Direct Visualization of Homogeneous Chemical Distribution in Functional Polyradical Microspheres.

We demonstrate that the post-functionalization of solid polymeric microspheres can generate fully and throughout functionalized materials, contrary to the expectation that core-shell structures are generated. We illustrate the full functionalization on the example of photochemically generated microspheres, which are subsequently transformed into polyradical systems. Given the all-organic nature of the functionalized microspheres, we pioneer characterization methods with high analytical sensitivity and spatial resolution by directly visualizing the inner chemical distribution of the post-functionalized microspheres based on characteristic electron energy loss signals in the transmission electron microscopy (TEM). Specifically, we successfully combine ultrasonic ultramicrotomy with electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) during TEM. Our findings open a key avenue for analyzing all-organic low-contrast soft matter material structures, while the specifically investigated system concomitantly holds promise as an all-radical solid-state functional material. This article is protected by copyright. All rights reserved.