Related Experiment Video
Updated: Jul 10, 2026

Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties
Published on: September 1, 2018
Structure-property relationships in major ampullate spider silk as deduced from polarized FTIR spectroscopy
P Papadopoulos1, J Sölter, F Kremer
1Institut für Experimentelle Physik I, Universität Leipzig, Leipzig, Germany. papadopoulos@physik.uni-leipzig.de
Abstract:
Polarized Fourier Transform Infrared (FTIR) spectroscopy is employed to study structure-property relationships in major ampullate spider silk being exposed to an external mechanical strain. From the measured infrared dichroism of aminoacid-residue - specific bands the molecular order parameter, the frequency width at half-maximum (FWHM) and the spectral position of the absorption maximum are determined in dependence on the external strain. For the highly ordered alanine-rich beta sheets a change in the vibrational potential is found for macroscopic strains as low as a few percent. It can be quantitatively described by a quantum-mechanical approach in which the mechanical strain is treated as a weak external perturbation. The immediate microscopic response to the external field proves that beta -sheeted crystals are tightly interconnected by pre-stretched chains as suggested recently (Y. Liu et al., Nat. Mater. 4, 901 (2005)).
Related Concept Videos
IR Spectrum Peak Splitting: Symmetric vs Asymmetric Vibrations
Globular and Fibrous Proteins
Globular proteins are also known as spheroproteins and typically are approximately round in shape. They contain a mix of amino acid types and contain differing sequences in their primary structures. Globular proteins have many different functions, such as enzymes, cellular messengers, and molecular transporters. These roles often require the proteins to be...
¹H NMR: Complex Splitting
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Spectroscopy of Carboxylic Acid Derivatives
In the...
