ILSEVIER PII: S0032-3861 (97)00034-7 Polymer Vol. 38 No. 20, pp. 5169-5172, 1997 ~ 1997 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0032-3861,/97/$17.00 + 0.00 Functionalization of 1,2-polybutadiene by ruthenium complex catalysed coupling with vinylsilanes Bogdan Marciniec*, Mariusz Lewandowski and Cezary Pietraszuk Faculty of Chemistry, A. Mickiewicz University, 60-780 Poznat~, Poland and Zenon Foltynowicz Faculty of Commodity Science. Pozna6 University of Economics, 60-967 Pozna6, Poland (Received 29 July 1996; revised 4 January 1997) Vinyl groups, i.e. 1,2-units of polybutadiene in the presence of various ruthenium complexes at elevated temperatures undergo an effective reaction of dehydrogenative coupling with vinyltrisubstituted silanes to yield silyl substituted units. This is a new type of functionalization of unsaturated polymers. The reaction products are identified by 1H and 13C n.m.r, and FTI.r. spectroscopies as well as g.p.c, methods. © 1997 Elsevier Science Ltd. (Keywords: 1,2-polybutadiene;coupling; vinylsilane) INTRODUCTION Degradation of polymers with CH=CH bonds in the chain to low-molecular-weight products via olefin metathesis has been predominantly applied for the study of crosslinked structure 1'2. Experimental procedure involves investigation of the degradation products by 3 g.c.-m.s, method . This method was applied to identify network structures in 1,4-polybutadiene after the reac- tion with dicumyl peroxide in solution 4. Copolymers of 5 5 1,3-butadiene with styrene, propene, divinylbenzene/ ethylvinylbenzene7, acrylonitrile 8-, vinyltrimethylsilane 2 and divinyldimethylsilane ~ have also been investigated. Cross-metathesis of unsaturated polymers with alkenes (mostly ethylene, octene) leading to oligomers, occurs in the presence of classical Mo and W catalysts 1-8. Silyl olefins, mainly allylsilanes, were used by Wagener in ADMET depolymerization of 1,4-polybutadiene to yield-- in the presence of well-defined Schrock catalyst-- perfectly difunctional (f = 2.0) telechelic polybutadiene oligomers according to Scheme 19,10: in ADMET (de)polymerization in the presence of Mo and W catalyst 12'~3, on the contrary, they can be used for the reduction of the molar mass of polymers 14. On the other hand, divinylsubstituted silanes 15 and siloxanes 16 appeared very reactive in the new type of polycondensation reaction catalyzed by ruthenium and rhodium complexes, giving unsaturated polymers accord- ing to Scheme 2. Recently, mechanistic evidence has been found (using monovinylsilanes) in support of the fact that the reaction occurs not via metathetical conversion (cleavage of the C---C bond), but via dehydrogenative silylation of olefins by vinylsilanes (i.e. cleavage of vinyl C-H in olefins and Si-Cviny 1 bondsl7). The same process proceeds in the cross-metathesis of vinylsilanes with olefins in the presence of many ruthenium complexes 18. Therefore, the aim of this work is to utilize vinylsilanes not for depolymerization of 1,4- and 1,2-polybutadiene polymer to yield low-molecular oligomers, but for mod- ification of polybutadiene to synthesize silylsubstituted polymers 19. R A [Mo]or [W] + "~. toluene L ~ ~ n R where R = CH2Si(CH3) 3 or CH2Si(CH3)2CI; n = 1 - 4 Scheme 1 Crosslinking of the unsaturated polymers via meta- thetical conversion of hexenyl silicone polymers proceed- ing in the presence of Mo and W catalysts has been reported recently t 1. Vinylsubstituted silanes are not active *To whom correspondence should be addressed EXPERIMENTAL Materials 1,2-Polybutadiene (Mn = 1000) and 1,4-polybutadiene (Mn = 400 000)werepurchased fromPolysciences, Inc. and used without additional purification. Vinyltriethoxysilane POLYMER Volume 38 Number 201997 5169