Innovative synthetic rubbers via ruthenium catalyst systems

Abstract

The trans-polypentenamer has unique relevance among the synthetic rubbers since it has similar phys. properties to the natural rubber. The polypentenamer additives have propitious effect on the tire properties and have been studied extensively for this application. Polypentenamer synthetic rubber was synthesized by ringopening metathesis polymn. (ROMP) using ruthenium catalyst systems. It was found that the cyclopentene conversion does not depend on the catalyst activity and catalyst loading. However the applied reaction temp. has a significant impact on the polymn. yield. Equil. of growing chain and monomer was obsd. and the thermodn. parameters were detd. as: ΔH = - 5.6 kcal · mol^(-1); ΔS = -18.5 cal · mol^(-1)· K^(-1). The effect of cyclopentene ring substituents on the equil. was also investigated by exptl. and computational methods. The calcd. and exptl. detd. activation parameters of the synthetic rubbers made from different substituted cyclopentene derivs. are being detd. This unique feature of the equil. polymn. opens a way for the synthesis of durable, environmentally friendly elastomers where tires can be not only synthesized by the transition metal catalyst systems but the used tires can be readily decompd. by the same way and the recovered monomers can be easily recycled. Figure 1. Ruthenium catalyzed ring-opening metathesis polymn. (ROMP) of cyclopentene.