Model linear block co-, ter-, and quaterpolymers of 1,3-cyclohexadiene with styrene, isoprene, and butadiene

The following linear block co-, ter-, and quaterpolymers of 1,3-cyclohexadiene (CHD) with styrene (S), isoprene (I), and butadiene (B) were synthesized by sequential anionic polymerization: PS-b-PCHD, PI-b-PCHD, PB-b-PCHD, PS-b-PB-b-PCHD, PB-b-PS-b-PCHD, PB-b-PI-b-PCHD, and PS-b-PB-b-PI-b-PCHD. sec-Butyllithium with either N,N,N′,N′'-tetramethylethylenediamine (TMEDA) or 1,4-diazobicyclo[2.2.2]octane (DABCO) was used as the initiating system. In all cases CHD was the last monomer added. The polar additive (TMEDA or DABCO) was always introduced to the polymerization solution prior to the addition of CHD and isoprene. The microstructures of the polydienes obtained in the different environments were determined by NMR spectroscopy. Thorough characterization by size exclusion chromatography coupled with multiangle laser light scattering, laser differential refractometry, osmometry, and NMR spectroscopy revealed that the synthesized polymeric materials exhibit high molecular and compositional homogeneity.