A Copper-Based Reverse ATRP Process for the Living Radical Polymerization of 4-Vinylpyridine: Discussion on Optimum Reaction Conditions

In this original experiment, reverse atom transfer radical polymerization technique using CuCl₂/hexamethyl tris[2-(dimethylamino)ethyl]amine (Me₆-TREN) as catalyst complex was applied to living radical polymerization of 4-vinylpyridine (4VP) with azobisisobutyronitrile (AIBN) as initiator. N,N-Dimethylformamide was used as solvent to improve the solubility of the reaction system. The polymerization not only showed the best control of molecular weight and its distribution, but also provided a rather rapid reaction rate with the molar ratio of [4VP]:[AIBN]:[CuCl₂]:[Me₆-TREN] = 400:1:2:2. The rate of polymerization increased with increasing the polymerization temperature and the apparent activation energy was calculated to be 51.5 kJ· mol¹. Use of Cl as the halogen in copper halide had many advantages over the use of Br. The resulting poly(4-vinylpyridine) was successfully used as the macroinitiator to proceed the block polymerization of styrene in the presence of CuCl/Me₆-TREN catalyst complex via a conventional ATRP process in DMF.