Raman Scattering Study  during the Dehydration Process of Polyacrylamide Gel

Hara, Kazuhiro; Masuike, Takeo; Nakamura, Atsushi; Okabe, Hirotaka; Hiramatsu, Nobuyasu

doi:10.1143/jjap.34.5700

Cited by 22 publications

(10 citation statements)

References 20 publications

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“…In addition to overall decreases in volume, other properties show drastic changes during dehydration and the gel exhibits a glasslike behavior . This has been confirmed with viscoelastic measurements, , via the observation of a low-frequency peak in Raman scattering, and also by inelastic neutron scattering experiments . Furthermore, a recent small-angle X-ray scattering (SAXS) study reveals a distinct mesoscopic structure in one heteropolymer hydrogel [ N -isopropylacrylamide−sodium acrylate (NIPA−SA)], which exhibits microphase separation upon dehydration .…”

Section: Introductionmentioning

confidence: 60%

“…For the SANS experiments, specimens were prepared by adding controlled amounts of the heavy water to the dehydrated NIPA−SA gels to examine the dependence of the mesoscopic structure on the water content, which was indicated by R wp , defined by the weight ratio of water (w) to the network polymer (p), where M S is the weight of the specimen including solvent (water) and M D is the weight of the specimen after complete desiccation at 100 °C for 1 h (which is considered to be the weight of the network polymer). For example, R wp was around 0.3 in the NIPA−SA gel of f S = 200 dried gently in air for 6 days, which indicates that there remains some bound water . All of the specimens investigated in the present study are listed in Table .…”

Section: Methodsmentioning

confidence: 85%

“…For example, R wp was around 0.3 in the NIPA-SA gel of f S ) 200 dried gently in air for 6 days, which indicates that there remains some bound water. 14 All of the specimens investigated in the present study are listed in Table 1. B. Small-Angle X-ray Scattering.…”

Section: Methodsmentioning

confidence: 99%

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Small-Angle Scattering Study of Mesoscopic Structures in Charged Gel and Their Evolution on Dehydration

Sugiyama¹,

Annaka²,

Hara³

et al. 2003

J. Phys. Chem. B

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Mesoscopic structures, with length scales ∼10 2 Å, were investigated by small-angle X-ray and neutron scattering (SAXS and SANS) in several N-isopropylacrylamide-sodium acrylate (NIPA-SA) copolymeric hydrogels with varying [NIPA]/[SA] ratios and water contents. The SAXS experiments reveal that, depending upon the [NIPA]/[SA] ratio, the dehydrated NIPA-SA gel shows two mesoscopic structures: one consists of randomly distributed SA-rich islands in NIPA matrix, while the other is a microphase-separated structure, composed of NIPA-rich and SA-rich domains. In addition, the SANS experiments reveal the mesoscopic structural features during the dehydration process. As the concentration of the network polymers increases, NIPA-rich and waterrich domains segregate in the gel. Then, an electrostatic interaction between the segregated domains induces a microphase-separated structure in the limit of the dehydrated NIPA-SA gel.

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Section: Introductionmentioning

confidence: 60%

Section: Methodsmentioning

confidence: 85%

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Small-Angle Scattering Study of Mesoscopic Structures in Charged Gel and Their Evolution on Dehydration

Sugiyama¹,

Annaka²,

Hara³

et al. 2003

J. Phys. Chem. B

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“…For instance, it is known that water can contribute favorably to the conformational stability of biopolymers, including proteins, DNA, or enzymes, and is essential for their biological functions. 1,2 Therefore, properties of water in hydrated polymer systems have been investigated using various experimental techniques such as differential scanning calorimetry (DSC), [3][4][5][6] nuclear magnetic resonance (NMR), 1,[7][8][9][10][11] infrared spectroscopy, 12,13 Raman spectroscopy, [14][15][16][17][18] dielectric spectroscopy, [19][20][21] X-ray diffraction, 2 and simulation. [22][23][24] The structure and properties of water in hydrated polymer systems differ from those of bulk water.…”

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of the Structure of Bound Water in Dried Glassy Poly-N,N,-dimethylacrylamide

Sekine

Ikeda-Fukazawa

2010

J. Phys. Chem. B

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Raman spectroscopy was used to investigate the temperature dependence of structural changes of bound water in dried glassy poly-N,N,-dimethylacrylamide in the temperature range 286.1-329.7 K. The results show that the frequency of the O-H stretching mode of the bound water that is present in the dried glassy polymer shifts to the higher side with increasing temperature. The rate changes at around 310 K, while that for the bulk water is constant in the temperature range studied. The rates of change of the frequencies for the C=O stretching mode and CH(3) rocking mode also change at around 310 K. These results indicate a significant change in the interaction between the bound water and polymer chains at 310 K. Temperature dependence of the local structure of the bound water was analyzed by applying a structural model of bulk water to the spectra of the O-H stretching region. The result shows that the density of a tetragonal water structure consisting of four hydrogen bonds increases with increasing temperature below 310 K and begins to decrease at temperatures above 310 K. Further, estimates of the water content indicate that the evaporation rate of the bound water significantly changes at around 310 K. These results suggest that the bound water present in the dried glassy polymer can be classified as being in two states. At temperatures below 310 K, the water that forms a shell layer around the polymer chains evaporates, while at temperatures above 310 K the water that is bound to polar groups of polymer chains begins to evaporate. The structural changes of bound water might have important implications for the interpretation of properties of hydrated polymer systems, including both biological and synthetic polymers.

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“…Besides, the dehydration of the hydrogel gives rise to the vitrification of the hydrogels [8][9][10][11][12]. Moreover, the resemblance between the dehydration process and the volume phase transition seems still important, because the related interactions are almost same between the dehydration process and the volume phase transition of the NIPA/SA gel and the properties of both the dehydrated NIPA/SA gel and shrunk NIPA/AAc gel by the volume phase transition should be almost identical.…”

Section: Introductionmentioning

confidence: 99%

SAXS Studies of Heterogeneous NIPA/SA Gels

Hara

Sueyoshi

Sugiyama

et al. 2009

Trans. Mat. Res. Soc. Japan

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After brief reviews on the high sensitivity to water content and multivalent-ion adsorption of a peak in the homogeneous NIPA/SA gels' the small angle X-ray scattering (SAXS) profiles, the influence of the crosslinker concentration, which gives rise to the heterogeneity in the NIPA/SA gel, on the SAXS peak has been reported. It has been found that there is a considerable change in the location and intensity of the SAXS peak around a certain crosslinker concentration where the gels become opaque.

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Raman Scattering Study during the Dehydration Process of Polyacrylamide Gel

Cited by 22 publications

References 20 publications

Small-Angle Scattering Study of Mesoscopic Structures in Charged Gel and Their Evolution on Dehydration

Small-Angle Scattering Study of Mesoscopic Structures in Charged Gel and Their Evolution on Dehydration

Temperature Dependence of the Structure of Bound Water in Dried Glassy Poly-N,N,-dimethylacrylamide

SAXS Studies of Heterogeneous NIPA/SA Gels

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