Many technological advances are driven by the ongoing emergence of nanostructured macromolecules as the key component to enable innovation. Yet, from a materials design perspective, we cannot presume that the bulk properties of macromolecules define their behavior when physically confined to nanoscale dimensions. This is, in fact, not true, as there is now convincing evidence that the nanoscale properties of macromolecules, including the glass transition temperature, can be profoundly different from the bulk. The precise origin of these effects remains unsettled, but a primary factor must be the presence of interfaces. Achieving breakthrough in this scientific problem is especially acute because, unlike atoms or small molecules, there is a presence of multiple competing length scales near these interfaces. At macromolecule interfaces, the dimensions of a single chains can exceed 10 nm, such that a gradient in properties can be long-range and dependent on chain conformation. An enduring barrier to establishing the needed fundamental understanding of macromolecular interfacial behavior, and thereby, nanoscale confinement behavior, has been the challenge to directly probe gradients in properties at site specific locations, and with nanometer resolution. In this talk, I will discuss how we have exploited polymer chemistry to enable a better understanding of how geometric confinement and interfaces modify the glassy properties of nanostructured macromolecules in homogenous and mixed systems.

Nanoscopic measurement of the glass transition in nanostructured macromolecules

ACS Spring Meeting 2021

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