References of "Schütz, Christina"
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See detailCorrelation between structural properties and iridescent colors of cellulose nanocrystalline films
Licen, M. V.; Majaron, B.; Noh, Junghyun UL et al

in Cellulose (2016)

We investigate the effect of shear flow applied during the drying of aqueous suspension of cellulose nanocrystals on optical reflective properties and structural characteristics of the resulting ... [more ▼]

We investigate the effect of shear flow applied during the drying of aqueous suspension of cellulose nanocrystals on optical reflective properties and structural characteristics of the resulting solidified films. Shear flow can significantly improve internal structural homogeneity of the films, while its effect on optical reflective properties is relatively minor. The measured width of the selective reflection peak is an order of magnitude larger than expected for an ideal helically modulated structure, which reflects a distribution of pitch values and possibly also of regimes of distorted helical modulation. We attribute these imperfections to the broad size distribution of the cellulose nanocrystals. [less ▲]

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See detailRod packing in chiral nematic cellulose nanocrystal dispersions studied by small angle X-ray scattering and laser diffraction
Schütz, Christina; Agthe, Michael; Fall, Andreas et al

in Langmuir (2015), 31(23), 6507-6513

The packing of cellulose nanocrystals (CNC) in the anisotropic chiral nematic phase has been investigated over a wide concentration range by small angle X-ray scattering (SAXS) and laser diffraction. The ... [more ▼]

The packing of cellulose nanocrystals (CNC) in the anisotropic chiral nematic phase has been investigated over a wide concentration range by small angle X-ray scattering (SAXS) and laser diffraction. The average separation distance between the CNCs and the average pitch of the chiral nematic phase have been determined over the entire isotropic-anisotropic biphasic region. The average separation distances range from 51 nm, at the onset of the anisotropic phase formation, to 25 nm above 6 vol% (fully liquid crystalline phase) whereas the average pitch varies from 15.5 μm down to ≈2 μm as φ increases from 2.5 up to 6.5 vol%. Using the cholesteric order, we determine that the twist angle between neighboring CNCs increases from about 1 ° up to 4 ° as φ increases from 2.5 up to 6.5 vol%. The dependence of the twisting on the volume fraction was related to the increase in the magnitude of the repulsive interactions between the charged rods as the average separation distance decrease. [less ▲]

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See detailMacroscopic control of helix orientation in films dried from cholesteric liquid crystalline cellulose nanocrystal suspensions

Park, Ji Hyun; Noh, Junghyun UL; Schütz, Christina et al

in Chemphyschem : A European Journal of Chemical Physics and Physical Chemistry (2014), 15(7), 1477-1484

The intrinsic ability of cellulose nanocrystals (CNCs) to self-organize into films and bulk materials with helical order in a cholesteric liquid crystal is scientifically intriguing and potentially ... [more ▼]

The intrinsic ability of cellulose nanocrystals (CNCs) to self-organize into films and bulk materials with helical order in a cholesteric liquid crystal is scientifically intriguing and potentially important for the production of renewable multifunctional materials with attractive optical properties. A major obstacle, however, has been the lack of control of helix direction, which results in a defect-rich, mosaic-like domain structure. Herein, a method for guiding the helix during film formation is introduced, which yields dramatically improved uniformity, as confirmed by using polarizing optical and scanning electron microscopy. By raising the CNC concentration in the initial suspension to the fully liquid crystalline range, a vertical helix orientation is promoted, as directed by the macroscopic phase boundaries. Further control of the helix orientation is achieved by subjecting the suspension to a circular shear flow during drying. [less ▲]

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See detailCellulose nanocrystal-based materials: from liquid crystal self-assembly and glass formation to multifunctional thin films
Lagerwall, Jan UL; Schütz, Christina; Salajkova, Michaela et al

in NPG Asia Materials (2014), 6(1), 80

Cellulose nanocrystals (CNCs), produced by the acid hydrolysis of wood, cotton or other cellulose-rich sources, constitute a renewable nanosized raw material with a broad range of envisaged uses: for ... [more ▼]

Cellulose nanocrystals (CNCs), produced by the acid hydrolysis of wood, cotton or other cellulose-rich sources, constitute a renewable nanosized raw material with a broad range of envisaged uses: for example, in composites, cosmetics and medical devices. The intriguing ability of CNCs to self-organize into a chiral nematic (cholesteric) liquid crystal phase with a helical arrangement has attracted significant interest, resulting in much research effort, as this arrangement gives dried CNC films a photonic band gap. The films thus acquire attractive optical properties, creating possibilities for use in applications such as security papers and mirrorless lasing. In this critical review, we discuss the sensitive balance between glass formation and liquid crystal self-assembly that governs the formation of the desired helical structure. We show that several as yet unclarified observations—some constituting severe obstacles for applications of CNCs—may result from competition between the two phenomena. Moreover, by comparison with the corresponding self-assembly processes of other rod-like nanoparticles, for example, carbon nanotubes and fd virus particles, we outline how further liquid crystal ordering phenomena may be expected from CNCs if the suspension parameters can be better controlled. Alternative interpretations of some unexpected phenomena are provided, and topics for future research are identified, as are new potential application strategies. [less ▲]

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