CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Tianyu Ren,Shengping You,Muyuan Zhang,Yuefei Wang,Wei Qi,Rongxin Su,Zhimin He
Herein, the lignin-to-fuel conversion process was studied using real lignin as feedstock. Unlike model compounds, real lignin poisons the catalyst, causing rapid deactivation. The problem of catalyst deactivation was analyzed in detail for improving the conversion efficiency. We found that heavy carbonaceous deposits on the inner surface of the catalyst were responsible for the fast deactivation encountered in the conventional one-step reaction process. Moreover, the ester structures in lignin, which have previously been neglected in research, were confirmed to considerably worsen catalyst deactivation because they induce easier polymerization and hinder lignin conversion. Based on these points, we developed a three-step method that eliminates serious catalyst deactivation in the lignin-to-fuel conversion process, involving depolymerization of lignin, extraction of lignin monomers and hydrodeoxygenation of lignin monomers. The fuel production was 8.1–17.6-times more efficient using this three-step method than using the one-step batch reaction.
研究领域:
化学工程
·
能源科学
✓ 已验证
DOI
高影响因子
Polymers
·
2019
·Vol. 11
·期 5
·838
·
IF 3.164
Ting Li,Tianze Zheng,Jiarui Han,Zhanli Liu,Zhao-Xia Guo,Zhuo Zhuang,Jun Xu,Bao-Hua Guo
Four linear polyurea elastomers synthesized from two different diisocyanates, two different chain extenders and a common aliphatic amine-terminated polyether were used as models to investigate the effects of both diisocyanate structure and aromatic disulfide chain extender on hard segmental packing and self-healing ability. Both direct investigation on hard segments and indirect investigation on chain mobility and soft segmental dynamics were carried out to compare the levels of hard segmental packing, leading to agreed conclusions that correlated well with the self-healing abilities of the polyureas. Both diisocyanate structure and disulfide bonds had significant effects on hard segmental packing and self-healing property. Diisocyanate structure had more pronounced effect than disulfide bonds. Bulky alicyclic isophorone diisocyanate (IPDI) resulted in looser hard segmental packing than linear aliphatic hexamethylene diisocyanate (HDI), whereas a disulfide chain extender also promoted self-healing ability through loosening of hard segmental packing compared to its C-C counterpart. The polyurea synthesized from IPDI and the disulfide chain extender exhibited the best self-healing ability among the four polyureas because it had the highest chain mobility ascribed to the loosest hard segmental packing. Therefore, a combination of bulky alicyclic diisocyanate and disulfide chain extender is recommended for the design of self-healing polyurea elastomers.Keywords:diisocyanate structure;disulfide bonds;hard segmental packing;self-healing;polyureas
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
COLLOID AND POLYMER SCIENCE
·
2020
·Vol. 298
·期 9
·1215-1226
·
IF 1.536
Xu Chang-An,Lu Mangeng,Tan Zhiyou,Qu Zhencai,Wu Kun,Shi Jun
A series of polysiloxane-based polyurethane elastomers with aliphatic and aromatic diisocyanate structures are prepared using a two-step polymerization method. First, tolylene diisocyanate (TDI); dicyclohexylmethane 4,4′-diisocyanate (H 12 MDI); and hexamethylene diisocyanate (HDI) separately react with polycarbonate diol (PCDL) to produce polyurethane prepolymer, and furthermore, polysiloxane (PDMS) is added to the system to produce different polymers. The effect of different diisocyanate structures on mechanical properties, thermal stability, surface topography, and hydrophobic properties are explored. The results show that when the mass loss is higher than 50% during thermal decomposition, TDIPU exhibits relatively excellent thermal stability, which may be caused by the exposure of the silicone inside the polymer. HDIPU shows high hydrophobicity and low surface free energy, which is mainly related to a large amount of Si enriched on the surface. These differences are mainly caused by different molecular structures.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2021
