rupture starts at uncovered water domains in the SDS-coated film, but at lateral surfactant/water interfaces in the C12EO5H-coated film. Our findings provide new insights into the stabilization mechanisms of NBFs and will facilitate the design and development of new films with improved properties.
School of Chemistry and Chemical Engineering and Key Laboratory for Thin Film and Microfabrication, Ministry of Education, Shanghai Jiao Tong University , Shanghai 200240, China.
Zhe
Z
Shen
Huai
H
Sun
Xiaoyan
X
Liu
Wenting
W
Liu
Ming
M
Tang
D004987:Ethers / Q000737:chemistry; D055595:Mechanical Phenomena; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D011092:Polyethylene Glycols / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013314:Stress, Mechanical; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*
D004987:Ethers; D013501:Surface-Active Agents; C077053:pentaethylene glycol monododecyl ether; D012967:Sodium Dodecyl Sulfate; D011092:Polyethylene Glycols