Direct observation of prefreezing at the interface melt-solid in polymer crystallization

作者：Loehmann Ann Kristin; Henze Thomas; Thurn Albrecht Thomas^*

来源：Proceedings of the National Academy of Sciences of the United States of America, 2014, 111(49): 17368-17372.

DOI：10.1073/pnas.1408492111

• semicrystalline polymers
• AFM
• thin films
• epitaxy

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.

• 出版日期2014-12-9