Inspired by Abalone Shell: Strengthening of Porous Ceramics with Polymers

INTRODUCTION Alumina ceramics have long been of technological importance. However, their brittleness limits their potential for use in structural applications. Traditional approaches proposed to improve the strength and reliability of ceramics include: decrease flaw size, improve fracture toughness and flaw insensitivity, and decrease applied stresses. Polymers on the other hand, although weak, posses very large inelastic strain. Mixing of polymers and ceramics on the molecular level can be thought of as a route to enhance the brittleness of ceramics or the strength of polymers. Polymer-ceramic nancomposites are divided into two categories: 1) polymer matrix reinforced with nanosize ceramic particles and 2) polymer chains molecularly dispersed into ceramic matrix. Recently, strength enhancement of porous ceramic matrices through infiltration of polymers into their porous structure has been observed for hydroxyapatite ceramics, intrinsically weak bio-ceramics, . However, the strength of this ceramic is similar to or lower than the strength of the polymer used for impregnation, thus strength enhancement is expected by the simple addition of a stronger material. In this study, we present an approach to enhance the mechanical properties of strong alumina ceramics through impregnation with acrylate based polymers ranging from homopolymer (poly(methyl methacrylate) (PMMA) to a zwitterionic ionomers with two nonionic monomers, a cationic monomer and an anionic monomer. The pristine alumina ceramic is at least five times stronger than the polymers used. Therefore, in this case a weaker material is used to strengthen a stronger one. The strength enhancement we observe correlates with polymer-alumina interactions on their interface.