Hao-yu Yu, Jian-wei Shao, Dong Chen, Shi-chao Wang, Li Wang, Wan-tai Yang. Synthesis of Thioether Compounds and Their Application in Initiating/Controlling the Radical Polymerization of Styrene. [J]. Acta Polymerica Sinica 0(11):1422-1429(2018)
DOI:
Hao-yu Yu, Jian-wei Shao, Dong Chen, Shi-chao Wang, Li Wang, Wan-tai Yang. Synthesis of Thioether Compounds and Their Application in Initiating/Controlling the Radical Polymerization of Styrene. [J]. Acta Polymerica Sinica 0(11):1422-1429(2018) DOI: 10.11777/j.issn1000-3304.2018.18107.
Synthesis of Thioether Compounds and Their Application in Initiating/Controlling the Radical Polymerization of Styrene
five thioethers containing 9-alkyl-9-phenylthio/methylthio-xanthene structure were synthesized. Xanthydrol was selected as the precursor for two 9-substituted xanthene intermediates. 9-(Phenylthio)-9
H
-xanthene was obtained
via
a condensation reaction between xanthydrol and thiophenol in the presence of perchloric acid as catalyst. 9-(Methylthio)-9
H
-xanthene was obtained
via
the thioetherification of the chlorinated product of xanthydrol with sodium methyl mercaptide. The sulfurated intermediates were deprotonated by
n
-butyl lithium
and transformed into five target products
via
substitution reactions with three alkyl halides individually.
1
H-NMR
13
C-NMR
FTIR and UV-Vis analyses were conducted to confirm and characterize the thioethers. Afterwards
a systematic study on the polymerization behavior of styrene (St) initiated by the thioethers was carried out in the absence and presence of a thermal initiator. Bulk polymerizations of St were initiated successfully by the thioethers at 80 °C with relatively low monomer conversions
and the reactions exhibited uncontrolled polymerization behaviors without obvious increase in number-average molecular weight (
M
n
) in the polymerization process with the PDI of polymeric products above 3.0. However
when the thioethers were used together with 2
2'-azobis(2
4-dimethyl)valeronitrile (ABVN) in the solution polymerization of St in toluene at 65 °C
higher monomer conversions compared with those of bulk polymerization and certain controllability could be achieved
reflected by a linear increase in
M
n
with conversion. Besides
the effects of molar ratio of ABVN to thioether and reaction temperature on the polymerization behavior of St were investigated in detail. A reduction in the molar ratio of ABVN to thioether would cause a reduction in the concentration of propagating radicals
and lead to a decrease in monomer conversion. But the PDI of polymeric product narrowed down indicating a controllable polymerization. Furthermore
elevated reaction temperature brought about an increased concentration of chain radical