Kinetic and ESR studies on radical polymerization behavior of N‐(2‐phenylethoxycarbonyl)methacrylamide

Abstract

Polymerization of N-(2-phenylethoxycarbonyl)methacrylamide (PECMA) with dimethyl 2,2Ј-azobisisobutyrate (MAIB) was investigated in tetrahydrofuran (THF) kinetically and by means of electron spin resonance (ESR). The overall activation energy of the polymerization was calculated to be 58 kJ/mol. The initial polymerization rate (R p ) is expressed by R p ϭ k[MAIB] 0.3 [PECMA] 2.3 at 60°C. Such unusual kinetics may be ascribable to primary radical termination and to acceleration of propagation due to monomer association. Propagating poly(PECMA) radical was observed as a 13-line spectrum by ESR under practical polymerization conditions. ESR-determined rate constants of propagation (k p , 4.7-10.5 L/mol s) and termination (k t , 4.6 ϫ 10 4 L/ml s) at 60°C are much lower than those of methacrylamide and methacrylate esters. The Arrhenius plots of k p and k t gave activation energies of propagation (24 kJ/mol) and termination (25 kJ/mol). The copolymerizations of PECMA with styrene (St) and acrylonitrile were examined at 60°C in THF. Copolymerization parameters obtained for the PECMA (M 1 ) Ϫ St(M 2 ) system are as follows: r 1 ϭ 0.58, r 2 ϭ 0.60, Q 1 ϭ 0.73, and e 1 ϭ ϩ0.22.

Kinetic study of the radical polymerization behavior of N‐(1‐phenylethylaminocarbonyl)methacrylamide

“…Similar activation energies are reported for the decompositions of MAIB (121 kJ/mol) and AIBN (126 kJ/mol) 13. The low E a value observed for PECMA was reported to result from the unusually high apparent activation energy of termination 5…”

“…From the plot, the overall activation energy (E a ) and frequency factor (A) of the polymerization were calculated to be E a = 84 kJ/mol and A = 1.578 × 10 10 L 1/2 /mol 1/2 s (estimated using the ideal rate equation), respectively. The E a value was much higher than that (58 kJ/mol)5 of the polymerization of PECMA with MAIB but was the same (84 kJ/mol) as the azobisisobutyronitrile (AIBN)‐initiated polymerizations of methyl methacrylate (MMA) and St 12. Similar activation energies are reported for the decompositions of MAIB (121 kJ/mol) and AIBN (126 kJ/mol) 13.…”

“…From the above results, R p at 60 °C in DMSO is given by eq 1: Thus, the rate equation (eq (1)) of the present polymerization is closely similar to that of the conventional radical polymerization involving bimolecular termination between the propagating polymer radicals. A higher exponent (2.3th) with respect to the monomer concentration was observed in the polymerization of PECMA carrying a conjugative urethane moiety with MAIB at 60 °C in tetrahydrofuran (THF) and was explained in terms of monomer association through hydrogen bonding 5. Urea derivative molecules are well known to strongly interact with each other through hydrogen bonding 14, 15.…”

“…Methacryloylisocyanate (MAI) has been satisfactorily employed for syntheses of new types of methacryl monomers, where the isocyanate group of MAI is allowed to easily react with alcohols, phenols, thiols, and amines 1–6. The reaction of MAI with a hydroxylic compound yields a monomer carrying an alkoxycarbonylcarbamoyl group as a conjugative substituent involving urethane moiety.…”

“…The reaction of MAI with a hydroxylic compound yields a monomer carrying an alkoxycarbonylcarbamoyl group as a conjugative substituent involving urethane moiety. In a previous paper,5 we reported kinetic results on the radical polymerization of N ‐(2‐phenylethoxycarbonyl)methacrylamide (PECMA) as a methacryl monomer carrying such a conjugative urethane moiety, which was prepared by the reaction of MAI with 2‐phenylethanol. Its rate constants of propagation (k p ) and termination (k t ) as determined by electron spin resonance (ESR) spectroscopy were much lower than those of methacrylamides and methacryl esters 7–10…”