Film Growth and Surface Roughness with Effective Fluctuating Covalent Bonds in Evaporating Aqueous Solution of Reactive Hydrophobic and Polar Groups: A Computer Simulation Model
Summary: A computer simulation model is proposed to study film growth and surface roughness in aqueous (A) solution of hydrophobic (H) and hydrophilic (P) groups on a simple three dimensional lattice of size with an adsorbing substrate. Each group is represented by a particle with appropriate characteristics occupying a unit cube (i.e., eight sites). The Metropolis algorithm is used to move each particle stochastically. The aqueous constituents are allowed to evaporate while the concentration of H and P is constant. Reactions proceed from the substrate and bonded particles can hop within a fluctuating bond length. The film thickness ( ) and its interface width ( ) are examined for hardcore and interacting particles for a range of temperature ( ). Simulation data show a rapid increase in and followed by its non‐monotonic growth and decay before reaching steady‐state and near equilibrium ( ) in asymptotic time step limit. The growth can be described by power laws, e.g., with a typical value of in initial time regime followed by at . For hardcore system, the equilibrium film thickness ( ) and surface roughness ( ) seem to scale linearly with the temperature, i.e., at low and at higher . For interacting functional groups in contrast, the long time (unsaturated) film thickness and surface roughness, and decay rapidly followed by a slow increase on raising the temperature.
Growth of the average film thickness at a temperature .
with an adsorbing substrate. Each group is represented by a particle with appropriate characteristics occupying a unit cube (i.e., eight sites). The Metropolis algorithm is used to move each particle stochastically. The aqueous constituents are allowed to evaporate while the concentration of H and P is constant. Reactions proceed from the substrate and bonded particles can hop within a fluctuating bond length. The film thickness (
) and its interface width (
) are examined for hardcore and interacting particles for a range of temperature (
). Simulation data show a rapid increase in 
and 
followed by its non‐monotonic growth and decay before reaching steady‐state and near equilibrium (
) in asymptotic time step limit. The growth can be described by power laws, e.g., 
with a typical value of 
in initial time regime followed by 
at 
. For hardcore system, the equilibrium film thickness (
) and surface roughness (
) seem to scale linearly with the temperature, i.e., 
at low 
and 
at higher 
. For interacting functional groups in contrast, the long time (unsaturated) film thickness and surface roughness, 
and 
decay rapidly followed by a slow increase on raising the temperature. 
.