Thermally Responsive Elastomeric Supramolecular Polymers Featuring Flexible Aliphatic Hydrogen-Bonding End-Groups

Abstract

The present paper details the synthesis, characterization, and preliminary physical analyses of a series of polyisobutylene derivatives featuring urethane and urea end-groups that enable supramolecular network formation to occur via hydrogen bonding. These polymers are readily accessible from relatively inexpensive and commercially available starting materials using a simple two-step synthetic approach. In the bulk, these supramolecular networks were found to possess thermoreversible and elastomeric characteristics as determined by temperature-dependent rheological analysis. These thermoreversible and elastomeric properties make these supramolecular materials potentially very useful in applications such as adhesives and healable surface coatings.

Supramolecular polymer adhesives: advanced materials inspired by nature

“…The ditopic macromonomers thus obtained are sufficiently long to minimize cyclization and supramolecular polymerization thus leads to high apparent molecular weights through linear chain extension (as opposed to low-molecular weight cyclic structures, which are observed in the case of lowmolecular weight ditopic monomers). 47 These macromonomers (number-average molecular weight, M n B 5500 g mol À1 ) form extended chains through simple hydrogen bonding, resulting in materials displaying a glass transition at ca. Such reinforcement strategy is found in some of nature's strongest materials such as spider silk, 46 where the segregation of protein's hydrophobic and hydrophilic domains contributes to their outstanding mechanical properties.…”

A toolbox of oligopeptide-modified polymers for tailored elastomers

“…To this end, we investigate a series of novel supramolecular materials from mixtures of oligopeptide-modified and unmodified poly(isobutylene)s (PIBs). Extending on previous examples of supramolecular networks [32][33][34][35][36][37][38][39] , these materials show an additional formation of defined nanostructures. The length-dependent aggregation of the oligopeptides results in the formation of either small hydrogenbonded aggregates that serve as physical cross-links in the material, or mixtures of single b-sheet tapes and stacked b-sheet nanofibrils that provide a secondary network and serve as a reinforcement (Fig.…”

“…However, the thermomechanical properties of the corresponding bulk materials have rarely been studied in much detail [29][30][31] . Supramolecular materials from polymers with other types of hydrogen-bonded end groups have frequently been used to obtain thermoplastic elastomers with superior processing behaviour at elevated temperatures [32][33][34][35][36][37][38][39] . In these materials, network formation by non-covalent interactions allows for dynamic reorganization processes, which is relevant for selfhealing or thermoresponsive materials 40,41 .…”

Stimuli‐Responsive Systems

“…Woodward and coworkers [42] prepared telechelic polymers bearing hydrogen-bonding sites at both ends from poly-(isobutylene) diol of M n ¼ 5.05 Â 10 3 and 4,4 0 -methylenebis(phenyl isocyanate) followed by an end-capping reaction with several alcohols and amines (Scheme 11.1).…”