GREEN CHEMISTRY
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2021
·Vol. 23
·期 4
·1871-1882
·
IF 10.182
Xiaoling Qu,Guangyuan Zhou,Rui Wang,Bolei Yuan,Min Jiang,Jun Tang
Alcoholysis is a potential method for the degradation of polyesters to their precursor building blocks, which can then be polymerized again to form new qualified polyester materials. This method therefore makes recycling possible in a permanent polymer–monomer–polymer loop. In this study, a series of metal-free tetrabutylphosphonium-based ionic liquids (ILs) were prepared as catalysts for the methanolysis of poly(ethylene 2,5-furandicarboxylate) (PEF), which is well known as an ideal alternative to the petroleum-based plastic poly(ethylene terephthalate) (PET). It was found that anions with stronger electronegativity were more efficient for the methanolysis of PEF. By adjusting the structures of the anions and cations of ILs, 1-butyl-3-methylimidazole acetate ([BMIm][OAc]) exhibited excellent catalytic activity in the methanolysis of PEF. The optimization of reaction parameters enabled the [BMIm][OAc]-catalyzed methanolysis of PEF with nearly 100% PEF degradation and a 77.6% dimethyl furan-2,5-dicarboxylate (DMFD) yield at 130 °C for 30 min. Furthermore, [BMIm][OAc] could keep high-activity after using for six times under the optimum conditions. Assisting with 1H NMR, FT-IR and density functional theory (DFT) calculations, an in-depth study was performed on the feasible synergetic catalytic mechanism of [BMIm][OAc] for the methanolysis of PEF, induced by hydrogen bonds formed between reactants and [BMIm][OAc]. Finally, on the basis of experimental results and scanning electron microscopy (SEM), it was confirmed that PEF with the spiral motif could be degraded under milder conditions than PET. Therefore, this strategy of using adjustable cation and anion structures in ILs provides an opportunity to develop other more efficient ILs for the alcoholysis of furan-based polymers via a green and mild pathway.
研究领域:
化学工程
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材料科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Pengtao Fang,Xingmei Lu,Qing Zhou,Dongxia Yan,Jiayu Xin,Junli Xu,Chunyan Shi,Yongquan Zhou,Shuqian Xia
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) α 2 -K 8 P 2 W 17 O 61 X(H 2 O)‧16H 2 O (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.
研究领域:
材料科学
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环境科学
·
高分子化学
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Han Hu,Jiayi Li,Shenggan Luo,Ying Tian,Jinggang Wang,Yi-Lei Zhao,Ruoyu Zhang,Jin Zhu
Nowadays, the promotion and application of aliphatic-aromatic copolyesters, such as poly (butylene adipate–co–terephthalate) (PBAT), are growing into a general trend. Although the structures of diacids exerted substantial impacts on degradation behavior, the underlying mechanisms have rarely been studied. In this work, 2,5-Furandicarboxylic acid was combined with succinic acid (PBSF), adipic acid (PBAF) and diglycolic acid (PBDF) to prepare three kinds of copolyesters. They showed unique degradation behaviors in buffer, enzyme environment and artificial seawater. These characteristics are closely related to the structural compositions of diacids. PBAFs displayed impressive biodegradability when catalyzed by Candida antarctica lipase B (CALB), while the more hydrophilic PBDFs exhibited faster hydrolysis in both buffer and artificial seawater. PBSFs, with hydrophobic and short segments, obtained a relatively slower rate of hydrolysis and enzymatic degradation. The reactivity sites and hydrolytic pathway were revealed by the combination of DFT calculation and Fukui function analysis. MD simulations, QM/MM optimizations and theozyme calculations showed that PBAF-CALB was prone to form a pre-reaction state, leading to the reduced energy barrier in the acylation process. This work revealed the effects of different structural features of diacids on polymer degradation and paved a way to design target biodegradable polymers in different degradation conditions.
研究领域:
材料科学
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环境科学
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生物化学
✓ 已验证
DOI
高影响因子
MACROMOLECULES
·
2022
·
IF 6.057
Han Hu,Jiayi Li,Qianfeng Wang,Xingyu Ouyang,Jinggang Wang,Yi-Lei Zhao,Cheng Kang,Ruoyu Zhang,Jin Zhu
A range of degradable polyesters have been developed as sustainable alternatives for commercial plastics; however, limitations of composting facilities and uncontrolled degradation in the environment hindered their viability. In this study, biobased itaconic acid was selected as an active site to control the degradation of polyesters. A series of PBXI copolyesters with Mw’s ranging from 4.86 to 8.31 × 104 g/mol and high intrinsic viscosities of more than 1.15 dL/g were successfully synthesized without any cross-linking by selecting appropriate reaction conditions, including condensation temperature and vacuum, effective inhibitor, and catalyst. The obtained copolyesters were semicrystalline, and their Tm’s could be regulated from 42.5 to 179.5 °C. They exhibited outstanding elastic modulus (120–598 MPa) and tensile strength (17.9–51.4 MPa) among degradable polymers. Degradation experiments demonstrated that the incorporation of itaconate segments could facilitate both the hydrolysis and enzymatic degradation of polyesters. The state-of-the-art computation and analysis via molecular dynamics (MD) simulations of PBXI–CALB complexes elucidated the enzymatic degradation mechanism. Experimental results proved that, at room temperature, the degradation could be stimulated and regulated by amines without a catalyst and the Mn’s of lactamization products rapidly decreased to less than 5000 g/mol within 24 h. Moreover, the copolymerized structure of copolyesters and solvent factors could influence the aza-Michael addition between amines and itaconate units. This work provides a strategy to synthesize biodegradable copolymers with the potential to undergo controlled and rapid in vivo degradation with outstanding mechanical properties.
研究领域:
材料科学
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环境科学
·
计算生物学
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2025
·
IF 9.2
Junyan Wu,Qingqing Zhao,Diandian Shi,Yiguo He,Zhen Miao,Haijiao Xie,Dianyu Wang,Shuzhuang Sun,Yadong Zhang
The ubiquitous use of plastic has resulted in an undeniable global impact on the environment. Glycolysis of polyethylene terephthalate (PET) is a promising plastic recycling approach, but the use of heavy metal catalysts may pose tremendous risks to both our environment and human health. In this work, we developed a method for in-situ generation of alkali metal catalysts, which generated magnesium alcohol (MgEG) through ligand exchange between acetylacetone and ethylene glycol (EG). By optimizing the reaction conditions, we achieved complete conversion of PET bottle flakes at 180 ℃ and obtained a bis(2-hydroxyethyl) terephthalate (BHET) yield of 85.9%. The structural characterization and density functional theory calculations demonstrated that EG in magnesium alcohol formed a quaternary ring with carbonyl group, reducing the reaction energy barrier. Moreover, this catalytic strategy exhibited reasonable catalytic activities on colored PET, PET mixed with other plastics and various polyesters, indicating the considerable potential for degradation of polyesters using non-heavy metal catalysts.
研究领域:
环境科学
·
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）