Polyampholyte synthesis by cyclopolymerization

The syntheses of N ‐2‐phenylallylacrylamide (I) and N ‐ethyl‐2‐phenallylacrylamide (II) are described. Both monomers can be polymerized with radical initiators to form cyclopolymers although complete cyclization does not occur. Lewis acids (ZnCl 2 in the case of I, Et 1.5 AlCl 1.5 in the case of II) result in the formation of higher molecular weight polymers in a shorter period of time. Polymers of I and II have been hydrolyzed to polyampholytes. The copolymerization of α‐methylstyrene–acrylamide in the presence of azobisisobutyronitrile (AIBN) and ZnCl 2 leads to the formation of a 1:1 copolymer, whereas styrene–acrylamide under the same conditions give a copolymer slightly dependent upon the monomer feed composition. Attempted cyclopolymerization of N ‐allylacrylamide (monomer I without the phenyl group) with ZnCl 2 –AlBN was not successful, only crosslinked polymer being obtained. An explanation is offered for the fact that I does not form a perfect cyclopolymer, although the α‐methylstyrene–acrylamide system forms a 1:1 copolymer.