New theory promises to reshape how we think about polymer superstructures

Scientists at the University of Massachusetts Amherst have solved a longstanding mystery surrounding a double-gyroid, a structure formed by collections ofmolecules. This shape is one of the most desirable for materials scientists, and has a wide range of applications, but until now, a predictable understanding of how these shapes form has been elusive.

Greg Grason, the paper's senior author and a professor of polymer science and engineering at the University of Massachusetts-Amherst, says there is a beautiful interplay between pure mathematics and materials science.

These forms can be a lot of different shapes. They can be simple, like a cylinder or sphere. We have revealed the hidden geometry that allows the double-gyroid form to be assumed.

What does a double-gyroid look like? It is not intuitive and is something in between a cylinder and a layer. Imagine a flat piece of window screen, a layer, and then twist it up into a saddle-shaped layer that fits into a box, so that its surface area stays as small as possible. That is a gyroid. When a second material is twisted into a gyroid, it fills in the gaps in the first gyroid. Each material forms a network of tubes. They form a material that is both symmetrical on 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 The material can be engineered to have different properties.

Double-gyroids exist in nature and have been observed, but until now nobody has figured out how block copolymers know how to form them. A new approach to thinking about the packing problem and how best to fill a finite container with material was borrowed from computational geometry by the authors. Understanding this formation requires knowing how the molecule measures the middle of shapes, like gyroids, that are far more complex than spheres and cylinders. The team's updated theoretical model is able to explain the puzzling formation of double-gyroids, and it holds promise for understanding how the packing problem works in a much broader array of self-assembled superstructures.

The researchers plan to work with synthetic chemists to refine their theory. The goal is to be able to engineer a wide variety of materials that can take advantage of the double-gyroid's structure and that can help advance a wide range of technologies.

More information: Abhiram Reddy et al, Medial packing and elastic asymmetry stabilize the double-gyroid in block copolymers, Nature Communications (2022). DOI: 10.1038/s41467-022-30343-2 Journal information: Nature Communications Citation: New theory promises to reshape how we think about polymer superstructures (2022, May 16) retrieved 16 May 2022 from https://phys.org/news/2022-05-theory-reshape-polymer-superstructures.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.