膦胺类稀土金属钇配合物催化十三烷二酸环乙撑酯与小环内酯共聚合

以一种新型膦胺类稀土金属钇配合物(2,4,6-Me3C6H2NPPh2)Y(CH2C6H4NMe2-o)2为催化剂,当十三烷二酸环乙撑酯(EB)与催化剂的物质的量之比为200时,采用一锅法在室温条件下实现了EB分别与δ-戊内酯和ε-己内酯的共聚合,制备了EB含量递变的聚酯共聚物。利用核磁共振(NMR)、差示扫描量热(DSC)、热重分析(TG)和广角X射线衍射(WAXD)等对共聚物进行了表征,研究了共聚物的序列结构、结晶性能及热性能。结果表明:反应24 h单体转化率即可达80%~90%。所得共聚物具有明显的嵌段结构,无规度(R)低(0.25~0.36),且嵌段结构可显著提升共聚物的热稳定性。

Copolymerization of Ethylene Brassylate with Small Lactones Using a Mono(phosphinoamide) Rare-Earth Yttrium Complex

On the basis of a novel mono(phosphinoamide)rare-earth yttrium complex,(2,4,6-Me3C6H2NPPh2)Y(CH2C6H4NMe2-o)2,the copolymerizations of ethylene brassylate(EB)withδ-valerolactone(δ-VL)andε-caprolactone(ε-CL)were realized,respectively.Copolymers with different compositions were synthesized through a one-pot ring-opening polymerization approach with a monomers/catalyst molar ratio of 200.Such an approach is featured by solvent-free and mild conditions(for 24 h at room temperature).The average sequence lengths and randomness characteristics of the copolymers were analyzed by nuclear magnetic resonance(NMR).Furthermore,the crystallization behaviors and thermal properties were investigated by differential scanning calorimetry(DSC),wide-angle X-ray diffraction(WAXD)and thermogravimetric analysis(TG).Results showed that the yields of the copolymers could reach 80%—90%when the reactions were conducted for 24 h.The composition ratios in products were in good agreement with the feed ratios.The catalyst was efficient for the copolymerization,resulting in the copolyesters with high molecular weights(Mn>3×10^4)and narrow molecular weight distributions.The number average length and randomness of copolymers indicated that the copolymers had a block structure and presented a deviation from the random distribution of sequences(R=0.25—0.36).The resulting block copolymers were able to crystallize over the entire range of composition,and the existence of EB sequences and the block structure had a significant effect on the thermal stability of the copolymers.