·Vol. 12
·期 16
·2421-2432
·
IF 5.582
Jiaxin Shi,Tianze Zheng,Yao Zhang,Baohua Guo,Jun Xu
Polyurethanes with covalent adaptive network (CAN) have received widespread attention due to their recyclability and self-healing properties. The strategy of regulating the dynamic network rearrangement kinetics through varying the monomer structure is particularly interesting. Herein, based on the phenol–carbamate dynamic bond, we design a strategy to regulate the rearrangement kinetics of the dynamic covalent network by adjusting the chemical structure of aliphatic isocyanates with the same initial cross-linking degree. Temperature-varying FTIR and stress relaxation experiments prove the feasibility of this strategy from the perspective of thermodynamics and kinetics. For the studied isocyanates, greater steric hindrance or attachment of benzyl groups can promote the rearrangement of CAN. The two factors can reduce the relaxation time by one order of magnitude, and the relaxation activation energy can be reduced by over 20 kJ mol−1. Regardless of the network rearrangement kinetics, all polyurethane samples show good self-healing and reprocessing performance. In addition, the mechanical properties and stability in a hot air environment also vary with the chemical structure of the isocyanates, e.g., the isocyanates with alicyclic structure can improve the thermal stability, and the mechanical properties are almost unchanged after 24 h of treatment at 100 °C under air conditions, while the other polyurethanes show obvious softening. The method to regulate the rearrangement kinetics of phenol–carbamate CAN via changing the chemical structure of the monomers would be beneficial for developing self-healing and recyclable cross-linked polyurethanes with variable properties synthesized from industrial chemical feedstocks.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2025
·
IF 6.3
Dehuan Kong,Xuebin Lian,Shibiao Chai,Yilin Jin,Jiehao Qu,Shuangfei Xiang,Shujun Zhao,Feiya Fu,Xiangdong Liu
Advanced adhesives design needs to meet multiple requirements of cohesion strength, interfacial activity, re-processability, and degradability, while there exist great challenges to integrate these into single crosslinking network. Here, a novel di-spiroborate structure was designed and synthesized, and then applied to prepare epoxidized soybean oil-based covalent adaptable networks (CANs) adhesives. It was found that the double six-membered ring structure enhanced the rigidity of polymer chains for improved cohesion strength. Moreover, the B-O bond not only optimized interfacial activity via the reactions between electron-deficient boron atoms and the donor groups and nucleophiles of substrate, but also endowed epoxy CANs with re-processability and desired degradability owing to its dynamic property. Given on the effects, the maximum shear strength reached 16.24 MPa, showing an 94.96 % increment compared to the control. Meanwhile, the epoxy CANs adhesives still displayed 85.4 % conservation of lap shear strength after 3 bonding and de-bonding tests. Moreover, the epoxy CANs could be degraded in 1 M HCl/H 2 O solution within 125 min, and the degraded adhesives could rebonding substrate presenting a shear strength of 7.1 MPa. This work provides significant guidance to construct innovative CANs and highlights the development of multi-functional adhesives.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2016
·Vol. 54
·期 14
·2171-2183
·
IF 3.114
Keling Hu,Dongping Zhao,Guolin Wu,Jianbiao Ma
Two series of renewable nipagin and eugenol-based copoly(ether ester)s, PDN1 1− x E1 x and PDN1 1− x E2 x ( x = 0%, 10%, 20%, 30%, 40%, 50%), were prepared in the melt with 1,10-decanediol as a comonomer. The synthesized poly(ether ester)s have weight-average molecular weights ( M w ) in the range of 20,400–37,200 g mol −1 , and dispersity ( D ) values between 1.7 and 1.9. Thermal gravimetric analysis (TGA) reveal that all the poly(ether ester)s exhibit a two-step degradation mechanism with an initial degradation temperature above 350 °C. Results from differential scanning calorimetric (DSC) and wide-angle X-ray diffraction (WXRD) analyses demonstrate that the poly(ether ester)s are all semicrystalline materials with glass transition temperature ( T g ) values ranging between −21.3 and −8.3 °C. The insertions of phenoxy-ether linkage and eugenol-derived composition have significant influence on the T g , crystallinity, Young's modulus, and tensile strength, as well as the toughening effect and degradability. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54 , 2171–2183
