Gelation, Phase Separation, and Fibril Formation in Aqueous Hydroxypropylmethylcellulose Solutions

Timothy P. Lodge, Amanda L. Maxwell, Joseph R. Lott, Peter W. Schmidt, John W. McAllister, Svetlana Morozova, Frank S. Bates, Yongfu Li, Robert L. Sammler

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The thermoresponsive behavior of a hydroxypropylmethylcellulose (HPMC) sample in aqueous solutions has been studied by a powerful combination of characterization tools, including rheology, turbidimetry, cryogenic transmission electron microscopy (cryoTEM), light scattering, small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS). Consistent with prior literature, solutions with concentrations ranging from 0.3 to 3 wt % exhibit a sharp drop in the dynamic viscoelastic moduli G′ and G″ upon heating near 57 °C. The drop in moduli is accompanied by an abrupt increase in turbidity. All the evidence is consistent with this corresponding to liquid-liquid phase separation, leading to polymer-rich droplets in a polymer-depleted matrix. Upon further heating, the moduli increase, and G′ exceeds G″, corresponding to gelation. CryoTEM in dilute solutions reveals that HPMC forms fibrils at the same temperature range where the moduli increase. SANS and SAXS confirm the appearance of fibrils over a range of concentration, and that their average diameter is ca. 18 nm; thus gelation is attributable to formation of a sample-spanning network of fibrils. These results are compared in detail with the closely related and well-studied methylcellulose (MC). The HPMC fibrils are generally shorter, more flexible, and contain more water than with MC, and the resulting gel at high temperatures has a much lower modulus. In addition to the differences in fibril structure, the key distinction between HPMC and MC is that the former undergoes liquid-liquid phase separation prior to forming fibrils and associated gelation, whereas the latter forms fibrils first. These results and their interpretation are compared with the prior literature, in light of the relatively recent discovery of the propensity of MC and HPMC to self-assemble into fibrils on heating.

Original languageEnglish (US)
Pages (from-to)816-824
Number of pages9
JournalBiomacromolecules
Volume19
Issue number3
DOIs
StatePublished - Jan 1 2018

Fingerprint

Gelation
Methylcellulose
Phase separation
Liquids
Neutron scattering
X ray scattering
Heating
Turbidity
Polymer matrix
Rheology
Light scattering
Cryogenics
Gels
Transmission electron microscopy
Polymers
Temperature
Hypromellose Derivatives
Water

How much support was provided by MRSEC?

  • Primary

Reporting period for MRSEC

  • Period 4

PubMed: MeSH publication types

  • Journal Article
  • Research Support, U.S. Gov't, Non-P.H.S.

Cite this

Lodge, T. P., Maxwell, A. L., Lott, J. R., Schmidt, P. W., McAllister, J. W., Morozova, S., ... Sammler, R. L. (2018). Gelation, Phase Separation, and Fibril Formation in Aqueous Hydroxypropylmethylcellulose Solutions. Biomacromolecules, 19(3), 816-824. https://doi.org/10.1021/acs.biomac.7b01611

Gelation, Phase Separation, and Fibril Formation in Aqueous Hydroxypropylmethylcellulose Solutions. / Lodge, Timothy P.; Maxwell, Amanda L.; Lott, Joseph R.; Schmidt, Peter W.; McAllister, John W.; Morozova, Svetlana; Bates, Frank S.; Li, Yongfu; Sammler, Robert L.

In: Biomacromolecules, Vol. 19, No. 3, 01.01.2018, p. 816-824.

Research output: Contribution to journalArticle

Lodge, TP, Maxwell, AL, Lott, JR, Schmidt, PW, McAllister, JW, Morozova, S, Bates, FS, Li, Y & Sammler, RL 2018, 'Gelation, Phase Separation, and Fibril Formation in Aqueous Hydroxypropylmethylcellulose Solutions', Biomacromolecules, vol. 19, no. 3, pp. 816-824. https://doi.org/10.1021/acs.biomac.7b01611
Lodge, Timothy P. ; Maxwell, Amanda L. ; Lott, Joseph R. ; Schmidt, Peter W. ; McAllister, John W. ; Morozova, Svetlana ; Bates, Frank S. ; Li, Yongfu ; Sammler, Robert L. / Gelation, Phase Separation, and Fibril Formation in Aqueous Hydroxypropylmethylcellulose Solutions. In: Biomacromolecules. 2018 ; Vol. 19, No. 3. pp. 816-824.
@article{146956f5a3e743b0bedaf79b7197d453,
title = "Gelation, Phase Separation, and Fibril Formation in Aqueous Hydroxypropylmethylcellulose Solutions",
abstract = "The thermoresponsive behavior of a hydroxypropylmethylcellulose (HPMC) sample in aqueous solutions has been studied by a powerful combination of characterization tools, including rheology, turbidimetry, cryogenic transmission electron microscopy (cryoTEM), light scattering, small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS). Consistent with prior literature, solutions with concentrations ranging from 0.3 to 3 wt {\%} exhibit a sharp drop in the dynamic viscoelastic moduli G′ and G″ upon heating near 57 °C. The drop in moduli is accompanied by an abrupt increase in turbidity. All the evidence is consistent with this corresponding to liquid-liquid phase separation, leading to polymer-rich droplets in a polymer-depleted matrix. Upon further heating, the moduli increase, and G′ exceeds G″, corresponding to gelation. CryoTEM in dilute solutions reveals that HPMC forms fibrils at the same temperature range where the moduli increase. SANS and SAXS confirm the appearance of fibrils over a range of concentration, and that their average diameter is ca. 18 nm; thus gelation is attributable to formation of a sample-spanning network of fibrils. These results are compared in detail with the closely related and well-studied methylcellulose (MC). The HPMC fibrils are generally shorter, more flexible, and contain more water than with MC, and the resulting gel at high temperatures has a much lower modulus. In addition to the differences in fibril structure, the key distinction between HPMC and MC is that the former undergoes liquid-liquid phase separation prior to forming fibrils and associated gelation, whereas the latter forms fibrils first. These results and their interpretation are compared with the prior literature, in light of the relatively recent discovery of the propensity of MC and HPMC to self-assemble into fibrils on heating.",
author = "Lodge, {Timothy P.} and Maxwell, {Amanda L.} and Lott, {Joseph R.} and Schmidt, {Peter W.} and McAllister, {John W.} and Svetlana Morozova and Bates, {Frank S.} and Yongfu Li and Sammler, {Robert L.}",
year = "2018",
month = "1",
day = "1",
doi = "10.1021/acs.biomac.7b01611",
language = "English (US)",
volume = "19",
pages = "816--824",
journal = "Biomacromolecules",
issn = "1525-7797",
publisher = "American Chemical Society",
number = "3",

