Thermally induced coupling of phase separation and gelation in an aqueous solution of hydroxypropylmethylcellulose (HPMC)

Kita, R.; Kaku, Takeshi; Ohashi, Hitoshi; Kurosu, Takeshi; Iida, Masamori; Yagihara, Shin; Dobashi, Toshiaki

doi:10.1016/s0378-4371(02)01523-6

Cited by 19 publications

(7 citation statements)

References 33 publications

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“…The NMR measurements should then reflect dynamic behaviors obtained from an average in the larger space and time scales. Nevertheless, the same conclusion of the existence of various mobile properties, or the broad distribution of water molecules, was obtained from [19], poly(ethylene glycol) (PEG) [19], poly(vinyl methyl ether) (PVME) [19], poly(ethylenimine) (PEI) [19], poly(acrylic acid) (PAA) [19], poly(allylamine) (PAlA) [19], Poly(N-isopropylacrylamide) (PNiPAM) [43], poly(acrylamide) (PAAm) [44], PAAm gels in water-acetone mixtures (PAAm gel Acetone) [20,44], PAAm gels in waterdimethyl sulfoxide mixtures (PAAm gel DMSO) [20], PAAm gels in water-1, 4-dioxane (PAAm gel 1, 4-dioxane) [20], trehalose [45,46], maltose [45,46], pullulan [47], glucose [45,46], rice [48], hydroxypropylmethylcellulose (HPMC) [46,49,50],1,2dipalmitoylsn-glycero-3-phosphacholine (liposome) [46,[51][52][53], denatured chicken egg white (glass egg) [46,54], ovalbumin (OVA) [46,[55][56][57][58], gelatin [46,58], bovine Achilles tendon (collagen) [46,58,59]. The red arrow indicates the maximum error estimated from the s value.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of water structures in cotton cloth by fractal analysis with broadband dielectric spectroscopy

et al. 2021

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Broadband dielectric spectroscopy measurements were performed on naturally dried cotton cloth, and a recently developed analytical technique for fractal analysis of water structures was applied to obtain existential states and locations of water molecules in the material. Three relaxation processes observed in GHz, MHz, and kHz frequency regions were attributed to dynamic behaviors of hydrogen bonding networks (HBNs) of water and interacting molecules, polymer chains with interacting ion and water molecules, and ions restricted on the interfaces of larger structures, respectively. Water molecules were heterogeneously distributed in the cotton cloth, and the HBNs remained as a broad GHz frequency process. Fractal analysis suggested that water molecules distributed in the material were characterized by a small value (0.55) of the Cole–Cole relaxation time distribution parameter, indicating spatial distribution of HBN fragments with various sizes in cotton cloth. This result was also supported by the T2 relaxation time obtained from nuclear magnetic resonance for naturally dried cotton yarn. Comparing previous results of dielectric relaxation measurements and fractal analysis with the τ–β diagram for various aqueous systems, the results determined that water molecules cannot exist inside cellulose microfibrils. The fractal analysis employed in this work can be applied to dynamic water structures in any material. The presented analytical technique with a universal τ–β diagram is expected to be an effective tool to clarify water structure detail even for heterogeneous hydrations of the low water content substances. Graphical abstract

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Section: Resultsmentioning

confidence: 99%

Evaluation of water structures in cotton cloth by fractal analysis with broadband dielectric spectroscopy

et al. 2021

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“…Figure 6 clearly shows that trajectories starting from pure water for aqueous systems with various water contents tend to locate in the upper right area of the τ – β diagram for aqueous mixtures of polymers [29], such as poly(vinylpyrrolidone) (PVP; weight average molecular weight (Mw) = 10,000), poly(ethylene glycol) (PEG; Mw = 8000), Poly (ethylenimine)(PEI; Mw = 50,000) and poly(acrylic acid) (PAA; Mw = 5000), poly(vinyl methyl ether) (PVME; Mw = 90,000), poly(allylamine) (PAlA; Mw = 10,000), and poly(vinyl alcohol) (PVA; Mw = 77,000). Aqueous solutions of glucose [30] and hydroxypropylmethylcellulose (HPMC) [31] and moist collagen [32] are also shown in this area.…”

Section: Resultsmentioning

confidence: 99%

Physical Meanings of Fractal Behaviors of Water in Aqueous and Biological Systems with Open-Ended Coaxial Electrodes

Yagihara

Kita

Shinyashiki

et al. 2019

Sensors

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The dynamics of a hydrogen bonding network (HBN) relating to macroscopic properties of hydrogen bonding liquids were observed as a significant relaxation process by dielectric spectroscopy measurements. In the cases of water and water rich mixtures including biological systems, a GHz frequency relaxation process appearing at around 20 GHz with the relaxation time of 8.2 ps is generally observed at 25 °C. The GHz frequency process can be explained as a rate process of exchanges in hydrogen bond (HB) and the rate becomes higher with increasing HB density. In the present work, this study analyzed the GHz frequency process observed by suitable open-ended coaxial electrodes, and physical meanings of the fractal nature of water structures were clarified in various aqueous systems. Dynamic behaviors of HBN were characterized by a combination of the average relaxation time and the distribution of the relaxation time. This fractal analysis offered an available approach to both solution and dispersion systems with characterization of the aggregation or dispersion state of water molecules. In the case of polymer-water mixtures, the HBN and polymer networks penetrate each other, however, the HBN were segmented and isolated more by dispersed and aggregated particles in the case of dispersion systems. These HBN fragments were characterized by smaller values of the fractal dimension obtained from the fractal analysis. Some examples of actual usages suggest that the fractal analysis is now one of the most effective tools to understand the molecular mechanism of HBN in aqueous complex materials including biological systems.

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“…Furthermore, Villetii et al found that in MC/NaCl solutions the mechanism of phase separation is also spinodal decomposition. Kita et al reported , that phase separation is limited by gelation in HPMC solutions. They suggest that a spontaneous pinning of spinodal decomposition occurs, as the structure formed in a shallower quench has a larger domain length than that formed by a deeper quench.…”

Section: Introductionmentioning

confidence: 99%

Interplay between Gelation and Phase Separation in Aqueous Solutions of Methylcellulose and Hydroxypropylmethylcellulose

et al. 2012

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Thermally-induced gelation in aqueous solutions of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) has been studied by rheological, optical microscopy and turbidimetry measurements. The structural and mechanical properties of these hydrogels are dominated by the interplay between phase separation and gelation. In MC solutions, phase separation takes place almost simultaneously with gelation. An increase in the storage modulus is coupled to the appearance of a bicontinuous structure upon heating. However, a thermal gap exists between phase separation and gelation in the case of HPMC solutions. The storage modulus shows a dramatic decrease during phase 2 separation, and then rises in the subsequent gelation. A macroporous structure forms in the gels via "viscoelastic phase separation" linked to "double phase separation".

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Thermally induced coupling of phase separation and gelation in an aqueous solution of hydroxypropylmethylcellulose (HPMC)

Cited by 19 publications

References 33 publications

Evaluation of water structures in cotton cloth by fractal analysis with broadband dielectric spectroscopy

Evaluation of water structures in cotton cloth by fractal analysis with broadband dielectric spectroscopy

Physical Meanings of Fractal Behaviors of Water in Aqueous and Biological Systems with Open-Ended Coaxial Electrodes

Interplay between Gelation and Phase Separation in Aqueous Solutions of Methylcellulose and Hydroxypropylmethylcellulose

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