Chain Dynamics in Supramolecular Polymer Networks

Abstract

Supramolecular polymer networks consist of macromolecules that are cross-linked by transient physical interactions such as hydrogen bonding or transition metal complexation. The utility of these networks is based on their mechanical properties, which lay between those of permanent networks and that of mechanically entangled, viscoelastic polymer solutions, depending on the strength of transient chain cross-linking. To benefit from this interplay, it is necessary to understand it. To promote this understanding, we use a modular toolkit to form supramolecular polymer networks that exhibit greatly varying strength of transient chain cross-linking but that are all derived from the very same precursor polymer. This strategy allows the impact of the strength of transient chain cross-linking on the network dynamics and mechanics to be studied with high consistency. We follow this approach to evaluate the diffusive mobility of labeled tracer chains within these transient networks. Our results reveal that the concentration dependence of the tracer-chain diffusivity is in agreement with theoretical predictions derived from the “sticky reptation” model by Rubinstein and Semenov, provided the chain association is stronger than a certain threshold.

Linear Viscoelastic and Dielectric Relaxation Response of Unentangled UPy-Based Supramolecular Networks

“…This observation has been previously observed in LVE of several hydrogen bonding associating polymers. 6,11,12,31,32 This could be due to either, (i) the relatively large PDI of the polymer, (ii) the polydispersity in UPy side group spacing along the backbone, or (iii) the signature response of hydrogen bonding polymers. Although concrete evidence is lacking, we hypothesize that the lack of a terminal response is most likely due to (ii), the polydisperse UPy side group spacing along the backbone.…”

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

“…The concept was further extended to mixtures of two different polymers ( Fig. 13 and Table 1, entries [11][12][13], where a multivalent poly(naphthalene tetracarboxylic diimide) polymer was mixed with bi-and trivalent pyrenyl-functionalized polymers [126][127][128], again displaying healing effects at elevated temperatures (200 C, some starting at~50 C) [128]. In many of these examples, the tensile modulus recovered up to 95% of the initial value [127], also indicating the contribution of multivalency effects [128], leading to a higher tensile strength of the final material [130].…”

“…Thus, motion of the whole polymer chain is controlled by the lifetime and concentration of supramolecular tie points. However, the polymer chains can also diffuse at timescales longer than the lifetime of the supramolecular interactions [12,13].…”

Effect and Evolution of Nanostructural Complexity in Sensitive Polymer Gels

“…The present set of samples covers regimes below and above this threshold. As a result, scaling relations of D ∼ c −4.75 and D ∼ c −3.36 can be predicted for the sticky‐tracer diffusivity in the two latter regimes, in good agreement with the preceding experimental findings, which can be fitted to D ∼ c −4.94 and D ∼ c −3.37 .…”

“…To address the second challenge, two newly developed modular toolkits to prepare supramolecular polymer gels are introduced that allow their polymer physical and supramolecular properties to be controlled independently . These toolkits also allow the polymer‐network architecture to be tailored from random crosslinking to model‐type uniform crosslinking, along with assessment of how these different structures affect the gel mechanics, dynamics, and temporal evolution . With these different strategies, systematic experimental assessment is delivered on the role and fate of nanostructural heterogeneity in responsive soft gel materials to allow these properties to be modeled in rational materials design.…”