In Situ Real-Time Observation of Polymer Folded-Chain Crystallization by Atomic Force Microscopy at the Molecular Level

The crystallization process of a folded-chain crystal (FCC) was clearly visualized at the molecular level in situ and in real time for the first time [1]. We deposited an amorphous isotactic poly(methyl methacrylate) monolayer on mica, and the crystallization of the monolayer under high humidity was followed by atomic force microscopy. Detailed crystallization behaviors, especially, the stepwise growth of the FCC with blocks shorter than the chain, chain slipping in the FCC, the formation of an anisotropic nucleus and its growth, and the formation of a small nucleus with a short lifetime, were clearly visualized at the molecular level. The stepwise growth of the FCC differed from that expected by the classical Lauritzen-Hoffman theory and was consistent with recent reports that indicated the formation of some ordered states in the amorphous phase. In addition, the crystallization process of a poly(lactide), which formed an extended-chain crystal (ECC) in a monolayer was also visualized, and will be discussed.
(1) Ono, Y.; Kumaki, J. Macromolecules 2018, 51, 7629-7636.