A Close Look at the Local Structure of Functional Polymers: The Example of Poly(Vinylidene Fluoride)

Functional macromolecular materials promise to enable important improvements in many aspects of everyday life, including for energy applications, novel electronics systems, or wearable health care products. In contrast to widely-used commodity plastics such as polyolefins, polyamides, or polyesters, it, however, remains challenging to advance detailed insights into the interrelation of structure and performance for functional polymers, limiting progress. The reason is that the macroscopic properties of such polymers often depend on local chain arrangements rather than long-range order only. Here, it is demonstrated on the example of the well-investigated ferroelectric poly(vinylidene fluoride) (PVDF) that modern nuclear magnetic resonance (NMR) spectroscopy enables the quantitative analysis of the complex solid-state structure of this polymer, providing unprecedented insight. The precise fractions of chain segments of different conformations are revealed, as well as their spatial distributions with respect to each other. Thereby, a significant population of short-range ordered chain segments is identified, a large fraction of which in close proximity to defects and disordered segments. Unsurprisingly, different environments lead to different structural dynamics - collectively showing that characterizing local order/disorder and their dynamics is imperative to accurately describe the properties of functional polymers such as PVDF.