How Rigid Are Anthranilamide Molecular Electrets?

Abstract

As important as molecular electrets are for electronic materials and devices, conformational fluctuations strongly impact their macrodipoles and intrinsic properties. Herein, we employ molecular dynamics (MD) simulations with the polarizable charge equilibrium (PQEq) method to investigate the persistence length (L_P) of molecular electrets composed of anthranilamide (Aa) residues. The PQEq-MD dissipates the accepted static notions about Aa macromolecules, and L_P represents the shortest Aa rigid segments. The classical model with a single L_P value does not describe these oligomers. Introducing multiple L_P values for the same macromolecule follows the observed trends and discerns the enhanced rigidity in their middle sections from the reduced stiffness at their terminal regions. Furthermore, L_P distinctly depends on solvent polarity. The Aa oligomers maintain extended conformations in nonpolar solvents with L_P exceeding 4 nm, while in polar media, increased conformational fluctuations reduce L_P to about 2 nm. These characteristics set key guidelines about the utility of Aa conjugates for charge-transfer systems within organic electronics and energy engineering.