Highly Transparent and Self-Extinguishing Nanofibrillated Cellulose-Monolayer Clay Nanoplatelet Hybrid Films

Abstract

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.

Bioinspired Environmentally Friendly Amorphous CaCO3-Based Transparent Composites Comprising Cellulose Nanofibers

“…51−56 The present CMC/CNF/ACC composite films exhibit around 90% of transparency at 600 nm, which is comparable to that of the state-of-the-art composite films based on CNFs with inorganic components. 57−59 In addition to the high transparency, 40/40/20 (CMC/CNF/ACC) showed 260 ± 20 MPa tensile strength and 15.8 ± 0.93 GPa Young’s modulus, which are comparable to other tailor-made composite films based on CNFs. 51−53,58,59…”

Non-toxic layered double hydroxide nanoplatelet dispersions for gas barrier coatings on flexible packaging

“…67 A concerted effort is now underway to both simplify film structures and to improve the gas barriers performance of polymeric materials. [68][69][70][71][72][73] One of the criteria to select the polymer for a coating mixture is its film formation property, which requires that the polymer molecules are mobile and stable during the early stage of solvent evaporation and/or solvent absorption into the substrate. 74 The polymer needs to be solvated to resist precipitation.…”

Interaction of divalent cations with carboxylate group in TEMPO-oxidized microfibrillated cellulose systems

“…Renewable and biodegradable polymers, such as cellulose, starch, chitosan, and hemicelluloses have recently been studied for many applications (Fang et al 2000;Xu et al 2005;Durango et al 2006;Nakagaito and Yano 2008;Escalante et al 2012). In general, oxidized microfibrillated cellulose (MFC), with high mechanical strength and low density, can be formed into hydrogels, aerogels, films, etc., depending on the target applications, ranging from biomedicine, tissue engineering, pharmaceutics and electronics/ optoelectronics to textiles, food, membranes and wood products (Chang et al 2010;García-González et al 2011;Ming et al 2017;Song et al 2017) MFC suspensions have been converted into films by several methods, like casting, vacuum filtration, solvent exchange, spraying, and spin-coating (Henriksson et al 2008;Wågberg et al 2008;Aulin et al 2010a, b;Spence et al 2010a, b). Cellulose networks in the films are formed by strong inter-and intramolecular interactions via physical and chemical crosslinking (Sannino et al 2009;Chang and Zhang 2011).…”