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Thermoresponsive Copolymer Poly(N‑Vinyl­caprolactam) Grafted Cellulose Nanocrystals: Synthesis, Structure, and Properties

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journal contribution
posted on 26.06.2017, 00:00 by Jinlong Zhang, Qinglin Wu, Mei-Chun Li, Kunlin Song, Xiuxuan Sun, Sun-Young Lee, Tingzhou Lei
A novel thermoresponsive copolymer poly­(N-vinylcaprolactam) grafted cellulose nanocrystals (PVCL-g-CNCs) was synthesized using surface-initiated atom transfer radical polymerization, and its temperature responsive behavior was studied in this work. The chemical structure characterization by Fourier transform infrared spectroscopy, solid-state CP/MAS 13C NMR spectroscopy, and X-ray photoelectron spectroscopy confirmed the presence of covalently grafting PVCL chains on the CNC surface. The crystalline structure and nanorod-shaped morphology of CNCs were well preserved after polymerization. Transmission electron microscope results indicated that the surface of CNCs was covered with grafted PVCL brushes. The viscoelastic properties of PVCL-g-CNC aqueous suspensions (1.0 wt %) by dynamic rheology measurements confirmed the thermally induced phase transition behavior. The work presented herein paves the way to design CNC-based advanced functional materials benefiting both from the intrinsic characteristics of CNCs and the new properties imparted by the temperature sensitive grafted polymer chains.