Correction: Porous monoliths synthesized via polymerization of styrene and divinyl benzene in nonaqueous deep-eutectic solvent-based HIPEs

Correction for ‘Porous monoliths synthesized via polymerization of styrene and divinyl benzene in nonaqueous deep-eutectic solvent-based HIPEs’ by M. G. Pérez-García et al., RSC Adv., 2015, 5, 23255–23260.

A master dynamic flow diagram for the shear thickening transition in micellar solutions

The shear thickening behavior of dilute micellar solutions of hexadecyltrimethylammonium-type surfactants with different counterions (tosylate, 3- and 4-fluorobenzoate, vinylbenzoate and salicylate) and of n-alkyltetradecylammonium bromide (CnTAB), with n = 14, 16 and 18, is examined here. These solutions undergo a shear thickening transition due to the formation of shear-induced structures (SISs) in the shear range studied. Here we report a relationship between the shear thickening intensity and the differences in the hydrophobicity of counterions according to the Hofmeister-like anion series, which leads to a master flow diagram. This master flow diagram is produced by plotting a normalized shear thickening intensity (Iη - 1)/(Imax - 1) versus CD/CD,max, where Iη is the shear-thickening intensity, defined as the largest viscosity obtained in the shear-thickening transition (STT) at a given surfactant concentration CD divided by the Newtonian viscosity η0, and Imax is the largest intensity value obtained in the STT at a surfactant concentration CD,max. The master flow diagram is built using several cetyltrimethylammonium-type surfactants with different counterions, according to a Hofmeister-like series, and by n-alkyltetradecylammonium bromide surfactants with different alkyl chain lengths.

Porous monoliths synthesized via polymerization of styrene and divinyl benzene in nonaqueous deep-eutectic solvent-based HIPEs

Due to their viscosity and polarity, DESs represent a suitable internal phase for HIPEs containing styrenic monomers in addition to acrylates, thus expanding on the range of monomers forming polymerizable DES-based HIPEs.

Thermodynamic approach to rheology of complex fluids: flow-concentration coupling

In this work, the generalized Bautista-Manero-Puig (BMP) model derived from extended irreversible thermodynamics (EIT) is used to analyze the coupling of stress with concentration in complex fluids. It is shown that this model is consistent with previous analyses that predict mechanical and thermodynamic instabilities in the shear-banding regime. In particular, for simple shear flows, the model presented here predicts the structure factor in the plane of shear and the onset of instabilities in the gradient-vorticity plane. Furthermore, the model predicts distinctive features of the models of Brochard-de Gennes and Schmitt as particular cases. For finite stress relaxation time, the generalized BMP model allows the prediction of transient structures normal to the vorticity axis. Instabilities are predicted in the regions of high viscosity, which suggest that the induction of a more viscous phase in a shear-thickening solution can lead the system to instability, in this case, the layering is predicted perpendicular to the vorticity direction. These transient structural patterns within the shear-thickening region correspond to spinodal phase separation. When the mechanical and thermodynamic instabilities are uncoupled, the model predictions agree with experiments and with the transient-gel model of Brochard and de Gennes.

Phase and rheological behavior of the polymerizable surfactant CTAVB and water

The phase and rheological behaviors of the polymerizable surfactant, cetyltrimethylammonium benzoate (CTAVB), and water as a function of surfactant concentration and temperature are investigated here. The critical micelle concentration (cmc) and the (cmc(2)), as well as the Krafft temperature (T(K)), are reported. A large highly viscous micellar solution region and hexagonal- and lamellar-phase regions were identified. The micellar solutions exhibit shear thickening in the dilute regime, below the overlapping or entanglement concentration. At higher concentrations, wormlike micelles form and the solutions show strong viscoelasticity and Maxwell behavior in the linear regime and shear banding flow in the nonlinear regime. The linear viscoelastic regime is analyzed with the Granek-Cates model, showing that the relaxation is controlled by the kinetics of reformation and scission of the micelles. The steady and unsteady responses in the nonlinear regime are compared with the predictions of the Bautista-Manero-Puig (BMP) model. Model predictions follow the experimental data closely.

A Composition Rule to Predict the Linear Viscoelastic Properties of Polybutadienes with Varying Microstructure

A composition rule is proposed here to predict the glass transition temperature (Tg), the zero shear-rate dynamic viscosity (η0′), the plateau modulus (G0) and the terminal relaxation time (λ) of narrow molecular weight distribution (MWD) polybutadienes with various vinyl contents in solution and in the melt from the knowledge of the vinyl fraction, polymer fraction in solution and average molecular weight. The predictions of the composition rule are compared with data of a variety of narrow MWD polybutadienes with varying microstructure.

Microstructured polyacrylamide hydrogels made with hydrophobic nanoparticles

Poly(methyl methacrylate) nanosize particles, made by microemulsion polymerization, were dispersed in an acrylamide aqueous solution, which was polymerized in the presence of a cross-linking agent to yield microstructured hydrogels. The kinetics of swelling and the mechanical properties of these hydrogels were investigated as a function of concentration of particles. The microstructured hydrogels exhibit higher equilibrium swelling and larger Young modulus than conventional (that is, without particles) polyacrylamide hydrogel. The morphology of the microstructured hydrogels was examined by transmission electron microscopy.

Microstructured Polyacrylamide Hydrogels Prepared Via Inverse Microemulsion Polymerization

The synthesis by a two-stage polymerization process of microstructured polyacrylamide hydrogels with large swelling capacity and improved mechanical properties is reported. First, crosslinked polyacrylamide particles of nanosize scale are made by inverse microemulsion polymerization. These particles are then dried and redispersed in an aqueous solution of acrylamide and polymerized in the presence of a crosslinking agent. The microstructured hydrogels, in contrast to transparent conventional polyacrylamide hydrogels, are translucid due to the presence of the dispersed particles. The swelling capacity of these hydrogels increases as the particle content increases and their Young and elastic moduli (at equilibrium swelling) diminish only slightly. Mechanical tests disclose that the microstructured hydrogels have larger Young moduli than conventional hydrogels with an identical degree of swelling. Copyright 2001 Academic Press.