Start
Feb 02, 2017 - 17:00
End
Feb 02, 2017 - 18:00
Venue
Rm. No. 118 Ground floor Chemical Engg. Dept.
Event Type
Speaker
Janani Sampath Ohio State University
Title
Effect of Deformation and Carboxyl Groups on the Structure and Dynamics of Model Polyethylene-co-Acrylic Acid Ionomers
Abstract: Ionomers are polymers with a small fraction of charged monomers; these bound ions along with free counterions tend to aggregate together strongly in the absence of solvent. They have a wide range of applications from dental fixtures and packaging to fuel cell mebranes. Ionic aggregates can act like temporary cross-links giving rise to interesting mechanical properties. I perform coarse-grained molecular dynamics simulations of ionomer melts with various spacings of charges along the chain representing experimental precisely spaced neutralized poly(ethylene-co-acrylic acid) materials. I study these systems during uniaxial tensile strain and calculate aggregate morphology dynamics and scattering profiles. Prior work established a useful coarse-grained model for fully neutralized acetic acid based ionomers which include COO – and Na + but no COOH groups. To better model typical experimental systems that are only partially neutralized I use additional “sticker” groups that represent COOH. Aggregate morphologies obtained using the sticker-based model are in good agreement with prior atomistic simulation results. I analyze the structure and dynamics of partially neutralized ionomers with differing chain architectures as well as rheological properties like viscosity and stress relaxation from equilibrium stress fluctuations. Bio: Janani Sampath is currently a PhD candidate at the Ohio State University in the William G Lowrie Department of Chemical Engineering advised by Dr. Lisa Hall. After obtaining her B.E from R.V College of Engineering in 2010 she was employed in the Unilever R&D facility in Bangalore as a Research Assistant for 3 years.Sampath’s current research is focused on
1) understanding how ionic aggregates and chain architecture determine the structure and dynamics of ionomers
2) developing a more realistic coarse-grained ionomer model that includes partial neutralization
3) developing a model ionomer-nanoparticle system to study the difference in behavior of aggregates close to the nanoparticle surface vs. the bulk.
Note: Attendance is mandatory for those enrolled in CL 704/702.