Hydration and dehydration behavior of N-isopropylacrylamide gel particles

Kogure, Hiroyuki; Nanami, Sunao; Masuda, Yuka; Toyama, Yoshiharu; Kubota, Kenji

doi:10.1007/s00396-005-1303-8

Cited by 45 publications

(63 citation statements)

References 54 publications

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“…Shikata and coworkers [15][16][17] determined from dielectric spectroscopy that hydration number of water bound on per monomer below the LCST is 11 and when the temperature is increased to LCST, all the 11 water molecules dehydrated from the monomer unit. This result is close to the value of 13 obtained from differential scanning calorimetry by Shibayama et al 18,19 Kogure et al 20 quantitatively evaluated the hydration number bound to one NiPAM monomer in PNIPAM gel by ultrasonic velocity and found that the hydration number at low and high temperatures were about 7.5 (20 8C) and 3 (40 8C), respectively. By quasielastic neutron scattering method, Philipp et al 21 revealed that the PNIPAM chain is partially dehydrated and the hydration number decreases from 8 to 2 during the phase transition.…”

supporting

confidence: 87%

Quantification of solvent water and hydration dynamic of thermo‐sensitive microgel by dielectric spectroscopy

Yang

Zhao

2017

J Polym Sci B Polym Phys

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The hydration of natural or synthetic macromolecules is of fundamental importance in our understanding of their structure and stability. Quantification of hydration water can promote the understanding to many complex biological mechanisms such as protein folding, as well as the dynamics and conformation of polymers. An approach to quantification of solvent water was developed by dielectric spectroscopy. Dielectric behaviors of PNIPAM microgels with different crosslink density distribution were measured in the range of 0.5–40 GHz and 15–50. An obvious relaxation process caused by free and bound water was found. Dielectric parameters of free and bound water show that the crosslink density distribution does not affect the volume phase transition temperature of microgels, but significantly influence the orientation dynamics of the solvent water. We found that the three kinds of microgel can be distinguished by the dielectric parameters of the bound water. In addition, the number of water in and outside microgel during the volume phase transition process was quantitatively calculated for the first time. This study provides the possibility for the quantification of water in complex biological process. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1859–1864

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confidence: 87%

Quantification of solvent water and hydration dynamic of thermo‐sensitive microgel by dielectric spectroscopy

Yang

Zhao

2017

J Polym Sci B Polym Phys

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“…[ 36 ] The repulsion at short distances (up to a few nm) is attributed to layers of structured water hydrating the surface of the colloidal aggregates. It has previously been shown that, even above T cp , the collapsed PNIPAM forms H-bonds with water, [37][38][39] which is a prerequisite for a hydration layer. Depletion forces can be ruled out as they are only very weak, on the order of −0.1 k B T , following a calculation on the basis of the Asakura-Oosawa theory.…”

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confidence: 99%

Quantifying the Interactions in the Aggregation of Thermoresponsive Polymers: The Effect of Cononsolvency

Kyriakos

Philipp

Lin

et al. 2016

Macromol. Rapid Commun.

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The aggregation kinetics of thermoresponsive core-shell micelles with a poly(N-isopropyl acrylamide) shell in pure water or in mixtures of water with the cosolvents methanol or ethanol at mole fractions of 5% is investigated during a temperature jump across the respective cloud point. Characteristically, these mixtures give rise to cononsolvency behavior. At the cloud point, aggregates are formed, and their growth is followed with time-resolved small-angle neutron scattering. Using the reversible association model, the interaction potential between the aggregates is determined from their growth rate in dependence on the cosolvents. The effect of the cosolvent is attributed to the interaction potential on the structured layer of hydration water around the aggregates. It is surmised that the latter is perturbed by the cosolvent and thus the residual repulsive hydration force between the aggregates is reduced. The larger the molar volume of the cosolvent, the more pronounced is the effect. This framework provides a molecular-level understanding of solvent-mediated effective interactions in polymer solutions and new opportunities for the rational control of self-assembly in complex soft matter systems.

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“…In contrast, NMR spectroscopy studies allow the local chemical environments to be analyzed and have been employed to investigate the LCST phase transition along with changes in the local hydrogen bonding environment during dehydration, 23,26,27,[29][30][31][32] and has been discussed in a recent review article. 33 NMR studies of the swelling/dehydration processes in PNI-PAAm have been previously detailed, 15,33,34 and include 1 H NMR spin-spin relaxation rate (R 2 5 1/T 2 ) investigations that revealed R 2 can be sensitive to the LCST transition, and in some instances represent the rapid exchange averaging between different water environments. These R 2 studies also support the argument that there are water populations with restricted dynamics even in the collapsed phase.…”

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confidence: 99%

Characterization of free, restricted, and entrapped water environments in poly(N‐isopropyl acrylamide) hydrogels via¹H HRMAS PFG NMRspectroscopy

Alam

Childress

Pastoor

et al. 2014

J Polym Sci B Polym Phys

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Different water environments in poly(N-isopropyl acrylamide) (PNIPAAm) hydrogels are identified and characterized using 1 H high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR). Local water environments corresponding to a "free" highly mobile species, along with waters showing restricted dynamics are resolved in these swollen hydro-gels. For photo-initiated polymerized PNIPAAm gels, an additional entrapped water species is observed. Spin-spin R 2 relaxation experiments support the argument of reduced mobility in the restricted and entrapped water species. By com-bining pulse field gradient techniques with HRMAS NMR it is possible to directly measure the self-diffusion rate for these different water environments. The behavior of the heterogeneous water environments through the lower critical solution temperature transition is described.

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Hydration and dehydration behavior of N-isopropylacrylamide gel particles

Cited by 45 publications

References 54 publications

Quantification of solvent water and hydration dynamic of thermo‐sensitive microgel by dielectric spectroscopy

Quantification of solvent water and hydration dynamic of thermo‐sensitive microgel by dielectric spectroscopy

Quantifying the Interactions in the Aggregation of Thermoresponsive Polymers: The Effect of Cononsolvency

Characterization of free, restricted, and entrapped water environments in poly(N‐isopropyl acrylamide) hydrogels via¹H HRMAS PFG NMRspectroscopy

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Hydration and dehydration behavior of N-isopropylacrylamide gel particles

Cited by 45 publications

References 54 publications

Quantification of solvent water and hydration dynamic of thermo‐sensitive microgel by dielectric spectroscopy

Quantification of solvent water and hydration dynamic of thermo‐sensitive microgel by dielectric spectroscopy

Quantifying the Interactions in the Aggregation of Thermoresponsive Polymers: The Effect of Cononsolvency

Characterization of free, restricted, and entrapped water environments in poly(N‐isopropyl acrylamide) hydrogels via1H HRMAS PFG NMRspectroscopy

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Characterization of free, restricted, and entrapped water environments in poly(N‐isopropyl acrylamide) hydrogels via¹H HRMAS PFG NMRspectroscopy