Rheology of a reversible supramolecular polymer studied by comparison of the effects of temperature and chain stoppers

Abstract

The rheology of a reversible supramolecular polymer is studied by comparing the effects of an increase in temperature and the addition of chain stoppers. The dependence of the zero-shear viscosity and the terminal relaxation time on temperature is exponential, and the activation energy for viscous flow can be calculated. Above a critical stopper fraction, power laws describe the stopper dependence of the viscosity and relaxation time. A simple model for the effect of the addition of chain stoppers on the average degree of polymerization adequately describes the results. A comparison of flow curves at several temperatures and stopper fractions reveals considerable differences between solutions with the same zero-shear viscosity. These are mainly associated with differences in the terminal relaxation time. A mechanism of shear-induced alignment and subsequent elongation of chains is proposed, with which the experimental results are consistent.

Supramolecular Polymer Networks: Preparation, Properties, and Potential

“…The strength is a result of the assembly of a self-complementary DDAA array of four hydrogen bonds [78], pre-organized by an intramolecular hydrogen bond and, therefore, markedly stabilized [77,79]. Meijer and coworkers attached these UPy motifs to both chain ends of polyethylene polymers to form viscous solutions in chloroform [78]; the viscosity is highly dependent on concentration and temperature and can be described by the Cates model for reversibly breaking wormlike micelles [80][81][82], which is also adaptable to supramolecular polymers above the overlap concentration [83][84][85][86][87]. To exclusively ascribe the observed viscosity to the formation of linear supramolecular polymers, a monofunctional UPy motif acting as a chain stopper was added; as a result, a dramatic decrease in viscosity was observed.…”

Temperature behaviour of viscous flow with proteins

“…The pre-exponential factor A is considered to be independent or nearly independent of temperature. The above equation is still widely used for different liquids such as solutions of polysaccharides (Lopez da Silva et al 1994;Jauregui et al 1995;de Paula and Rodrigues 1995;Kar and Arslan 1999;de Vasconcelos et al 2000;Desbrieres 2002;Durand 2007), proteins (Tiffany and Koretz 2002), supramolecular polymers (Knoben et al 2007), colloidal suspensions (Gun'ko et al 2006) and others (Hayakawa et al 1991;Bourret et al 1994;Kamimura et al 2006;Magerramov et al 2007). A very convenient way of data presentation in this case is plotting the viscosity versus T -1 in a ln-normal plot.…”

Controlling supramolecular polymerization through multicomponent self‐assembly

“…147,154 Bouteiller, Cohen Stuart and coworkers furthermore reported rheometry, dynamic and static light scattering, as well as vapor pressure osmometry in cyclohexane to provide further evidence that the chain stopper methodology can be used to adjust the average chain length independently of monomer concentration and temperature, which is impossible for conventional single component supramolecular polymers. [154][155][156] Given the very large association constant of EHUT in cyclohexane (estimated to be around 10 9 M 21 ) the number average degree of polymerization (DP N ) was found to be independent of the monomer concentration and proportional to 1/x (fraction of chain stopper…”