Molecular Structure of Poly(methyl methacrylate) Surface. I. Combination of Interface-Sensitive Infrared–Visible Sum Frequency Generation, Molecular Dynamics Simulations, and ab Initio Calculations

Langmuir ◽  
2014 ◽  
Vol 30 (39) ◽  
pp. 11609-11618 ◽  
Author(s):  
He Zhu ◽  
Kshitij C. Jha ◽  
Ram S. Bhatta ◽  
Mesfin Tsige ◽  
Ali Dhinojwala
Keyword(s):  
Molecular Structure ◽  
Molecular Dynamics ◽  
Methyl Methacrylate ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Sum Frequency Generation ◽  
Poly Methyl Methacrylate ◽  
Sum Frequency ◽  
Dynamics Simulations

The study of polythiophene/water interfaces by sum-frequency generation spectroscopy and molecular dynamics simulations

2015 ◽  
Vol 3 (31) ◽  
pp. 6429-6438 ◽  
Author(s):  
S. Bellani ◽  
M. Porro ◽  
C. Caddeo ◽  
M. I. Saba ◽  
P. B. Miranda ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Molecular Orientation ◽  
Sum Frequency Generation ◽  
Sum Frequency ◽  
Sum Frequency Generation Spectroscopy ◽  
Frequency Generation ◽  
Dynamics Simulations

Polythiophene/water interfaces are investigated by sum frequency generation spectroscopy and molecular dynamics simulations, showing a preferential edge-on molecular orientation.

scholarly journals Surface energy of nanoparticles – influence of particle size and structure

2018 ◽  
Vol 9 ◽  
pp. 2265-2276 ◽  
Author(s):  
Dieter Vollath ◽  
Franz Dieter Fischer ◽  
David Holec
Keyword(s):  
Molecular Dynamics ◽  
Particle Size ◽  
Surface Energy ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Definition Of ◽  
Dynamics Simulations ◽  
Classical Thermodynamics ◽  
A Minor

The surface energy, particularly for nanoparticles, is one of the most important quantities in understanding the thermodynamics of particles. Therefore, it is astonishing that there is still great uncertainty about its value. The uncertainty increases if one questions its dependence on particle size. Different approaches, such as classical thermodynamics calculations, molecular dynamics simulations, and ab initio calculations, exist to predict this quantity. Generally, considerations based on classical thermodynamics lead to the prediction of decreasing values of the surface energy with decreasing particle size. This phenomenon is caused by the reduced number of next neighbors of surface atoms with decreasing particle size, a phenomenon that is partly compensated by the reduction of the binding energy between the atoms with decreasing particle size. Furthermore, this compensating effect may be expected by the formation of a disordered or quasi-liquid layer at the surface. The atomistic approach, based either on molecular dynamics simulations or ab initio calculations, generally leads to values with an opposite tendency. However, it is shown that this result is based on an insufficient definition of the particle size. A more realistic definition of the particle size is possible only by a detailed analysis of the electronic structure obtained from initio calculations. Except for minor variations caused by changes in the structure, only a minor dependence of the surface energy on the particle size is found. The main conclusion of this work is that surface energy values for the equivalent bulk materials should be used if detailed data for nanoparticles are not available.

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