γ‐poly(glutamic acid) as an initiator of cationic polymerization of N‐vinylcarbazole and N‐vinyl‐2‐pyrrolidone

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Abstract
The cationic polymerization of vinyl monomers initiated by biosynthesized γ‐poly(glutamic acid) (γ‐PGA) powder surface was carried out in a heterogeneous system. It was found that the polymerization of N‐vinylcarbazole (NVC) and N‐vinyl‐2‐pyrrolidone (NVPD) is initiated by γ‐PGA powder. The grafting of polymers onto γ‐PGA surface was scarcely observed. The apparent activation energy of the polymerization of NVC and NVPD was estimated to be 20.2 and 24.8 kJ/mol, respectively. The polymerization was totally inhibited by the addition of triethylamine and pyridine, but not hydroquinone. The polymerization rate in nitrobenzene was larger than that in toluene. These results indicated the cationic nature of the polymerization. γ‐PGA treated with KOH did not show the initiating activity of the polymerization. Therefore, carboxyl groups on γ‐PGA powder surface play an important role in the initiation of the polymerization. It may be suggested that the polymerization is initiated by proton addition to monomer from carboxyl groups on γ‐PGA powder surface and the propagation proceeds with carboxylate anion on the surface as counter ion. © 1993 John Wiley & Sons, Inc.