Temperature dependent IR-Transition Moment Orientational Analysis applied to thin supported films of Poly-ε-Caprolactone

Wilhelm Kossack & Friedrich Kremer

Peter-Debye-Institute for Soft Matter, Leipzig University, Linnestraße 5, Leipzig Germany

We present a technique to obtain Infrared (IR)-spectra in dependence of temperature (T) and atmospheric composition, but also in dependence on polarization and inclination of the incident light. Based on the obtained spectra the three dimensional molecular order parameter tensors of IR-active transition dipole moments in 7 μm-thin films of Poly-ε-Caprolcatone (PCL) are monitored in dry nitrogen for 35°C < T < 59°C. Crystallinity and macroscopic order of the crystallites remain largely unaltered up to T ≈ 50°C, above which both quantities decline. These reductions are interpreted as the melting of a thermodynamically less stable, surface induced layer of flat on lamellae,1 which formed at highest temperatures, in the beginning of the non-isothermal crystallization process. The results illustrate the fertility of temperature dependent, IR-Transition Moment Orientational Analysis (IR-TMOA)2 to understand kinetic and thermodynamic factors in the evolution of ordered, complex structures.

[1] W. Kossack, A. Seidlitz, T. Thurn-Albrecht, F. Kremer, Macromolecules 49, 3442 (2016). (link)
[2] W. Kossack, P. Papadopoulos, P. Heinze, H. Finkelmann, Macromolecules 43, 7532 (2010). (link)