Synthesis and characterization of high-softening-point methylene-bridged pitches by visible light irradiation assisted free-radical bromination

Chuanzhang Ge, Haixiao Yang, Jin Miyawaki, Isao Mochida, Seong Ho Yoon, Wenming Qiao, Donghui Long, Licheng Ling

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

A novel methylene-bridged polymeric pitch was successfully synthesized from 1-methylnaphthalene (1-MNP) using bromine as a sacrificial agent for C-C bond construction. 1-MNP was reacted with bromine in the presence of strong visible light irradiation (40-70 kcal/mol), yielding exclusively side-chain substituted 1-methylnaphthalene (M-Br). After a thermal dehydrobromination/polycondensation reaction at 200-270 °C, high quality carbonaceous isotropic pitches with a softening point of 196-250 °C were obtained. The optimized factors influencing the photobromination, including reaction temperature, substrate concentration and properties of solvents were determined. The dehydrobromination reaction kinetic followed a pseudo-first-order reaction model with apparent reaction activation energy of 122.6 kJ/mol. The as-prepared polymeric pitches consisted of numbers of repeated monomers with a linear structure of methylene bridged naphthalene rings. The unique structure of the pitches resulted in high value of C/H ratio, high molecular weight and 100% soluble in toluene. Moreover, the pitches exhibited very low viscosity at temperatures near the softening point, and their viscosities experienced a unique transition from shear-thinning to shear-thickening and then to shear-thinning process. The coke obtained from short molecular pitch by carbonizing at 550 °C show an anisotropic phase of flow domains both in atmospheric pressure and pressured conditions.

Original languageEnglish
Pages (from-to)780-788
Number of pages9
JournalCarbon
Volume95
DOIs
Publication statusPublished - Oct 11 2015

Fingerprint

Shear thinning
Bromine
Free radicals
Free Radicals
Irradiation
Viscosity
Naphthalene
Polycondensation
Reaction kinetics
Coke
Atmospheric pressure
Toluene
Activation energy
Monomers
Molecular weight
Temperature
Substrates
1-methylnaphthalene
Hot Temperature

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)

Cite this

Synthesis and characterization of high-softening-point methylene-bridged pitches by visible light irradiation assisted free-radical bromination. / Ge, Chuanzhang; Yang, Haixiao; Miyawaki, Jin; Mochida, Isao; Yoon, Seong Ho; Qiao, Wenming; Long, Donghui; Ling, Licheng.

In: Carbon, Vol. 95, 11.10.2015, p. 780-788.

Research output: Contribution to journalArticle

Ge, Chuanzhang ; Yang, Haixiao ; Miyawaki, Jin ; Mochida, Isao ; Yoon, Seong Ho ; Qiao, Wenming ; Long, Donghui ; Ling, Licheng. / Synthesis and characterization of high-softening-point methylene-bridged pitches by visible light irradiation assisted free-radical bromination. In: Carbon. 2015 ; Vol. 95. pp. 780-788.
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