Hydrophobic up-conversion carboxylated nanocellulose/fluoride phosphor composite films modified with alkyl ketene dimer

• Published in: Carbohydrate polymers 2020-12, Vol.250, p.116866, Article 116866
• Main Authors: Fedorov, Pavel P., Luginina, Anna A., Kuznetsov, Sergey V., Voronov, Valery V., Yapryntsev, Alexey D., Lyapin, Andrey A., Pynenkov, Aleksandr A., Nishchev, Konstantin N., Chernova, Elena V., Petukhov, Dmitriy I., Kuryakov, Vladimir N., Gainutdinov, Radmir V., Ivanov, Vladimir K.
• Format: Article
• Language: English
• Subjects: CaF2:Hо; Carboxylic Acids - chemistry; Cellulose - chemistry; Ethylenes - chemistry; Fluorides - chemistry; Hydrophobic and Hydrophilic Interactions; Hydrophobization; Ketones - chemistry; Nanocomposite; Nanocomposites - chemistry; Phosphates - chemistry; Polymers - chemistry; SrF2:Hо; TEMPO-oxidized cellulose nanofibrils; Up-conversion luminescence
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2020.116866

[Display omitted] •Composite film based on carboxylated nanocellulose and fluoride phosphor was created.•Composite films were prepared by film casting method using alkyl ketene dimer (AKD).•The use of AKD as modificator resulted in hydrophobic properties of the films.•The film showed the stable up-conversion luminescence under high humidity conditions.•The films demonstrated great potential as visualizers of 2 micron laser radiations. Hydrophobic up-conversion nanocomposite films have been developed based on TEMPO-oxidized cellulose nanofibrils (TOCNF) modified with alkyl ketene dimer (AKD) as a matrix and MF2:Ho (M = Ca, Sr) as a phosphor. Fabrication of homogeneous, strong and translucent TOCNF/MF2:Ho-AKD films with water contact angle of 123 ± 2° was accomplished with mild drying at 110 °C. These hydrophobic nanocomposite films demonstrated stable up-conversion luminescence in the visible spectral range upon excitation of the 5I7 level of Ho3+ ions by laser irradiation at 1912 nm both under ambient conditions and in a humid atmosphere (92 ± 2% humidity). The absence of luminescence quenching in a high humidity atmosphere for TOCNF/MF2:Ho-AKD composite films was considered to be due to the reliable shielding effect of the hydrophobic TOCNF-AKD matrix. The films show promise for visualizing 2 μm laser radiation in medicine and monitoring of the atmosphere.