Cross Metathesis and Hydrogenation in Polynorbornene–Poly(5-hydroxyoctenamer) Mixture in the Presence of Grubbs' CatalystsстатьяИсследовательская статья
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Дата последнего поиска статьи во внешних источниках: 22 февраля 2019 г.
Аннотация:Abstract—An exchange reaction of cross metathesis between polynorbornene and poly(5-hydroxyoctenamer)
in a chloroform–methanol mixture (10 : 1 v/v) in the presence of Ru carbene Grubbs complexes Gr-1
and Gr-2 has been studied. Gr-2 catalyst has a much higher activity and allows one to obtain multiblock
copolymers, which cannot be synthesized directly from norbornene and 5-hydroxy-1-cyclooctene. The average
length of the copolymer blocks varies in a wide range depending on the reaction conditions. The individual
stages of the process have been studied with the use of in situ monitoring of transformations of Ru carbene
complexes by 1Н NMR spectroscopy and ex situ analysis of heterodyad evolution in copolymers via 13C NMR
spectroscopy. As has been shown, poly(5-hydroxyoctenamer) forms Ru carbene complexes with the catalyst
more easily than polynorbornene; in this case, the incorporation of a substituent in the octenamer unit retards
the polymer cross metathesis. It has been found that, in systems containing Gr-2 and hydroxyoctenamer
blocks, the formed ruthenium hydride complexes initiated hydrogenation process. The hydrogenation results
in the origination of crystallinity in the initially amorphous polymers, which opens up the possibilities for the
targeted control of the multiblock copolymers properties.