Optical Properties of Slot‐Die Coated Hybrid Colloid/Cellulose‐Nanofibril Thin Films

Harder, Constantin; Alexakis, Alexandros Efraim; Bulut, Yusuf; Xiong, Shuxian; Sochor, Benedikt; Pan, Guangjiu; Zhong, Hao‐Jie; Goordeyeva, Korneliya; Reus, Manuel A.; Körstgens, Volker; Jeromin, Arno; Keller, Thomas F.; Söderberg, Daniel; Malmström, Eva; Müller‐Buschbaum, Peter; Roth, Stephan V.

doi:10.1002/adom.202203058

Cited by 6 publications

(6 citation statements)

References 81 publications

(122 reference statements)

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“…If the temperature is higher than T g , the colloid melts imbibes into the CNF network and adheres to the CNF. The melting of the colloids is corroborated by our previous work …”

Section: Resultsmentioning

confidence: 99%

Poly(sobrerol methacrylate) Colloidal Inks Sprayed onto Cellulose Nanofibril Thin Films for Anticounterfeiting Applications

Harder,

Betker,

Alexakis

et al. 2024

ACS Appl. Nano Mater.

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The colloidal layer formation on porous materials is a crucial step for printing and applying functional coatings, which can be used to fabricate anticounterfeiting paper. The deposition of colloidal layers and subsequent thermal treatment allows for modifying the hydrophilicity of the surface of a material. In the present work, wood-based colloidal inks are applied by spray deposition on spray-deposited porous cellulose nanofibrils (CNF) films. The surface modification by thermal annealing of the fabricated colloid-cellulose hybrid thin films is investigated in terms of layering and hydrophobicity. The polymer colloids in the inks are core−shell nanoparticles with different sizes and glass transition temperatures (T g ), thus enabling different and low thermal treatment temperatures. The ratio between the core polymers, poly(sobrerol methacrylate) (PSobMA), and poly(-butyl methacrylate) (PBMA) determines the T g and hence allows for tailoring of the T g . The layer formation of the colloidal inks on the porous CNF layer depends on the imbibition properties of the CNF layer which is determined by their morphology. The water adhesion of the CNF layer decreases due to the deposition of the colloids and thermal treatment except for the colloids with a size smaller than the void size of the porous CNF film. In this case, the colloids are imbibed into the CNF layer when T g of the colloids is reached and the polymer chains transit in a mobile phase. Tailored aggregate and nanoscale-embedded hybrid structures are achieved depending on the colloid properties. The imbibition of these colloids into the porous CNF films is verified with grazing incidence small-angle X-ray scattering. This study shows a route for tuning the nanoscale structure and macroscopic physicochemical properties useful for anticounterfeiting paper.

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“…If the temperature is higher than T g , the colloid melts imbibes into the CNF network and adheres to the CNF. The melting of the colloids is corroborated by our previous work …”

Section: Resultsmentioning

confidence: 99%

Poly(sobrerol methacrylate) Colloidal Inks Sprayed onto Cellulose Nanofibril Thin Films for Anticounterfeiting Applications

Harder,

Betker,

Alexakis

et al. 2024

ACS Appl. Nano Mater.

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“…For C/M-EtOH, the orientation on both meso-/nanoscale are decreased due to the rough surface, large porosity, and residual deformation. The presence of residual deformation in CNF should be a general behavior; when smaller molecules or colloids are in contact with the CNF network, this small molecule can spontaneously fill the voids, relaxing some of the residual strain. One may note that grazing incidence X-ray scattering studies can provide details about the nature of voids in the structure …”

Section: Resultsmentioning

confidence: 99%

“…One may note that grazing incidence X-ray scattering studies can provide details about the nature of voids in the structure. 36 We further investigated the mechanical properties of these samples after drying. As shown in Figure S19 and Table S2, addition of MTM increases the Young's modulus.…”

Section: Sample Preparation and X-ray Measurements Duringmentioning

confidence: 99%

Residual Strain and Nanostructural Effects during Drying of Nanocellulose/Clay Nanosheet Hybrids: Synchrotron X-ray Scattering Results

Chen

Medina

et al. 2023

ACS Nano

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Cellulose nanofibrils (CNF) with 2D silicate nanoplatelet reinforcement readily form multifunctional composites by vacuum-assisted self-assembly from hydrocolloidal mixtures. The final nanostructure is formed during drying. The crystalline nature of CNF and montmorillonite (MTM) made it possible to use synchrotron X-ray scattering (WAXS, SAXS) to monitor structural development during drying from water and from ethanol. Nanostructural changes in the CNF and MTM crystals were investigated. Changes in the out-of-plane orientation of CNF and MTM were determined. Residual drying strains previously predicted from theory were confirmed in both cellulose and MTM platelets due to capillary forces. The formation of tactoid platelet stacks could be followed. We propose that after filtration, the constituent nanoparticles in the swollen, solid gel already have a “fixed” location, although self-assembly and ordering processes take place during drying.

