Fast Upcycling of Poly(ethylene terephthalate) into Catalyst-Free Vitrimers
Fast Upcycling of Poly(ethylene terephthalate) into Catalyst-Free Vitrimers
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DOI：
10.1021/acssuschemeng.2c06829
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发表时间：
2023-01
期刊：
影响因子：
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通讯作者：
Shanxuan Wu;Yi-dong Li;Zhi Hu;J. Zeng
中科院分区：
文献类型：
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作者：
Shanxuan Wu;Yi-dong Li;Zhi Hu;J. Zeng
我们报道了一种无催化剂技术，通过将 PET 与 N,N'-四缩水甘油基二氨基二苯甲烷 (TGDDM) 在几分钟内进行熔融反应来制造基于酯交换的聚对苯二甲酸乙二醇酯 (PET) 玻璃体。我们详细研究了TGDDM含量对反应机理和最终产物化学结构的影响。在低TGDDM含量（≤0.5 wt%）下，通过PET的羧基与TGDDM的环氧基之间的扩链反应获得支化热塑性PET。在中等 TGDDM 含量（0.7-1.0 wt%）下，通过 PET 的原始羧基和羟基与 TGDDM 的环氧基团之间的交联反应，获得了交联密度相对较低的 PET 玻璃体。在高TGDDM含量（1.2-2.0wt％）下，PET原有的羧基和羟基与TGDDM的部分环氧基反应，首先形成可溶性扩链产物，然后在TGDDM部分的叔胺催化下，PET的酯基热分解生成新形成的官能团消耗多余的环氧基，得到PET玻璃体。交联网络结构赋予PET玻璃体增强的耐热性和抗蠕变性。由于内部叔胺催化下羟基与酯基之间发生快速酯交换反应，所得PET玻璃体能够快速松弛应力，并表现出优异的加工性能和焊接性能。我们相信，简便的制造技术在大规模生产中显示出将 PET 升级为玻璃体的巨大潜力。
We reported a catalyst-free technique to fabricate transesterification-based poly(ethylene terephthalate) (PET) vitrimers via melt reacting PET withN,N′-tetraglycidyldiaminodiphenyl methane (TGDDM) in several minutes. We investigated the effect of TGDDM content on the reaction mechanism and chemical structure of the final products in detail. At low TGDDM content (≤0.5 wt %), branched thermoplastic PET was obtained by the chain-extension reaction between carboxyl groups of PET and epoxy groups of TGDDM. At medium TGDDM content (0.7–1.0 wt %), PET vitrimers with relatively low cross-link density were achieved through the cross-linking reaction between original carboxyl plus hydroxyl groups of PET and epoxy groups of TGDDM. At high TGDDM content (1.2–2.0 wt %), soluble chain-extended products were first formed through reacting original carboxyl and hydroxyl groups of PET with part of epoxy groups of TGDDM, and PET vitrimers were then obtained after the excess epoxy groups were consumed by the newly formed functional groups, which were generated by thermal decomposition of ester groups of PET under catalyzation of tertiary amines of TGDDM moieties. The cross-linked network structure endowed the PET vitrimers with enhanced heat resistance and creep resistance. The obtained PET vitrimers could relax stress rapidly and showed excellent processability and weldability, owing to the fast transesterification between hydroxyl and ester groups under catalyzation of internal tertiary amines. We believe that the facile fabrication technique showed great potentiality for upcycling of PET into vitrimers in large-scale production.