Spreading of polymer droplets on corrugated and flat subrates under complete wetting conditions a... more Spreading of polymer droplets on corrugated and flat subrates under complete wetting conditions are studied by molecular dynamics simulations using a coarse grained bead-spring model. To minimize finite size effects, large droplets of size ˜ 200,000 monomers are studied, significantly larger than previous studies. Simulations using Langevin and dissipative particle dynamics (DPD) thermostats are compared. These two thermostats were chosen since the DPD thermostat produces the correct hydrodynamic forces while the Langevin thermostat does not. For the corrugated substrate consisting of mobile atoms in an fcc lattice, the results are insensitive to whether both the polymer and substrate atoms or only the substrate atoms are coupled to the thermostat. The kinetics are strongly effected by the shape of the starting droplet. For spherical droplets, the initial growth kinetics of the droplet radius scales as t^1/2 for both the corrugated and flat substrates. At later times, the growth slows to t^a, where a 1/7 for Langevin dynamics and 1/10 for DPD dynamics in agreement with theoretical predictions. For droplet which are initally hemispherical in shape, only the slower growth laws are observed. Results for the spreading of two component fluid droplets will also be discussed.
Modelling and Simulation in Materials Science and Engineering - MODEL SIMUL MATER SCI ENG, 2003
A simple procedure is used to formulate a Cu-Pb pair interaction function within the embedded ato... more A simple procedure is used to formulate a Cu-Pb pair interaction function within the embedded atom (EAM) method framework. Embedding, density and pair functions for pure Cu and pure Pb are taken from previously published EAM studies. Optimization of the Cu-Pb potential was achieved by comparing with experiment the computed heats of mixing for Cu-Pb liquid alloys and the equilibrium phase diagram, the latter being determined via a thermodynamic integration technique. The topology of the temperature-composition phase diagram computed with this EAM potential is consistent with experiment and features a liquid-liquid miscibility gap, low solubility of Pb in solid Cu and a monotectic reaction at approximately 1012 K.
Spreading of polymer droplets on corrugated and flat subrates under complete wetting conditions a... more Spreading of polymer droplets on corrugated and flat subrates under complete wetting conditions are studied by molecular dynamics simulations using a coarse grained bead-spring model. To minimize finite size effects, large droplets of size ˜ 200,000 monomers are studied, significantly larger than previous studies. Simulations using Langevin and dissipative particle dynamics (DPD) thermostats are compared. These two thermostats were chosen since the DPD thermostat produces the correct hydrodynamic forces while the Langevin thermostat does not. For the corrugated substrate consisting of mobile atoms in an fcc lattice, the results are insensitive to whether both the polymer and substrate atoms or only the substrate atoms are coupled to the thermostat. The kinetics are strongly effected by the shape of the starting droplet. For spherical droplets, the initial growth kinetics of the droplet radius scales as t^1/2 for both the corrugated and flat substrates. At later times, the growth slows to t^a, where a 1/7 for Langevin dynamics and 1/10 for DPD dynamics in agreement with theoretical predictions. For droplet which are initally hemispherical in shape, only the slower growth laws are observed. Results for the spreading of two component fluid droplets will also be discussed.
Modelling and Simulation in Materials Science and Engineering - MODEL SIMUL MATER SCI ENG, 2003
A simple procedure is used to formulate a Cu-Pb pair interaction function within the embedded ato... more A simple procedure is used to formulate a Cu-Pb pair interaction function within the embedded atom (EAM) method framework. Embedding, density and pair functions for pure Cu and pure Pb are taken from previously published EAM studies. Optimization of the Cu-Pb potential was achieved by comparing with experiment the computed heats of mixing for Cu-Pb liquid alloys and the equilibrium phase diagram, the latter being determined via a thermodynamic integration technique. The topology of the temperature-composition phase diagram computed with this EAM potential is consistent with experiment and features a liquid-liquid miscibility gap, low solubility of Pb in solid Cu and a monotectic reaction at approximately 1012 K.
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