ИСТИНА

This reaction belongs to interchain exchange type and proceeds via breaking up of C=C double bonds and formation of new ones in the presence of Ru-based Grubbs initiators. With this approach, we synthesized copolymers of norbornene with cyclooctene, cyclopentene, cyclododecene, butadiene, and isoprene, which are hard or even impossible to obtain by other methods. We were also able to introduce various functional groups (acetoxy-, carbohy-, hydroxy-, trimethylsilyl-, bromine) in the copolymers either by use of substituted monomers for obtaining the initial homopolymers, or by post-modification of the cross-metathesis products.In situ 1H and ex situ 13C NMR were implemented for monitoring of the reaction kinetics in terms of the Ru-carbene concentrations and dyad composition of the copolymer product. A quantitative model of the reaction kinetics was developed. This makes possible to regulate the degree of copolymer blockiness by varying the reaction time, ratio of reacting polymers and amount of initiator. In its turn, the chain structure determines copolymer crystallinity and tendency to microphase separation, which were probed with DSC, including thermal fractionation, and rheological measurements. It was shown that in some cases macromolecular cross-metathesis is accompanied by hydrogenation of C=C double bonds, which may lead to an increase in the copolymer crystallinity. At low polymer concentrations, one should also take into account intramolecular cross-metathesis, which results in the formation of cyclic macromolecules.