Synergy of Macrocycles and Macromolecular Topologies: An Efficient [3₄]Triazolophane-Based Synthesis of Cage-Shaped Polymers

Abstract

The development of complex topologies such as macromolecular cages constitutes a fascinating aspect of polymer chemistry. In the present work, a novel strategy involving self-closing bifunctional end-groups, which under specific conditions, are allowed to assemble themselves into a predefined thermodynamically favored macrostructure, was designed to fulfill the topological conversion of star-shaped polymers to their respective cage-shaped polymers. A series of four different well-defined four-arm star-shaped poly­(ε-caprolactone) polymers varying in molar masses were successfully synthesized, end-functionalized, and closed into cage-shaped polymers by formation of [3 4 ]­triazolophane macrocycle units. The obtained cage-shaped polymers feature interesting properties that depend drastically on the chain length of the arms and seem to differ from previous reported polymer cages.

The power of architecture – cage-shaped PEO and its application as a polymer electrolyte

“…Noteworthy, a single Gaussian curve shape was retained while maintaining a low dispersity of Đ = 1.14, indicating the absence of PEO end-func or PEO star . This is in accordance with the results of the FT-IR spectra, in which the alkyne proton stretching signal, the broadening of the aromatic protons stretching signals and the strong attenuation of the azide double bond 21 and the natural propensity of PEO to stabilize numerous ionic species, the presence of the main [M + 2Cl] 2− distribution and of the additional minor distributions are very plausible (ESI II/4 †). Now with sufficient material in hand, the thermal properties of the cage-shaped PEO were characterized by differential scanning calorimetry (DSC) and compared to the starshaped PEO.…”

“…Yet only in 2020, the first example of cageshaped PEO synthesis was published by Matsushita and co-workers. 20 Recently, we reported on a novel cage polymer synthesized via a closing reaction based on an intramolecular tetramerization of end-functionalized m-azidoethynylbenzene into [3 4 ]-triazolophane macrocycles, 21 which was demonstrated for a series of four-arm cage-shaped poly(ε-caprolactone)s (ε-PCLs), all exhibiting a reduced crystallinity induced by the topological conversion in accordance with former reports of similar ε-PCL structures. 19b Despite being studied for 20 years, it is interesting to note that cage polymers hardly found any broader application so far.…”

“…The functional end-group 3-azido-5-ethynylbenzoic acid was synthetized beforehand in accordance with our previous study. 21 The PEO star esterification was successfully conducted under mild conditions by EDC coupling, yielding end-functionalized star-shaped PEO (PEO end-func ) in 94% yield after purification by chromatography. Again, the quantitative end-functionalization and the polymer purity were ensured by 1 H-NMR analysis.…”

One‐Shot Intrablock Cross‐Linking of Linear Diblock Copolymer to Realize Janus‐Shaped Single‐Chain Nanoparticles

“…Inspired by the self‐folding of biomacromolecules, such as proteins and nucleic acids, intramolecular cross‐linking reactions of random‐coiled synthetic polymers into defined structures, e.g., cyclic polymers, [1–5] cage‐shaped polymers, [6–10] and single‐chain nanoparticles (SCNPs), [11–18] have attracted significant interest. Among these unique single‐chain technologies, the intramolecular cross‐linking of linear polymers bearing cross‐linkable functionalities along the main chain to generate a three‐dimensional SCNP had been widely studied, aiming at creating functional nanomaterials, such as catalysts, [19–23] nanocarriers, [24–27] and stimuli‐responsive sensors [28–31] …”

One‐Shot Intrablock Cross‐Linking of Linear Diblock Copolymer to Realize Janus‐Shaped Single‐Chain Nanoparticles

“…Inspired by the self-folding of biomacromolecules,such as proteins and nucleic acids,i ntramolecular cross-linking reactions of random-coiled synthetic polymers into defined structures,e.g., cyclic polymers, [1][2][3][4][5] cage-shaped polymers, [6][7][8][9][10] and single-chain nanoparticles (SCNPs), [11][12][13][14][15][16][17][18] have attracted significant interest. Among these unique single-chain technologies,t he intramolecular cross-linking of linear polymers bearing cross-linkable functionalities along the main chain to generate athree-dimensional SCNP had been widely studied, aiming at creating functional nanomaterials,s uch as catalysts, [19][20][21][22][23] nanocarriers, [24][25][26][27] and stimuli-responsive sensors.…”