Thermoresponsive xylan hydrogels via copper-catalyzed azide-alkyne cycloaddition.
Carbohydr Polym 2013;
102:637-44. [PMID:
24507329 DOI:
10.1016/j.carbpol.2013.11.058]
[Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 10/30/2013] [Accepted: 11/27/2013] [Indexed: 01/08/2023]
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.
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