At the molecular level, polymers contain structural defects known as loops. Researchers at MIT were the first to identify these defects, and the same researchers have now found an easy way to reduce them.
The technique used simply requires one of the components of the polymer network to be added very slowly to a large quantity of the second component. In doing so, the number of loops was halved in a variety of polymer network structures. It is hoped that this method could be applied in industrial settings to strengthen widely used polymers.
History of the loop defect
Researcher Jeremiah A. Johnson, the Firmenich Career Development Associate Professor of Chemistry at MIT and the senior author of the paper, and his research group were the first to measure the number of loops in a polymer network in 2012. The findings showed that loops could account for anywhere from 9 to 100% of a network, depending on the concentration of polymer chains in the starting material and other factors. The measurements were validated with theoretical predictions by MIT associate professor of chemical engineering Bradley Olsen.
Johnson and Olsen were later able to calculate how the loops weaken a material, leading to the latest work that seeks to reduce loop formation. The team’s work was funded by the National Science Foundation.
Johnson's lab is now working on applying this strategy to a variety of materials, including gels used to grow cells for tissue engineering.
You can learn more about this research in the MIT news release as well as in the team’s published work in Proceedings of the National Academy of Sciences.