Small angle neutron scattering studies on structural inhomogeneities in polymer gels: irradiation cross-linked gels vs chemically cross-linked gels

Norisuye, Tomohisa; Masui, Naoki; Kida, Yusuke; Ikuta, Daigo; Kokufuta, Etsuo; Itô, Shôji; Panyukov, Sergey; Shibayama, Mitsuhiro

doi:10.1016/s0032-3861(02)00343-9

Cited by 87 publications

(83 citation statements)

References 33 publications

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“…Experimentally, small-angle X-ray scattering (SAXS) 28 and small-angle neutron scattering (SANS) have been extensively employed to elucidate the inhomogeneities in polymer gels. [29][30][31][32][33][34] As a matter of fact, inhomogeneities are one of the most interesting topics in SANS of polymer gels. 7,35 These methods provide information on static scattering, i.e., the ensemble average of concentration.…”

Section: What Are Structure Inhomogeneities In Gels?mentioning

confidence: 99%

“…Figure 15 shows SANS intensity curves obtained for (a) monomer cross-linked (BIS) gels and (b) polymer cross-linked (-ray irradiated) gels. 34 It is clear from the figure that the monomer cross-linked gels are much more inhomogeneous than the polymer cross-linked gels. The solid, dashed, and dotted lines denote the calculated curves for SðqÞ (the total structure factor), CðqÞ (the frozen inhomogeneities), and GðqÞ (the dynamic inhomogeneities), respectively, based on the Panyukov-Rabin theory (see Eqs.…”

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confidence: 94%

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Universality and Specificity of Polymer Gels Viewed by Scattering Methods

Shibayama¹

2006

Bulletin of the Chemical Society of Japan

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Concentration fluctuations in polymer gels are composed of dynamic thermal fluctuations and frozen inhomogeneities. Particularly, the latter is a characteristic of gels and is due to cross-linking. The frozen inhomogeneities manifest unique properties in polymer gels. Speckle patterns are commonly observed in gels. The time-correlation function of the scattering intensity entails a power-law behavior at the sol-gel transition. The appearance of speckle patterns is related to the nonergodicity of gels, and the power-law behavior corresponds to the self-similarity of clusters at the gelation threshold. In this review, it will be demonstrated that light scattering is one of the most powerful tools for structure characterization of polymer gels. Then, the universality and specificity of polymer gels will be examined for various types of gels, including physical gels, composite gels, and gelators.

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Section: What Are Structure Inhomogeneities In Gels?mentioning

confidence: 99%

mentioning

confidence: 94%

Universality and Specificity of Polymer Gels Viewed by Scattering Methods

Shibayama¹

2006

Bulletin of the Chemical Society of Japan

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107

112

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“…Small angle neutron scattering studies demonstrate that the poly(NIPPAm) hydrogels crosslinked by g-ray irradiation are more homogeneous than the hydrogels crosslinked by conventional polymerization with BIS. [129] The differences in the hydrogel structure can be successfully interpreted by the statisticalmechanical Panyukov-Rabin theory. [130] The structure of hydrogels is also determined by the functionality and the hydrophilicity of crosslinkers.…”

Section: Electrolytesmentioning

confidence: 99%

Modeling Investigation of Hydrogel Volume Transition

Chen

et al. 2004

Macro Theory & Simulations

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Summary: This paper provides an overview of the latest development in modeling and simulation of volume transition behaviors of hydrogels with models at both macroscopic and molecular levels. Energy conservation law, mass conservation law and momentum conservation law provide good starting points for developing models for hydrogel volume transition. Thermodynamic models, transport models, multiphasic mixture theory and molecular simulation are discussed. Thermodynamic models provide qualitative description of equilibrium volume transition of hydrogels. Both transport models and multiphasic mixture theory can predict transient and equilibrium volume transition of hydrogels. Molecular simulation provides mechanistic understanding of hydrogel volume transition. Several key parameters are summarized for future model development.

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“…We discuss the correlation between the hierarchical, two-step internal fracture and the heterogeneity of the PAMPS network. It is well known that common gels contain spatial inhomogeneity in the network 23,24 . One reason is frozen concentration fluctuation by gelation 23 .…”

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confidence: 99%

“…One reason is frozen concentration fluctuation by gelation 23 . The other reason, which is specific for gels synthesized from monomers and cross-linkers, is hierarchical 5 gelation process which results in spatial inhomogeneity of crosslinking points 24 . Based on the scattering results, it is deduced that; in gelation process, 1) small gel clusters (microgels) are formed first, then 2) the microgels are connected to form bulk gels containing large inhomogeneity, as illustrated in Figure 8(a, b) 24 .…”

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confidence: 99%

Characterization of internal fracture process of double network hydrogels under uniaxial elongation

et al. 2013

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5Previously we revealed that the high toughness of double network hydrogels (DN gels) derives from the internal fracture of the brittle network during deformation, which dissipates energy as sacrificial bonds. In this study, we intend to elucidate the detailed internal fracture process of DN gels. We quantitatively analysed the tensile hysteresis and re-swelling behaviour of a DN gel that shows a well-defined necking and strain hardening, and obtained the following new findings: 1) Fracture of the 1 st network PAMPS 10 starts far below the yielding strain, and 90% of the initially load-bearing PAMPS chains already breaks at the necking point.2) The dominant internal fracture process occurs in the necking and hardening region although the softening mainly occurs before necking.3) The internal fracture efficiency is very high, 85% of the work is used for the internal fracture and 9% of all PAMPS chains break at sample failure. 4) The internal fracture is anisotropic, fracture occurs preferentially perpendicular to the tensile direction than 15 other two directions, but the fracture anisotropy decreases in the hardening region. Result 1) and 2) is in agreement with a hierarchical structural model of PAMPS network. Based on these findings, we present a revised description of the fracture process of DN gels.

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Small angle neutron scattering studies on structural inhomogeneities in polymer gels: irradiation cross-linked gels vs chemically cross-linked gels

Cited by 87 publications

References 33 publications

Universality and Specificity of Polymer Gels Viewed by Scattering Methods

Universality and Specificity of Polymer Gels Viewed by Scattering Methods

Modeling Investigation of Hydrogel Volume Transition

Characterization of internal fracture process of double network hydrogels under uniaxial elongation

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