Oligoisoprene macromonomer, which bears a terminal vinyl group, was prepared by the metathesis degradation of high-molecular-weight polyisoprene with ethylene for coordination polymerization. The ethenolysis of polyisoprene using the 2nd-generation Grubbs catalyst (G2) at ambient pressure gave heterotelechelic (α-vinyl-ω-vinylidene) oligoisoprene, keeping the stereoregularity in high yield, whereas the 1st generation Grubbs catalyst was immediately deactivated. In such metathesis degradation, an intramolecular side reaction giving cyclic oligomers may be competitive, but ethenolysis proceeded with high selectivity, probably because of the least steric effect of ethylene. The ethenolysis is also applicable for the degradation of natural rubber-derived polyisoprene, although the catalytic activity decreased. The prepared oligoisoprene macromonomer was successfully copolymerized with ethylene using a phenoxyimine-ligated titanium catalyst, and the reactivity of the macromonomer was almost the same as that of 1-hexadecene. The oligoisoprene-grafted polyethylene showed a typical stress‒strain curve, of which the tensile modulus and yielding stress are comparable to those of linear low-density polyethylene.

低聚异戊二烯大分子单体是通过高分子量聚异戊二烯与乙烯复分解降解进行配位聚合而制得的末端带有乙烯基的低聚异戊二烯大分子单体。使用第二代格鲁布斯催化剂（G2）在环境压力下对聚异戊二烯进行乙烯醇解，得到杂遥爪（α-乙烯基-ω-亚乙烯基）低聚异戊二烯，保持高产率的立构规整性，而第一代格鲁布斯催化剂立即失活。在这种复分解降解中，产生环状低聚物的分子内副反应可能是竞争性的，但乙烯醇分解以高选择性进行，可能是因为乙烯的空间效应最小。尽管催化活性有所下降，但乙烯醇分解也适用于天然橡胶衍生的聚异戊二烯的降解。采用苯氧亚胺配位钛催化剂，制备的低聚异戊二烯大分子单体与乙烯成功共聚，且该大分子单体的反应活性与1-十六烯几乎相同。低聚异戊二烯接枝聚乙烯表现出典型的应力-应变曲线，其拉伸模量和屈服应力与线性低密度聚乙烯相当。