Exploiting the Thermotropic Behavior of Hydroxypropyl Cellulose to Produce Edible Photonic Pigments

Ming, Siyi; Zhang, Xiaotian; Chan, Chun Lam Clement; Wang, Zhen; Bay, Mélanie M.; Parker, Richard; Vignolini, Silvia

doi:10.1002/adsu.202200469

Cited by 8 publications

(10 citation statements)

References 46 publications

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“…They could also explain the pitch difference reported between polydomain suspension in large capillaries and the monodomain Frank-Pryce-like droplets prior to kinetic arrest. 287 This explanation was also recently proposed to account for highly buckled structures in dried cholesteric solutions of hydroxypropyl cellulose, 392,393 a system for which 2.5 ≤ ν ≤ 4. Importantly, at the onset of the HH instability there are no focal conics, but rather a simple undulation of the cholesteric helical axis, which is exactly the structure visible in the reported cross-sectional view (Figure 19c) and much different from the structure proposed in ref 388.…”

Section: Elastic Instabilitiesmentioning

confidence: 84%

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications

Frka-Petesic,

Parton,

Honorato-Rios

et al. 2023

Chem. Rev.

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Widespread concerns over the impact of human activity on the environment have resulted in a desire to replace artificial functional materials with naturally derived alternatives. As such, polysaccharides are drawing increasing attention due to offering a renewable, biodegradable, and biocompatible feedstock for functional nanomaterials. In particular, nanocrystals of cellulose and chitin have emerged as versatile and sustainable building blocks for diverse applications, ranging from mechanical reinforcement to structural coloration. Much of this interest arises from the tendency of these colloidally stable nanoparticles to self-organize in water into a lyotropic cholesteric liquid crystal, which can be readily manipulated in terms of its periodicity, structure, and geometry. Importantly, this helicoidal ordering can be retained into the solid-state, offering an accessible route to complex nanostructured films, coatings, and particles. In this review, the process of forming iridescent, structurally colored films from suspensions of cellulose nanocrystals (CNCs) is summarized and the mechanisms underlying the chemical and physical phenomena at each stage in the process explored. Analogy is then drawn with chitin nanocrystals (ChNCs), allowing for key differences to be critically assessed and strategies toward structural coloration to be presented. Importantly, the progress toward translating this technology from academia to industry is summarized, with unresolved scientific and technical questions put forward as challenges to the community.

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Section: Elastic Instabilitiesmentioning

confidence: 84%

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications

Frka-Petesic,

Parton,

Honorato-Rios

et al. 2023

Chem. Rev.

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“…Temperature sensitivity is an inherent property of HPC mesophase. Typically, at higher temperatures, the structural color of HPC CLCs red-shifts due to increase of p. [39][40][41] We reasoned that the as-prepared HPC microbubbles would retain this property since the ETPTA resin shell provided a stable and transparent shield. In addition, AM molecules can form hydrogen bonds with both HPC and water molecules (Figure 6A), which facilitates the self-assembly of HPC and does not impede the intrinsic temperature-responsiveness of HPC (Figure 6B).…”

Section: Resultsmentioning

confidence: 99%

Bioinspired Confined Assembly of Cellulosic Cholesteric Liquid Crystal Bubbles

Wang,

Zhang,

Wang

et al. 2024

Advanced Science

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Construction of biomimetic models for structural color evolution not only gives new photonic phenomena but also provide cues for biological morphogenesis. Here, a novel confined self‐assembly method is proposed for the generation of hydroxypropyl cellulose (HPC)‐based cholesteric liquid crystals (CLCs) microbubbles. The assembly process relies on the combination of droplet microfluidics, solvent extraction, and a volume confined environment. The as‐prepared HPC structural color microbubbles have a transparent shell, an orderly arranged cholesteric liquid crystal (CLC) middle layer, and an innermost bubble core. The size of the microbubble, shell thickness, and the color of the CLC layer can be adjusted by altering the microfluidic parameters. Intriguingly, benefited from the compartmentalization effect provided by droplet microfluidics, microbubbles with multiple cores of different color combinations are generated under precise control. The self‐assembled CLCs microbubbles have bright structural color, suspending ability, and good temperature‐sensitive characteristics, making them ideal underwater sensors. The present confined assembly approach will shed light on creating novel photonic structures and the HPC microbubble will find widespread applications in multifunctional sensing, optical display, and other related fields are believed.

