Can Polyelectrolyte Mechanical Properties be Directly Modulated by an Electric Field? A Molecular Dynamics Study

Abstract

Multifunctionality in polymers facilitates their application in emerging technologies. Electrical fields are a preferred stimulus because of the speed and ease of application to bulk polymers. While a wide range of electrically triggered actuators are developed, and electrically controlled adhesion between gels is demonstrated, modification of bulk mechanical properties via electrical stimuli remains elusive. Polymers with covalently incorporated ionic charge (polyelectrolytes) should be well suited to achieving this goal since the mechanical properties depend on electrostatic interactions and these charges are intrinsically susceptible to electric fields. Molecular dynamics simulations are utilized here to investigate whether electric fields can modulate the mechanical properties of polyelectrolytes and to understand the governing mechanisms. Mechanical property modulation by electric field is found to be sensitive to the charge distribution—charges must be tightly attached to the polymer backbone, and responsivity is greater if a single backbone contains both positive and negative charges. The dominant mechanisms are reorientation and stretching of the polymer chains, which also elongate the ionic clusters to maintain strong electrostatic interactions throughout deformation. These insights are critical for future experimental realization of polymers with electric field regulated mechanical properties.

An Enhanced Scheme for Multiscale Modeling of Thermomechanical Properties of Polymer Bulks

“…The robustness of the CG potentials is attributed to four features: analytical functions, NPT ensemble, PVT properties, and nonbonded interactions, among which more attractive vdw interactions are regarded as the most critical for the identified enhancement of the thermomechanical properties. Such CG potentials with explicit electrostatic interactions hold great promise in directly simulating the electrical properties of various polymer materials …”

“…Such CG potentials with explicit electrostatic interactions hold great promise in directly simulating the electrical properties of various polymer materials. 128 ■ ASSOCIATED CONTENT * sı Supporting Information…”

Electromagnetic bioeffects: a multiscale molecular simulation perspective

“…MD simulations were used to investigate the ability of EFs to modulate the mechanical properties of polyelectrolytes and to understand the governing mechanisms. 193 Mechanical property modulation by EF was found to be sensitive to the charge distribution—charges must be tightly attached to the polymer backbone, and responsivity is greater if a single backbone contains both positive and negative charges. The dominant mechanisms are reorientation and stretching of the polymer chains, which also elongate the ionic clusters to maintain strong electrostatic interactions throughout deformation.…”