Powered by nothing more than ambient moisture, a plastic film writhes across a table top, contorting and twisting onto itself in a manner researchers hope to harness for use in biomedical or mechanical actuators. Developed by researchers at the Massachusetts Institute of Technology (MIT; Cambridge, Mass.), the material, which is made up of two polymers, is described in a paper entitled, “Bio-inspired Polymer Composite Actuator and Generator Driven by Water Gradients.”
One of that paper’s authors, Mingming Ma, told Plastics Technology that the composite is made via electrochemical polymerization of pyrrole in an organic solution, utilizing polypyrrole and polyol-borate. A process Ma admits is thus far confined to the lab.
“The electrochemical polymerization of polypyrrole-based plastics has not reached industry scale,” Ma said. The current lab scale output is still focused on developing applications for this water-responsive material, according to Ma, including water-responsive switches or indicators.
In testing, the composite film absorbed up to 10% of water by weight from humid air, playing off a hypothesis stated in the associated technical paper.
“Polymeric materials that reversibly change shape, size or mechanical properties in response to external stimuli have attracted considerable interest due to their potential applications as actuators for biomedical and mechanical purposes…We hypothesized that the composite of a soft water-responsive gel within a rigid polymer matrix would yield a better water-responsive actuator. We made a dynamic polymer composite of rigid PPy imbedded with a flexible, inter-penetrating polyol-borate network that would be responsive to water sorption and desorption.”
Whatever comes of the technology, it certainly makes for stunning video in its currrent form.