Connecting supramolecular bond lifetime and network mobility for scratch healing in poly(butyl acrylate) ionomers containing sodium, zinc and cobalt

Abstract

In this work, we correlate network dynamics, supramolecular reversibility and the macroscopic surface scratch healing behavior for a series of elastomeric ionomers based on an amorphous backbone with varying fractions of carboxylate pendant groups completely neutralized by Na(+), Zn(2+) or Co(2+) as the counter ions. Our results based on temperature dependent dynamic rheology with simultaneous FTIR analysis clearly indicate that the effective supramolecular bond lifetime (τ(b)) is an important parameter to ascertain the ideal range of viscoelasticity for good macroscopic healing. The reversible coordination increased with higher valence metal ions and ionic content. Both rheological and spectroscopic analyses show a decrease in supramolecular assembly with temperature. The temperature dependent τ(b) was used to calculate the activation energy (Ea) of dissociation for the ionic clusters. According to self-healing experiments based on macroscale surface scratching, a supramolecular bond lifetime between 10 and 100 s results in samples with complete surface scratch healing and good mechanical robustness.

Effect of the Dianhydride/Branched Diamine Ratio on the Architecture and Room Temperature Healing Behavior of Polyetherimides

“…As seen in Table II, the plateau moduli (G N ) for these polyimides are of the order of 10 5 -10 6 Pa. Such values are in agreement with similar values obtained for supramolecular self-healing polymers based on metal ionic interactions in rubbery poly(n-butyl acrylate) ionomers (39), hydrogen bonding end groups in poly(isobutylene) (40) and ionic networks reacting neutralized citric acid and aliphatic diamines (41). When the relation of rubber elasticity, G N = ρRT/M e , is applied to these polymers and the molecular weight between effective interactions M e is calculated, values of M e between 2000 and 4000 g/mol are obtained (Table II).…”

“…τ b values between 10 s and 100 s are claimed to lead to a combination of healing in reasonable times and decent mechanical properties (39). Nevertheless, in the present work, the τ b principle was not applicable as three crossovers interplay and affect healing as shown in section 3.1.…”

Intrinsic self-healing polymers with a high E-modulus based on dynamic reversible urea bonds

“…Thus, times in the range of 1 μs ⩽ τ ⩽ 60 s (the corresponding frequencies were 0.02-1.000.000 Hz) could be correlated to the excellent healing properties. 17 Furthermore, we plotted the results of the frequency-dependent rheology measurements in a double-logarithmic plot showing that lim…”

“…[3][4][5] In contrast, intrinsic self-healing materials can recover their properties due to the presence of specific reversible chemical bonds, which is beneficial due to the possibility of multiple healing steps at the same location. 6 These binding motifs can be composed of either dynamic covalent bonds, [7][8][9] for example, the Diels-Alder reaction [10][11][12] or radical-based systems, 13 or supramolecular interactions, such as hydrogen or halogen bonds, [14][15][16] ionic interactions, 17 π-π interactions, 18 host-guest interactions 19 or metal-ligand interactions. [20][21][22][23] Often there is a trade-off between the mechanical properties and the healing efficiency (Figure 1).…”

Tuning the modulus of nanostructured ionomer films of core–shell nanoparticles based on poly(n-butyl acrylate)

“…studied self-healing for PBA ionomers cast from solution and proposed that reversible ionic crosslinks were formed 18 . Ionomers prepared using polymer chains with precisely sequenced ionic groups have also been studied 19 .…”