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

Abstract

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 3 µm 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.