Copolymers of norbornene and cyclooctene were synthesized for the first time by the cross-metathesis of polynorbornene with polyoctenamer. This strategy made it possible to use the 1^st generation Grubbs catalyst, which exhibits low activity toward copolymerization of those monomers. Statistical multiblock copolymers with average block lengths varying from 200 to 2 units were obtained.

Multiblock copolymers constitute a basis for an emerging class of nanomaterials that combine various functional properties with durability and enhanced mechanical characteristics. Our mini-review addresses synthetic approaches to the design of multiblock copolymers from unsaturated monomers and polymers using olefin metathesis reactions and other ways of chemical modification across double C=C bonds. The main techniques, actively developed during the last decade and discussed here, are the coupling of end-functionalized blocks, sequential ring-opening metathesis polymerization, and cross metathesis between unsaturated polymers, or macromolecular cross metathesis. The last topic attracts special interest due to its relative simplicity and broad opportunities to tailor the structure and hence the properties of the copolymer products. Whenever possible, we analyze the structure–property relations for multiblock copolymers and point to their possible practical applications.

Interfacial polymerization of tri- and bifunctional monomers (A3B2 polymerization) is investigated by dissipative particle dynamics to reveal an effect of cross-linking on the reaction kinetics and structure of the growing polymer film. Regardless of the comonomer reactivity and miscibility, the kinetics in an initially bilayer melt passes from the reaction to diffusion control. Within the crossover period, branched macromolecules undergo gelation, which drastically changes the scenario of the polymerization process. Comparison with the previously studied linear interfacial polymerization (Berezkin, A. V.; Kudryavtsev, Y. V. Linear Interfacial Polymerization: Theory and Simulations with Dissipative Particle Dynamics J. Chem. Phys. 2014, 141, 194906) shows similar conversion rates but very different product characteristics. Cross-linked polymer films are markedly heterogeneous in density, their average polymerization degree grows with the comonomer miscibility, and end groups are mostly trapped deeply in t...

The cross-metathesis of polynorbornene and polyoctenamer in d-chloroform mediated by the 1^st generation Grubbs’ catalyst Cl₂(PCy₃)₂Ru=CHPh is studied by monitoring the kinetics of carbene transformation and evolution of the dyad composition of polymer chains with in situ ¹H and ex situ ¹³C NMR spectroscopy. The results are interpreted in terms of a simple kinetic two-stage model. At the first stage of the reaction all Ru-benzylidene carbenes are transformed into Ru-polyoctenamers within an hour, while the polymer molar mass is considerably decreased. The second stage actually including interpolymeric reactions proceeds much slower and takes one day or more to achieve a random copolymer of norbornene and cyclooctene. Its rate is limited by the interaction of polyoctenamer-bound carbenes with polynorbornene units, which is hampered, presumably due to steric reasons. Polynorbornene-bound carbenes are detected in very low concentrations throughout the whole process thus indicating their higher reactivity, as compared with the polyoctenamer-bound ones. Macroscopic homogeneity of the reacting media is proved by dynamic light scattering from solutions containing the polymer mixture and its components. In general, the studied process can be considered as a new way to unsaturated multiblock statistical copolymers. Their structure can be controlled by the amount of catalyst, mixture composition, and reaction time. It is remarkable that this goal can be achieved with a catalyst that is not suitable for ring-opening metathesis copolymerization of norbornene and cis-cyclooctene because of their substantially different monomer reactivities.