Hierarchically Nanostructured Polyisobutylene-Based Ionic Liquids

Abstract

A new type of highly temperature stable ionic liquid (IL) with strongly temperature dependent nanostructures is reported. The molecular design relies on the use of a liquid polymer with an ionic liquid headgroup, introducing liquid properties by both the polymeric and the ionic liquid (IL) headgroup. The IL polymers (poly(isobutylene)s) 3a–3c (PIB-ILs) were prepared by a combination of living carbocationic polymerization (LCCP) and subsequent “click” chemistry for attachment of methylimidazolium (3a), pyrrolidinium (3b), and triethylammonium cations (3c). All three investigated PIB-ILs exhibited pronounced nanostructural organization at room temperature depending strongly on the nature of the anchored cation. Whereas the morphology of the imidazolium-based PIB-IL 3a shows high thermal stability up to the decomposition temperature, order–order (OOT) and lattice disorder–order transitions (LDOT) characteristic for common ionomers could be observed in the case of pyrrolidinium 3b and ammonium-based 3c PIB-ILs. Control of flow behavior as well as adjustable relaxation times from the liquid to the viscoelastic regime can be adjusted by choice of the appropriate IL headgroup.

Timescales of self-healing in human bone tissue and polymeric ionic liquids

“…The synthetic process of the specimens PIB-IL 3a-3c is described in Ref. 22 . All three use bromide as anion but differ in the cation.…”

“…The temperature increase weakens the electrostatic interaction between the ionic clusters leading to an increase in mobility of polymer chains. 22 There are, however, remarkable differences between different materials: The methylimidazolium-based cation (PIB-IL 3a) is stable (up to nearly 300°C), but structural recovery is slowed down or does even not take place due to thermal decomposition (see Figure 5 and Ref. 22 ).…”

“…22 There are, however, remarkable differences between different materials: The methylimidazolium-based cation (PIB-IL 3a) is stable (up to nearly 300°C), but structural recovery is slowed down or does even not take place due to thermal decomposition (see Figure 5 and Ref. 22 ). A possible explanation would be a strong π-π stacking between neighboring imidazolium rings, which could stabilize the structure, but can be irreversibly destroyed.…”

“…In PIB-IL 3b, recovery takes some days, but only approximately 1 day for PIB-IL 3c, probably due to the much more flexible structure of the cation in this compound. 22 Exchanging the anionic component of the IL by the exchange of bromide with the more flexible and weakly coordinating Tf 2 N anion, leads to a slight decrease of the temperature stability (to a temperature of about 60°C), but much shorter times for structural recovery: No matter which cationic components of the ILs was used, the timescale for recovery was below 15 min, the time required to collect one SAXS pattern. This is a clear indication of the decisive role of the anion.…”

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

“…Thus, a large structural variety of hydrogen bonding moieties exists, which allows tuning of the stability/lability and, therefore, of the inherent dynamics of hydrogen-bonded polymers. However, self-healing is not only determined by the absolute strength of the applied hydrogen bonds [25], but also by phase segregation effects between the polymeric interphases [26,27]. The strength of hydrogen bonds in the solid and melt states of polymers is generally not known and is certainly different from the values known from polymer solutions.…”