Crystalline styrene-butadiene-styrene (SBS) triblock copolymers consisting of elastic cispolybutadiene (cis-PB) chemically bonded with crystallizable syndiotactic polystyrene (syn-PS) were synthesized through a stereospecific sequential triblock copolymerization of S with B catalyzed by C 5 Me 5 TiMe 3 /B(C 6 F 5 ) 3 / trioctylaluminum (Al(oct) 3 ) under controllable polymerization conditions. The first polymerization step was conducted at -25 °C, yielding syn-PS with controllable molecular weight by changing the polymerization time.The second one was started with the addition of excess B to the progressing syn-PS polymerization at -40 °C, yielding syn-PS/cis-PB diblock copolymer with high block efficiencies. The third one was conducted at -25 °C just by removal of the unreacted B in order to enhance the reinsertion and propagation of the remained S, yielding crystalline SBS triblock copolymers with relatively high PS compositions. The livingness of the whole polymerization process was confirmed through a linear increase of the molecular weights of the polymer products obtained in each step against their polymer yields, while keeping the polydispersity values almost constant. The 13 C NMR analysis of the copolymer product proves that the PS blocks were highly syndiotactic ([rrrr] > 95%), and the PB block was primarily cis-1,4 structure (>70%). Cross-fractionation chromatography (CFC) was used to evaluate the contamination of the dead polymers in the crystalline SBS. Transmission electronic microscopy (TEM) was used to observe the phased separation morphology of the PS and PB blocks in the crystalline SBS. The existence of the syn-PS blocks in the crystalline SBS was further confirmed with the observation of a strong endothermic peak at 272 °C in their differential scanning calorimetry (DSC) curves. Preliminary results on the heat deformation stability as well as the chemical resistance property of this new material have also been evaluated in comparison with those of the corresponding anionic SBS materials.

Cis-specific living polymerizations of 1,3-butadiene (BD) catalyzed by the catalyst system composed of C5H4RTiCl3 (4a, R = H; 4b, R = n-butyl; 4c, R = isopropyl; 4d, R = tert-butyl; 4e, R = trimethylsilyl) with methylaluminoxane (MAO) to give polyBDs with narrow molar mass distribution and high cis content are described. Polybutadienes (polyBDs) prepared by the catalyst at −25 °C are monodispersed (M w / M n = 1.04−1.05) in all cases. From the comparison with propagation rate constants (k p), the order of polymerization activity was as follows:  4d > 4e > 4c > 4b = 4a. The microstructures of polyBDs were all dominated by the cis configuration. The complex 4d having bulky tert-butyl group showed higher cis specicficity. Both k ps and cis specificity in the polymerization of BD were strongly affected by the substituents introduced on the cyclopentadienyl ring.