Long-lived polymer radicals in the polymerization of n-methylmethacrylamide in cyclohexane

✍ Scribed by T. Sato; M. Oka; H. Tanaka; T. Ota

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 424 KB
• Volume: 23
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(87)90139-x

✦ Synopsis

The polymerization of N-methylmethacrylamide (NMMAm) with azo-bis-isobutyronitrile (AIBN) was kinetically investigated in cyclohexane which has a small affinity for NMMAm monomer. The polymerization proceeded heterogeneously. The polymerization rate (Rp) was expressed by the following equation:

The overall activation energy of the polymerization was calculated to be 104 kJ/mol. The initiator efficiency of AIBN was determined to be 0.47 and 0.51 at 45 ° and 50"C, respectively. The polymerization system was found to contain long-lived poly(NMMAm) radicals. The formation rate of the living polymer radicals was determined by ESR and then the efficiency of living polymer radical formation was estimated to be 0.28 and 0.29 at 45 ° and 50°C. Comparison of the efficiency of the initiator with that of living polymer radical formation reveals that about 60% of cyanopropyl radicals escaping from the solvent cage were converted into living poly(NMMAm) radicals. From an electron microscopic examination, the resulting poly(NMMAm) was found to form coral-like conglomerates.