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Crystallization Behavior of Single Isotactic Poly(methyl Methacrylate) Chains Visualized by Atomic Force Microscopy

Takahiro Anzai, Mariko Kawauchi, Takehiro Kawauchi, Jiro Kumaki

J Phys Chem B. 2015 Jan 8;119(1):338-47.

PMID: 25496047

Abstract:

We have, for the first time, successfully visualized the crystallization behavior of a single isolated polymer chain at the molecular level by atomic force microscopy (AFM). Previously, we found that isotactic poly(methyl methacrylate) (it-PMMA) formed two-dimensional folded chain crystals composed of double-stranded helices upon compression of its Langmuir monolayer on a water surface, and the molecular images of the crystals deposited on mica were clearly visualized by AFM (Kumaki, J.; et al. J. Am. Chem. Soc. 2005, 127, 5788). In the present study, a high-molecular-weight it-PMMA was diluted in a monolayer of an it-PMMA oligomer which cannot crystallize at the experimental temperature due to its low molecular weight. At a low surface pressure, isolated amorphous chains of the high-molecular-weight it-PMMA solubilized in the oligomer monolayer were observed. On compression, the isolated chains converted to crystals composed of a single chain, typically some small crystallites linked by an amorphous chain like a necklace. Detailed AFM observations of the crystals indicated that the crystalline nuclei preferentially formed at the ends of the chains, and the size of the nuclei was almost independent of the molecular weight of it-PMMA over a wide range. At an extremely slow compression, crystallization was promoted, resulting in crystallization of the whole chain. The crystallization behavior of a single isolated chain provides new insights in understanding the polymer crystallization process.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP25188981 Poly(methyl methacrylate), isotactic Poly(methyl methacrylate), isotactic 25188-98-1 Price
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