Polymer architectures assisted by dynamic covalent bonds: synthesis and properties of boronate-functionalized polyrotaxane and graft polyrotaxane

Abstract

Poly [2]rotaxane and graft polyrotaxane were synthesized from a mixture of poly(crown ether) (polyester-10 and polyisoxazole-13) as a trunk polymer, boronic-acid-terminated secondary ammonium salt 5 as an axle component, and diol as an end-capping group by pseudorotaxane formation and subsequent catalyst-free dehydrative bondage between the boronic acid and the diol moieties. Trunk polymers 10 and 13 were prepared by copolymerization of diol-or diyne-substituted dibenzo-24-crown-8-ether 9 or 11 and ditopic comonomers such as bifunctional acid dichloride and nitrile N-oxide. The use of the sufficiently bulky and stable homoditopic nitrile N-oxide 12 gave the high-molecular-weight isoxazole-containing poly(crown ether) 13 efficiently and without accidental penetration of the propagation end into the crown cavity, which would have caused gelation. The treatment of these poly(crown ether)s with boronic acid 5 in CH 2 Cl 2 gave the corresponding polypseudorotaxanes, and subsequent graftonto reaction with pinacol and a polymeric terminal diol gave poly[2]rotaxane and graft polyrotaxane. The chemical stability of these supramolecular architectures primarily depends on the bulkiness of the diol group as the end-capping moiety and the inherence originating from the dynamic covalent bond of boronate, as determined by detailed 1 H nuclear magnetic resonance study of model [2]rotaxanes 6-8 and the dissociation behavior of the polymers.

Rotaxanes and pseudorotaxanes with threads containing viologen units

“…[111][112][113][114] One should mention here also pillarene-based pseudorotaxanes, 115,116 they are a new class of supramolecular structures yet not so thoroughly studied as other, longer known species. A growing attention is paid now to polyrotaxanes 117,118 and polypseudorotaxanes 119,120 which are a topic of increasing number of reports.…”

Supramolecular Organogel Based on Crown Ether and Secondary Ammoniumion Functionalized Glycidyl Triazole Polymers

“…All solvents, poly(epichlorohydrin) ( M w = 700 kDa), 3,3-dimethyl-1-butyne, tetrakisacetonitrile copper(I) hexafluorophosphate (Cu(MeCN) 4 ·PF 6 ), cation exchange resin Dowex Marathon MSC hydrogen form, ethylenediaminetetraacetic acid two sodium salt (EDTA·2Na), and hexafluorophosphoric acid (HPF 6 ) were purchased from Sigma-Aldrich Co. Glycidyl azide polymer (GAP), acetylene-terminated DB24C8 and DBA were synthesized according to the literature. ,,− …”

Applications of reversible covalent chemistry in analytical sample preparation

“…The major applications of DCC are found in the field of organic synthesis in general, 11,13 and in dynamic supramolecular or polymer chemistry in particular. [14][15][16] West and Otto furthermore reviewed recent applications of RCC in the field of drug delivery. 17 However, due to its general nature, RCC is usually not recognized as an analytical concept in its own right.…”