Inverse Thermoreversible Mechanical Stiffening and Birefringence in a Methylcellulose/Cellulose Nanocrystal Hydrogel

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Hynninen, Ville
dc.contributor.author Hietala, Sami
dc.contributor.author McKee, Jason R.
dc.contributor.author Murtomäki, Lasse
dc.contributor.author Rojas Gaona, Orlando
dc.contributor.author Ikkala, Olli
dc.contributor.author Nonappa, Nonappa
dc.date.accessioned 2018-10-02T11:30:49Z
dc.date.available 2018-10-02T11:30:49Z
dc.date.issued 2018-05-07
dc.identifier.citation Hynninen , V , Hietala , S , McKee , J R , Murtomäki , L , Rojas Gaona , O , Ikkala , O & Nonappa , N 2018 , ' Inverse Thermoreversible Mechanical Stiffening and Birefringence in a Methylcellulose/Cellulose Nanocrystal Hydrogel ' BIOMACROMOLECULES , vol 19 , no. 7 , pp. 2795-2804 . DOI: 10.1021/acs.biomac.8b00392 en
dc.identifier.issn 1525-7797
dc.identifier.issn 1526-4602
dc.identifier.other PURE UUID: 57c63aa6-8b66-40cc-a94d-4be377e8a0ff
dc.identifier.other PURE ITEMURL: https://research.aalto.fi/en/publications/inverse-thermoreversible-mechanical-stiffening-and-birefringence-in-a-methylcellulosecellulose-nanocrystal-hydrogel(57c63aa6-8b66-40cc-a94d-4be377e8a0ff).html
dc.identifier.other PURE FILEURL: https://research.aalto.fi/files/28294490/acs.biomac.8b00392.pdf
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/34119
dc.description.abstract We show that composite hydrogels comprising methyl cellulose (MC) and cellulose nanocrystal (CNC) colloidal rods display a reversible and enhanced rheological storage modulus and optical birefringence upon heating, i.e., inverse thermoreversibility. Dynamic rheology, quantitative polarized optical microscopy, isothermal titration calorimetry (ITC), circular dichroism (CD), and scanning and transmission electron microscopy (SEM and TEM) were used for characterization. The concentration of CNCs in aqueous media was varied up to 3.5 wt % (i.e, keeping the concentration below the critical aq concentration) while maintaining the MC aq concentration at 1.0 wt %. At 20 °C, MC/CNC underwent gelation upon passing the CNC concentration of 1.5 wt %. At this point, the storage modulus (G′) reached a plateau, and the birefringence underwent a stepwise increase, thus suggesting a percolative phenomenon. The storage modulus (G′) of the composite gels was an order of magnitude higher at 60 °C compared to that at 20 °C. ITC results suggested that, at 60 °C, the CNC rods were entropically driven to interact with MC chains, which according to recent studies collapse at this temperature into ring-like, colloidal-scale persistent fibrils with hollow cross-sections. Consequently, the tendency of the MC to form more persistent aggregates promotes the interactions between the CNC chiral aggregates towards enhanced storage modulus and birefringence. At room temperature, ITC shows enthalpic binding between CNCs and MC with the latter comprising aqueous, molecularly dispersed polymer chains that lead to looser and less birefringent material. TEM, SEM, and CD indicate CNC chiral fragments within a MC/CNC composite gel. Thus, MC/CNC hybrid networks offer materials with tunable rheological properties and access to liquid crystalline properties at low CNC concentrations. en
dc.format.extent 2795-2804
dc.format.mimetype application/pdf
dc.language.iso en en
dc.relation.ispartofseries BIOMACROMOLECULES en
dc.relation.ispartofseries Volume 19, issue 7 en
dc.rights openAccess en
dc.subject.other 114 Physical sciences en
dc.title Inverse Thermoreversible Mechanical Stiffening and Birefringence in a Methylcellulose/Cellulose Nanocrystal Hydrogel en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.contributor.department Molecular Materials
dc.contributor.department University of Helsinki
dc.contributor.department Betulium Oy
dc.contributor.department Physical Chemistry and Electrochemistry
dc.contributor.department Bio-based Colloids and Materials
dc.contributor.department Department of Bioproducts and Biosystems
dc.contributor.department Department of Applied Physics en
dc.contributor.department Department of Chemistry and Materials Science en
dc.subject.keyword 114 Physical sciences
dc.identifier.urn URN:NBN:fi:aalto-201810025202
dc.identifier.doi 10.1021/acs.biomac.8b00392
dc.type.version publishedVersion


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