ИСТИНА

The multiblock copolymers of different structure can be obtained using Gr-1 catalyst, though it is not suitable for effective ring-opening copolymerization of NB and COE. New NB-COE multiblock copolymers were identified and characterized by NMR, GPC, and DSC methods. 1H NMR spectroscopy was also used to monitor the interaction of Gr-1 with macromolecules. It was found that, contrary to the ROMP process, COE units form Ru-carbene complexes much faster than NB ones, presumably due to steric reasons. On the whole, the cross-metathesis reaction proceeds slowly and decreasing the average lengths of PNB and PCOE blocks from more than 200 to 2 units takes of the order of a day. The obtained copolymers possess a statistical multiblock chain structure, which can be controlled by altering the reaction time and catalyst concentration. During the reaction course a decrease in the copolymer molecular weight and crystallinity takes place. The crystallinity of resulting copolymers is lost when the average crystallizable COE block length approaches 2 units. The glass transition temperature also depends on the average length of COE blocks, ranging from -44 to -32 oC for the copolymers as compared to -79 oC for the PCOE. Our study opens broad perspectives for the controlled synthesis of statistical multiblock copolymers via the cross-metathesis reactions between polymers with carbon–carbon double bonds in their backbone.