Synthesis and characterization of graft copolymer of EAA with poly(2-ethyl-2-oxazoline)

The title graft copolymer was synthesized by a two-step polymerization process. In the first step the monomer of 2-ethyl-2-oxazoline (EOX) was polymerized by cationic ring-opening polymerization with MeOTs as initiator in toluene. The prepolymer of poly( N-propionyl-ethylenimine) (PEOX) having living propagating end of oxazolinium ion in toluene was obtained with average molecular weight less than 10,000g/mol. Then the EAA (ethylene-acrylic acid copolymer) was grafted through the reaction of pendant carboxy group of EAA with the terminated living oxazolinium ion of PEOX in toluene. The effect of various parameters such as reaction condition of cationic polymerization, grafting reaction time and temperature, reactive group in EAA and PEOX molar ratio, and carboxy group content in EAA on grafting degree and average degree of polymerization in the graft chain were evaluated. It was found that there was a maximum grafting degree of graft copolymers, when the EAA/PEOX: molar ratio is in the range of 5 similar to 6. The graft copolymer EAA-g-PEOX with grafting degree>25 % can be obtained under some specific conditions,such copolymer can be used as compatiblizer in PBT/PP blends to improve the compatibility of the two phases and the mechanical properties.