Tailoring Polyamide Thermal and Mechanical Properties via Cis/Trans Isomerism

Presenter: 

Elizabeth S. Sterner

Authors: 

Elizabeth S. Sterner, Tanya Chantawansri, Weiguo Hu, Alex Hsieh, Timothy M. Swager

Author Affiliation: 

Massachusetts Institute of Technology, Institute for Soldier Nanotechnologies, Army Research Labs, University of Massachusetts - Amherst

Abstract: 

Polyaramid materials are considered to be the gold standard in impact resistant body armor materials, but their challenging synthesis and processing, as well as poor UV-resistance leading to loss of performance make designing improved materials highly desirable. By combining the good fiber-forming properties of polyamide backbones with cycloaliphatic content conferring greater molecular dynamics modes, we have explored a panel of materials that both show promise as polyaramid replacements and illuminate structure-property relationships that govern thermal transitions and mechanical response. These materials were synthesized by interfacial polymerization and explored by conventional spectroscopy, solid state NMR measurements, molecular modeling simulations, and thermomechanical characterization to determine how varying between linear and aromatic content, as well as varying the cis/trans isomerism of the cycloaliphatic monomers leads to large changes in the crystallinity, thermal transitions and mechanical responses of polyamides.