High strength and low swelling composite hydrogels from gelatin and delignified wood

Shennan Wang,Kai Li,Qi Zhou

doi:10.1038/s41598-020-74860-w

Shennan Wang, Kai Li + Show 1 more

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https://doi.org/10.1038/s41598-020-74860-w

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Abstract

A delignified wood template with hydrophilic characteristics and high porosity was obtained by removal of lignin. Gelatin was infiltrated into the delignified wood and further crosslinked with a natural crosslinker genipin to form hydrogels. The composite hydrogels showed high mechanical strength under compression and low swelling in physiological condition. The effect of genipin concentrations (1, 50 and 100 mM) on structure and properties of the composite hydrogels were studied. A porous honeycomb structure with tunable pore size and porosity was observed in the freeze-dried composite hydrogels. High elastic modulus of 11.82 ± 1.51 MPa and high compressive yield stress of 689.3 ± 34.9 kPa were achieved for the composite hydrogel with a water content as high as 81%. The equilibrium water uptake of the freeze-dried hydrogel in phosphate buffered saline at 37 °C was as low as 407.5%. These enables the delignified wood structure an excellent template in composite hydrogel preparation by using infiltration and in-situ synthesis, particularly when high mechanical strength and stiffness are desired.

Highlights

A delignified wood template with hydrophilic characteristics and high porosity was obtained by removal of lignin
Bacterial cellulose (BC)/gelatin composite hydrogels crosslinked with N-(3-dimethy-laminopropyl)-N′-ethylcarbodiimide hydrochloride have showed significant enhancement in mechanical strength and stiffness owing to the natural ultrafine-fibre network structures of B C25–27
A bio-based composite hydrogel composed of gelatin and delignified wood was successfully prepared through infiltration of gelatin into the porous wood template at 50 °C and subsequent crosslinking with genipin at 4 °C

Summary

Introduction

A delignified wood template with hydrophilic characteristics and high porosity was obtained by removal of lignin. The equilibrium water uptake of the freeze-dried hydrogel in phosphate buffered saline at 37 °C was as low as 407.5% These enables the delignified wood structure an excellent template in composite hydrogel preparation by using infiltration and in-situ synthesis, when high mechanical strength and stiffness are desired. The wood/PAM hydrogel demonstrated remarkably enhanced fracture tensile strength and modulus as compared to the PAM hydrogel owing to the skeletons of natural aligned cellulose nanofibers (CNFs) and the strong interfacial hydrogen bonding in the hydrogel This top-down approach opened up a new way to synthesize strong hydrogels exploiting the advantages of the cellular structure with highly aligned CNFs bundles in the cell walls in delignified wood, which provides mechanical support and liquid conduction through the natural aligned micro and nano channels. This is rather challenging and requires shear-induced alignment when using CNFs by bottom-up assembly a pproaches[28,29]

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