低聚物
降级(电信)
共聚物
聚合物
高分子
催化作用
材料科学
化学工程
单体
产量(工程)
聚合物降解
高分子化学
化学
有机化学
计算机科学
复合材料
工程类
电信
生物化学
作者
Pengtao Fang,Xingmei Lü,Qing Zhou,Dongxia Yan,Jiayu Xin,Junli Xu,Chao Shi,Yongquan Zhou,Shuqian Xia
标识
DOI:10.1016/j.cej.2022.138988
摘要
Controlled degradation of macromolecules or natural macromolecules is important for their subsequent utilization. Normally, it is easier to degrade them to monomers than to oligomers in designated molecular weight range, the controlled degradation is much difficult to achieve and has been challenge for the utilization of macromolecules. Here, we proposed a strategy for simultaneous degradation of the inner and outer layers of PET, which avoid the degradation of polymers from the outside to the inside and achieved the controlled degradation. Under high temperature and micro-pressure conditions, PET is transformed from dense to flocculent structure by the swelling effect, which satisfies the need for simultaneous degradation of the inner and outer layers. In addition, a stable "Dawson" type Polyoxometalates (POMs) α2-K8P2W17O61X(H2O)‧16H2O (X = Zn, Mn, Co, Ni, Cu) with limited number of catalytic activity center was synthesized and applied to PET alcoholysis to obtain oligomer with given molecular weight range. Under the optimal conditions, PET: EG: POM catalyst = 1.0: 4.0: 0.02 (wt%), 240 °C, 10 min, PET was completely degraded and obtained the oligomer products (Mn < 2000 g/mol) with 72.1 % yield. By investigating the mechanism of the controlled alcoholysis, the formation of flocculent PET was be the key factor in achieving controlled degradation; hydrogen bonding and coordination of POMs are the key interactions to achieve rapid alcoholysis. Finally, oligomers were applied in the preparation of PET-PLA copolymers to follow sustainable route. The incorporation of bio-based polymers demonstrates better inclusiveness to the environment and contributes to harmonious development.
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