A New Family of Styrene/Diene Rubbers

Abstract

International audienceThe insertion of single styrene units into polyisoprene is demonstrated using borohydrido rare earth/dialkylmagnesium systems. This yields a new family of styrene/diene copolymers (SBR rubbers). The resulting poly[(1,4-trans-isoprene)-co-styrene] exhibits quite narrow molecular weight distributions, up to 30% inserted styrene, and a 96–98% 1,4-trans-microstructure. The presence of a bulky and electron-rich ligand in the coordination sphere of the metal leads to an increase of the amount of styrene inserted and narrower chemical composition and molecular weight distributions. The presence of significant quantities of styrene in the medium does not alter the selectivity of the reaction, in contrast with cis-specific polymerizations

Catalytic Chain Transfer (co‐)Polymerization: Unprecedented Polyisoprene CCG and a New Concept to Tune the Composition of a Statistical Copolymer

“…We reported recently halflanthanidocenes/dialkylmagnesium catalytic systems that show good potentialities for styrene transfer polymerization,3 and notably the first polystyrene CCG. The same catalytic systems had also shown good potentialities for the polymerization of isoprene4 and its statistical copolymerization with styrene 5. The literature devoted to the transmetalation of a growing polydiene chain between a transition metal and aluminum, magnesium, or zinc show that so far, the transfer generally occurs with a moderate efficiency,6–12 apart from a tris(aryloxy) lanthanide–dialkylmagnesium mediated butadiene oligomerization from our group 11.…”

Trans-stereospecific polymerization of butadiene and random copolymerization with styrene using borohydrido neodymium/magnesium dialkyl catalysts

“…It is noteworthy that with a feed rich in butadiene, the presence of 20 % styrene yet impacted negatively the rate of the polymerization (29 % yield, run 18). isoprene/styrene copolymerization with catalysts of the same family [45]. Such insertions of isolated styrene in trans-PB sequences (TTTSTTT) contrast with some reports of styrene inserted in cis-PB by the fact that the styrene insertions were followed by a singular trans unit (CCCSTCCC) [44,65].…”

“…Similar copolymers having trans-polydiene arrangement were much less reported [14,37]. Using a neodymium-based organometallic pre-catalyst associated with an equivalent amount of dialkylmagnesium reagent, up to 32% molar styrene was randomly inserted into polyisoprene without modifying the trans-stereoregularity of the polyisoprene backbone [45]. In chain transfer copolymerization conditions, ie in excess of Mg co-catalyst, the styrene was inserted at a 49 % molar ratio [46].…”

Simultaneous qualitation and quantitation of natural trans-1,4-polyisoprene from Eucommia ulmoides Oliver by gel permeation chromatography (GPC)

“…Although TPI can be also synthesized by industrial schemes [8,9], synthetic polymeric material may contain a small amount of cis-1,4-polyisoprene and 3,4-polyisoprene apart from trans-1,4-polyisoprene, which will distribute randomly as monomer, dyad, or triad sequences along macromolecular chain [10], and negatively affect rubber mechanical and machining properties consequentially. Therefore, investigation of the content and molecular-weight distribution (MWD) of natural TPI in plant tissues is very important in respect of harvesting higher rubber yield plant and cultivating suitable clone.…”