Biomimetic“Nacre-like”Films Prepared via Layer-by-Layer Self-assembly of Mica,Polyvinyl Alcohol and Polymethyl Methacrylate

A film with“brick-and-mortar”structure was prepared by layer-by-layer(LBL)technique using polyvinyl alcohol(PVA)and polymethyl methacrylate(PMMA)as the flexible material or“mortar”and mica as the rigid material or“brick”.The film deposited on a glass slide after self-assembly cycles had a thickness of 3μm thick and an uneven,wavy surface.The film exhibits enhanced mechanical properties,i e,the hardness and indentation modulus values could reach 6.14 and 68.41 GPa,respectively.The hardness and elastic toughness were found to be depended on three factors,i e,the ratio of PVA to mica,the number of self-assembly cycles,and the pretreatment method of the mica suspension.The self-assembly process was driven by formation of the hydrogen bonds between the silanol groups of mica and the hydroxyl groups of PVA and carbonyl groups of PMMA.