Temperature-induced chiral nematic phase changes of suspensions of poly(N,N-dimethylaminoethyl methacrylate)-grafted cellulose nanocrystals
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Temperature-induced copolymers of poly(N,N-dimethylaminoethyl methacrylate)-grafted cellulose nanocrystals (PDMAEMA-grafted CNC) were synthesized by surface-initiated atom transfer radical polymerization (ATRP). The graft copolymers were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC). The size of the original CNC was 10–40 nm in width and 100–400 nm in length, as characterized by atomic force microscopy (AFM). The liquid-crystalline properties of the graft copolymers were investigated by using polarizing optical microscopy (POM). The graft copolymers exhibited fingerprint texture in lyotropic state. The temperature-induced fingerprint texture changes of PDMAEMA-grafted CNC aqueous suspensions were investigated at various temperatures. With increasing temperature, the spacing of the fingerprint lines decreases. Temperature-induced changes of PDMAEMA polymer chains result in changes of fingerprint texture.
KeywordsCellulose nanocrystals (CNC) Poly(N,N-dimethylaminoethyl methacrylate) Thermosensitive polymer Chiral nematic phase Liquid crystals
This work was financially supported by the New Century Excellent Talents in University (NCET-05-0707), the Scientific Research Fund of Hunan Provincial Education Department (06A068), the Cultivation Found of the Key Scientific and Technical Innovation Project, Ministry of Education of China (No. 207075), the National Nature Science Foundation of China (20874082), and the Open Project Program of the Key Laboratory of Low-Dimensional Materials and Application Technology of the Ministry of Education (KF0611).
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