Ultrasonic investigation of the states of water in hydrogels

Koda, Shinobu; Yamashita, Kiyoo; Iwai, Satoshi; Nomura, Hiroyasu; Iwata, Masashi

doi:10.1016/s0032-3861(05)80035-7

Cited by 24 publications

(17 citation statements)

References 33 publications

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“…6 Both the thermal and the mechanical properties of hydrogels depend on several factors: molecular weight, concentration of aqueous solution, temperature and time of freezing steps, number of freezing-thawing cycles during the preparation steps, and how the water molecules are organized inside the material. [3][4][5][6][7] PVA hydrogels prepared using aqueous solutions subjected to repeated freezing-thawing cycles present the following characteristics: stability at room temperature, highly rubber elasticity, retention of its original shape, and high mechanical strength.…”

Section: Introductionmentioning

confidence: 99%

“…Several experimental methods have been used to study how the water molecules are organized in synthetic hydrogels, including ultrasonic measurements, 7 differential scanning calorimetry (DSC), 4,5,8 -14 nuclear magnetic resonance, 4,[11][12][13][14][15] infrared and Raman spectroscopy, 15 and differential thermal analysis. 16 Physical states or different states of water have been used to nominate the different types of ordered water molecules.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, the description of the states of the water remains controversial. While some authors classified them in three states: free water, nonfreezable bound water and freezable bound water 6,9 -11,14,15 ; some others considered only two states: freezable and nonfreezable water 4,7,8,[12][13][14] ; and others considered at the same results can be explained without postulating these different states. 17 Luminescence methods are now being considered a very useful tool in studying several polymer properties because of their sensitivity and selectivity ability, providing a nondestructive analytical method.…”

Section: Introductionmentioning

confidence: 99%

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Thermal transitions of poly(vinyl alcohol) hydrogel sensed by a fluorescent probe

Dibbern-Brunelli

Atvars²

2000

J. Appl. Polym. Sci.

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ABSTRACT:Fluorescence from the fluorescein molecule has been used to study of phase transition processes in five poly(vinyl alcohol) (PVA) hydrogels in the temperature range 75-350 K. These hydrogels were prepared with PVA with molecular weight ϭ 124,000 -186,000, 99ϩ% hydrolyzed, by repeated freezing-thawing cycles in five compositions: 9.9, 11.1, 13.3, 16.5, and 20.9 PVA w/w %. Plots of total fluorescence intensity versus temperature, normalized with the fluorescence signal at 75 K, and of the emission wavelength maximum versus temperature indicated that the dynamic of the guest deactivation was dependent on the hydrogel thermal transitions. These thermal transition processes were compared to three model systems: uranine (fluorescein di-sodium salt) in water, fluorescein in water/ethanol (85%/15% v/v), and fluorescein/PVA homopolymer. Small spectral shifts were obtained for these model systems over the entire temperature range attributed to the hot band effect. Nevertheless, larger spectral shifts were obtained for hydrogels, indicating that shifts of the chemical dissociation equilibrium was occurring in this last case. Slope changes of both intensity and wavelength maximum plots versus temperature occurred at the same temperature values, and we attributed the onset of the hydrogel thermal transition as the sol-gel transition occurring at T Х 370 K; at 320 K we observed the glass transition temperature of PVA plasticized by water molecules; at T Х 240 Ϯ 5 K we attributed the melting point of water molecules bonded to the PVA chains (freezable bond molecules); at T Х 270 Ϯ 5 K we observed the melting point of free water molecules (bulk water); and, at 135-145 K the water glass transition.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal transitions of poly(vinyl alcohol) hydrogel sensed by a fluorescent probe

Dibbern-Brunelli

Atvars²

2000

J. Appl. Polym. Sci.

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“…All solutions were sonicated to ensure mixing. There are reports that sonication at a power of 80 W, can degrade PEO at a molecular mass of 8.6 Â 10 4 g/mol [22]. The PEO block of the copolymer is already small (5.8 Â 10 3 g/mol) and the power of the sonicator was lower (40 W).…”

Section: Sample Preparationmentioning

confidence: 99%

Micelles of polybutadiene-b-poly(ethylene oxide) in deuterated methanol and deuterated cyclohexane

Kumi

Greer

2012

Journal of Colloid and Interface Science

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“…[1][2][3][4] During the deformation process, these mechanical properties are affected by changes in the molecular orientation and packing state, and ultrasonic propagation in the materials is quite sensitive to their changes. Yap et al 5 studied the acoustic properties of PMMA poly(methyl methacrylate) under uniaxial tensile stress using the Brillouin scattering method and reported the strain dependence of the ultrasonic velocities.…”

Section: Introductionmentioning

confidence: 99%

Acoustic characteristics of PMMA in the steady stress-strain state investigated by coherent Brillouin scattering method

Sakurai

Matsuoka

Koda

et al. 2000

J. Appl. Polym. Sci.

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ABSTRACT:The acoustic properties of PMMA poly(methyl methacrylate) deformed by tensile stress were investigated by the coherent Brillouin scattering method. The ultrasonic velocities of PMMA in steady stress-strain states were measured in the frequency range of 100 MHz to 1 GHz. The ultrasonic velocities decreased with increasing strain, and the ratio of the decrease increased with increasing strain rate. This result indicates that the crazing residues still remain in the steady stress-strain states, and the amount of the residues depends upon the strain rate. The velocity dispersion was observed around 400 MHz for virgin and deformed PMMA and reproduced with a single relaxation process. The relaxation process is assigned to the ␥-relaxation according to the dispersion map for methyl group relaxation in PMMA. The relaxation frequency and strength were independent of the applied stress and strain. The viscoelastic and plastic deformations have little effect on the ␥-relaxation.

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Ultrasonic investigation of the states of water in hydrogels

Cited by 24 publications

References 33 publications

Thermal transitions of poly(vinyl alcohol) hydrogel sensed by a fluorescent probe

Thermal transitions of poly(vinyl alcohol) hydrogel sensed by a fluorescent probe

Micelles of polybutadiene-b-poly(ethylene oxide) in deuterated methanol and deuterated cyclohexane

Acoustic characteristics of PMMA in the steady stress-strain state investigated by coherent Brillouin scattering method

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