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“…Furthermore, they were found to give a colorimetric response to changes in temperature, pressure, and solvent environment. Alternatively, to produce edible photonic pigments, an emulsified HPC mesophase can be dried at elevated temperature, resulting in solid microparticles of pure HPC with visible color (Figure d,e) . By exploiting the thermotropic behavior of the HPC mesophase, the final pitch could be tuned solely via the drying temperature, allowing for a range of colors to be produced from a single formulation.…”

Section: Polymer Mesophases For Responsive Structural Colormentioning

confidence: 99%

Bioinspired Photonic Materials from Cellulose: Fabrication, Optical Analysis, and Applications

et al. 2023

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Metrics & MoreArticle RecommendationsCONSPECTUS: Polysaccharides are a class of biopolymers that are widely exploited in living organisms for a diversity of applications, ranging from structural reinforcement to energy storage. Among the numerous types of polysaccharides found in the natural world, cellulose is the most abundant and widespread, as it is found in virtually all plants. Cellulose is typically organized into nanoscale crystalline fibrils within the cell wall to give structural integrity to plant tissue. However, in several species, such fibrils are organized into helicoidal nanostructures with a periodicity comparable to visible light (i.e., in the range 250−450 nm), resulting in structural coloration. As such, when taking bioinspiration as a design principle, it is clear that helicoidal cellulose architectures are a promising approach to developing sustainable photonic materials. Different forms of cellulose-derived materials have been shown to produce structural color by exploiting self-assembly processes. For example, crystalline nanoparticles of cellulose can be extracted from natural sources, such as cotton or wood, by strong acid hydrolysis. Such "cellulose nanocrystals" (CNCs) have been shown to form colloidal suspensions in water that can spontaneously self-organize into a cholesteric liquid crystal phase, mimicking the natural helicoidal architecture. Upon drying, this nanoscale ordering can be retained into the solid state, enabling the specific reflection of visible light. Using this approach, colors from across the entire visible spectrum can be produced, alongside striking visual effects such as iridescence or a metallic shine. Similarly, polymeric cellulose derivatives can also organize into a cholesteric liquid crystal. In particular, edible hydroxypropyl cellulose (HPC) is known to produce colorful mesophases at high concentrations in water (ca. 60−70 wt %). This solution state behavior allows for interesting visual effects such as mechanochromism (enabling its use in low-cost colorimetric pressure or strain sensors), while trapping the structure into the solid state enables the production of structurally colored films, particles and 3D printed objects.In this article, we summarize the state-of-the-art for CNC and HPC-based photonic materials, encompassing the underlying selfassembly processes, strategies to design their photonic response, and current approaches to translate this burgeoning green technology toward commercial application in a wide range of sectors, from packaging to cosmetics and food. This overview is supported by a summary of the analytical techniques required to characterize these photonic materials and approaches to model their optical response. Finally, we present several unresolved scientific questions and outstanding technical challenges that the wider community should seek to address to develop these sustainable photonic materials.

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Exploiting the Thermotropic Behavior of Hydroxypropyl Cellulose to Produce Edible Photonic Pigments

Cited by 8 publications

References 46 publications

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications

Structural Color from Cellulose Nanocrystals or Chitin Nanocrystals: Self-Assembly, Optics, and Applications

Bioinspired Confined Assembly of Cellulosic Cholesteric Liquid Crystal Bubbles

Bioinspired Photonic Materials from Cellulose: Fabrication, Optical Analysis, and Applications

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