Structural Dynamics Evolution of EVOH during Polymer Upcycling Reaction by Ex-Situ Electrochemical Impedance Spectroscopy

Ethylene vinyl alcohol copolymers (EVOH) have several applications including food packaging given its exceptional vapor and oil barrier performance. While EVOH traditionally has a branched architecture, we study a linear EVOH synthesized by hydroboration/oxidation of alkenes in polycyclooctene . This new synthetic route produces EVOH with partially unsaturated or fully saturated backbones and a range of hydroxyl functionality.

In this study, we use electrochemical impedance spectroscopy (EIS) to investigate the structural dynamics of these novel polymers. Surprisingly, an additional relaxation process between the slowest segmental and fastest subsegmental dynamics, is revealed via extremely deep quenching to ~160K below the glass transition temperature (T_g). Coupling our EIS experiments with X-ray scattering and thermal analysis we correlate the dynamics to the semicrystalline structure. These findings are expected to address an important polymer physics question of how the amorphous polymer segments form a glass region between lamellar crystals, particularly the existence of rigid amorphous fraction (RAF) and mobile amorphous fraction (MAF) in semicrystalline polymers. Finally, we expect to correlate the subsegmental relaxations to oxygen transport behavior.