Diffusion of Molecular and Macromolecular Polyolefin
Probes in Cylindrical Block Copolymer Structures As Observed by High
Temperature Single Molecule Fluorescence Microscopy
posted on 2018-02-22, 00:32authored byMoritz Baier, Dominik Wöll, Stefan Mecking
Highly sensitive
fluorescence microscopy methods allow for the
observation of single bright fluorescent probes. Analysis of their
trajectories gives access to the mode of diffusion and the heterogeneity
in motion of individual probes. Especially for structured soft materials,
this information is of paramount importance for a multitude of possible
applications such as nanoelectronics, nanophotonics, or nanomembrane
technology. Compared to biological systems, utilization for materials
research faces the challenge that relevant processes occur at elevated
temperature, often above 100 °C, and that fluorescence labeling
procedures are yet less evolved. We investigated the motion of single
probes in block copolymer morphologies from room temperature to over
100 °C with a custom-made heating device to allow for such high
temperatures without damaging the optics of a commercial optical microscope
and also with the possibility to measure under a nitrogen atmosphere
to reduce photobleaching of the dyes. Apart from tracking single perylenediimide
derivative as a molecular probe, we labeled polyolefin chains with
this chromophore and observed their diffusion. For the synthesis of
the polyolefins, as the most important class of polymeric materials
in general, we present a protocol that provides high quality samples
in terms of molecular weights, molecular weight distributions, and
proven degree of dye functionalization. The dependency of temperature,
block copolymer composition, and probe size on the diffusion behavior
is elaborated.