Thermodynamic and spectroscopic analysis of the conformational transition of poly(vinyl alcohol) by temperature-dependent FTIR

Shan Han; Ye Mei Luan; Shu Feng Pang; Yun Hong Zhang

doi:10.1016/j.saa.2014.11.100

Thermodynamic and spectroscopic analysis of the conformational transition of poly(vinyl alcohol) by temperature-dependent FTIR

Shan Han, Ye Mei Luan, Shu Feng Pang^*, Yun Hong Zhang

^*Corresponding author for this work

School of Chemistry and Chemical Engineering

Research output: Contribution to journal › Article › peer-review

8 Citations (Scopus)

Abstract

The conformational change of poly(vinyl alcohol) has been studied by Fourier transform infrared spectroscopy at various temperatures in the 4000-400 cm^-1 region. The molecular motion and the trans/gauche content are sensitive to the CH, CC stretching modes. FTIR spectra show that the I₂₉₂₀/I₂₈₄₉ decreases from 1.84 to 1.0 with increasing temperature, companying the decrease in I₁₀₄₇/I₁₀₉₅ from 0.78 to 0.58, implying the conformational transition from trans to gauche in alkyl chain. Based on the van't Hoff relation, the enthalpies and entropies have been calculated in different temperatures, which are 4.61 kJ mol^-1 and 15.23 J mol^-1 K^-1, respectively, in the region of 80-140°C. From the CO stretching mode and OH band, it can be concluded that the intermolecular hydrogen bonds decrease owing to elevating temperature, which leads to more gauche conformers.

Original language	English
Pages (from-to)	37-42
Number of pages	6
Journal	Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Volume	139
Issue number	1
DOIs	https://doi.org/10.1016/j.saa.2014.11.100
Publication status	Published - 2015

Keywords

Conformational changes
FTIR spectroscopy
Poly(vinyl alcohol)
TGA
Temperature-dependent

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10.1016/j.saa.2014.11.100

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title = "Thermodynamic and spectroscopic analysis of the conformational transition of poly(vinyl alcohol) by temperature-dependent FTIR",

abstract = "The conformational change of poly(vinyl alcohol) has been studied by Fourier transform infrared spectroscopy at various temperatures in the 4000-400 cm-1 region. The molecular motion and the trans/gauche content are sensitive to the CH, CC stretching modes. FTIR spectra show that the I2920/I2849 decreases from 1.84 to 1.0 with increasing temperature, companying the decrease in I1047/I1095 from 0.78 to 0.58, implying the conformational transition from trans to gauche in alkyl chain. Based on the van't Hoff relation, the enthalpies and entropies have been calculated in different temperatures, which are 4.61 kJ mol-1 and 15.23 J mol-1 K-1, respectively, in the region of 80-140°C. From the CO stretching mode and OH band, it can be concluded that the intermolecular hydrogen bonds decrease owing to elevating temperature, which leads to more gauche conformers.",

keywords = "Conformational changes, FTIR spectroscopy, Poly(vinyl alcohol), TGA, Temperature-dependent",

author = "Shan Han and Luan, {Ye Mei} and Pang, {Shu Feng} and Zhang, {Yun Hong}",

year = "2015",

doi = "10.1016/j.saa.2014.11.100",

language = "English",

volume = "139",

pages = "37--42",

journal = "Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy",

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publisher = "Elsevier B.V.",

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T1 - Thermodynamic and spectroscopic analysis of the conformational transition of poly(vinyl alcohol) by temperature-dependent FTIR

AU - Han, Shan

AU - Luan, Ye Mei

AU - Pang, Shu Feng

AU - Zhang, Yun Hong

PY - 2015

Y1 - 2015

N2 - The conformational change of poly(vinyl alcohol) has been studied by Fourier transform infrared spectroscopy at various temperatures in the 4000-400 cm-1 region. The molecular motion and the trans/gauche content are sensitive to the CH, CC stretching modes. FTIR spectra show that the I2920/I2849 decreases from 1.84 to 1.0 with increasing temperature, companying the decrease in I1047/I1095 from 0.78 to 0.58, implying the conformational transition from trans to gauche in alkyl chain. Based on the van't Hoff relation, the enthalpies and entropies have been calculated in different temperatures, which are 4.61 kJ mol-1 and 15.23 J mol-1 K-1, respectively, in the region of 80-140°C. From the CO stretching mode and OH band, it can be concluded that the intermolecular hydrogen bonds decrease owing to elevating temperature, which leads to more gauche conformers.

AB - The conformational change of poly(vinyl alcohol) has been studied by Fourier transform infrared spectroscopy at various temperatures in the 4000-400 cm-1 region. The molecular motion and the trans/gauche content are sensitive to the CH, CC stretching modes. FTIR spectra show that the I2920/I2849 decreases from 1.84 to 1.0 with increasing temperature, companying the decrease in I1047/I1095 from 0.78 to 0.58, implying the conformational transition from trans to gauche in alkyl chain. Based on the van't Hoff relation, the enthalpies and entropies have been calculated in different temperatures, which are 4.61 kJ mol-1 and 15.23 J mol-1 K-1, respectively, in the region of 80-140°C. From the CO stretching mode and OH band, it can be concluded that the intermolecular hydrogen bonds decrease owing to elevating temperature, which leads to more gauche conformers.

KW - Conformational changes

KW - FTIR spectroscopy

KW - Poly(vinyl alcohol)

KW - TGA

KW - Temperature-dependent

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DO - 10.1016/j.saa.2014.11.100

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JO - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

JF - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

IS - 1

ER -

Thermodynamic and spectroscopic analysis of the conformational transition of poly(vinyl alcohol) by temperature-dependent FTIR

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