Metal‐Organic Frameworks for Practical Separation of Cyclic and Linear Polymers

The purification step in the manufacturing of cyclic polymers is difficult as complete fractionation to eliminate linear impurities requires considerable effort. Here, we report a new polymer separation methodology that uses metal‐organic frameworks (MOFs) to discriminate between linear and cyclic polyethylene glycols (PEGs) via selective polymer insertion into the MOF nanopores. Preparation of a MOF‐packed column allowed analytical and preparative chromatographic separation of these topologically distinct pairs. In addition, gram‐scale PEGs with only cyclic structures were successfully obtained from a crude reaction mixture by using MOF as an adsorbent. Metal‐organic frameworks (MOFs) can discriminate topological architectures of macromolecules, such as linear and cyclic structures, via selective polymer insertion into the nanopores. This realizes new polymer separation technology that enables practical and efficient isolation of cyclic polyethylene glycols (PEGs) from the chaotic mixture with linear impurities in a gram scale.