Molecular Weight Dependence of Methylcellulose Fibrillar Networks

Peter W. Schmidt, Svetlana Morozova, Paige M. Owens, Roland Adden, Yongfu Li, Frank S. Bates, Timothy P Lodge

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Gelation of aqueous methylcellulose (MC) solutions upon heating has been shown to result from the formation of a network of semiflexible fibrils, with diameters of 15 ± 2 nm. Here, we investigate the impact of MC molecular weight on the elasticity and structure of aqueous gels at concentrations between 0.1 and 3 wt %. Small-amplitude oscillatory shear measurements conducted at a fixed concentration reveal that the gel modulus increases monotonically by a factor of 5 for weight-average molecular weights (Mw) between 22 and 550 kg/mol. Small-angle X-ray scattering data, fit to a semiflexible cylinder model, demonstrate that the fibril radius, Kuhn length, and volume fraction are approximately constant throughout this molecular weight range. Small-angle light scattering shows that the fibrillar-rich and fibrillar-depleted domains within the gel are associated with an essentially invariant heterogeneity correlation length. Direct visualization by cryo-TEM reveals that lower molecular weight MC forms fibrils of lower average length. The distribution of fibril lengths measured by cryo-TEM and the distribution of the polymer chain contour lengths are similar, especially for shorter chains, and these features are correlated to network connectivity. We propose that the underlying fibril structure consists of bundles of polymer chains with a preferred orientation coincident with the fibril axis, while the fibril diameter is controlled by a circumferential helical pitch associated with the single chain Kuhn length and interactions between chains.

Original languageEnglish (US)
Pages (from-to)7767-7775
Number of pages9
JournalMacromolecules
Volume51
Issue number19
DOIs
StatePublished - Oct 9 2018

Fingerprint

Methylcellulose
Molecular weight
Gels
Polymers
Transmission electron microscopy
Gelation
X ray scattering
Chain length
Light scattering
Elasticity
Volume fraction
Visualization
Heating

How much support was provided by MRSEC?

  • Primary

Reporting period for MRSEC

  • Period 5

Cite this

Molecular Weight Dependence of Methylcellulose Fibrillar Networks. / Schmidt, Peter W.; Morozova, Svetlana; Owens, Paige M.; Adden, Roland; Li, Yongfu; Bates, Frank S.; Lodge, Timothy P.

In: Macromolecules, Vol. 51, No. 19, 09.10.2018, p. 7767-7775.

Research output: Contribution to journalArticle

Schmidt, Peter W. ; Morozova, Svetlana ; Owens, Paige M. ; Adden, Roland ; Li, Yongfu ; Bates, Frank S. ; Lodge, Timothy P. / Molecular Weight Dependence of Methylcellulose Fibrillar Networks. In: Macromolecules. 2018 ; Vol. 51, No. 19. pp. 7767-7775.
@article{05cd08838a1b430c9d6ac99cce913601,
title = "Molecular Weight Dependence of Methylcellulose Fibrillar Networks",
abstract = "Gelation of aqueous methylcellulose (MC) solutions upon heating has been shown to result from the formation of a network of semiflexible fibrils, with diameters of 15 ± 2 nm. Here, we investigate the impact of MC molecular weight on the elasticity and structure of aqueous gels at concentrations between 0.1 and 3 wt {\%}. Small-amplitude oscillatory shear measurements conducted at a fixed concentration reveal that the gel modulus increases monotonically by a factor of 5 for weight-average molecular weights (Mw) between 22 and 550 kg/mol. Small-angle X-ray scattering data, fit to a semiflexible cylinder model, demonstrate that the fibril radius, Kuhn length, and volume fraction are approximately constant throughout this molecular weight range. Small-angle light scattering shows that the fibrillar-rich and fibrillar-depleted domains within the gel are associated with an essentially invariant heterogeneity correlation length. Direct visualization by cryo-TEM reveals that lower molecular weight MC forms fibrils of lower average length. The distribution of fibril lengths measured by cryo-TEM and the distribution of the polymer chain contour lengths are similar, especially for shorter chains, and these features are correlated to network connectivity. We propose that the underlying fibril structure consists of bundles of polymer chains with a preferred orientation coincident with the fibril axis, while the fibril diameter is controlled by a circumferential helical pitch associated with the single chain Kuhn length and interactions between chains.",
author = "Schmidt, {Peter W.} and Svetlana Morozova and Owens, {Paige M.} and Roland Adden and Yongfu Li and Bates, {Frank S.} and Lodge, {Timothy P}",
year = "2018",
month = "10",
day = "9",
doi = "10.1021/acs.macromol.8b01292",
language = "English (US)",
volume = "51",
pages = "7767--7775",
journal = "Macromolecules",
issn = "0024-9297",
publisher = "American Chemical Society",
number = "19",