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“…In addition to the self-assembly strategy, external force methods, such as shearing, , pressing, , or slot-die coating, have been used for arranging colloidal particles into well-ordered structures. Among these methods, hot-pressing has been employed to produce mechanically stable and high-quality colored CPC films, mainly because of its ability to maintain a uniform force field.…”

Section: Introductionmentioning

confidence: 99%

Colloidal Photonic Composites with a Long-Range Order by Hot-Pressing Polymer Brush-Grafted Silica Colloids

Zhang,

Lyu,

Chen

et al. 2024

ACS Appl. Mater. Interfaces

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Colloidal photonic composites (CPCs) are unique optical materials that combine flexible and responsive polymers with colloidal photonic crystals, and they have promising applications in colorful displays, optical anticounterfeiting, and visual sensors. However, conventional self-assembly strategies for constructing CPCs via solvent evaporation have faced limitations due to the meticulous regulation required during the evaporation process and typically long preparation durations. Here, we present an external force method to achieve a long-range ordered arrangement in CPCs by hot-pressing poly(2-[[(butylamino)carbonyl]oxy]ethyl acrylate (PBCOE)) brush-grafted silica colloidal particles (SiO 2 -g-PBCOE). We show that the hot-pressing conditions (i.e., temperature and pressure) and the silica volume fraction (φ silica ) of the SiO 2 -g-PBCOE colloidal particles play crucial roles in determining their ordering and optical properties. By optimization of the hot-pressing temperature up to 100 °C and pressure of 5 MPa, a long-range ordered arrangement of SiO 2 -g-PBCOE colloidal particles with a φ silica of 20.3% can be achieved. For the effect of structural features, our findings reveal that SiO 2 -g-PBCOE colloidal particles featuring a higher φ silica are more prone to obtain a long-range ordered arrangement compared to a lower φ silica under hot-pressing conditions at relatively low temperature and pressure (50 °C and 5 MPa), which is mainly attributed to the chain entanglement and hydrogen bonding interactions induced by grafted longer polymer brushes, leading to additional energy inputs and weakening the ordering. Significantly, the critical φ silica (φ c ) of SiO 2 -g-PBCOE colloidal particles is discerned, strongly influencing the optical properties of the hot-pressed films. Specifically, a hot-pressed SiO 2 -g-PBCOE film with a critical φ silica of 29.3% displays enhanced optical properties characterized by intensified reflection peaks, narrowed full width at half-maximum (FWHM), and brilliant structural colors. Notably, in this work, we reveal the mechanism of hot-pressing-driven core−shell colloidal particle ordering and the key factors affecting the ordering of colloidal particles, i.e., chain entanglement and hydrogen-bonding interactions, which play a crucial role in obtaining CPCs with controllable structures. Moreover, angle-dependent structural color is observed in the hot-pressed SiO 2 -g-PBCOE film with a φ silica content of 29.3% due to the unique attributes of the highly ordered arrangement, while the films exhibit mechanochromic properties due to chain entanglement and hydrogen bonding interactions. This work provides valuable insights into the rapid construction of highly ordered CPCs and establishes a solid foundation for external force-assisted ordering of colloidal particles.

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Optical Properties of Slot‐Die Coated Hybrid Colloid/Cellulose‐Nanofibril Thin Films

Cited by 6 publications

References 81 publications

Poly(sobrerol methacrylate) Colloidal Inks Sprayed onto Cellulose Nanofibril Thin Films for Anticounterfeiting Applications

Poly(sobrerol methacrylate) Colloidal Inks Sprayed onto Cellulose Nanofibril Thin Films for Anticounterfeiting Applications

Residual Strain and Nanostructural Effects during Drying of Nanocellulose/Clay Nanosheet Hybrids: Synchrotron X-ray Scattering Results

Colloidal Photonic Composites with a Long-Range Order by Hot-Pressing Polymer Brush-Grafted Silica Colloids

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