High‐Performance TiO₂ Nanoparticle/DOPA‐Polymer Composites

Abstract

Many natural materials are complex composites whose mechanical properties are often outstanding considering the weak constituents from which they are assembled. Nacre, made of inorganic (CaCO3 ) and organic constituents, is a textbook example because of its strength and toughness, which are related to its hierarchical structure and its well-defined organic-inorganic interface. Emulating the construction principles of nacre using simple inorganic materials and polymers is essential for understanding how chemical composition and structure determine biomaterial functions. A hard multilayered nanocomposite is assembled based on alternating layers of TiO2 nanoparticles and a 3-hydroxy-tyramine (DOPA) substituted polymer (DOPA-polymer), strongly cemented together by chelation through infiltration of the polymer into the TiO2 mesocrystal. With a Young's modulus of 17.5 ± 2.5 GPa and a hardness of 1.1 ± 0.3 GPa the resulting material exhibits high resistance against elastic as well as plastic deformation. A key feature leading to the high strength is the strong adhesion of the DOPA-polymer to the TiO2 nanoparticles.

Tuning underwater adhesion with cation–π interactions

“…We rationalize this observation by noting that Maier et al 32 studied monolayers of a small molecule, for which adhesive failure necessarily occurs at the molecule-mica interface. Here, the failure plane is shifted out into the peptide film, which results in cohesive failure, as is the case for most practical adhesives composed of larger molecules, such as peptides and proteins, that assemble to encapsulate particles and/or cover surface heterogeneities [11][12][13]46 . For large molecule multilayers that strongly bind to surfaces through multiple parallel covalent bonds, hydrogen bonds and/or strong ionic bonds, molecule-molecule interactions are often weaker (and/or more transient) than molecule-surface interactions.…”

Synthesis of Mesoporous Supraparticles on Superamphiphobic Surfaces

“…Moreover, an inorganic/organic (TiO 2 /polydopaminacrylamide) dispersion mixture was applied to demonstrate the formation of TiO 2 /polydopaminacrylamide composite particles (Figure S5, Supporting Information). TiO 2 /polydopaminacrylamide forms a material with a high yield stiffness and hardness due to strong interfacial bonding through metal complexation by the dopamine surface ligand . Not only mixed composite particles but also core–shell supraparticles could be formed via a sequential drying process with SnO 2 and TiO 2 NP dispersions.…”

Surface Chemistry Directs the Tunable Assembly of TiO2 Anatase Nanocubes into Three‐Dimensional Mesocrystals

“…The autoclave was heated to 120 °C for 4.5 h to induce peptization and subsequently for 6 h to 195 °C to induce nucleation and particle growth. The resulting nanoparticle dispersion had an orange‐red color (due to charge transfer between the non‐innocent DHCA ligand, and the Ti 4+ centers of the TiO 2 surfaces) and contained functionalized TiO 2 nanoparticles in high concentrations.…”

“…Typically, the particle solubility is low, and particle dispersions are difficult to process. TiO 2 and other metal oxide nanocrystals can easily be functionalized with catechol‐type ligands , , . In particular, the high solubility of TiO 2 nanocubes functionalized with DHCA permits the preparation of stable and highly concentrated nanocrystal dispersions (up to 200 g/L in alkaline ammonia solution) , .…”