Issue 2, 2019

A versatile synthetic strategy for macromolecular cages: intramolecular consecutive cyclization of star-shaped polymers

Abstract

Cage-shaped polymers, or “macromolecular cages”, are of great interest as the macromolecular analogues of molecular cages because of their various potential applications in supramolecular chemistry and materials science. However, the systematic synthesis of macromolecular cages remains a great challenge. Herein, we describe a robust and versatile synthetic strategy for macromolecular cages with defined arm numbers and sizes based on the intramolecular consecutive cyclization of highly reactive norbornene groups attached to each end of the arms of a star-shaped polymer precursor. The cyclizations of three-, four-, six-, and eight-armed star-shaped poly(ε-caprolactone)s (PCLs) bearing a norbornenyl group at each arm terminus were effected with Grubbs' third generation catalyst at high dilution. 1H NMR, SEC, and MALDI-TOF MS analyses revealed that the reaction proceeded to produce the desired macromolecular cages with sufficient purity. The molecular sizes of the macromolecular cages were controlled by simply changing the molecular weight of the star-shaped polymer precursors. Systematic investigation of the structure–property relationships confirmed that the macromolecular cages adopt a much more compact conformation, in both the solution and bulk states, as compared to their linear and star-shaped counterparts. This synthetic approach marks a significant advance in the synthesis of complex macromolecular architectures and provides a platform for novel applications using cage-shaped molecules with polymer frameworks.

Graphical abstract: A versatile synthetic strategy for macromolecular cages: intramolecular consecutive cyclization of star-shaped polymers

Supplementary files

Article information

Article type
Edge Article
Submitted
10 Sep 2018
Accepted
10 Oct 2018
First published
11 Oct 2018
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2019,10, 440-446

A versatile synthetic strategy for macromolecular cages: intramolecular consecutive cyclization of star-shaped polymers

Y. Mato, K. Honda, K. Tajima, T. Yamamoto, T. Isono and T. Satoh, Chem. Sci., 2019, 10, 440 DOI: 10.1039/C8SC04006K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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