Reversible gelation of poly(dimethylsiloxane) with ionic and hydrogen-bonding substituents

Klok, Harm‐Anton; Rebrov, Evgeney A.; Muzafarov, А. М.; Michelberger, Walter; Möller, Martin

doi:10.1002/(sici)1099-0488(19990315)37:6<485::aid-polb1>3.0.co;2-t

Cited by 17 publications

(20 citation statements)

References 24 publications

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“…More extensive substitution along the backbone in bulk associating polymers can actually result in the formation of thermoplastic elastomers that display a well-developed rubbery plateau similar to a covalently cross-linked rubber, except that the material can be melted and recycled, unlike a cross-linked rubber (Hilger et al 1990). This latter case is similar to the results seen here for gliadin(30%), other reported results described above for gliadin or gliadinenriched gluten subfractions and for the hydrogen bonding PDMS samples of Klok et al (1999). In contrast, weaker thermoreversible gels are obtained at intermediate degrees of physical cross-linking above the critical gelation point and generally only show a frequency-independent rubbery plateau at moderate to high frequencies (ω > 6.28 rad/sec) (or short times in creep), but show a frequency-dependent dynamic moduli at lower frequencies.…”

Section: Discussionsupporting

confidence: 88%

“…As discussed in more detail in Lee and Mulvaney (2003) in the context of gluten and glutenin gels and Rao et al (2001) and Edwards et al (2001) for wheat flour doughs, the introduction of just a few mol% of associating groups along the synthetic polymer backbone leads to very high melt viscosities and enhanced viscoelastic properties at low concentration and low molecular weight, relative to the unmodified linear polymer of the same molecular weight. Also, secondary interactions incorporated into synthetic associating polymers can be exploited to enhance the compatibility of polymers or components that are incompatible in the absence of these secondary associations (Klok et al 1999). This sounds qualitatively similar to the plasticizing or compatibilizing effect that gliadin has been shown to exert on glutenin.…”

Section: Associating Polymersmentioning

confidence: 80%

“…They also noted that the role of noncovalent intermolecular associations in determining the rheological and functional properties of hydrated cereal systems was more analogous to so-called associating synthetic linear polymers than entangled linear flexible polymers. Also, secondary interactions incorporated into synthetic associating polymers can be exploited to enhance the compatibility of polymers or components that are incompatible in the absence of these secondary associations (Klok et al 1999). Because synthetic polymers have nonpolar backbones, the associating groups are polar, often including hydrogen bonding chemical groups.…”

Section: Associating Polymersmentioning

confidence: 99%

“…Klok et al (1999) showed that the frequency denoting the onset of non-Newtonian behavior of η′ for a hydrogen bonding PDMS sample was shifted first to lower frequencies at high temperatures as the rubbery network developed due to physical cross-linking. Klok et al (1999) showed that the frequency denoting the onset of non-Newtonian behavior of η′ for a hydrogen bonding PDMS sample was shifted first to lower frequencies at high temperatures as the rubbery network developed due to physical cross-linking.…”

Section: Dynamic Viscositymentioning

confidence: 99%

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Effect of Moisture Content on Viscoelastic Properties of Hydrated Gliadin

2004

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Cereal Chem. 81(2):207-219The effect of moisture content on the linear viscoelastic properties of gliadin hydrated to 30 and 40% moisture content [gliadin(30%) and gliadin(40%), respectively] was determined. These two moisture contents bracketed the equilibrium moisture content of gliadin, which was 37.6%. Time-temperature-superposition was used to develop master curves of the elastic modulus (G′), viscous modulus (G′′), dynamic viscosity (η′), and tan δ (G′′/G′) from isothermal frequency sweep data obtained at 25-80°C.Smooth master curves were obtained for all of the viscoelastic functions for both gliadins. G′ and G′′ showed a power law dependency on frequency (with G′′ > G′) for frequencies <0.1 rad/sec for gliadin(30%) and <1 rad/sec for gliadin(40%). The low-frequency-limiting slopes on log-log coordinates for G′ and G′′ were 0.700 and 0.646 for gliadin(30%), respectively. Corresponding values were 0.658 and 0.614 for gliadin(40%). G′ crossed over G′′ at a frequency of ≈0.3 rad/sec for gliadin(30%), while G′ and G′′ for gliadin(40%) only became congruent at higher frequencies.Both gliadin samples showed appreciable frequency dependence of η′ over the entire frequency range, while η′ was greater for gliadin(30%) than for gliadin(40%) at all frequencies, but especially at the lowest frequencies. Tan δ increased gradually from a value of ≈1 at 0.1 rad/sec to ≈2 at the lowest frequency of 0.0002 rad/sec for both gliadins, but tan δ decreased rapidly for gliadin(30%) for frequencies >0.1 rad/sec. Thus, the main difference between gliadin(30%) and gliadin(40%) was that elastic effects (G′ > G′′ and decreased tan δ were more prominent for gliadin(30%) at the higher frequencies. In addition, the frequency dependence of G′, G′′, η′, and tan δ for the two gliadin samples was compared directly with two samples of poly(dimethylsiloxane) (PDMS) a linear silicone-based entangled polymer with molecular weights (MW) of 140,000 and 385,000. The substantial differences in the magnitude and overall patterns of the frequency dependence of the viscoelastic functions between the gliadin and PDMS samples was attributed to the dominant effect that noncovalent secondary associations apparently have on the linear viscoelasticity of the gliadins. The energy of activation for flow (determined from the temperature dependence of the shift factors) for the gliadin samples for the range 25-45°C was higher than is typical for entangled linear polymer melts. The activation energy decreased for temperatures greater than ≈60°C for gliadin(30%) and ≈50°C for gliadin(40%). Thus, hydrated gliadin cannot be considered to be a simple viscoelastic liquid.

