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An associative polymer carries many stickers that can form reversible associations. For more than 30 years, the understanding has been that reversible associations change the shape of linear viscoelastic spectra by adding a rubbery plateau in the intermediate frequency range, at which associations have not yet relaxed and thus effectively act as crosslinks. Here, we design and synthesize new classes of unentangled associative polymers carrying unprecedentedly high fractions of stickers, up to eight per Kuhn segment, that can form strong pairwise hydrogen bonding of ∼20k_{B}T without microphase separation. We experimentally show that reversible bonds significantly slow down the polymer dynamics but nearly do not change the shape of linear viscoelastic spectra. This behavior can be explained by a renormalized Rouse model that highlights an unexpected influence of reversible bonds on the structural relaxation of associative polymers.
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http://dx.doi.org/10.1103/PhysRevLett.130.228101 | DOI Listing |
J Chem Phys
September 2025
Dipartimento di Fisica, Sapienza Università di Roma, P.le Aldo Moro 5, 00185 Rome, Italy.
Associative polymers (APs) with reversible, specific interactions between "sticker" sites exhibit a phase behavior that depends on a delicate balance between distinct contributions controlling the binding. For highly bonded systems, it is entropy that mostly determines whether, upon increasing concentration, the network forms progressively or via a first-order transition. With the aim of introducing an experimentally viable system tailored to test the subtle dependence of the phase behavior on binding site topology, we numerically investigate APs made of DNA, where "sticker" sites formed by short DNA sequences are interspersed in a flexible backbone of poly-T spacers.
View Article and Find Full Text PDFNanoscale Adv
August 2025
School of Engineering, Brown University Providence Rhode Island USA
Electrically conductive hydrogels are of interest as scaffolds for tissue engineering applications involving the growth, implantation, or attachment of electrically active cells. Such hydrogels should exhibit soft mechanics, tunable conductivity to match native tissue, biocompatibility, and biodegradability into non-toxic, clearable species. Common conductors based on metals or polymers can be challenged by insufficient biocompatibility or biodegradability.
View Article and Find Full Text PDFEnviron Res
August 2025
Provincial Key Laboratory of Oil and Gas Chemical Technology, College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing, Heilongjiang, 163318, China. Electronic address:
High-viscosity hydrolyzed polyacrylamide (HPAM) in oilfield recovery fluids severely impedes oil-water separation, yet existing catalytic degradation methods are limited to low-concentration HPAM (<500 mg/L) and suffer from excessive oxidant/catalyst consumption. Herein, we report a bimetallic CuCo-MOF-74/peroxymonosulfate (PMS) system capable of degrading high-concentration HPAM (1000 mg/L) under ultralow catalyst (7 mg/L) and oxidant (0.2 mM) loadings across a broad pH range (5-11).
View Article and Find Full Text PDFACS Omega
August 2025
Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University and Research, Bornse Weilanden 9, NL-6708 WG Wageningen, The Netherlands.
The calculation of spinodals for mixtures composed of many macromolecular components ( ≥ 2, not counting the solvent explicitly as a component) for a model including interactions up to quadratic terms in concentration is extended to the case of negative (second-order) virial coefficients, typically indicating attractive interactions between the components. Surprisingly, it is found that different permutations of the signs of the virial coefficients do not always lead to different spinodals. This observation is explained by means of an analysis of the effects of the signs of the virial coefficients in calculations in a parameter space introduced previously as "linear programming space", in which calculations for the spinodal can be done efficiently.
View Article and Find Full Text PDFInorg Chem
August 2025
Univ Brest, UMR-CNRS 6521 CEMCA, 6 avenue Victor le Gorgeu, Brest 29238, France.
Two derivatives of tacn (1,4,7-triazacyclononane) are investigated for their complexation with Cu(II), Zn(II), and Mn(II). The different denticities of macrocyclic ligands and offer the possibility to modulate the coordination environment and stability of the complexes. [Cu()]ClO(HO) exhibits a square-pyramidal penta-coordinated geometry in the solid state, while UV-visible and EPR spectroscopies and DFT are consistent with a hexa-coordinated species in solutions.
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