Supramolecular Soft Adhesive Materials

Abstract

The rheological and adhesive properties of bis‐urea functionalized low‐molecular‐weight polyisobutylenes (PIBUT) are investigated. The polymers, which can interact through supramolecular hydrogen bonds, can self‐organize over times of the order of days at room temperature. This organized structure has been identified by small angle X‐ray scattering (SAXS) and its rheological properties indicate the behaviour of a soft viscoelastic gel. The ordered structure can be disrupted by temperature and shear so that at 80 °C, the material behaves as a highly viscoelastic fluid and no SAXS peak is observed. When cooled back at room temperature, the PIBUT retrieves its ordered structure and gel properties after 20 h of annealing. This very slow molecular dynamics gives PIBUT a highly dissipative nature upon deformation, which combined with strongly interacting moieties results in very interesting adhesive properties both on steel surfaces but more importantly on typical low adhesion surfaces such as silicone. A strategy based on the controlled incorporation of supramolecular bonds in a covalently crosslinked network appears promising for the development of a new generation of highly interacting and dissipative soft adhesives.

Linear rheology of bis-urea functionalized supramolecular poly(butylacrylate)s: Part I – weak stickers

“…This regime, in which the scission/recombination mechanism is faster than the diffusion of aggregates, is characterized by the Maxwell-like behavior in the terminal part of the relaxation spectrum. Closer to our system, centerfunctionalized poly(isobutylene) chains self-assemble into comb-shaped aggregates 35,21 in solutions of a non-polar solvent and form a less well-defined structure in the melt 22 with the polymer side chains playing the role of a viscous solvent. These results encouraged us to look for the characteristic rheological signature of worm-like micelles in our PnBAX supramolecular system in the first regime.…”

“…In solution these chains self-associate into cylindrical structures 21 while in the melt they form highly dynamic structures which show some long range order below 50°C and have very interesting properties as soft adhesives 22 .…”

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 .…”

Intrinsic Self-Healing Polymers Based on Supramolecular Interactions: State of the Art and Future Directions

“…The length of the tubes could be tuned by varying the concentration and/or the solvent [94,95]. The supramolecular association present strongly influences the bulk properties and, therefore, the self-healing ability within the bulk material could be estimated as a result of the dissipative nature upon deformation [95,96]. The investigated polymers showed a self-organization behavior over a timescale of days, resulting in viscoelastic soft gels at room temperature, which disrupted at 80 C but retrieved their structure after 20 h of annealing, highlighting their potential as dissipative soft adhesives and self-healing materials [96].…”