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Metal–organic nanotubes (MONTs) are 1-dimensional crystalline porous materials that are formed from ligands and metals in a manner identical to more typical 3-dimensional metal–organic frameworks (MOFs). MONTs form anisotropically in one dimension making them excellent candidates for linker engineering for control of chemical composition and spacing. A novel series of MONTs was synthesized utilizing a mixture of 1,2,4-ditriazole ligands containing both a fully protonated aryl moiety and its tetrafluorinated analog in ratios of, 0 : 1, 1 : 4, 1 : 1, 4 : 1, and 1 : 0, respectively. All MONTs were characterized by both bulk and nanoscale measurements, including SCXRD, PXRD, ssNMR and TEM, to determine the resulting co-polymer architecture (alternating, block, or statistical) and the ligand ratios in the solid materials. All characterization methods point towards statistical copolymerization of the materials in a manner analogous to 3D MOFs, all of which notably could be achieved without destructive analytical methods. 

In this report, we explore the internal structural features of polyMOFs consisting of equal mass ratios of metal-coordinating poly(benzenedicarboxylic acid) blocks and non-coordinating poly(ethylene glycol) (PEG) blocks. The studies reveal alternating lamellae of metal-rich, crystalline regions and metal-deficient non-crystalline polymer, which span the length of hundreds of nanometers. Polymers consisting of random PEG blocks, PEG end-blocks, or non-coordinating poly(cyclooctadiene) (COD) show similar alternation of metal-rich and metal-deficient regions, indicating a universal self-assembly mechanism. A variety of techniques were employed to interrogate the internal structure of the polyMOFs, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and small-angle synchrotron X-ray scattering (SAXS). Independent of the copolymer architecture or composition, the internal structure of the polyMOF crystals showed similar lamellar self-assembly at single-nanometer length scales. 

The positional effect of stimuli-responsive units in tri-component copolymer vesicles is studied to explore variations in the host–guest properties of the assembly. We study this by placing pH-responsive diisopropylaminoethyl moieties in three distinct locations of a block copolymer assembly. In two of the three variations, these functionalities were randomly distributed in the hydrophobic or the hydrophilic domains of an amphiphilic diblock copolymer. In a third variation, this responsive functionality was incorporated as the middle block in a triblock copolymer. The results reveal that the solvent exposure of the responsive units holds the key for controlling the rate of molecular release from these polymer vesicles. The study also shows that equilibrium changes in the morphology of an assembly are not good indicators of the responsive host–guest properties of a polymer assembly.