Acetylation improves thermal stability and transmittance in FOLED substrates based on nanocellulose films

Bleached softwood pulp was used to prepare nanofibrillated cellulose (NFC) by mechanical grinding and a high-pressure homogenization process. Acetylation improved the aspect ratio and dispersion of the NFC; however, highly acetylated NFC was not able to form a film by vacuum filtration if the NFC : acetic anhydride (AA) ratio was greater than 1 : 6. An NFC film prepared by acetylated NFC has potential as a flexible organic light-emitting device (FOLED) substrate. Acetylation improved the thermal stability and transmittance of NFC films, which were optimal at 5.43 ppm K^-1 and 65%, respectively, when the ratio of NFC : AA was 1 : 3. Moreover, both the mechanical properties and flexibility of the NFC films were well maintained when the NFC : AA ratio was 1 : 3. Additionally, all NFC films prepared by acetylated NFC were smooth, flat, and uniform.