Assembly of AIEgen‐Based Fluorescent Metal–Organic Framework Nanosheets and Seaweed Cellulose Nanofibrils for Humidity Sensing and UV‐Shielding

Abstract

Integrating synthetic low‐dimensional nanomaterials such as metal–organic framework (MOF) nanosheets with a sustainable biopolymer is a promising strategy to endow composites with attractive structural and functional properties for expanded applications. Herein, aggregation‐induced‐emission luminogen (AIEgen)‐based MOF bulk crystals are successfully exfoliated into ultrathin 2D nanosheets. Seaweed cellulose nanofibrils (CNFs) are assembled with low amounts (0.3 to 4.0 wt%) of the 2D nanosheets to generate luminescent composites. The 2D nanosheets are adsorbed onto the CNFs in dilute water suspensions owing to the flexibility of the MOF nanosheets and the high aspect ratio of the CNFs. Transparent films are prepared by solution casting from a water suspension of the CNF‐MOF assembly. The fluorescence emission of the composite films is enhanced because of the favored affinity between MOF nanosheets and CNFs. Remarkably, these films demonstrate excellent UV‐shielding capacity and high optical transmittance at the visible wavelength range. The composite films also show reversible changes in fluorescence emission intensity in response to ambient humidity. The tensile strength and modulus of the composite films are also enhanced owing to the increased adhesion between CNFs through the adsorbed MOF nanosheets. This work provides a novel pathway to fabricate luminescent CNFs‐based composites with tunable optical properties for functional materials.

Rational Design of Stable Fluorescent and Hydrophobic Cellulose-based Film for Full-band UV-blocking by Surface Modification

“…(Jancic et al, 2021) Moreover, TOCNF-MDF lm had high transmittance at 550 nm while it can only block 52.8% of UVA. (Tan et al, 2022) However, in this work, the surface modi cation process not only preserves the high light transmittance (86% transmittance at 550 nm) of the lm, but also render the material excellent UV-shielding ability (almost 100% UV-blocking) .…”

Metal–Organic Frameworks and Their Composites for Environmental Applications

“…The principle of solvothermal method resembles that of hydrothermal method, but the difference is that the solvent used is not limited to water. [97][98][99][100] There are three main steps: 1) uni-formly dispersing the raw materials in an organic solvents; 2) transferring the mixture into a sealed autoclave and setting the reaction temperature; and 3) cooling, solvent washing, centrifuging, and finally drying to obtain the final material. [88] MOF-based materials synthesized by solvothermal method has higher specific surface area and larger pore volume.…”

Transparent Cellulose‐Based Film with High UV‐Blocking Performance Fabricated by Surface Modification using Biginelli Reaction

“…In comparison, the transparency and UV protection properties of the reported cellulose-based UV-blocking films are summarized and shown in Figure 4f. [13,14,16,[40][41][42][43][44][45] Most materials (composites) have poor UV-blocking properties or low transparency. For example, the cellulose/10% TiO2 film exhibits a high UVshielding of 98%.…”