title: Thermoresponsive xylan hydrogels via copper-catalyzed azide-alkyne cycloaddition.
abstract: In the present work, hydrogels of birch wood xylan and thermoresponsive poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol) (PEG-PPG-PEG) were prepared using copper catalyzed alkyne-azide cycloaddition (CuAAC) in aqueous reaction conditions. First, reactive azide groups were introduced on the backbone of xylan by etherification of 1-azido-2,3-epoxypropane in alkaline water/isopropanol-mixture at ambient temperature, providing degree of substitution (DS) values up to 0.28. On the second step, the azide groups were reacted with propargyl bifunctional PEG-PPG-PEG utilizing CuAAC, leading to formation of crosslinked hydrogels. The novel xylan derivatives were characterized with liquid and solid state nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA). The temperature controlled swelling behavior of the developed hydrogels was evaluated in the range of 7-70 °C by water absorption and compressive stress-strain measurements, which showed a reduction in water content and change in stiffness with increasing temperature. The morphology of the hydrogels at different temperatures was studied by scanning electron microscopy (SEM), which showed a reduction in pore size with increasing temperature.
authors: Department of Biotechnology and Chemical Technology, Aalto University School of Chemical Technology, Kemistintie 1, 02150 Espoo, Finland.
authors: Nikolaos
authors: N
authors: Pahimanolis
authors: Department of Biotechnology and Chemical Technology, Aalto University School of Chemical Technology, Kemistintie 1, 02150 Espoo, Finland.
authors: Anni
authors: A
authors: Sorvari
authors: Department of Biotechnology and Chemical Technology, Aalto University School of Chemical Technology, Kemistintie 1, 02150 Espoo, Finland.
authors: Nguyen Dang
authors: ND
authors: Luong
authors: Department of Biotechnology and Chemical Technology, Aalto University School of Chemical Technology, Kemistintie 1, 02150 Espoo, Finland. Electronic address: jukka.seppala@aalto.fi.
authors: Jukka
authors: J
authors: Seppälä
keywords: Click chemistry; Etherification; Hydrogel; Modification of polysaccharides; Thermoresponsive; Xylan