}

TY - JOUR

T1 - Molecular Weight Dependence of Methylcellulose Fibrillar Networks

AU - Schmidt, Peter W.

AU - Morozova, Svetlana

AU - Owens, Paige M.

AU - Adden, Roland

AU - Li, Yongfu

AU - Bates, Frank S.

AU - Lodge, Timothy P

PY - 2018/10/9

Y1 - 2018/10/9

N2 - Gelation of aqueous methylcellulose (MC) solutions upon heating has been shown to result from the formation of a network of semiflexible fibrils, with diameters of 15 ± 2 nm. Here, we investigate the impact of MC molecular weight on the elasticity and structure of aqueous gels at concentrations between 0.1 and 3 wt %. Small-amplitude oscillatory shear measurements conducted at a fixed concentration reveal that the gel modulus increases monotonically by a factor of 5 for weight-average molecular weights (Mw) between 22 and 550 kg/mol. Small-angle X-ray scattering data, fit to a semiflexible cylinder model, demonstrate that the fibril radius, Kuhn length, and volume fraction are approximately constant throughout this molecular weight range. Small-angle light scattering shows that the fibrillar-rich and fibrillar-depleted domains within the gel are associated with an essentially invariant heterogeneity correlation length. Direct visualization by cryo-TEM reveals that lower molecular weight MC forms fibrils of lower average length. The distribution of fibril lengths measured by cryo-TEM and the distribution of the polymer chain contour lengths are similar, especially for shorter chains, and these features are correlated to network connectivity. We propose that the underlying fibril structure consists of bundles of polymer chains with a preferred orientation coincident with the fibril axis, while the fibril diameter is controlled by a circumferential helical pitch associated with the single chain Kuhn length and interactions between chains.

AB - Gelation of aqueous methylcellulose (MC) solutions upon heating has been shown to result from the formation of a network of semiflexible fibrils, with diameters of 15 ± 2 nm. Here, we investigate the impact of MC molecular weight on the elasticity and structure of aqueous gels at concentrations between 0.1 and 3 wt %. Small-amplitude oscillatory shear measurements conducted at a fixed concentration reveal that the gel modulus increases monotonically by a factor of 5 for weight-average molecular weights (Mw) between 22 and 550 kg/mol. Small-angle X-ray scattering data, fit to a semiflexible cylinder model, demonstrate that the fibril radius, Kuhn length, and volume fraction are approximately constant throughout this molecular weight range. Small-angle light scattering shows that the fibrillar-rich and fibrillar-depleted domains within the gel are associated with an essentially invariant heterogeneity correlation length. Direct visualization by cryo-TEM reveals that lower molecular weight MC forms fibrils of lower average length. The distribution of fibril lengths measured by cryo-TEM and the distribution of the polymer chain contour lengths are similar, especially for shorter chains, and these features are correlated to network connectivity. We propose that the underlying fibril structure consists of bundles of polymer chains with a preferred orientation coincident with the fibril axis, while the fibril diameter is controlled by a circumferential helical pitch associated with the single chain Kuhn length and interactions between chains.

UR - http://www.scopus.com/inward/record.url?scp=85054135564&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85054135564&partnerID=8YFLogxK

U2 - 10.1021/acs.macromol.8b01292

DO - 10.1021/acs.macromol.8b01292

M3 - Article

AN - SCOPUS:85054135564

VL - 51

SP - 7767

EP - 7775

JO - Macromolecules

JF - Macromolecules

SN - 0024-9297

IS - 19

ER -