Initiation of polymerization with substituted ethanes, 14 Free‐radical polymerization of methyl methacrylate and styrene with substituted adiponitriles

Tetraarylsuccinonitriles 1 show an atypical “stepwise” initiation mechanism in freeradical polymerization, particularly in the case of methyl methacrylate (MMA) as monomer. In the prior phase of the polymerization reaction very high concentrations of primary radicals lead to the formation of short‐chain telechelics with both end groups originating from the initiator. In the further course of polymerization these telechelics are able to from radicals by release of initiator end groups and so to “re‐initiate” free‐radical polymerization (‘resusciatable’ radical polymerization). In this communication a general synthesis method of MMA telechelics with a formal degree of polymerization of one is presented. These 2,2,5,5‐tetraaryl‐3‐methoxycarbonyl‐3‐methyladiponitriles 4 dissociate with Arrhenius activation energies in the range of 150 ± 10 kJ/mol. When using these telechelics as initiators in free‐radical polymerization of MMA and styrene, respectively, above 80°C no repeated telechelic formation phase is observed and polymer formation starts immediately from the beginning. The polymers obtained have weight‐average molecular weights of 200 000 to 950000 (poly(methyl methacrylate)) and 50000 to 400000 (polystyrene), respectively.