}

TY - JOUR

T1 - Gelation, Phase Separation, and Fibril Formation in Aqueous Hydroxypropylmethylcellulose Solutions

AU - Lodge, Timothy P.

AU - Maxwell, Amanda L.

AU - Lott, Joseph R.

AU - Schmidt, Peter W.

AU - McAllister, John W.

AU - Morozova, Svetlana

AU - Bates, Frank S.

AU - Li, Yongfu

AU - Sammler, Robert L.

PY - 2018/1/1

Y1 - 2018/1/1

N2 - The thermoresponsive behavior of a hydroxypropylmethylcellulose (HPMC) sample in aqueous solutions has been studied by a powerful combination of characterization tools, including rheology, turbidimetry, cryogenic transmission electron microscopy (cryoTEM), light scattering, small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS). Consistent with prior literature, solutions with concentrations ranging from 0.3 to 3 wt % exhibit a sharp drop in the dynamic viscoelastic moduli G′ and G″ upon heating near 57 °C. The drop in moduli is accompanied by an abrupt increase in turbidity. All the evidence is consistent with this corresponding to liquid-liquid phase separation, leading to polymer-rich droplets in a polymer-depleted matrix. Upon further heating, the moduli increase, and G′ exceeds G″, corresponding to gelation. CryoTEM in dilute solutions reveals that HPMC forms fibrils at the same temperature range where the moduli increase. SANS and SAXS confirm the appearance of fibrils over a range of concentration, and that their average diameter is ca. 18 nm; thus gelation is attributable to formation of a sample-spanning network of fibrils. These results are compared in detail with the closely related and well-studied methylcellulose (MC). The HPMC fibrils are generally shorter, more flexible, and contain more water than with MC, and the resulting gel at high temperatures has a much lower modulus. In addition to the differences in fibril structure, the key distinction between HPMC and MC is that the former undergoes liquid-liquid phase separation prior to forming fibrils and associated gelation, whereas the latter forms fibrils first. These results and their interpretation are compared with the prior literature, in light of the relatively recent discovery of the propensity of MC and HPMC to self-assemble into fibrils on heating.

AB - The thermoresponsive behavior of a hydroxypropylmethylcellulose (HPMC) sample in aqueous solutions has been studied by a powerful combination of characterization tools, including rheology, turbidimetry, cryogenic transmission electron microscopy (cryoTEM), light scattering, small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS). Consistent with prior literature, solutions with concentrations ranging from 0.3 to 3 wt % exhibit a sharp drop in the dynamic viscoelastic moduli G′ and G″ upon heating near 57 °C. The drop in moduli is accompanied by an abrupt increase in turbidity. All the evidence is consistent with this corresponding to liquid-liquid phase separation, leading to polymer-rich droplets in a polymer-depleted matrix. Upon further heating, the moduli increase, and G′ exceeds G″, corresponding to gelation. CryoTEM in dilute solutions reveals that HPMC forms fibrils at the same temperature range where the moduli increase. SANS and SAXS confirm the appearance of fibrils over a range of concentration, and that their average diameter is ca. 18 nm; thus gelation is attributable to formation of a sample-spanning network of fibrils. These results are compared in detail with the closely related and well-studied methylcellulose (MC). The HPMC fibrils are generally shorter, more flexible, and contain more water than with MC, and the resulting gel at high temperatures has a much lower modulus. In addition to the differences in fibril structure, the key distinction between HPMC and MC is that the former undergoes liquid-liquid phase separation prior to forming fibrils and associated gelation, whereas the latter forms fibrils first. These results and their interpretation are compared with the prior literature, in light of the relatively recent discovery of the propensity of MC and HPMC to self-assemble into fibrils on heating.

UR - http://www.scopus.com/inward/record.url?scp=85043588361&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85043588361&partnerID=8YFLogxK

U2 - 10.1021/acs.biomac.7b01611

DO - 10.1021/acs.biomac.7b01611

M3 - Article

C2 - 29489329

AN - SCOPUS:85043588361

VL - 19

SP - 816

EP - 824

JO - Biomacromolecules

JF - Biomacromolecules

SN - 1525-7797

IS - 3

ER -