High strength of hemicelluloses based hydrogels by freeze/thaw technique

•Rod-like chitin nanowhiskers were produced successfully by acid treatment.•Hydrogels were prepared by freeze–thaw technique with the three polymers.•The designed hydrogels had higher thermal stability and compressive strength.•The hydrogels could be a promising candidate for tissue engineering applications. Novel hydrogels were prepared from hemicelluloses, polyvinyl alcohol (PVA), and chitin nanowhiskers through 0, 1, 3, 5, 7, and 9 times of freeze/thaw cycle. These hydrogels were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), swelling property, and compressive strength. The repeated freeze/thaw cycles induced physically crosslinked chains packing among these polymers, and a phase separation caused by the hydrogen bonds. Larger pores led to a high swelling degree, whereas the formation of compact structure after multiple freeze/thaw cycles resulted in high mechanical strength and thermal stability. The highest compressive strength of these hydrogels was achieved by the 9 times of freeze/thaw cycles with compressive stress of 10.5MPa. This work provides a remarkable way for the preparation of hydrogels with good mechanical properties by physical method.