Chitosan–graphene oxide films and CO2-dried porous aerogel microspheres: Interfacial interplay and stability

[Display omitted] •Chitosan biopolymer enables the preparation of stable graphene oxide solution, thin films and porous aerogel microspheres.•Increased hydrophobicity, thermal properties and mechanical properties were noticed for chitosan–graphene oxide hybrid materials.•Selective reduction of graphene oxide in porous beads affords chitosan-reduced graphene oxide microspheres.•Chitosan–graphene oxide is more stable compared to chitosan-clay hybrid material. The intimate interplay of chitosan (CS) and graphene oxide (GO) in aqueous acidic solution has been explored to design upon casting, nanostructured “brick-and-mortar” films (CS-GO-f) and by acidic-to-basic pH inversion, porous CO2-dried aerogel microspheres (CS-GO-m). Owing to the presence of oxygenated functional groups in GO, good-quality crack-free hybrid films were obtained. Mechanical properties were improved independently of the GO content and it was found that a 20wt% loading affords hybrid film characterized with a Young modulus three times superior to that reached with the same loading of layered clay. The presence of graphene oxide was found to be detrimental for the thermal stability of the polysaccharide at T