Structure formation of hydrophobically end-capped polyethylene oxide in the solid state

Young Wook Choi, Jaehyun Park, Youngmi Park, Kyungbae Kim, Youngil Lee, Daewon Sohn

Research output: Contribution to journalArticle

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Abstract

The conformational transition of hydrophobically end-capped polyethylene oxide), HP-PEO-HP [hydrophobic-poly(ethylene oxide)-hydrophobic], was studied using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR) methods. Conformational transitions of HP-PEO-HP from a planar zigzag to a 7/2 helical conformation were observed as the molecular weight of the PEO main chain increased. HP-PEO-HP 1(18), with a PEO molecular weight of 1000 and 18 hydrocarbons on each end, has mainly an a-helical structure in poor solvents, whereas a and β conformations coexist in good solvents. This means that the a-helical structure caused by the hydrogen bonds between the urethane linkages was broken by the high chain mobility caused by the melted adjacent chains of PEO, and instead, the β-sheet was formed by the interaction of multiple hydrogen bonds. Another indication of hydrogen bonds breaking at increasing temperature is the transition of the N-H stretching peak in the FTIR data. HP-PEO-HP 2(18) and 4(18), which have 18 hydrocarbons on each end and PEO molecular weights of 2000 and 4000, respectively, and consist mostly of PEO, showed spherulites. This result also suggests that the PEO molecule has a 7/2 zigzag helical conformation. In contrast, HP-PEO-HP 1(18), which is composed of less PEO than HP-PEO-HP 2(18) and 4(18), did not show a spherulite structure.

Original languageEnglish
Pages (from-to)12959-12963
Number of pages5
JournalJournal of Physical Chemistry B
Volume111
Issue number45
DOIs
StatePublished - 2007 Nov 15

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ethylene oxide
Polyethylene oxides
polyethylenes
solid state
oxides
molecular weight
spherulites
hydrogen bonds
hydrocarbons
infrared spectroscopy
urethanes
Conformations
Hydrogen bonds
Molecular weight
linkages
Hydrocarbons
indication
heat measurement
Fourier transform infrared spectroscopy
scanning

Cite this

Choi, Young Wook ; Park, Jaehyun ; Park, Youngmi ; Kim, Kyungbae ; Lee, Youngil ; Sohn, Daewon. / Structure formation of hydrophobically end-capped polyethylene oxide in the solid state. In: Journal of Physical Chemistry B. 2007 ; Vol. 111, No. 45. pp. 12959-12963.
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Structure formation of hydrophobically end-capped polyethylene oxide in the solid state. / Choi, Young Wook; Park, Jaehyun; Park, Youngmi; Kim, Kyungbae; Lee, Youngil; Sohn, Daewon.

In: Journal of Physical Chemistry B, Vol. 111, No. 45, 15.11.2007, p. 12959-12963.

Research output: Contribution to journalArticle

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