Berlin 2024 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Poster II

CPP 21.12: Poster

Dienstag, 19. März 2024, 18:00–20:00, Poster E

Influence of interfacial interactions on the kinetics, morphology, and crystal orientation of interface-induced polymer crystallization — •Marthinus van Niekerk, Oleksandr Dolynchuk, and Thomas Thurn-Albrecht — Experimental Polymer Physics, Institute of Physics, Martin Luther University Halle-Wittenberg, Germany

Initiation of polymer crystallization at an interface to a solid can strongly affect crystallization kinetics that normally surpass that of homogeneous nucleation in the bulk. While heterogeneous nucleation is an activated process occurring below Tm, the process of prefreezing produces a crystalline layer above Tm, which thickens upon cooling. Both prefreezing and heterogeneous nucleation are dependent on interfacial interactions between a polymer and the underlying substrate. We present a systematic study of the crystallization of a model polymer, poly(є-caprolactone) (PCL), on several substrates to elucidate the effects of interfacial interactions. We employ a system of dewetted PCL droplets on various substrates, allowing identification of individual nucleation events. AFM imaging confirms the existence of isolated droplets. Studies with polarized microscopy show large differences in the crystallization rate of PCL droplets during cooling from the melt on different substrates. X-ray scattering shows anisotropic scattering from PCL droplets, which varies according to the substrate, proving that the substrate induces orientation of crystalline lamellae. Thus, we demonstrate the effects of interfacial interactions on interface-induced polymer crystallization.

Keywords: Prefreezing; Heterogeneous nucleation; Crystallization; Interfaces; Substrates