Abstract
Depolymerization of an engineering plastic, poly(2,6-dimethyl-1, 4-phenylene oxide) (PPO), was accomplished by using 2,6-dimethylphenol (DMP) under oxidative conditions. The addition of an excess amount of DMP to a solution of PPO in the presence of a CuCl/pyridine catalyst yielded oligomeric products. When PPO (Mn = 1.0 × 104, M w/Mn = 1.2) was allowed to react with a sufficient amount of DMP, the molecular weight of the product decreased to Mn = 4.9 × 102 (Mw/Mn = 1.5). By a prolonged reaction with the oxidant, the oligomeric product was repolymerized to produce PPO essentially identical to the starting material, making the oligomer useful as a reusable resource. During the depolymerization reaction, an intermediate phenoxyl radical was observed by ESR spectroscopy. Kinetic analysis showed that the rate of the oxidation of PPO was about 10 times higher than that of DMP. These results show that a monomeric phenoxyl radical attacks the polymeric phenoxyl to induce the redistribution via a quinone ketal intermediate, leading to the substantial decrease in the molecular weight of PPO, which is much faster than the chain growth.
| Original language | English |
|---|---|
| Pages (from-to) | 4240-4246 |
| Number of pages | 7 |
| Journal | Chemistry - A European Journal |
| Volume | 9 |
| Issue number | 17 |
| DOIs | |
| Publication status | Published - 2003 Sep 5 |
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Keywords
- Depolymerization
- Green chemistry
- Polymerization
- Polyphenyleneoxide
- Reaction mechanisms
ASJC Scopus subject areas
- Chemistry(all)
Cite this
Depolymerization of poly(2,6-dimethyl-1,4-phenylene oxide) under oxidative conditions. / Saito, Kei; Masuyama, Toru; Oyaizu, Kenichi; Nishide, Hiroyuki.
In: Chemistry - A European Journal, Vol. 9, No. 17, 05.09.2003, p. 4240-4246.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Depolymerization of poly(2,6-dimethyl-1,4-phenylene oxide) under oxidative conditions
AU - Saito, Kei
AU - Masuyama, Toru
AU - Oyaizu, Kenichi
AU - Nishide, Hiroyuki
PY - 2003/9/5
Y1 - 2003/9/5
N2 - Depolymerization of an engineering plastic, poly(2,6-dimethyl-1, 4-phenylene oxide) (PPO), was accomplished by using 2,6-dimethylphenol (DMP) under oxidative conditions. The addition of an excess amount of DMP to a solution of PPO in the presence of a CuCl/pyridine catalyst yielded oligomeric products. When PPO (Mn = 1.0 × 104, M w/Mn = 1.2) was allowed to react with a sufficient amount of DMP, the molecular weight of the product decreased to Mn = 4.9 × 102 (Mw/Mn = 1.5). By a prolonged reaction with the oxidant, the oligomeric product was repolymerized to produce PPO essentially identical to the starting material, making the oligomer useful as a reusable resource. During the depolymerization reaction, an intermediate phenoxyl radical was observed by ESR spectroscopy. Kinetic analysis showed that the rate of the oxidation of PPO was about 10 times higher than that of DMP. These results show that a monomeric phenoxyl radical attacks the polymeric phenoxyl to induce the redistribution via a quinone ketal intermediate, leading to the substantial decrease in the molecular weight of PPO, which is much faster than the chain growth.
AB - Depolymerization of an engineering plastic, poly(2,6-dimethyl-1, 4-phenylene oxide) (PPO), was accomplished by using 2,6-dimethylphenol (DMP) under oxidative conditions. The addition of an excess amount of DMP to a solution of PPO in the presence of a CuCl/pyridine catalyst yielded oligomeric products. When PPO (Mn = 1.0 × 104, M w/Mn = 1.2) was allowed to react with a sufficient amount of DMP, the molecular weight of the product decreased to Mn = 4.9 × 102 (Mw/Mn = 1.5). By a prolonged reaction with the oxidant, the oligomeric product was repolymerized to produce PPO essentially identical to the starting material, making the oligomer useful as a reusable resource. During the depolymerization reaction, an intermediate phenoxyl radical was observed by ESR spectroscopy. Kinetic analysis showed that the rate of the oxidation of PPO was about 10 times higher than that of DMP. These results show that a monomeric phenoxyl radical attacks the polymeric phenoxyl to induce the redistribution via a quinone ketal intermediate, leading to the substantial decrease in the molecular weight of PPO, which is much faster than the chain growth.
KW - Depolymerization
KW - Green chemistry
KW - Polymerization
KW - Polyphenyleneoxide
KW - Reaction mechanisms
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UR - http://www.scopus.com/inward/citedby.url?scp=0141426619&partnerID=8YFLogxK
U2 - 10.1002/chem.200204669
DO - 10.1002/chem.200204669
M3 - Article
VL - 9
SP - 4240
EP - 4246
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 17
ER -