Effect of Fiber Alignment on Optical Properties of Cellulose Nanocrystal Films

Le, Edward; Wang, Wei‐Chih; Liu, Chao Shih; Wang, Chih‐Wei

doi:10.1109/isot.2014.80

Cited by 3 publications

(3 citation statements)

References 13 publications

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“…Despite quantitatively observing the general alignment with the micrographs and further confirming by integrating the pixel's gray values transversally to the printing direction (Figure 2e,f), it was not possible to distinguish the LC mesogens alignment from the well-established alignment of the cellulose particles. 32,33,44,45 Nevertheless, samples that were cured at 60 °C, above the nematic to isotropic phase transition temperature (T NI ) of the uncured resin, presented only a slight change in light intensity when analyzed at a 45°angle with respect to the polarizer. This change is assumed to come from the alignment of CNC, indicating that the isotropic LC mesogens did not present an overall alignment (SI Figure S3).…”

Section: Methodsmentioning

confidence: 99%

Photoresponsive Movement in 3D Printed Cellulose Nanocomposites

Müller

Demongeot

Vaucher

et al. 2022

ACS Appl. Mater. Interfaces

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Photoresponsive soft liquid crystalline elastomers (LCEs) transform light’s energy into dynamic shape changes and are considered promising candidates for production of soft robotic or muscle-like devices. 3D printing allows access to elaborated geometries as well as control of the photoactuated movements; however, this development is still in its infancy and only a limited choice of LCE is yet available. Herein, we propose to introduce biocompatible and sustainable cellulose nanocrystals (CNC) into an LCE in order to facilitate the printing process by direct ink writing (DIW) and to benefit from the anisotropic mechanical properties resulting from the extrusion-induced alignment of such nanoparticles. After a first printing step where the rheological influence of CNC allows the production of self-standing structures, a doping process introduces the azobenzene photoswitches in the composite, conferring photomechanical behaviors to the printed material. This approach results in soft composites, with an elastic modulus around 20–30 MPa, that present fully reversible photosoftening of 35% and photomechanical actuation occurring less than 3 s after illumination. The presence of CNC as reinforcement particles allows precise tailoring of mechanical properties, rendering such phototriggered materials suitable candidates for the production of actuators and 3D structures with particular and dynamic load cases.

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Section: Methodsmentioning

confidence: 99%

Photoresponsive Movement in 3D Printed Cellulose Nanocomposites

Müller

Demongeot

Vaucher

et al. 2022

ACS Appl. Mater. Interfaces

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“…Printed samples prepared with the CNC-DR1 ink revealed a strong alignment of the particles along the printing direction, when observed with an optical microscope equipped with cross polarizer filters (Figure c). The well-known birefringence , of CNC causes the strong change in intensity observed in the polarized microscopy images. CNC aligned to the light polarization (0°) allow undisturbed light transmission and its cancellation by the analyzer filter, leading to a dark image.…”

Section: Resultsmentioning

confidence: 99%

Functionalized Cellulose Nanocrystals as Active Reinforcements for Light-Actuated 3D-Printed Structures

et al. 2022

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Conventional manufacturing techniques allow the production of photoresponsive cellulose nanocrystals (CNC)-based composites that can reversibly modify their optical, mechanical, or chemical properties upon light irradiation. However, such materials are often limited to 2D films or simple shapes and do not benefit from spatial tailoring of mechanical properties resulting from CNC alignment. Herein, we propose the direct ink writing (DIW) of 3D complex structures that combine CNC reinforcement effects with photoinduced responses. After grafting azobenzene photochromes onto the CNC surfaces, up to 15 wt % of modified nanoparticles can be introduced into a polyurethane acrylate matrix. The influence of CNC on rheological properties allows DIW of self-standing 3D structures presenting local shear-induced alignment of the active reinforcements. The printed composites, with longitudinal elastic modulus of 30 MPa, react to visible-light irradiation with 30–50% reversible softening and present a shape memory behavior. The phototunable energy absorption of 3D complex structures is demonstrated by harnessing both geometrical and photoresponsive effects, enabling dynamic mechanical responses to environmental stimuli. Functionalized CNC in 3D printable inks have the potential to allow the rapid prototyping of several devices with tailored mechanical properties, suitable for applications requiring dynamic responses to environmental changes.

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“…Self-assembled CNC membranes with a chiral nematic crystal structure can reflect left-handed circularly polarized light, ,,, while nanofabricated CNC membranes with alignment structures display positive uniaxial birefringence. − With combinations of such optically active structures, Janus-like CNC membranes exhibit asymmetric optical properties, enabling advanced light management functions. Recently, bilayer chiral nematic photonic CNC membranes with different helical pitches were constructed by a straightforward sequential casting procedure .…”

Section: Janus Cnm Membranes and Their Applicationmentioning

confidence: 99%

Naturally Derived Janus Cellulose Nanomaterials: Anisotropic Cellulose Nanomaterial Building Blocks and Their Assembly into Asymmetric Structures

et al. 2022

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Naturally derived cellulose nanomaterials (CNMs) with desirable physicochemical properties have drawn tremendous attention for their versatile applications in a broad range of fields. More recently, Janus amphiphilic cellulose nanomaterial particles with asymmetric structures (i.e., reducing and nonreducing ends and crystalline and amorphous domains) have been in the spotlight, offering a rich and sophisticated toolbox for Janus nanomaterials. With careful surface and interfacial engineering, Janus CNM particles have demonstrated great potential as surface modifiers, emulsifiers, stabilizers, compatibilizers, and dispersants in emulsions, nanocomposites, and suspensions. Naturally derived Janus CNM particles offer a fascinating opportunity for scaling up the production of self-standing Janus CNM membranes. Nevertheless, most Janus CNM membranes to date are constructed by asymmetric fabrication or asymmetric modification without considering the Janus traits of CNM particles. More future research should focus on the self-assembly of Janus CNM particles into bulk self-standing Janus CNM membranes to enable more straightforward and sustainable approaches for Janus membranes. This review explores the fabrication, structure–property relationship, and Janus configuration mechanisms of Janus CNM particles and membranes. Janus CNM membranes are highlighted for their versatile applications in liquid, thermal, and light management. This review also highlights the significant advances and future perspectives in the construction and application of sustainable Janus CNM particles and membranes.

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Effect of Fiber Alignment on Optical Properties of Cellulose Nanocrystal Films

Cited by 3 publications

References 13 publications

Photoresponsive Movement in 3D Printed Cellulose Nanocomposites

Photoresponsive Movement in 3D Printed Cellulose Nanocomposites

Functionalized Cellulose Nanocrystals as Active Reinforcements for Light-Actuated 3D-Printed Structures

Naturally Derived Janus Cellulose Nanomaterials: Anisotropic Cellulose Nanomaterial Building Blocks and Their Assembly into Asymmetric Structures

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