Supramolecular Alternating Block Copolymers via Metal Coordination

Abstract

A bimetallic ruthenium olefin metathesis initiator was synthesized and used to polymerize functionalized norbornenes, affording polymers that are living at both polymer chain-ends. Using this bis-ruthenium initiator strategy and combining it with functional chain-terminators, highly-efficient syntheses of either SCS-Pd(II) pincer- or pyridine-functionalized symmetrical telechelic polymers were developed. The terminal functional group incorporation was confirmed by 1H NMR spectroscopy analyses. The telechelic polymers were self-assembled into block copolymers by means of metal coordination between corresponding terminal recognition units. The self-assembly process was monitored by 1H NMR spectroscopy revealing nearly quantitative functionalization. The resulting supramolecular block copolymers were further characterized by viscometry and dynamic light scattering.

Controlling supramolecular polymerization through multicomponent self‐assembly

“…231 The use of metal coordination chemistry to build metallosupramolecular polymers has been extensively investigated, aided by the large variety of ligands or metal ions, which effect the strength, dynamics and reversibility of the supramolecular linkage. [232][233][234][235][236][237][238][239] A number of excellent reviews in this specific area highlight the influence of the ligand metal interaction, solvent polarity and coordination capability on the degree of polymerization and the dynamic properties. [240][241][242][243][244] It is interesting to point out that in noncoordinating solvents coordination polymers can be kinetically inert and behave like conventional covalent polymers, whereas the presences of traces of coordinating solvent or free ligand increases the exchange rate for the metal coordination bond and impart supramolecular behavior such as stimuli-responsive behavior toward external stimuli.…”

Single‐Chain Self‐Folding of Synthetic Polymers Induced by Metal–Ligand Complexation

“…Non‐covalent interactions such as hydrogen bonding, host–guest systems, and metal–ligand coordination are extensively utilized to construct well‐defined supramolecular architectures. Compared to alternative reversible non‐covalent interactions characteristic for supramolecular chemistry, metal–ligand coordination has proven to be one of the most prominent supramolecular motifs, due to its ease of accessibility and strong binding constants . For example, the group of Meijer reported the single‐chain self‐folding of polymeric chains via multiple hydrogen bonding, which carry catalytic Ru as a catalyst for the reduction of cyclohexanone to cyclohexanol .…”

End‐Functionalized Palladium SCS Pincer Polymers via Controlled Radical Polymerizations

“…Our research design requires a controlled polymerization technique for the fabrication of Pd II ‐pincer containing polymer chains with low dispersities while avoiding postpolymerization methods. The use of ROMP as a method to fabricate well‐defined Pd II ‐pincer functionalized polymers has been achieved, facilitated by the high functional group tolerance of the Grubbs initiators toward supramolecular metal‐center‐containing complexes . As such, an entire class of ring‐strained monomers with various side chain functionalities can be employed toward the fabrication of MC polymers.…”