The second-generation Hoveyda–Grubbs (HG2) catalyst, which has a small initiation to propagation rate ratio (k_i/k_p) in ring-opening metathesis polymerization (ROMP), was successfully used in a recently developed catalytic living ROMP. This proved that slow-initiating catalysts can enable ROMP in a living fashion to produce polymers with narrow dispersity and controlled molecular weight. The molecular weight control experiments show a linear relationship between polymer molecular weight and monomer to chain-transfer agent (CTA) ratio. Different norbornene-derivatives can be utilized as monomers. Di-block copolymers and tri-block copolymers can be synthesized either using the first polymer block as macro-CTA or continuously adding different monomers sequentially. Mono-telechelic polymers, with functional end groups such as protected carboxylic acid, alcohol and amine can also be achieved. All polymers were fully characterized using NMR, GPC and MALDI-ToF analytical techniques. This procedure provides access to well-defined end-functional polymers at lower cost and with reduced rare metal residues that might be of interest for biomedical, materials, industrial and academic use.

中文翻译：

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第二代Hoveyda–Grubbs催化剂通过活性活泼开环易位聚合反应合成单端端聚合物

第二代Hoveyda-Grubbs（HG2）催化剂在开环复分解聚合（ROMP）中具有较小的引发与扩散速率比（k _i / k _p），已成功用于最近开发的催化活性ROMP。这证明缓慢引发的催化剂可以使ROMP以活泼的方式产生具有窄分散性和受控分子量的聚合物。分子量控制实验表明聚合物分子量与单体与链转移剂（CTA）之间呈线性关系）比率。可以使用不同的降冰片烯衍生物作为单体。可以使用第一种聚合物嵌段作为大分子CTA或依次连续添加不同的单体来合成二嵌段共聚物和三嵌段共聚物。具有功能性端基如受保护的羧酸，醇和胺的单遥聚物也可以得到。使用NMR，GPC和MALDI-ToF分析技术对所有聚合物进行了全面表征。该程序可以以较低的成本和减少的稀有金属残留物获得定义明确的最终功能聚合物，这对于生物医学，材料，工业和学术用途可能是有意义的。