Divergent Shear Thinning and Shear Thickening Behavior of Supramolecular Polymer Networks in Semidilute Entangled Polymer Solutions

Abstract

The steady shear behavior of metallo-supramolecular polymer networks formed by bis-Pd(II) cross-linkers and semidilute entangled solutions of poly(4-vinylpyridine) (PVP) in dimethyl sulfoxide (DMSO) or N,N-dimethyl formamide (DMF) is reported. The steady shear behavior of the networks depends on the dissociation rate and association rate of the cross-linkers, the concentration of cross-linkers, and the concentration of the polymer solution. The divergent steady shear behavior—shear thinning versus shear thickening—of samples with identical structure but different cross-linker dynamics (J. Phys. Chem. Lett. 2010, 1, 1683-1686) is further explored in this paper. The divergent steady shear behavior for networks with different cross-linkers is connected to a competition between different time scales: the average time that a cross-linker remains open (τ1) and the local relaxation time of a segment of polymer chain (τsegment). When τ1 is larger than τsegment, shear thickening is observed. When τ1 is smaller than τsegment, only shear thinning is observed.

On the shear thickening behavior of micellar aqueous solutions of cetyltrimethylammonium fluorobenzoates: Effect of the fluor position

“…Notice that the 1.5 and 2.0 wt.% CTA3FB sample exhibit shear thickening at high shear rates after the shear thinning zone at intermediate shear rates, followed by another shear thinning region at the highest shear rates examined. This behavior was qualitatively reported recently in supramolecular polymer networks in semidilute entangled solutions of poly(4-vinylpyridine) in dimethylsulfoxide [35]. Fig.…”

Supramolecular Guest–Host Interactions for the Preparation of Biomedical Materials

“…Craig and coworkers extensively studied the relationship of bond kinetics and 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 13 polymer relaxation timescales, demonstrating that disadvantageous shear-thickening behavior arises if polymer relaxation occurs more rapidly than reconnection of broken crosslinks. [78][79] As such, the decreased polymer relaxation may be accomplished through formation of multifold junctions in highly modified guest-host hydrogels to enforce shear-thinning behavior and ease of injection. 80 The physical chemistry underlying the flow process, as well as other fundamental behaviors of supramolecular networks have been recently reviewed.…”

The influences of particle–particle interaction and viscosity of carrier fluid on characteristics of silica and calcium carbonate suspensions-coated Twaron® composite

“…[11]; (b) curves of viscosity versus shear rate corresponding to four different classification of steady shear behaviour. [35] The steady shear behaviours could be qualitatively classified into one of four categories shown schematically in Figure 4(b), depending on the relative contributions from rate-dependent shear thinning and shear thickening. As shown in Figure 4(b), type I behaviour denotes a sample that transmits from Newtonian to shear thickening behaviour over a critical shear rate.…”

“…Note that these classifications are qualitative only. [35] Diagrams in Figure 3(a) can be interpreted based on the above-stated facts. In the 15 wt.% silica suspension, mild shear thinning behaviour, then more severe local shear thinning, and finally, shear thickening behaviours are observed.…”