Graft polymerization of methyl methacrylate initiated by pendant azo groups introduced onto γ‐poly(glutamic acid)

Abstract

AbstractThe grafting of poly(methyl methacrylate) (PMMA) onto biosynthesized γ‐poly(glutamic acid) (γ‐PGA) initiated by pendant azo groups introduced onto γ‐PGA was performed. The introduction of pendant azo groups onto γ‐PGA was achieved by the reaction of carboxyl groups of γ‐PGA with azo initiators having hydroxyl or amino groups, such as 2,2‐azobis[2‐(hydroxymethyl)propionitrile] (AHP), 2,2′‐azobis[2‐methyl‐N‐(2‐hydroxyethyl)propionamide] (AMHP), and 2,2′‐azobis[2‐(2‐imidazolin‐2‐yl)propane] (AIP), using N,N′‐dicyclohexylcarbodiimide. The amount of pendant AHP groups introduced onto γ‐PGA was estimated to be 0.15 mmol/g. Untreated γ‐PGA failed to initiate the polymerization of MMA. On the contrary, the polymerization of MMA was found to be initiated in the presence of γ‐PGA having azo groups: the polymerization rate was proportional to the square root of the concentration of γ‐PGA having pendant azo groups. During the polymerization PMMA was grafted onto γ‐PGA; the percentage of grafting of PMMA onto γ‐PGA obtained from the graft polymerization initiated by pendant AHP, AMHP, and AIP groups was evaluated to be 65.0, 53.1, and 29.0%, respectively. Differential scanning calorimetric analysis shows that the endotherm transition point of γ‐PGA at 220°C disappears by the grafting of PMMA onto the polymer. © 1993 John Wiley & Sons, Inc.