Date of Graduation


Document Type


Degree Name

Bachelor of Science in Mechanical Engineering

Degree Level



Mechanical Engineering


Spearot, Douglas E.


Jensen, David C.

Second Reader

Kumar, Suresh

Third Reader

Stewart, John


Experimental and computational techniques were used to test the permeation of water through polydimethylsiloxane (PDMS). The experimental portion consisted of creating a permeation cell in such a way that water’s only path to escape was through a PDMS membrane. Weight measurements were recorded and turned into a permeation coefficient of water through different types of PDMS. The membranes were then stretched to a certain amount to study the effect on water permeation. The computational part used Large-scale Atomic / Molecular Massively Parallel Simulator (LAMMPS) to study the diffusion coefficient of water through PDMS. The initial step was to translate coarse-grain water model parameters into LAMMPS so that water could be accurately modeled. The next process involved calculating and including the parameters for both water-PDMS interaction sites and PDMS-PDMS interaction sites. Three restart files, differing in random numbers in the code, were used to create input files for the molecular dynamics simulations. Each restart file was used to produce 3 input files at 3 different temperatures, 200K, 300K, and 400K, creating a total of 9 simulations. The 300K file was put under 3 different pressures, 50 atm, 100 atm, and 150 atm, to mimic the PDMS under stretch /strain. The simulations would provide insight into diffusion-stretch correlation. The 100 atm file was run at 200K and 400K also to test temperature dependence with strain on the PDMS.


Stewart, Gay