Usually large objects, particles and macromolecules, of dissimilar chemical nature do not mix. In new research published in Nature Materials, researchers in the Sheiko Group, in collaboration with the Rubinstein Group, have shown that mixing can be enhanced by changing the molecular architecture from linear chains to branched/brush-like molecules, while maintaining the same chemical structure. Macromolecules typically phase separately unless their shapes and chemical compositions are tailored to explicitly drive mixing. This propensity may be overcome for copolymers wherein chemically dissimilar components are covalently tethered to one another. But now research has shown that physical constraints can drive spontaneous mixing of chemically different species.