Radical heterogeneous polymerization behavior of N-methyl-α-fluoroacrylamide in benzene

• Published in: Journal of polymer science. Part A, Polymer chemistry Polymer chemistry, 2001-07, Vol.39 (13), p.2196-2205
• Main Authors: Sato, Tsuneyuki, Maeda, Yoshinori, Seno, Makiko, Hirano, Tomohiro
• Format: Article
• Language: English
• Subjects: Applied sciences; copolymerization; electron spin resonance (ESR) spectrum; Exact sciences and technology; heterogeneous polymerization; long-lived polymer radical; N-methyl-α-fluoroacrylamide; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; radical polymerization; tacticity
• ISSN: 0887-624X; 1099-0518
• DOI: 10.1002/pola.1196

The polymerization of N‐methyl‐α‐fluoroacrylamide (NMFAm) initiated with dimethyl 2,2′‐azobisisobutyrate (MAIB) in benzene was studied kinetically and with electron spin resonance. The polymerization proceeded heterogeneously with the highly efficient formation of long‐lived poly(NMFAm) radicals. The overall activation energy of the polymerization was 111 kJ/mol. The polymerization rate (Rp) at 50 °C is given by Rp = k[MAIB]0.75±0.05 [NMFAm]0.44±0.05. The concentration of the long‐lived polymer radical increased linearly with time. The formation rate (Rp•) of the long‐lived polymer radical at 50 °C is expressed by Rp• = k[MAIB]1.0±0.1 [NMFAm]0±0.1. The overall activation energy of the long‐lived radical formation was 128 kJ/mol, which agreed with the energy of initiation (129 kJ/mol), which was separately estimated. A comparison of Rp• with the initiation rate led to the conclusion that 1‐methoxycarbonyl‐1‐methylethyl radicals (primary radicals from MAIB), escaping from the solvent cage, were quantitatively converted into the long‐lived poly(NMFAm) radicals. Thus, this polymerization involves completely unimolecular termination due to polymer radical occlusion. 1H NMR‐determined tacticities of resulting poly(NMFAm) were estimated to be rr = 0.34, mr = 0.48, and mm = 0.18. The copolymerization of NMFAm(M1) and St(M2) with MAIB at 50 °C in benzene gave monomer reactivity ratios of r1 = 0.61 and r2 = 1.79. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2196–2205, 2001 The radical polymerization of N‐methyl‐α‐fluoroacrylamide (NMFAm) with dimethyl 2,2′‐azobisisobutyrate(MAIB) proceeds heterogeneously in benzene. The polymerization system involves long‐lived poly(NMFAm) radicals. The primary radicals from MAIB, escaping from the solvent cage, are quantitatively converted into the long‐lived poly(NMFAm) radicals. As a result, the polymerization involves completely unimolecular termination due to polymer radical occlusion.