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Section: Discussionsupporting

confidence: 88%

Section: Associating Polymersmentioning

confidence: 80%

Section: Associating Polymersmentioning

confidence: 99%

Section: Dynamic Viscositymentioning

confidence: 99%

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Effect of Moisture Content on Viscoelastic Properties of Hydrated Gliadin

2004

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“…The effects of hydrogen bonding at the chain ends on the physical properties of polysiloxane and its suspension systems were reported 10–12. However, the effect on the physical properties of PET has been scarcely investigated.…”

Section: Introductionmentioning

confidence: 99%

Effects of hydroxyl‐group end capping and branching on the physical properties of tailored polyethylene terephthalates

Kim

2001

J Polym Sci B Polym Phys

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Polyethylene terephthalates (PETs) with well‐defined chemical structures were prepared by molecular design, and the effect of the chemical structure on the physical properties of PET was investigated. Hydroxyl‐group end‐capped PETs with ηinh = 0.4–0.6 dL/g exhibited a viscosity behavior similar to Bingham fluids, although other PETs with similar molecular weights (MWs) showed Newtonian flow behavior. This rheological feature was more noticeable for hydroxyl‐group end‐capped branched PETs. In addition, hydroxyl‐group end‐capped branched PETs became solidlike from 80 rad/s as the frequency was increased. On the other hand, hydroxyl end‐capped linear PETs showed a noticeable viscoelastic transition peak around 20 rad/s. High MW linear and branched PETs with ηinh ≥ 0.9 prepared by multistep synthesis showed non‐Newtonian fluid behavior. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1027–1035, 2001

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Zwitterionic Silicone Materials Derived from Aza‐Michael Reaction of Amino‐Functional PDMS with Acrylic Acid

Genest

Portinha

Pouget

et al. 2020

Macromol. Rapid Commun.

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Supramolecular zwitterionic silicones are synthesized by aza‐Michael reaction between acrylic acid and amine‐functional polydimethylsiloxanes. The in‐depth characterization of this chemistry, applied for the first time to silicones, is investigated first with model alkylamines (hexylamine, 2‐ethylhexylamine and N‐propylethylenediamine), a model oligosiloxane (3‐aminopropylmethyl bis(trimethylsiloxy)silane), and finally various amino‐polysiloxanes. It is shown that after a first acid–base reaction resulting in ionic pairing, aza‐Michael addition proceeds smoothly in mild conditions (50 °C, 1‐week reaction). Both monoadducts and di‐adducts, together with residual amine, are observed by NMR. The supramolecular assembly of the thus‐created zwitterionic moieties is highlighted by a concomitant increase in viscosity and phase separation, as observed by transmission electron microscopy, bringing an additional glass transition at –40 °C assigned to highly polar ionic clusters. Below the stoichiometry in acrylic acid, all zwitterionic silicones follow the same classical behavior of nonentangled polymers according to the Rouse model, whereas upon introducing an excess of acrylic acid to amino groups, an enhancement of the elasticity is observed. Finally, silicone elastomers with solid‐like behavior and elastomeric mechanical properties are obtained using a high molar mass polymer bearing bifunctional N‐(2‐aminoethyl)‐3‐aminopropyl units that favor a high degree of physical crosslinking.

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Reversible gelation of poly(dimethylsiloxane) with ionic and hydrogen-bonding substituents

Cited by 17 publications

References 24 publications

Effect of Moisture Content on Viscoelastic Properties of Hydrated Gliadin

Effect of Moisture Content on Viscoelastic Properties of Hydrated Gliadin

Effects of hydroxyl‐group end capping and branching on the physical properties of tailored polyethylene terephthalates

Zwitterionic Silicone Materials Derived from Aza‐Michael Reaction of Amino‐Functional PDMS with Acrylic Acid

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