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Thickening Processes of Lamellar Crystal Monolayers of a Low‐Molecular‐Weight PEO Fraction on a Solid Surface
Author(s) -
Zhai Xuemei,
Zhang Gouliang,
Ma Zhenpeng,
Tang Xiongfeng,
Wang Wei
Publication year - 2007
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200600511
Subject(s) - lamellar structure , lamella (surface anatomy) , metastability , monolayer , crystallography , thickening , crystal (programming language) , materials science , chemistry , solid state , composite material , nanotechnology , polymer science , organic chemistry , computer science , programming language
Using hot‐stage atomic force microscopy, the thickening processes of monolayer crystals of PEO ( $\overline M _{\rm n} $ = 5 000 g · mol −1 and $\overline M _{\rm w} /\overline M _{\rm n} $ = 1.008) from one‐folded (FC1) to extended‐chain (EC) lamellae are experimentally monitored at three temperatures: 50, 52, and 58 °C. At 50 °C some small areas in large FC1 crystals spontaneously thicken into EC crystals. At 52 °C the spontaneously thickened area further expands so as to inductively thicken the entire FC1 lamella into EC lamella. At 58 °C EC crystals first force the adjacent FC1 crystals to melt and then absorb the melted molecules to grow laterally into large EC lamellae till all FC1 lamellae vanish. The three thickening steps express the main thickening process of lamellar crystals from a metastable state to another metastable (or equilibrium) state. The possible mechanisms are discussed in the text.