(563e) Force Field Parameterization and Monte Carlo Simulation of Alkoxy-Ethanol Surfactant

Alkoxy-ethanol
is highly associating molecule which contains ether (-O-) and hydroxyl (-OH)
group in the same molecule. It has both inter- and intra-molecular hydrogen
bonding, thus the complex interaction makes it difficult to estimate the
thermophysical properties of its fluid mixtures. When simulating the pure alkoxy-ethanol
or its mixture system, the positive charge of hydroxyl hydrogen plays an
important role because it could form partial hydrogen bonding with both the
proton accepters.

The TraPPE and NERD
force filed is the two most widely used force fields which provide the robust
molecular simulation framework for various thermophysical properties'
estimation, especially phase equilibrium study. These two force fields use the
united atom based approach to represent the CH, CH2, CH3 groups which enables the
transferability of their force field parameters to a wide range of molecular
species. With this simulation methodology, coexistence properties can be
predicted with relatively high levels of accuracy. Basically these two force
fields have very similar energy expression each other, but they don't consider
the hydrogen bonding term explicitly in its energy expression. Therefore the
effect of hydrogen bonding should be investigated for some specific system such
as alkoxy-ethanol and its mixture system.

On this united
atom base, the force field parameters of alkoxy-ethanol have been optimized and
the molecular structure and coexisting properties of alkoxy-ethanol and its
mixture has been studied. The results are compared to simulation results using
NERD and TraPPE parameters.