POLYMER DEGRADATION AND STABILITY
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2024
·
IF 6.3
Tengfei Han,Benzhi Ju,Shufen Zhang
Despite covalent adaptable networks (CANs) imparting the reprocessing performance of crosslinked polymers, due to reversible bond exchange of the dynamic covalent bonds ; it is still a huge challenge to design catalyst-free, fast reprocessing, controlled degradation and raw material recycling biomass base CANs. Here, for the first time, we prepared cellulose CANs base on hemiacetal and acetal bonds (ACCs) via aldehyde and hydroxyl reaction of the dialdehyde crosslinker with hydroxypropyl cellulose (HPC). By regulating the crosslink density and chemical structure of the crosslinked network, ACCs exhibit tunable thermal and mechanical properties. The crosslinked network structure of the ACCs benefits from the rapid bond exchange of the hemiacetal and acetal bonds at elevated temperatures, which allows for rapid stress relaxation and thus, superior reprocessing properties. In addition, it was found that the dynamic exchange of acetals in the ACCs is influenced by the chain length and flexibility of the crosslinker. Moreover, ACCs possess good degradation and cellulose feedstock recycling properties due to the acid sensitivity of the acetal bonds. This work provides an effective solution to the problems of resource waste caused by petroleum-based thermoset plastics.
研究领域:
材料科学
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化学工程
·
生物化学
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产品关联
DOI
高影响因子
JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE
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2018
·Vol. 98
·期 12
·4733-4741
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IF 2.379
Chunfeng Liu,Qi Li,Chengtuo Niu,Feiyun Zheng,Yun Zhao
BACKGROUND Acetaldehyde is an important flavor component in beer which is possibly carcinogenic to humans. Owing to the limitations of present detection methods, only free-state acetaldehyde in beers has been focused on, while acetal in beers has hardly been reported so far. RESULTS A sensitive headspace gas chromatography method was developed for the determination of diethylacetal and acetaldehyde in beer. The column DB-23 was chosen with a total run time of 22.5 min. The optimal addition amount of NaCl, equilibrium temperature and equilibrium time were 2.0 g, 70 °C and 30 min respectively. For both diethylacetal and acetaldehyde analyses, the limit of detection was 0.005 mg L −1 with relative standard deviation < 5.5%. The recoveries of acetaldehyde and diethylacetal were 95–110 and 95–115% respectively. The diethylacetal and acetaldehyde average contents in 24 beer products were 11.83 and 4.36 mg L −1 respectively. The Pearson correlation coefficient between diethylacetal and acetaldehyde was the highest (0.963). Both diethylacetal and acetaldehyde contents increased to a peak value after fermentation for 3 days and then decreased to a lower value. During both normal and forced aging storage, the diethylacetal content decreased and the acetaldehyde content increased gradually over time. When beers were forced aged for 4 days, the increased ratio of acetaldehyde could be above 40.00%. CONCLUSION The newly established method can be used to assess acetaldehyde level and flavor quality in beer more scientifically. © 2018 Society of Chemical Industry
研究领域:
食品科学
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分析化学
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产品关联
DOI
PubMed
高影响因子
Frontiers in Chemistry
·
2020
·
IF 3.693
Zhao Xinyue,Shan Pengfei,Liu Haiwei,Li Daai,Cai Peihan,Li Zhongyu,Li Zhihui
A synthetic route to prepare a poly(ethylene glycol) with a single cinnamaldehyde acetal unit in the polymer chain, was successfully established using a newly synthesized cinnamaldehyde acetal diethylene glycol (CADEG) as initiator. This HO-PEG(ca)-OH is non-toxic and would be degraded into a cinnamaldehyde and two PEG diols in acid environment. A whole polyethylene glycol based hydrogel was easily fabricated by thiol-ene “click” reaction in alkalescence aqueous solution using acrylate-PEG(ca)-acrylate and 4-arm PEG-SH as raw materials at room temperature. The gel time was dependent on the pH of the solution and its alkalinity can promote gel. The hydrogel can be degradable in acidic conditions and the stronger the acidity, the faster the degradation. This HO-PEG(ca)-OH also can be used in synthesis of cinnamaldehyde containing PEG derivatives, block copolymers or other acid degradable materials.
