Optical super-resolution microscopy (OSRM) provides fluorescence imaging capabilities below the diffraction limit of light. Specific labeling of distinct constituents in multicomponent systems, such as block copolymers (BCPs), with compatible optical probes enables multicolor OSRM imaging of diffraction-limited features with nanometer-scale resolution. While such approaches are well established in biology, their application to materials science has been considerably slower. This gradual implementation is largely due to the lack of appropriate OSRM probes that, e.g. by facile mixing or surface modification, enable orthogonal labeling of specific nanostructures in the condensed state without compromising polymer self-assembly. Here, OSRM probes in the form of ultrasmall (&lt;10 nm–diameter) nanoparticles—aluminosilicate Cornell prime or aC’ dots—encapsulating different fluorescent dyes are tailored to visualize both nanodomains of polystyrene-block-poly[(allyl glycidyl ether)-co-(ethylene oxide)] (PS-b-P(AGE-co-EO)) di-BCP thin films. Careful design of nanoprobe surface chemical properties allows either selective compatibilization with the PS matrix or preferential reactivity with surface allyl groups of the hydrophilic P(AGE-co-EO) minority domain. Stochastic optical reconstruction microscopy (STORM) imaging of resulting polymer–inorganic nanocomposite thin films shows nanodomain features of the two chemically dissimilar blocks consistent with atomic force microscopy results. The incorporation of PS-compatible nanoparticle probes leads to subtle yet identifiable changes to mesostructure; that is, nanodomain compatibility facilitates minimal disruption to self-assembly while enabling straightforward multicolor OSRM on resulting BCP nanocomposite thin films. The chemical orthogonality of these nanoprobes to distinctly label different nanodomains opens up opportunities for optical imaging of in situ BCP self-assembly on the nanoscale using OSRM.

Orthogonal nanoprobes for one- and two-color optical super-resolution characterization of distinct nanodomains in self-assembled diblock copolymer composite thin films

ACS Spring Meeting 2021

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