High-Performance TiO2 Nanoparticle/DOPA-Polymer Composites

• Published in: Macromolecular rapid communications. 2015-06, Vol.36 (11), p.1129-1137
• Main Authors: Liaqat, Faroha, Tahir, Muhammad Nawaz, Schechtel, Eugen, Kappl, Michael, Auernhammer, Günter K., Char, Kookheon, Zentel, Rudolf, Butt, Hans-Jürgen, Tremel, Wolfgang
• Format: Article
• Language: English
• Subjects: Calcium Carbonate - chemistry; catechol polymers; Dihydroxyphenylalanine - chemistry; Elastic Modulus; fracture toughness; inorganic-organic nanocomposites; Metal Nanoparticles - chemistry; Metal Nanoparticles - ultrastructure; metal-coordination bonding; Microscopy, Atomic Force; Polymers - chemical synthesis; Polymers - chemistry; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; TiO2 nanoparticles; Titanium - chemistry
• ISSN: 1022-1336; 1521-3927
• DOI: 10.1002/marc.201400706

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. A route to a synthetic nanocomposite is demonstrated by assembling hard and tough multilayered nanocomposites from alternating layers of TiO2 nanoparticles and a mussel‐mimetic 3‐hydroxy‐tyramine (DOPA)‐polymer. 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.