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We investigate the viscosity dependence on concentration and molecular weight of semiflexible polyelectrolyte sodium carboxymethylcellulose (NaCMC) in aqueous salt-free and NaCl solutions. Combining new measurements and extensive literature data, we establish relevant power laws and crossovers over a wide range of degree of polymerization (N) as well as polymer (c) and salt (c s) concentrations. In salt-free solution, the overlap concentration shows the expected c* ∝ N -2 dependence, and the entanglement crossover scales as c e ∝ N -0.6±0.3, in strong disagreement with scaling theory for which c e ∝ c* is expected, but matching the behavior found for flexible polyelectrolytes. A second crossover, to a steep concentration dependence for specific viscosity (ηsp ∝ c 3.5±0.2), commonly assigned to the concentrated regime, is shown to follow c** ∝ N -0.6±0.2 (with c**/c e ≃ 6) which thus suggests instead a dynamic crossover, possibly related to entanglement. The scaling of c* and c e in 0.01 and 0.1 M NaCl shows neutral polymer in good solvent behavior, characteristic of highly screened polyelectrolyte solutions. This unified scaling picture enables the estimation of viscosity of ubiquitous NaCMC solutions as a function of N, c, and c s and establishes the behavior expected for a range of semiflexible polyelectrolyte solutions. [ABSTRACT FROM AUTHOR]

Keywords: Cellulose; Chaotropic Effect; Hydrogel; Polyoxometalate; Superchaotropic EN Cellulose Chaotropic Effect Hydrogel Polyoxometalate Superchaotropic 1 1 1 01/11/23 20230116 NES 230116 B Synergy between salt and sugar b Nanometric ions like Keggin polyoxometalates are revealed to induce the cross-linking and hydrogel formation of polymeric sugars, namely non-ionic cellulose ethers, as reported by Max Hohenschutz, Walter Richtering, and co-workers in their Communication (e202210208). This novel gelation phenomenon exceeds the thickening effects of typical additives like classical salts and surfactants by orders of magnitude and is due to the superchaotropicity of the nano-ions, which drives them out of the water bulk onto the polymers. Cellulose, Chaotropic Effect, Hydrogel, Polyoxometalate, Superchaotropic. [Extracted from the article]

Back Cover: Superchaotropic Nano-ion Binding as a Gelation Motif in Cellulose Ether Solutions (Angew. This novel gelation phenomenon exceeds the thickening effects of typical additives like classical salts and surfactants by orders of magnitude and is due to the superchaotropicity of the nano-ions, which drives them out of the water bulk onto the polymers. Keywords: Cellulose; Chaotropic Effect; Hydrogel; Polyoxometalate; Superchaotropic EN Cellulose Chaotropic Effect Hydrogel Polyoxometalate Superchaotropic 1 1 1 01/11/23 20230116 NES 230116 B Synergy between salt and sugar b Nanometric ions like Keggin polyoxometalates are revealed to induce the cross-linking and hydrogel formation of polymeric sugars, namely non-ionic cellulose ethers, as reported by Max Hohenschutz, Walter Richtering, and co-workers in their Communication (e202210208). [Extracted from the article]

ABSTRACT We report a small angle neutron scattering (SANS) and rheology study of cellulose derivative polyelectrolyte sodium carboxymethyl cellulose with a degree of substitution of 1.2. Using SANS, we establish that this polymer is molecularly dissolved in water with a locally stiff conformation with a stretching parameter [ABSTRACT FROM AUTHOR]

Thermoresponsive polymeric gels are a class of smart materials with the ability to absorb or release large amounts of solvent when changes in their environment occur. Scaling theories of gel swelling (de Gennes' c∗ theorem and Obukhov's model) predict that the swelling of a gel correlates with that of a linear chain with equal degree of polymerization to that of a network strand. Data on linear and cross‐linked poly(N‐isopropylacrylamide) (PNIPAM) in aqueous solutions of different molar masses under θ temperature and good solvent conditions are examined. The Kuhn length of PNIPAM is evaluated to be LK = 4 ± 1 nm, in strong disagreement with previous estimates by single molecule force spectroscopy. The excluded volume strength (B) varies with the reduced temperature (τ) as B ≃ 4.7τ nm. While the power law exponent for the equilibrium swelling as a function of degree of cross‐linking is close to the scaling predictions, the degree of swelling observed in cross‐linked networks is two to three orders of magnitude larger than that expected from scaling models. The large differences between theoretical predictions and experimental results probably arise from the highly inhomogeneous nature of PNIPAM gels. The swelling of linear and cross‐linked poly(isopropylacrylamide) (PNIPAM) is evaluated at the θ temperature and in good solvent. Experimental results are compared with various scaling theories, which are found to underpredict the swelling of cross‐linked PNIPAM. The differences between theory and experiments are assigned to the inhomogeneous structure of PNIPAM gels and microgels. [ABSTRACT FROM AUTHOR]

Understanding and engineering the flow-response of complex and non-Newtonian fluids at a molecular level is a key challenge for their practical utilisation. Here we demonstrate the coupling of microfluidics with small angle neutron scattering (SANS). Microdevices with high neutron transmission (up to 98%), low scattering background (), broad solvent compatibility and high pressure tolerance (≈3-15 bar) are rapidly prototyped via frontal photo polymerisation. Scattering from single microchannels of widths down to 60 μm, with beam footprint of 500 μm diameter, was successfully obtained in the scattering vector range 0.01-0.3 Å−1, corresponding to real space dimensions of . We demonstrate our approach by investigating the molecular re-orientation and alignment underpinning the flow response of two model complex fluids, namely cetyl trimethylammonium chloride/pentanol/D2O and sodium lauryl sulfate/octanol/brine lamellar systems. Finally, we assess the applicability and outlook of microfluidic-SANS for high-throughput and flow processing studies, with emphasis of soft matter. [ABSTRACT FROM AUTHOR]