Linear and Nonlinear Rheological Behavior of Fibrillar Methylcellulose Hydrogels

McAllister, John W.; Lott, Joseph; Schmidt, Paul G.; Sammler, Robert L.; Bates, Frank S.; Lodge, Timothy P.

doi:10.1021/acsmacrolett.5b00150

Cited by 68 publications

(106 citation statements)

References 35 publications

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“…These studies demonstrate that the sol-gel transition is a spinodal process (Takeshita et al 2010) or a nucleation and growth mechanism (Arvidson et al 2012). The cryo-TEM even revealed that MC chains associate into nanofibrils with uniform diameter of 15 ± 2 nm in the MC gels, which clearly explains the formation of optically turbid gel or precipitation (Lott et al 2013a, b;McAllister et al 2015).…”

Section: Introductionmentioning

confidence: 98%

“…Through another methodology, most researchers focus on using instrumental techniques to elucidate the thermodynamic mechanisms involved in the sol-gel transition and/or phase separation. These techniques include turbidity, laser light scattering, viscometry, rheology, differential scanning calorimetry (Arvidson et al 2012;Fairclough et al 2012;Lu et al 2002;Xu et al 2004), and recently by mid/near infrared spectroscopy (Jing and Wu 2013), small-angle neutron scattering combined with cryogenic transmission electron microscopy (cryo-TEM) (Lott et al 2013a, b;McAllister et al 2015). These studies demonstrate that the sol-gel transition is a spinodal process (Takeshita et al 2010) or a nucleation and growth mechanism (Arvidson et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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Thermal inverse phase transition of azobenzene hydroxypropylcellulose in aqueous solutions

Zhang

Liu

2016

Cellulose

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Water soluble 2-azobenzenoxy-ethoxyhydroxpropylcelluloses (azo-EHPC) were synthesized by etherification reaction of bromoethoxy-azobenzene (BEA) with hydroxypropylcellulose (HPC) to study their phase transition behavior in aq. solution. The degree of substitution (DS) of the water soluble azoEHPCs was less than 0.066. Their chemical structure and thermal property were characterized by proton nuclear magnetic resonance ( 1 H-NMR), fourier transform infrared spectroscopy (FT-IR), and differential scanning calorimetry. The azo-EHPC showed a reversible sol-gel transition behavior in its aq. solution, i.e. a clear azo-EHPC aq. solution became turbid when the solution temperature surpassed a lower critical solution temperature (LCST). The sol-gel transition phenomenon was investigated by optical microscopy and turbidimetric measurement. It was found that the LCST was related to the cis-/transconformation of the azobenzene side group, the type of cyclodextrin (CD), concentration of azo-EHPC, and NaCl concentration. The LCST of azo-EHPC was lower than that of HPC (36.6°C) by at most 13.6°C, and the LCST of trans-azo-EHPC was less than that of cis-azo-EHPC by ca. 3°C. Additionally, the presence of CD in solutions displayed a positive effect on the LCST, i.e. increasing the LCST by 3-5°C. And this impact was more profound on the azo-EHPC with higher DS values. The thermoreversible phase transition mechanism was discussed. We proposed that the effect of DS, conformation of azobenzene group, azo-EHPC concentration, salt concentration, and CD on the LCST of azo-EHPCs was a rearrangement of the hydrophilic/hydrophobic interaction between side azobenzene groups and water molecules.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Thermal inverse phase transition of azobenzene hydroxypropylcellulose in aqueous solutions

Zhang

Liu

2016

Cellulose

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“…[10][11][12][13] For example, beyond a critical strain value these networks strain-stiffen, which also corresponds to the demonstration of negative normal stress. 11,12,14 Interestingly, such behavior has not been widely reported for semiflexible polysaccharides networks. To address that, here, we investigate the rheological/mechanical properties of a model polysaccharide network, ionically cross-linked alginate hydrogels.…”

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confidence: 99%

Strain stiffening and negative normal stress in alginate hydrogels

Hashemnejad

Kundu

2016

J Polym Sci B Polym Phys

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Alginate hydrogels are polysaccharide biopolymer networks widely useful in biomedical and food applications. Here, we report nonlinear mechanical responses of ionically crosslinked alginate hydrogels captured using large amplitude oscillatory shear experiments. Gelation was performed in situ in a rheometer and the rheological investigations on these samples captured the strain-stiffening behavior for these gels as a function of oscillatory strain. In addition, negative normal stress was observed, which has not been reported earlier for any polysaccharide networks. The magnitude of negative normal stress increases with the applied strain amplitude and can exceed that of the shear stress at large-strain. Fitting a constitutive relationship to the stress-strain curves reveals that the mode of deformation involves stretching of the alginate chains and bending of both the chains and the junction zones. The contribution of bending increases near saturation of G blocks as Ca 21 concentration was increased. The results presented here provide an improved understanding of the deformation behavior of alginate hydrogels and such understanding can be extended to other crosslinked polysaccharide networks. V C 2016

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“…It has been pointed out that hydrophobic and hydrophilic regions within cellulose ethers play an important role with respect to thermal behavior, rheology, and solubility . Recent studies by cryogenic transmission electron microscopy and small angle neutron scattering on thermally induced gel formation of MC have shown that prior to gelling, a fibrillar structure is formed which in a yet unknown way form joints, but hydrophobic–hydrophobic interactions of domains probably play an important role. Polysaccharide derivatives are usually prepared by postmodification of their functional groups, the so‐called “polymer analog reaction” and show structural dispersity with respect to molecular weight, regioselectivity, and distribution of substituents over the polymer chains.…”

Section: Introductionmentioning

confidence: 99%

Block‐Structured 1,4‐d‐Glucans by Transglycosidation of Cellulose Ethers

Rother

Radke

Mischnick

2016

Macro Chemistry & Physics

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Multiblock structured glucan ethers are prepared for the first time by BF3·OEt2 promoted transglycosidation of two cellulose ether homopolymers. First, model studies are performed with equimolar mixtures of methyl cellulose (MC) and deuteromethyl cellulose (MC‐d3), varying the amount of Lewis acid and temperature. Reaction is monitored by 1H NMR spectroscopy and electrospray ionization mass spectrometry after partial hydrolysis of products. Cross reaction is proved and the decrease of average block length with time is monitored and found to approximate random distribution. The method is successfully applied to a mixture of ethyl cellulose and MC. Decreases of molecular weight, of dispersity, and of glass transition temperature Tg with reaction time are followed.

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Linear and Nonlinear Rheological Behavior of Fibrillar Methylcellulose Hydrogels

Cited by 68 publications

References 35 publications

Thermal inverse phase transition of azobenzene hydroxypropylcellulose in aqueous solutions

Thermal inverse phase transition of azobenzene hydroxypropylcellulose in aqueous solutions

Strain stiffening and negative normal stress in alginate hydrogels

Block‐Structured 1,4‐d‐Glucans by Transglycosidation of Cellulose Ethers

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