Synthesis of linear polyolefin elastomers containing divinylbenzene units and applications in cross-linking, functionalization, and graft reactions

This paper discusses the synthesis of linear polyolefin elastomers containing divinylbenzene (DVB) units, including poly(ethylene-ter-propylene-ter-divinylbenzene) (EP-DVB) and poly(ethylene-ter-1-octene-ter-divinylbenzene) (EO-VDB). Several metallocene catalysts were evaluated to identify a system that can carry out monoenchainment of DVB and produce terpolymer with uniform molecular structure. Some resulting EP-DVB and EO-DVB terpolymers prepared by a rac-Et(Ind) ₂ZrCl₂/MAO catalyst show good solubility in common organic solvents, controllable DVB content, high molecular weight, and narrow molecular weight and composition distributions. The uniform terpolymer microstructure also exhibits a DSC curve with a sharp glass transition temperature (T_g) that corresponds to its composition. Some EP-DVB and EO-DVB terpolymers with DVB content <2 mol % show low T_g's, below -45 and -55 °C, respectively. In turn, the pendent styrene moieties in the terpolymers are very versatile and engage in facile thermal and UV cross-linking and functionalization reactions (including maleation and metalation reactions) and in graft reactions. Several interesting thermoplastic elastomers containing a polyolefin elastomer backbone and several PS (amorphous) or s-PS (crystalline) side chains have been prepared by anionic graft-from and metallocene graft-through processes, respectively.