Effect of swelling and deswelling on the elasticity of polymer networks in the dilute to semi-dilute region

2014

Polym J

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The realization of an ideal polymer network that is free from heterogeneity is one of the ultimate goals in polymer science. Heterogeneity is known to be an inherent property of polymer networks. To realize an ideal polymer network, we need to develop methods to achieve a homogeneous network structure and to confirm the network homogeneity. This is a dilemma, as the former method needs to be verified by the latter method, while the latter method needs to be examined by the former method. To resolve this situation, a series of studies on polymer networks with well-defined properties is needed. We recently designed and fabricated novel Tetra-polyethyleneglycol (PEG) hydrogels. Characterization by small angle neutron scattering, infrared spectroscopy, nuclear magnetic resonance and tearing experiments indicates that Tetra-PEG gels have highly suppressed heterogeneity. In this review, we show a series of experimental results from Tetra-PEG gels and discuss the results in terms of network homogeneity. Finally, using Tetra-PEG gels as a model system, we examine models for predicting the elastic modulus of polymer gels and show that Tetra-PEG gels are useful as a model system for evaluating models that predict the physical properties of polymer networks.

Section: Introductionmentioning

confidence: 99%

Experimental verification of homogeneity in polymer gels

2014

Polym J

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“…f s -Dependence of E s for the 10 k and 20 k Tetra-PEG gels with different f 0 s. Circles and triangles represent the data of the 10 k and 20 k Tetra-PEG gels, respectively. The data are reproduced from Sakai et al [41] with a permission of the Royal Society of Chemistry.…”

Section: Resultsmentioning

confidence: 99%

“…As for the equilibrium swelling, the relationship between polymer volume [41] with a permission of the Royal Society of Chemistry. Figure 7.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 2 shows the f m -dependence of E m for the Tetra-PEG gels prepared near f Ã with N ¼ 227. Circles and triangles represent the data for those partially swollen and deswollen by H 2 O, [41] and the ionic liquid (IL: 1-butyl-3-methylimidazolium tetrafluoroborate); [42] both solvent has similar solvent qualities against PEG (n PEG ¼ 0.59, n IL ¼ 0.56). Practically nonvolatile nature of IL was utilized to prevent the crystallization of PEG by elevating the temperature.…”

Section: Effect Of Swelling and Deswelling On The Mechanical Propertimentioning

confidence: 99%

“…Circle data are reproduced from Sakai et al [41] with permission from the Royal Society of Chemistry. Triangle data are reproduced from Katashima et al [42] with permission from the American Institute of Physics.…”

Section: Effect Of Swelling and Deswelling On The Fractal Dimension Omentioning

confidence: 99%

See 2 more Smart Citations

Effect of Swelling and Deswelling on Mechanical Properties of Polymer Gels

Katashima

Chung

Macromolecular Symposia

2015

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Summary: Polymer gels exhibit some unique features that are not seen in the uncrosslinked polymer system, rubber elasticity and swelling. In this paper, we review our recent studies towards the molecular understanding of the relationship between the elasticity and the swelling ratio using the Tetra-PEG gels. The dependence of the polymer volume fraction of interest state (f m ) on the elasticity exhibits the power-law behaviors and the crossovers at f Ã and f c due to the presence of the excluded volume effect and the supercoiling. The Obukhov model successfully describes the power-law behaviors. The fractal dimension of network strands (D f ) based on the stress-elongation relationships using the Pincus blob revealed that the gyration radius of the network strands decreases with deswelling in affine manner. As for the equilibrium swelling, the definite f 0 -dependences of f m and E s are observed due to the effect of the excluded volume effect at preparation state. The Obukhov model can predict this result, while the C Ã theorem cannot predict it. Using the polymer gels with precisely controlled network structures, we successfully verify the molecular models to describe the relationships between the elasticity and the swelling degree of polymer gels.

Rubber‐Like Elasticity

Sakumichi

Encyclopedia of Polymer Science and Technology

2023

Rubber‐like elasticity, which is a property to sustain very large deformations without rupture up to about 10 times from the original length followed by complete recovery, is manifested in polymeric materials with a three‐dimensional network structure consisting of long, flexible polymer chains. Rubber‐like elasticity originates from the decrease in entropy of the chains between cross‐linking points resulting from the elongation. In addition, there is an internal energetic component to the elasticity, which can be extracted from thermoelastic experiments. This is related to conformational energy changes of the polymer chains and, in polymer gels containing large amounts of solvent, to energy changes in solvent‐polymer interactions. Because the network structures of polymeric materials cannot be directly observed, the theoretical models for predicting the correlation between the structure and physical properties are uncertain. However, estimating structures by combining existing models with measured physical properties is important for guiding material design. This article overviews experimental and theoretical aspects of rubber‐like elasticity.