How to Choose a Secondary Interaction to Improve Stretchability of Associative Polymers?

Abstract

This study focuses on the stretchability of brittle ionomers after introducing three types of hydrogen bonds, i.e., dual, triple, and quadruple hydrogen bonds. The introduction of dual or triple hydrogen bonds that are weaker than the ionic association improves the stretchability, and better improvement has been achieved for the triple hydrogen bonds. In comparison, the introduction of quadruple hydrogen bonds that are equally strong as the ionic association does not show this type of improvement. This result strongly indicates that there is an optimized strength ratio between the first (the stronger ionic) network and the secondary (the weaker hydrogen-bonding) network, i.e., the secondary network should be considerably weaker but still not too weaker than the first network. When this condition is satisfied, continuous dissociation and association of the secondary network weaken the chain retraction after the strain-induced breakup of the first network, thereby suppressing the formation of defects or microscopic cracks that potentially grow into the macroscopic fracture.

Nonlinear Extensional Rheology of Poly(n-alkyl methacrylate) Melts with a Fixed Number of Kuhn Segments and Entanglements per Chain

“…The phenomenon of the stress overshoot is a more delicate issue. A similar phenomenon has been observed in polymer chains having long chain branches , or strong interchain attractions, like the ionic associations. − For the latter case, the overshoot has been attributed to the strain-induced breakup of the associations and the following chain retraction. For linear chains with no strong association, we looked back carefully at the experimental results reported in the literature and noticed a similar overshoot for PMMA, , but not for PS.…”

When Polymer Chains Are Highly Aligned: A Perspective on Extensional Rheology

“…Their extensional rheology is also very interesting but more challenging. As reported by Yang et al, even for unentangled associative polymers, their rheological behavior in extensional flow may change dramatically by changing the strength of associating bonds. Much more possibilities can be explored by introducing associating bonds into entangled polymer systems with different macromolecular architectures.…”

Recent advances in high-strength and high-toughness polyurethanes based on supramolecular interactions

“…120 SPUs based on H-bonding interactions have been widely reported in many studies, and the self-assembly of multiple H-bonds forms very strong but reversible interactions and can be incorporated into almost any type of polymer backbone. [121][122][123][124][125] For example, Leibler's group reported a series of H-bonding systems that rely on high-density associations and long-lived associations to achieve self-healing. 82,[126][127][128] They exploited not only the reversible properties of H-bonds but also their directionality as a tool for self-association within the network to construct supramolecular repairable rubbers based on H-bonding interactions.…”