Reversible Addition Fragmentation Chain Transfer Polymerization Using Dithionaphthalate As RAFT Agent

2-cyanoprop-2-yI-dithionaphthalate (a-CPDN) and 2-cyanoprop-2-yl-2-dithionaphthalate (P-CPDN) were synthesized and used as chain transfer agents for reversible addition-fragmentation chain transfer (RAFT) polymerizations. In addition, the following systems were also successfully carried out: (1) RAFT polymerizations of glycidyl methacrylate (GMA) using a-CPDN as RA FT agent in the presence of 2, 2'-azobisisobutyronitrile (AIBN). (2) RAFT bulk polymerization of iso-butyl methacrylate (i-BMA) using a-CPDN as RAFT agent in the presence of AIBN. (3) RAFT polymerizations of styrene (St) in bulk using P-CPDN as RAFT agent and with or without AIBN as initiator.It was found that RAFT polymerizations of GMA both in bulk and in solvent using a-CPDN as RAFT agent in the presence of AIBN could be proceeded in a controlled way, and the polymerization rate was first order with respect to monomer concentration, and molecular weight increased linearly with monomet conversion up to 96.7% at 60 C, 98.9% at 80 C in bulk and 64.3% at 60 C in benzene solution. The polymerization rate of GMA in bulk was obvious faster than that in benzene solution. The molecular weights (Mn) obtained from gel permeation chromatographic (GPC) closed to the theoretical values (Mn,th) and the Mw/Mn of polymer were relatively low up to high conversion in all cases. It was confirmed by chain extension reaction that AIBN initiated polymerizations of GMA using a-CPDN as RAFT agent were well controlled and were consistent with RAFT mechanism. The epoxy group remained intact in the polymers after the RAFT polymerization of GMA as indicated by the 1H-NMR spectrum.The RAFT bulk polymerization of i-BMA using a-CPDN as RAFT agent in the presence of AIBN showed that i-BMA could polymerize in a controlled way, i.e., the polymerization rate was first order with respect to monomer concentration, molecular weight increased linearly with monomer conversion, and Mw/Mn were relatively low(Mw/Mn < 1.2). The structure of the polymer was characterized by 'H-NMR. Chain extension experiment of resulted polymer was successfully carried out. The influences of [i-BMA]0/[ a-CPDN]0/[AIBN]o molar ratio and reaction temperature were investigated.The RAFT polymerizations of styrene in bulk using -CPDN as RAFT agent and with or without AIBN initiated showed that styrene could be polymerized in a controlled way. The polymer molecular weights increased linearly with monomer conversions and were closed to the theoretical values. At the same time the Mw/Mn of polymer remained in the relatively low values (lower than 1.3). The suitable malor ratio between [P-CPDN]0 and [AIBN]o was confirmed to be 2 to 3 when using AIBN initiating the polymerizations. The controllability of polymerization was best at 100C when thermal initiated thepolymerizations.In conclusion, the reversible addition fragmentation chain transfer polymerization using dithionaphthalate as RAFT agent showed controlled free radical characters: well controlled molecular weight, narrow polydispersity and linear relationship between molecular weight and monomer conversion. The dithionaphthalates are effective RAFT agents.