In situ atomic force microscopy observation of crystallization of isolated polymer chains

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01993
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 35020:Polymer materials-related
• Research Institution: Yamagata University
• Principal Investigator: Kumaki Jiro 山形大学, 大学院有機材料システム研究科, 客員教授 (00500290)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 高分子結晶構造 / 原子間力顕微鏡 / 折り畳み鎖結晶 / 孤立鎖 / 結晶化メカニズム / 高分子超薄膜

Outline of Final Research Achievements

The crystallization process of a single isolated polymer chain into a folded-chain crystal (FCC) was visualized at the molecular level in situ and in real time by atomic force microscopy (AFM). The sample was a single Langmuir monolayer deposited on mica, in which isotactic poly(methyl methacrylate) (it-PMMA) was solubilized as isolated chains in an it-oligo(MMA) monolayer. The nucleation occurred at any point of the chain and the crystal grew by winding the residual part of the amorphous chain. The growth of a crystal formed at the end of an amorphous chain was observed. Unexpectedly, the crystal grew not only on the side where the amorphous chain was attached but also significantly on the opposite side where no amorphous chain was attached, indicating that the chains significantly slipped inside the folded crystal and crystallized on the opposite side. The crystallization behavior of a single isolated chain provides new insight in understanding the polymer crystallization process.

Free Research Field

高分子構造・物性、高分子超薄膜、原子間力顕微鏡

Academic Significance and Societal Importance of the Research Achievements

折りたたみ鎖結晶は高分子の最も一般的な結晶形態であるが、構造が複雑でその結晶化過程は不明な点が多い。本研究では、高分子一分子鎖を孤立させた状態で結晶化させ、孤立鎖の結晶化過程を初めて実時間で原子間力顕微鏡観察することに成功した。高分子鎖の任意の位置で結晶化が開始すること、折りたたみ鎖結晶化の際に、分子鎖が結晶内部を顕著に滑って結晶化していることなど、孤立鎖の結晶挙動を観察することで初めて明らかになった。