Scientists tasked with creating better plastic films have been at a loss when it comes to observing how synthetic polymers react under mechanical stress – the polymers are just too small for a microscope to keep track of while being stretched. Now a team of physicists from Technische Universitaet Muenchen (TUM) has come up with a solution. They’re using a muscle filament protein to build polymer networks that can be observed by a microscope, and by doing so have already determined why some polymers get tougher with repeated stress, while others get softer.

Prof. Andreas Bausch and his colleagues are utilizing the protein actin to create the biosynthetic networks, as actin filaments are easily seen through a fluorescence microscope – even when they’re moving while being stretched. By combining a rheometer (used to study mechanical properties of materials) and a confocal microscope, they were able to film the actin network in three dimensions throughout the mechanical deformation process.

According to the TUM team, the fashion in which the network structure reorganizes itself lies behind the difference in stress responses of different plastic polymers.

The research was recently published in the journal Nature Communications.