Synthesis, characterization and use of ATRP bifunctional initiator with trichloromethyl end-groups

摘要

A huge number of studies have been recently devoted to Atom transfer radical polymerization (ATRP) as one of thee methods of controlled radical processes and, likely, most promisig, which lead to tailored polymers. As the ATRP is initiated with organic halide-type compounds, very wide spectrum of initiators has been described, in combinations with various catalysts (salts of transition metals in the lower oxidation state) and various complexing ligands. Thus, alkylhalides with aliphatic or aromatic moieties combined with various catalysts and ligands are frequently used as initiators of styrene derivatives or methacrylates. For instance, benzylbromide or 1-phenylethylbromide in a combination with Cu(I) catalyst were successfully used for controlled ATRP of styrene and its derivatives, due to their steric resemblance, however, they are not the best initiators for methacrylate polymerization. For instance, MMA can be polymerized in a controllable way using CCl_3Br as an initiator in the presence of Ru or Ni-based catalysts. More, when initiated with CHCl_3 under catalysis of CuCl(bpy)_3, polymerization of styrene proceeds controllably and the product has expected molecular weight, however, polymerization initiated with di- or monochlormethanes under the same conditions is a process without control. Similarly, polymerization of MMA initiated with CHCl_3 or CCl_4 catalyzed with Ru-compounds is a controlled process, whereas with di- or monochlormethanes, MMA cannot be polymerized under the same conditions. Thus, it can be concluded, that polyhalogenated alkyls are generally better ATRP initiators than monohalogenated ones and, moreover, they can act as bifunctional initiators in some special cases. Therefore, a novel type of bifunctional ATRP initiator with trichloromethyl end-groups was synthesized by a reaction of 1,3-bis(1-isocyanato-1-methylenthyl)benzene (I) with 2,2,2-trichloroethan-1-ol (II) giving 1,3-bis{1-methyl-1-[2,2,2-trichloroethoxy)carbonylaminol ethyl} benzene (III) according to the following scheme, bearing two active sites in meta-positions capable to initiate ATRP.