Elastic modulus and equilibrium swelling of networks crosslinked by end-linking oligodimethylsiloxane at solution state

Urayama, Kenji; Kawamura, Takanobu; Kohjiya, Shinzo

doi:10.1063/1.472320

Cited by 67 publications

(64 citation statements)

References 49 publications

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“…In contrast, the C Ã theorem does not predict any crossovers, or even any f 0 -dependence of f s and E s , where f s and E s are determined only by N. These results strongly suggest that the C Ã theorem is inapplicable to describe the equilibrium swelling state, but it is determined by the balance between the osmotic and elastic free energies. These results are in accordance with those obtained in the PDMS network with trapped entanglmements, [24] suggesting that the Obukhov model is regardless of the concentration regime. Figure 7 shows the relationship between the elastic modulus (E s ) and the polymer .…”

Section: à076supporting

confidence: 92%

Effect of Swelling and Deswelling on Mechanical Properties of Polymer Gels

Katashima

Chung

Sakai

2015

Macromolecular Symposia

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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.

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Section: à076supporting

confidence: 92%

Effect of Swelling and Deswelling on Mechanical Properties of Polymer Gels

Katashima

Chung

Sakai

2015

Macromolecular Symposia

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“…In contrast, later work clearly shows that the modulus does depend upon the degree of dilution. [9,15,[24][25][26][27]. Vasiliev et al [25] noticed that the use of a mixture of a good solvent and a non-solvent results in phase separation during crosslinking.…”

Section: Introductionmentioning

confidence: 99%

“…In some studies, the PDMS networks are cured for 2 -3 days at 75°C [10,22,23]. Furthermore a few authors crosslink the networks in solution [8,9,15,[24][25][26][27]. If the network is crosslinked in bulk, entanglements are trapped whenever the PDMS chain length exceeds the entanglement molecular weight.…”

Section: Introductionmentioning

confidence: 99%

Some experimental results for the end-linked polydimethylsiloxane network system

Larsen

Sommer‐Larsen²,

Hassager

2004

E-Polymers

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Small-strain equilibrium modulus data of polydimethylsiloxane (PDMS) networks are reviewed. 58 different articles in the literature with values of the modulus of end-linked PDMS networks were found [1-58] including more than 250 values of the small-strain equilibrium modulus as function of variables in the crosslinking system. The dominating variable is shown to be the molecular weight of PDMS as expected, whereas the functionality of the crosslinker methylhydrosiloxane/dimethylsiloxane copolymer is shown to be less important in good agreement with the phantom model. The data collected was fitted to the phenomenological model of Langley and Graessley including an entanglement contribution. The fitted entanglement plateau (0.16 MPa) is in good agreement with literature values and with the theoretical prediction of the tube model. Experimental data for the Mooney-Rivlin constants was found and it was shown that C 2 is constant with increasing functionality. Furthermore it was found that trapped entanglements can be split into two categories, viz. locked entanglements contributing to the C 1 term and traditionally trapped entanglements contributing to C 2 .

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“…2,9 The entanglements formed by different network strands act as additional crosslinks because they are not disentangled even in the long time limit owing to the presence of crosslinks; this is in contrast to the finite life times of transient entanglements in uncrosslinked polymer melts. 5,[10][11][12][13] Many entanglement theories with different physical basis have been proposed, but most of the earlier attempts to experimentally verify these theories relied solely on the uniaxial deformation data. Several physically different models apparently predict the uniaxial data of the same elastomers.…”

Section: Multiaxial Deformation Behaviors Of End-linked Pdms Networkmentioning

confidence: 99%

Network Topology–Mechanical Properties Relationships of Model Elastomers

Urayama

2008

Polym J

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We review our recent studies on the mechanical properties of model elastomers with well-characterized network structures. Model elastomers were prepared by end-linking precursor poly(dimethylsiloxane) (PDMS) of known molecular weight with multifunctional crosslinkers. We then strictly assessed the modern entanglement models for rubber elasticity on the basis of the stress-strain data under general biaxial strains covering almost the entire range of accessible deformations for the model PDMS networks. We also demonstrated marked extensibility of more than 3000% for the deswollen networks prepared by removing the solvent from the end-linked gels prepared in the diluted state. The highly deswollen networks comprising the considerably compact conformation (supercoil) exhibited unusually weak strain dependence of stress. We also studied the viscoelastic properties of PDMS networks containing either unattached free chains or pendant chains. The former systems provided a model system to investigate the dynamics of the guest chains in invariant networks. The dynamics of the guest chains, as functions of their own sizes as well as the mesh sizes of host networks, were compared with the predictions of reptation theories. With the model networks with pendant chains, we elucidated the correlation between the damping properties and the amount of pendant chains. The elastomers with highly irregular structures exhibited high damping almost independent of both temperature and frequency.KEY WORDS: Elastomers / Gels / Rubber Elasticity / Rheology / Reptation / Entanglements / Crosslinked polymer networks composed of flexible strands exhibit many unique properties that stem from their threedimensional network structures: they behave as soft solids because they do not flow macroscopically owing to the presence of crosslinks, but they still possess a liquid nature due to the weak constraints at the crosslinks, allowing the micro-Brownian motion of network strands. Rubber elasticity-reversible large deformability under small external forces-is one of the salient characteristics of polymer networks, and hence, they are often called ''elastomers.'' Elastomers are widely employed in industry, and the fundamental aspects of their physical properties have been extensively investigated over the past half century.1,2 The molecular understanding of their physical properties, however, still remains incomplete because their network structures are not well characterized:3 the rubbery networks prepared by randomcrosslinking of the precursor chains have inhomogeneous structures with a broad length distribution of the network strands; in addition, the characterization of the strand length distribution in elastomers is not possible by current analytical techniques. However, end-linking end-reactive precursor chains of known molecular weight using multifunctional crosslinkers affords a tailor-made model network with a wellcharacterized structure. [4][5][6] To the first-order approximation (which is accurate in the case of the complete reaction), the...

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Elastic modulus and equilibrium swelling of networks crosslinked by end-linking oligodimethylsiloxane at solution state

Cited by 67 publications

References 49 publications

Effect of Swelling and Deswelling on Mechanical Properties of Polymer Gels

Effect of Swelling and Deswelling on Mechanical Properties of Polymer Gels

Some experimental results for the end-linked polydimethylsiloxane network system

Network Topology–Mechanical Properties Relationships of Model Elastomers

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