Infrared actuation in aligned polymer-nanotube composites

TL;DR

This study demonstrates reversible infrared-induced actuation in polymer-nanotube composites, with the response depending on nanotube alignment and polymer type, supported by a model based on tube orientation and photon response.

Contribution

It introduces a model linking nanotube alignment to actuation behavior and shows the universality of the response across different polymer systems.

Findings

Reversible actuation observed in composites under infrared light.

Actuation correlates with nanotube alignment degree.

A phenomenological model describes the response based on tube orientation.

Abstract

Rubber composites containing multi-walled carbon nanotubes have been irradiated with near infrared light to study their reversible photo-mechanical actuation response. We demonstrate that the actuation is reproducible across differing polymer systems. The response is directly related to the degree of uniaxial alignment of the nanotubes in the matrix, contracting the samples along the alignment axis. The actuation stroke depends on the specific polymer being tested, however, the general response is universal for all composites tested. We conduct a detailed study of tube alignment induced by stress and propose a model for the reversible actuation behavior, based on the orientational averaging of the local response. The single phenomenological parameter of this model describes the response of an individual tube to adsorption of low-energy photons; its experimentally determined value may suggest some ideas about such a response.