title: Direct observation of prefreezing at the interface melt-solid in polymer crystallization.
abstract: Crystallization is almost always initiated at an interface to a solid. This observation is classically explained by the assumption of a reduced barrier for crystal nucleation at the interface. However, an interface can also induce crystallization by prefreezing (i.e., the formation of a crystalline layer that is already stable above the bulk melting temperature). We present an atomic force microscopy (AFM)-based in situ observation of a prefreezing process at the interface of a polymeric model system and a crystalline solid. Explicitly, we show an interfacial ordered layer that forms well above the bulk melting temperature with thickness that increases on approaching melt-solid coexistence. Below the melting temperature, the ordered layer initiates crystal growth into the bulk, leading to an oriented, homogeneous semicrystalline structure.
authors.affiliation: Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany.
authors.forename: Ann-Kristin
authors.initials: AK
authors.lastname: Löhmann
authors.affiliation: Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Henze
authors.affiliation: Institute of Physics, Martin Luther University Halle-Wittenberg, 06099 Halle, Germany thurn-albrecht@physik.uni-halle.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Thurn-Albrecht
keywords: AFM; epitaxy; semicrystalline polymers; thin films