64 / 2021-06-01 18:06:41

High Transmittance and Haze Films from Cellulose Nanofibrils via the Defibrillation and Carboxylation of Potassium Permanganate

Carboxylated Cellulose nanofibrils (COOH-CNFs), Potassium Permanganate oxidation, High transmittance and high haze, Flexible electronic products, LED diffuser

As an excellent substrate for flexible electronic products and energy equipment, cellulose has attracted much attention because of its rich source, biodegradability, renewability and sustainability. High transmittance and high haze are important parameters for solar cells and liquid crystal displays and other optical devices. In this study, we utilized a green and efficient defibrillation and carboxylation method of KMnO₄ oxidation synergize with slight high pressure homogenization to kraft softwood pulp to produce high quality COOH-CNFs with high yield at mild reaction conditions (50°C, 1wt% sulfuric acid medium). The as-prepared COOH-CNFs were well retained the crystalline structure of the pulp with coexisting crystalline and amorphous regions. This structure gives CNFs films unique optical properties, the highest transmittance of 95.39% and extremely high haze above 90%, and no obvious absorption in the ultraviolet-visible light range (take air as the baseline). The resulted CNFs were characterized in terms of fibrillation yield, morphological features, crystal structure and surface chemistry, mechanical behavior. This novel approach for producing CNF seems to be promising not only for its green and sustainable features but also for its less effluent discharge and low cost of reagents, more valuable is the resulted CNFs film have excellent optical performance, indicating they can be a promising candidate for many advanced functional materials, especially for flexible optical devices.