Efficient Bimodal Ring-opening Polymerization of ¥å-Caprolactone Catalyzedby Titanium Complexes with N-Alkoxy-¥â-ketoiminate Ligands

Bulletin of the Korean chemical society

Ik-Mo Lee¹  Jin San Yoon¹  Min Ho Cho¹ 

关键词: N-Alkoxy-¥â-ketoiminate;    Titanium complexes;    ¥å-Caprolactone;    Ring-opening polymerization;    Transesterification;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

A series of titanium complexes containing terdentate �?-ketoiminate ligands were found to be efficient for the ring-opening polymerization of �?-caprolactone (�?-CL), producing poly(�?-caprolactone) (PCL) with bimodal distribution. Steric factors imposed by methyl substituents on the back bone of the alkoxy group affected significantly the polymerization rate and physical properties of the resulting PCL. Intra- and intermolecular transesterifications rather than disproportional rearrangements were responsible for the bimodal behavior and for the change in the molecular weight (M_w). Dilution with toluene reduced yield, and lowered polydispersity (PDI) and Mw of PCL, while the catalytic activities of the dimeric complex, [Ti(Oi-Pr)₂(N-alkoxy-�?- ketoiminate)]₂ and Ti(Oi-Pr)₄ were not sensitive to the added solvent. The dimeric complex showed living character, while other catalysts suffered from chain termination reactions.

【 授权许可】

Unknown