Hydrophobic hydration of poly-N-isopropyl acrylamide: a matter of the mean energetic state of water

Bischofberger, Irmgard; Calzolari, Davide C. E.; Rios, Paolo De Los; Jelezarov, Ilian; Trappe, Véronique

doi:10.1038/srep04377

Cited by 147 publications

(203 citation statements)

References 61 publications

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“…This phenomenon favors the formation of intra‐chain interactions over the interaction of polymer chains with water molecules below the transition temperature. More information on mechanistic of poly(NIPAM) phase transition at the molecular level can be found elsewhere …”

Section: Recent Advances In the Development Of Water Soluble Flocculantsmentioning

confidence: 99%

Water Soluble Polymer Flocculants: Synthesis, Characterization, and Performance Assessment

Vajihinejad

Gumfekar

Bazoubandi

et al. 2018

Macro Materials & Eng

126

100

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Water soluble polymer flocculants are important constituents of solid–liquid separation units for the treatment of a variety of process‐affected effluents. The systematic development of a flocculant relies on a good understanding of flocculation process, polymer synthesis, polymer characterization, and, not the least, flocculation performance assessment as desired for a particular treatment process, all of which are essential to establish meaningful relationships between flocculant microstructure and flocculation efficiency. The aim of this article is to communicate the bigger picture of this research area to the readers. The recent advances in the application of bio/natural, synthetic, and stimuli‐responsive flocculants are reviewed. Then, the basic polymer reaction engineering tools to control the microstructure of flocculants are provided and the techniques for the quantification of flocculant microstructure are concisely discussed. This is followed by a review of the methods used for the characterization of particle‐polymer force measurement, and flocculation/dewatering assessment with attention to the characterization of aggregate structures.

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Section: Recent Advances In the Development Of Water Soluble Flocculantsmentioning

confidence: 99%

Water Soluble Polymer Flocculants: Synthesis, Characterization, and Performance Assessment

Vajihinejad

Gumfekar

Bazoubandi

et al. 2018

Macro Materials & Eng

126

100

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“…Despite numerous efforts, the mechanism of the temperature‐induced phase separation is not fully understood yet and still under intense investigation . It is generally believed that hydrophobic hydration, that is, the enthalpically favored hydration of hydrophobic entities, plays a key role in the phase transition of PNIPAM in water . At a low temperature, water molecules form “ice‐like structure” or a local rigid structure around the hydrophobic groups, leading to their hydration and the full solution of the polymer.…”

Section: Introductionmentioning

confidence: 99%

Unexpected Large Depression of VPTT of a PNIPAM Microgel by Low Concentration of PVA

Tang

Weng

Guan

et al. 2017

Macro Chemistry & Physics

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Many low molecular weight and polymeric additives are found to be able to shift the phase transition temperature of poly(N‐isopropylacrylamide) (PNIPAM), however, a large change can only be observed at a high concentration of the additive. Particularly, poly(vinyl alcohol) (PVA), a polymeric additive, can only induce a very small change in the phase transition temperature of PNIPAM, even at a high concentration. Unexpectedly, it is found that a low concentration of PVA can dramatically reduce the volume phase transition temperature (VPTT) of the surface layer of poly(N‐isopropylacrylamide‐co‐2‐acrylamido‐phenylboronic acid) (P(NIPAM‐2‐AAPBA)) microgel. The concentration of PVA is about three orders of magnitude lower than the required concentration for other additives to achieve a comparable decrease in phase transition temperature of PNIPAM. The lowered VPTT cannot be explained by a change in the ionization degree of the PBA groups, or cross‐link density, or hydrophilicity–hydrophobicity balance of the gel. Instead, it is proposed that the adsorption of PVA chains onto the P(NIPAM‐2‐AAPBA) microgel spheres shortens the distance between the PVA and PNIPAM chains, allowing they influence the thermal behavior of PNIPAM more effectively and hence dramatically reducing the phase transition temperature of the latter.

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“…Their results showed that the LCST is driven by the complete dehydration of the PNiPAM chains, showing the importance of bound water near the polymer. Bischofberger et al have performed turbidity and dynamic light scattering on the ternary system of PNiPAM, water, and alcohol. Their results indicate that the thermodynamic description of the solvent is more important than the specific description of local solvent structure.…”

Section: Introductionmentioning

confidence: 99%

Spherically Symmetric Solvent is Sufficient to Explain the LCST Mechanism in Polymer Solutions

Bharadwaj

Kumar

Komura

et al. 2016

Macro Theory & Simulations

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The mechanism of the lower critical solution temperature (LCST) in thermoresponsive polymer solutions has been studied by means of a coarse‐grained single polymer chain simulation and a theoretical approach. The simulation model includes solvent explicitly and thus accounts for solvent interactions and entropy directly. The theoretical model consists of a single chain polymer in an implicit solvent where the effect of solvent is included through the intrapolymer solvophobic potential proposed by Kolomeisky and Widom. The results of this study indicate that the LCST behavior is determined by the competition between the mean energy difference between the bulk and bound solvent, and the entropy loss due to the bound solvent. At low temperatures, solvent molecules are bound to the polymer and the solvophobicity of the polymer is screened, resulting in a coiled state. At high temperatures the entropy loss due to bound solvent offsets the energy gain due to binding which causes the solvent molecules to unbind, leading to the collapse of the polymer chain to a globular state. Furthermore, the coarse‐grained nature of these models indicates that mean interaction energies are sufficient to explain LCST in comparison to specific solvent structural arrangements.

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Hydrophobic hydration of poly-N-isopropyl acrylamide: a matter of the mean energetic state of water

Cited by 147 publications

References 61 publications

Water Soluble Polymer Flocculants: Synthesis, Characterization, and Performance Assessment

Water Soluble Polymer Flocculants: Synthesis, Characterization, and Performance Assessment

Unexpected Large Depression of VPTT of a PNIPAM Microgel by Low Concentration of PVA

Spherically Symmetric Solvent is Sufficient to Explain the LCST Mechanism in Polymer Solutions

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