Gelation and post-gelation mechanism of methylcellulose in an aqueous medium: 1H NMR and dynamic compressive rheological studies.

Abstract

Methylcellulose (MC) has become crucial in 3D bioprinting in the last decade. Researchers investigated MC aqueous solutions blended with biopolymers at room temperature, focusing on rheological studies. Even at low concentrations, the gel state of MC, which provides structural strength through hydrophilic and hydrophobic associations, was explored for injection-based 3D printability. Post-gelation phenomena were examined at 80 °C using a dynamic mechanical analyzer (DMA), revealing increased storage and loss moduli with frequency, indicating a robust gel network structure. Optical microscopy reveals that upon heating from 40 to 80 °C, the structural strength is enhanced via the formation of hydrophobic confirmations, starting from the micro-helical structure to the associated microarray. These microarrays are further synchronized to withstand the high frequency of the DMA probe. Compressive rheology outcomes allow us to elaborate on the possibility of injection-based 3D printability of aqueous MC gel at 80 °C. ¹H and ¹³C NMR studies probed hydrophobic interactions among MC chains, showing evidence of H-bonding through temperature-dependent shifts. UV/Vis experiments traced gel formation, depicting a time-dependent network formation process. Overall experiments indicated that adjusting temperature could control gelation time, allowing precise tuning of the printing process and achieving fine layers (10 μm) in the printed membrane with maximum hydrophobic clusters.