Metal–Organic Framework Nanopores Identify Single Monomer Mutation on Synthetic Polymer Chain

Here, we demonstrate that the nanopores of a metal-organic framework (MOF) can recognize even a single-monomeric difference within a long synthetic polymer chain comprising over 600 repeating units. Specifically, MOF-808, featuring three-dimensional pores with apertures of ca. 1.0 nm, does not adsorb polystyrene (PS) homopolymers from a toluene solution. Strikingly, it exhibits significant adsorption of PS chains bearing even only a single substitution within the polymer backbone. Furthermore, the location and chemical nature of the point mutation critically influence the polymer infiltration behavior. This high-precision structural recognition occurs at the MOF/solution interface, where the relatively polar mutation group prolongs the residence time of polymer chains at the MOF surface compared with their unmodified counterparts, thereby increasing the probability of successful pore entry from the chain ends. Leveraging this mechanism, we achieve the highly challenging task of isolating the PS homopolymer fraction from a complex mixture of PS homopolymer and random copolymer that contains only a few percent of methyl methacrylate as the comonomer. This work provides a proof of concept for MOF-based mutation recognition in synthetic polymers and opens a pathway toward extending this approach to a wider range of polymer systems.