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A viable solution toward "green" optoelectronics is rooted in our ability to fabricate optoelectronics on transparent nanofibrillated cellulose (NFC) film substrates. However, the flammability of transparent NFC film poses a severe fire hazard in optoelectronic devices. Despite many efforts toward enhancing the fire-retardant features of transparent NFC film, making NFC film fire-retardant while maintaining its high transparency (≥90%) remains an ambitious objective. Herein, we combine NFC with NFC-dispersed monolayer clay nanoplatelets as a fire retardant to prepare highly transparent NFC-monolayer clay nanoplatelet hybrid films with a superb self-extinguishing behavior. Homogeneous and stable monolayer clay nanoplatelet dispersion was initially obtained by using NFC as a green dispersing agent with the assistance of ultrasonication and then used to blend with NFC to prepare highly transparent and self-extinguishing hybrid films by a water evaporation-induced self-assembly process. As the content of monolayer clay nanoplatelets increased from 5 wt % to 50 wt %, the obtained hybrid films presented enhanced self-extinguishing behavior (limiting oxygen index sharply increased from 21% to 96.5%) while retaining a ∼90% transparency at 600 nm. More significantly, the underlying mechanisms for the high transparency and excellent self-extinguishing behavior of these hybrid films with a clay nanoplatelet content of over 30 wt % were unveiled by a series of characterizations such as SEM, XRD, TGA, and limiting oxygen index tester. This work offers an alternative environmentally friendly, self-extinguishing, and highly transparent substrate to next-generation optoelectronics, and is aimed at providing a viable solution to environmental concerns that are caused by ever-increasing electronic waste.

A large number of wool fiber by-products, short and coarse wool fibers are difficult to spin and are disposed of by the wool industry, creating a burden on the environment. In this study, L-cysteine hydrochloride and sodium sulfite were used as reducing agents to extract keratin from natural wool in an ethanol-water mixed system. The molecular weight of the extracted keratin is up to 130 kDa with a high yield of 67%. It has been proven that the reducing agent destroyed partial disulfide bonds, ethanol destroyed partial hydrogen bonds and hydrophobic interactions, and the α-helix chain was converted into a β-folded chain and random coil after extraction by instrumental analysis using a Fourier transform infrared spectrometer and X-ray diffraction. The recombination of small keratin molecules can be proven by the increase in protein particle size and molecular weight via a particle size analyzer and SDS-PAGE respectively.

Carboxylated nanofibrillated cellulose extracted from wood fibers was used as a green dispersant to effectively disperse clay particles in water.

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