Megasupramolecules for safer, cleaner fuel by end association of long telechelic polymers

Abstract

We used statistical mechanics to design polymers that defy conventional wisdom by self-assembling into “megasupramolecules” (≥5000 kg/mol) at low concentration (≤0.3 weight percent). Theoretical treatment of the distribution of individual subunits—end-functional polymers—among cyclic and linear supramolecules (ring-chain equilibrium) predicts that megasupramolecules can form at low total polymer concentration if, and only if, the backbones are long (>400 kg/mol) and end-association strength is optimal. Viscometry and scattering measurements of long telechelic polymers having polycyclooctadiene backbones and acid or amine end groups verify the formation of megasupramolecules. They control misting and reduce drag in the same manner as ultralong covalent polymers. With individual building blocks short enough to avoid hydrodynamic chain scission (weight-average molecular weights of 400 to 1000 kg/mol) and reversible linkages that protect covalent bonds, these megasupramolecules overcome the obstacles of shear degradation and engine incompatibility.

Inertioelastic Poiseuille flow over a wavy surface

“…These vorticity amplification effects should be considered in all evaluations of vorticity dynamics in inertioelastic flows with streamline curvature.The addition of even minute quantities (parts per million, ppm) of high-molecular-weight flexible polymers to a Newtonian solvent imparts a small but important degree of elasticity to the fluid, dramatically modifying its macroscopic flow behavior. Some well-known examples are the increase of the pressure drop measured across porous beds [1,2], the reduction of turbulent drag [3][4][5], and the modification of jet breakup, spray atomization, and drop impact behavior [6][7][8].In the context of turbulent drag reduction, dilute polymer additives dampen streamwise vorticity via a mechanism attributed to a resistive polymer torque (the curl of the polymer force) [9][10][11]. However, recent experiments and simulations indicate that such fluids can support an entirely new elastoinertial turbulence (EIT) dominated by spanwise vorticity rolls [12,13].…”

Ligament Mediated Fragmentation of Viscoelastic Liquids

“…Fragmentation of a viscoelastic jet or sheet is a fundamental component of many industrial and biological processes [1,2]. One important metric of a fragmentation process is the final droplet size distribution, and understanding the role of material properties (e.g., fluid viscosity and relaxation time) on the polydispersity of such distributions is of crucial importance [3,4].…”

Micro-scale extensional rheometry using hyperbolic converging/diverging channels and jet breakup

“…These high values of the extensional viscosity can dramatically change the filament thinning dynamics at high strain rates and small length scales in a number of important application such as inkjetting, atomization, microfluidic cell sorting, etc. 6,8,58 Measurements with the EVROC device for the low viscosity solutions (green, blue, and magenta colors in Figure 3(a)) are largely polluted by nonlinear inertia effects, but Figures 4(a) and 4(b) clearly show that jetting rheometry is a reliable alternative for determining the extensional rheology of very dilute polymer solutions. The ROJER instrument not only differentiates between the extensional rheology of the different solutions in a qualitative manner (Figure 3(d)) but also quantitatively measures elongational properties in the elasto-capillary regime at constant strain rate that agree well with predictions of microstructural constitutive equations such as the FENE-P.…”

“…[3][4][5] Similarly, in many important industrial applications such as paint coating, inkjet printing, emulsification, and anti-mist fuel combustion, the rheological properties of weakly viscoelastic liquids play a significant role. [6][7][8][9] One important characteristic behavior of viscoelastic liquids is the resistance that the underlying microstructure exhibits to deformation in elongational flows. This resistance is characterized by the extensional viscosity, and the value of g E for viscoelastic solutions can be several orders of magnitude higher than the corresponding shear viscosities.…”