Synthesis and characterization of stereotriblock polybutadiene containing crystallizable high trans-1,4-polybutadiene block by barium salt of di(ethylene glycol) ethylether/triisobutylaluminium/dilithium

A series of high trans -1,4-low- cis -1,4-high trans -1,4-stereotriblock polybutadienes (HTPB- b -LCPB- b -HTPBs) were synthesized through a sequential anionic polymerization of butadiene (Bd) initiated by barium salt of di(ethylene glycol) ethylether/triisobutylaluminium/dilithium (BaDEGEE/TIBA/DLi). The polymers consisted of elastic low- cis -1,4-polybutadiene (LCPB) chemically bonded with crystallizable high trans -1,4-polybutadiene (HTPB). The block ratios (HTPB:LCPB:HTPB) were designed at 25:50:25 (molar ratio) and finally determined by SEC. The microstructures and sequences of the specimens were investigated by FTIR and NMR. The resultant HTPB- b -LCPB- b -HTPBs consisted of LCPB block with 52.5% trans -1,4 content and HTPB block with 55.9–85.8% trans -1,4 content. According to differential scanning calorimetry (DSC), HTPB- b -LCPB- b -HTPB showed a significant cold crystallization which was discussed in terms of entanglement concept. The cold crystallization temperature ( T cc ) decreased whereas the melting temperature ( T m ) increased with the increasing trans -1,4 content of HTPB block.