Fluorophores as Probes of Multi-Scale Polymer Dynamics

Problem/Societal Impact Statement:

Polymers have structure and corresponding dynamics spanning multiple length scales. Chemical bonds dominate at ~0.1 nm, segmental dynamics at ~1 nm, entire chain dynamics at ~10 nm, and cooperative rearrangements can have effects up to 100 nm from a perturbation. Studying the relationships between polymer dynamics on these different length scales is critical for a better fundamental understanding of polymers, which will form the basis of advanced polymer technologies.

Approach to Problem:

Fluorophores have seen great success in polymer science and biology as probes of segmental dynamics and entire chain dynamics (i.e., diffusion). Our research focuses on combining these different measurement techniques to study polymers across length scales with relative experimental ease.

Progress So Far: We have synthesized a variety of polymers and performed Fluorescence Correlation Spectroscopy (FCS), Fluorescence Imaging Microscopy (FLIM), and Fluorescence Recovery After Photobleaching (FRAP). We are studying the relationships between these measurements and the physical properties of polymers that they can detect.

Favorite Moment: FRAP is a very fun experiment. You get to shoot a laser at your sample until the fluorophore undergoes some reaction and is no longer fluorescent, then watch as your polymers diffuse into the “bleached” region. Also, fluorophores can turn amazing colors that are almost unbelievable. Pictures don’t do them justice, but I have attached one below anyway.

Lead student:

Walter Young

Related publication (s):

R. Katsumata, A.R. Dulaney, C.B. Kim, and C.J. Ellison*, “Glass transition and in-plane self-diffusion of unentangled polymer melt nanoconfined by different interfaces,” Macromolecules, 51, 7509-7517 (2018). [DOI]