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
·
2023
·
IF 5
Xu Pan,Wei Bai,Jinfang Liu,Wenfu Zhang,Xuefeng Sheng,Yang Zhou,Jianfu Zhang
Acrylate-modified aqueous polyurethane has become a widely used material due to its good physical and versatile chemical properties. However, owing to damage resulting from daily use, which often limits polymer performance, it is important to prepare a transparent and repairable polyurethane material. In this work, an acrylate-modified aqueous polyurethane based on the reversible structure of oxime–carbamate of butanedione oxime (POU) was prepared. The visible-light transmittance of the POU film could exceed 70%; its tensile strength and elongation at break could reach 3.0 MPa and 493%, respectively, and the POU film had a tensile strength of 3.9 MPa and elongation at break of 589% after repair. In addition, the POU has adjustable fluorescence properties, which makes this material suitable for potential application in the field of information encryption.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
Nature Communications
·
2023
·Vol. 14
·期 1
·1-8
·
IF 16.6
Zhang Xun,Guo Wenqi,Zhang Chengjian,Zhang Xinghong
Our society is pursuing chemically recyclable polymers to accelerate the green revolution in plastics. Here, we develop a recyclable polyester library from the alternating copolymerization of aldehyde and cyclic anhydride. Although these two monomer sets have little or no thermodynamic driving force for homopolymerization, their copolymerization demonstrates the unexpected alternating characteristics. In addition to readily available monomers, the method is performed under mild conditions, uses common Lewis/Brønsted acids as catalysts, achieves the facile tuning of polyester structure using two distinct monomer sets, and yields 60 polyesters. Interestingly, the copolymerization exhibits the chemical reversibility attributed to its relatively low enthalpy, which makes the resulting polyesters perform closed-loop recycling to monomers at high temperatures. This study provides a modular, efficient, and facile synthesis of recyclable polyesters using sustainable monomers.
研究领域:
材料科学
·
高分子化学
·
可持续化学
✓ 已验证
DOI
PubMed
高影响因子
COMPOSITES PART B-ENGINEERING
·
2023
·
IF 13.1
Hongzhi Feng,Xiwei Xu,Binbo Wang,Yi Su,Yanlin Liu,Chuanzhi Zhang,Jin Zhu,Songqi Ma
Recyclable carbon fiber reinforced polymer (CFRP) composites have attracted considerable attention in recent years due to the combined merits of excellent mechanical and thermal properties, recyclability and reprocessability. This paper reports on the successful preparation of closed-loop recyclable CFRP by in-situ polymerization and dynamic cross-linking (ISPDC) technology. The SEM, XPS and monofilament tensile curves were measured to investigate the morphology, chemical details, and mechanical properties of the recycled carbon fiber (CF); the chemical structure of the degraded resin was further characterized and analyzed according to the NMR and FTIR spectra. The obtained results show that under mild acidic conditions, the CFRP was degraded to high-quality recycled CF and linear polymer with methacrylic acid units, which can be used to prepare regenerated CFRP. In addition, due to the dynamic feature of the hemiacetal ester structure in the CFRP matrix, the CFRP also exhibited multiple functions, such as rapid welding, reprocessing, shape shifting, and self-healing, as well as the extremely long shelf life of composite prepregs . Our analysis of the recycling and dynamic exchange processes indicates that the strategy of embedding a releasable linker is dominant for the preparation of closed-loop recyclable and multifunctional CFRP.
研究领域:
材料科学
·
高分子化学
·
复合材料
✓ 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）