SYNTHESIS OF HYDROXYL-TERMINATED POLYBUTADIENE POSSESSING HIGH CONTENT OF 1,4-UNITS VIA ANIONIC POLYMERIZATION

The hydroxyl-terminated polybutadiene (HTPB) possessing high content of 1,4-units was synthesized by anionic polymerization of butadiene, using alkyllithium containing silicon-protected hydroxyl group as initiator and cyclohexane as solvent. The polymers were characterized by GPC, IR and H-1-NMR. The mechanical properties of cured films were also evaluated. The results show that the content of 1,4-units for HTPBs made by anionic polymerization reaches up to 90%. The molecular weight distribution is very narrow (<= 1.05). The functionality of hydroxyl groups approaches 2. Compared with free radical HTPB, the elongation at break of anionic HTPB films increased by 70%, while the tensile strength remained nearly unchanged. This new HTPB can be very useful in solid propellant.