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Paper Information

Journal:   IRANIAN JOURNAL OF POLYMER SCIENCE AND TECHNOLOGY (PERSIAN)   JUNE-JULY 2017 , Volume 30 , Number 2 ; Page(s) 95 To 104.
 
Paper: 

EFFECTS OF MOLECULAR IODINE AND 4-TERT-BUTYLCATECHOL RADICAL INHIBITOR ON THE RADICAL POLYMERIZATION OF STYRENE

 
 
Author(s):  BOZORG MOJTABA, ABDOLLAHI MAHDI*, SEMSARZADEH MOHAMMAD ALI
 
* POLYMER REACTION ENGINEERING DEPARTMENT, FACULTY OF CHEMICAL ENGINEERING, TARBIAT MODARES UNIVERSITY, TEHRAN, IRAN
 
Abstract: 

The presence of molecular iodine was studied in relation the molecular weight and molecular weight distribution of polystyrene, produced by radical poly merization. Radical polymerization of styrene initiated by azobisisobutyronitrile (AIBN) was performed at 70°C in the presence of -? 2, 2 molecular iodine. The synthesized polymers were characterized by gel permeation chromatography (GPC) and proton- nuclear magnetic resonance (1H NMR) techniques.
The results of these reactions including conversion data, number-average molecular weight and molecular weight distribution were compared with those obtained for styrene radical polymerization initiated by AIBN at the same temperature in the absence of molecular iodine. It was found that the presence of iodine had a profound effect on the molecular weight and its distribution in the produced polystyrene. This was attributed to the ability of iodine to control the polymerization of styrene initiated by AIBN via reverse iodine transfer polymerization (RITP) mechanism. The polymer produced by this method had a molecular weight of 10600 g/mol with a molecular weight polydispersity index of 1.3. Due to the importance of induction period in reverse iodine transfer radical polymerization, increasing the temperature to 120°C during the induction period resulted in shorter induction periods and the produced species led to better control of the molecular weight. Also, due to the role of iodine molecules as a radical inhibitor, the presence of a secondary radical inhibitor, i.e.
4-tert-butylcatechol, along with the iodine was investigated in radical polymerization of polystyrene initiated by AIBN. It was observed that the secondary radical inhibitor prevented the consumption of the iodine molecules by the radicals produced from decomposition of the AIBN initiator; therefore, alkyl halides were not produced during the induction period.

 
Keyword(s): RADICAL POLYMERIZATION, STYRENE, INHIBITOR, CONTROLLED POLYMERIZATION, REVERSE IODINE TRANSFER POLYMERIZATION
 
References: 
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