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Open AccessArticle

Dual Light- and pH-Responsive Composite of Polyazo-Derivative Grafted Cellulose Nanocrystals

State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China
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Materials 2018, 11(9), 1725; https://doi.org/10.3390/ma11091725
Received: 9 August 2018 / Revised: 8 September 2018 / Accepted: 10 September 2018 / Published: 14 September 2018
As a type of functional group, azo-derivatives are commonly used to synthesize responsive materials. Cellulose nanocrystals (CNCs), prepared by acid hydrolysis of cotton, were dewatered and reacted with 2-bromoisobuturyl bromide to form a macro-initiator, which grafted 6-[4-(4-methoxyphenyl-azo) phenoxy] hexyl methacrylate (MMAZO) via atom transfer radical polymerization. The successful grafting was supported by Fourier transform infrared spectroscopy (FT-IR) and Solid magnetic resonance carbon spectrum (MAS 13C-NMR). The morphology and surface composition of the poly{6-[4-(4-methoxyphenylazo) phenoxy] hexyl methacrylate} (PMMAZO)-grafted CNCs were confirmed with Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The grafting rate on the macro-initiator of CNCs was over 870%, and the polydispersities of branched polymers were narrow. The crystal structure of CNCs did not change after grafting, as determined by X-ray diffraction (XRD). The polymer PMMAZO improved the thermal stability of cellulose nanocrystals, as shown by thermogravimetry analysis (TGA). Then the PMMAZO-grafted CNCs were mixed with polyurethane and casted to form a composite film. The film showed a significant light and pH response, which may be suitable for visual acid-alkali measurement and reversible optical storage. View Full-Text
Keywords: cellulose nanocrystals; azo-derivatives; atom transfer radical polymerization; light- and pH-responsive cellulose nanocrystals; azo-derivatives; atom transfer radical polymerization; light- and pH-responsive
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MDPI and ACS Style

Liu, X.; Li, M.; Zheng, X.; Retulainen, E.; Fu, S. Dual Light- and pH-Responsive Composite of Polyazo-Derivative Grafted Cellulose Nanocrystals. Materials 2018, 11, 1725.

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