Co-localised Raman and force spectroscopy reveal the roles of hydrogen bonds and n-n interactions in defining the mechanical properties of diphenylalanine nano- And micro- Tubes

Abstract

An integrated atomic force and polarized Raman microscope were used to measure the elastic properties of individual diphenylalanine (FF) nano- And micro- Tubes and to obtain quantitative information regarding the inter-molecular interactions that define their mechanical properties. For individual tubes, co-localised force spectroscopy and Raman spectroscopy measurements allowed the calculation of the Young's and shear moduli (25 ± 5 GPa and 0.28 ±0.05 GPa, respectively) and the contribution of hydrogen bonding network to the Young's modulus (∼17.6 GPa). The n-n interactions between the phenyl rings, dominated by T- Type arrangements, were estimated based on previously published X-ray data to only 0.20GPa. These results provide experimental evidence obtained from individual FF tubes that the network of H-bonds dominates the elastic properties of the FF tubes.