Catalyst Control of Nanoscale Characteristic Length of the Glass Transition in Organic Strong Glass-Formers.

Abstract

We report the nanoscale characteristic length (ξα) in organic strong glass-formers at glass transition. Catalyst-dependent ξα of the epoxy-based covalent adaptable networks (CANs) is observed, that is, the more efficient the catalyst for the cross-linking reactions, the larger the ξα is, and upon thermal heating, the more broad the glass transition will be. The observed structural properties at glass transition can be correlated with the topology freezing transition where the fluctuations of network topology aroused from the bond exchange reactions are frozen. This study proposes the catalyst-dependent structural properties in CANs and may fill the structural gap between the glass transition and topology freezing transition of organic strong glass-formers.