Physically crosslinked freeze-thaw cryogels reinforced with functional nanocellulose derivatives (CM-CNFs) derived...

Natural polysaccharides are abundant, cost-effective, renewable, accessible to modification, and possess biodegradable and biocompatible properties. Sugarcane bagasse, a widely available agro-industrial byproduct, was utilized as a source for preparing nanocellulose fibers (NCFs) and carboxymethyl cellulose nanofibers (CM-CNFs). A combination of chemical and mechanical processes was used to isolate the fibers, followed by carboxymethylation to introduce functional groups and enhance dispersion in polymer matrices. Structural and chemical differences between NCFs and CM-CNFs were evident through FTIR, XRD, and SEM analysis, with carboxymethylation yielding 66.67 % CM-CNFs. IGC analysis revealed increased polarity and surface energy in CM-CNFs due to carboxymethylation, providing insights into the fibers' interfacial behaviour and compatibility with hydrophilic and hydrophobic polymers. The nanofibers were subsequently incorporated into a blended polymer matrix to assess their reinforcement potential, where CM-CNFs exhibited improved dispersion and stronger interfacial adhesion due to their surface modification. The synthesized CM-CNF reinforces freeze thaw cryogel, enhancing visco-elastic nature of polymer matrix with immense tensile strain (∼300 %), excellent cytocompatibility (>92 %), and significant biodegradability (>60 %). The results highlight the potential of functionalized nanocellulose fibers from agro-waste as sustainable reinforcing agents and provide a molecular-level understanding of their surface behaviour critical to polymer composite applications.