Internal friction can be measured with the Jarzynski equality

Abstract

A simple protocol for the extraction of the internal friction coefficient of polymers is presented. The proposed scheme necessitates repeatedly stretching the polymer molecule, and measuring the average work dissipated in the process by applying the Jarzynski equality. The internal friction coefficient is then estimated from the average dissipated work in the hypothetical limit of zero solvent viscosity. The validity of the protocol is established through Brownian dynamics simulations of a single-mode spring-dashpot model for a polymer. Well-established single-molecule manipulation techniques, such as optical tweezer-based pulling, can be used to implement the suggested protocol experimentally.