Supramolecular crosslinking of biomimetic poly(2-hydroxyethyl methacrylate) nanocomposite reinforced with multi-walled carbon nanotubes

Evolving technology sets new requirements to material development all the time. Many scientists are trying to meet these requirements by the means of biomimetics. Biomaterials, like spider silk and nacre, have exceptional properties which derive from their hierarchical organization and supramolecular interactions. Spider silk has attracted plenty of attention during the past decades. It has high tensile strength and very good elongation properties but in addition to these, researchers are interested in of the energy dissipating properties which arise from sacrificial bonding and hidden lengths in the protein structure. Production of synthetic spider silk has been approached in several ways. Different nanocomposites consisting of polymers and carbon nanotubes have been studied extensively. In these nanocomposites, carbon nanotubes are used to mimic reinforcing β-sheets which enable high tensile strength of spider silk. Polymer is used to simulate the non-crystalline regions which give rise to high elongation of spider silk. In this Master's thesis, a review of supramolecular concepts enabling biomimetic research is presented. Also chemical and physical structure and properties of spider silk and carbon nanotubes and their role in different biomimetic materials are presented. The experimental part of this thesis consists of functionalization of multi-walled carbon nanotubes and poly(2-hydroxyethyl methacrylate) with 2-ureido-4[1H]-pyrimidinone hexamethylene isocyanate. These materials were used to prepare nanocomposites via self-assembly. The aim of this study was to prepare two-component nanocomposite with high tensile strength. Tensile tests on the nanocomposites were carried out and major improvement in the mechanical properties were observed. Even though the ultimate strength of the materials did not reach expected values, the composites functionalized with dimerizing ureidopyrimidinone-motifs resisted crack growth like predicted