We report a synthetic methodology for decorating a surface of metal–organic frameworks (MOFs) with polymers through postsynthetic modification. Well-defined polymers with reversibly deactivated radical species at their chain end were reacted with vinyl-functionalized MOFs in the presence of a radical initiator. The radical addition forms a C–C bond between the polymer end with the functional group at the MOF ligand. We used sterically bulky star polymers containing electron-deficient maleimide chain ends, which facilitated modification of the external surface, yielding polymer-grafted MOF composite particles. A patchy MOF particle can also be obtained by simultaneously grafting two polymers and jammed at the immiscible liquid–liquid interface. We further show that the selective removal of a sacrificial polymer would partially expose the surface of MOFs to external environment, which hinders the uptake of macromolecular guests above the critical hydrodynamic size. Overall, four polymer@MOF composites have successfully been achieved through the present postsynthetic patchworks on MOFs with star polymers and selective etching process.

Surface modification offers an efficient and economical route to installing functional groups on a polymer surface. This work demonstrates that primary amine groups can be introduced onto a polymer surface via Buchwald–Hartwig amination, and the functionalized substrates can be chemically bonded to produce functional microfluidic devices. By activating the C-Cl bond in commercially used poly(chloro-p-xylylene) (parylene C) by Pd catalystand substituting Cl with the amine source, the amine groups are successfully
installed in a facile and recyclable manner. The substrates can be covalently bonded with each other via amine-isocyanate chemistry, providing much higher bonding strength compared to previous methods based on noncovalent adhesive coatings. As a result, transparent and flexible microfluidic channels can be fabricated that are compatible with organic solvents and high pressure. Retention of amine group reactivity in the channel suggests the potential of this methodology for the surface immobilization of functional
molecules for microfluidic reactors and biosensors.