研究领域:
材料科学
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生物医学工程
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DOI
PubMed
高影响因子
EUROPEAN POLYMER JOURNAL
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2020
·
IF 3.862
Shaobai Wang,Kangzhou Xie,Donglin Tang
Polyvinyl alcohol (PVA) is a reactive polymer since there are abundant hydroxyl groups so various chemical transitions are feasible for PVA. In this study, we utilized the oxidation of PVA followed with a ketalization to achieve the configuration of reversible polyketal networks. The oxidation of PVA was performed by using a benign oxidation system in which hydrogen peroxide acts as the green oxidant and p -toluene sulfonic acid (TSA) as the catalyst. Both fully oxidized PVA (polyketone, PK) and partially oxidized PVA (PVA-OXI) were obtained by controlling the oxidation time. Polyketals (PKLs) were prepared by ketalization of PVA with PK, or by self-ketalization of PVA-OXI. Under the catalysis TSA , only dark PKLs were obtained. However, with ionic liquid [BMIm]HSO 4 as the catalyst, PKLs were colorless and transparent. The PKLs originated from a feed ratio of PVA/PK = 4/1 (w/w) seems tougher than other samples. When the PKL films were hydrolysed at 90 °C and recasted, the recycled (or reprocessed) PKL films appears the same as the fresh one, from the appearance to the chemical structure, and further to the mechanical properties. PKLs can be prepared by self-ketalization as well from PVA-OXI but the mechanical properties of the obtained PKLs seem not as good as those from ketalization of PVA and PK. The discoveries in this work open a door to easy but efficient modification of OH-abundant polymers, especially for polysaccharides.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
Polymers
·
2017
·Vol. 9
·期 12
·698
·
IF 3.364
Yinglei Zhai,Xing Zhou,Lina Jia,Chao Ma,Ronghua Song,Yanhao Deng,Xueyao Hu,Wei Sun
The differences in micro-environment between cancer cells and the normal ones offer the possibility to develop stimuli-responsive drug-delivery systems for overcoming the drawbacks in the clinical use of anticancer drugs, such as paclitaxel, doxorubicin, and etc. Hence, we developed a novel endosomal pH-sensitive paclitaxel (PTX) prodrug micelles based on functionalized poly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) diblock polymer with an acid-cleavable acetal (Ace) linkage (mPEG-PCL-Ace-PTX). The mPEG-PCL-Ace-PTX5with a high drug content of 23.5 wt % was self-assembled in phosphate buffer (pH 7.4, 10 mM) into nanosized micelles with an average diameter of 68.5 nm. The in vitro release studies demonstrated that mPEG-PCL-Ace-PTX5micelles was highly pH-sensitive, in which 16.8%, 32.8%, and 48.2% of parent free PTX was released from mPEG-PCL-Ace-PTX5micelles in 48 h at pH 7.4, 6.0, and 5.0, respectively. Thiazolyl Blue Tetrazolium Bromide (MTT) assays suggested that the pH-sensitive PTX prodrug micelles displayed higher therapeutic efficacy against MCF-7 cells compared with free PTX. Therefore, the PTX prodrug micelles with acetal bond may offer a promising strategy for cancer therapy.Keywords:prodrug;polymer micelles;pH-sensitive;acetal;paclitaxel
研究领域:
药学
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肿瘤学
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DOI
PubMed
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
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2024
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IF 5.6
Shuai Li,Jiang Zhong,Wenxiong Zhang,Zhenhua Xiong,Fei Gao,Yongluo Qiao,Liang Shen
Conventional polyurethanes from non-renewable resources have been widely used for their excellent mechanical properties and thermal stability, which are difficult to be reprocessed and recycled due to the permanent crosslinked networks. In this study, dynamic acetal bonds were synthesized using bio-based vanillin and then embedded in polymer with castor oil to construct bio-based recyclable polyurethane. The ratio of castor oil to bio-spiroacetal diols was varied to control the thermodynamics and mechanical performance of bio-based polyurethanes. Experimental results of dynamic mechanical analysis, differential scanning calorimetry, tensile test and stress relaxation test suggested that a decrease in the content of acetal diols as a hard segment, led to a decrease in the glass transition temperature and tensile strength. Additionally, the activation energy initially increased and then decreased. The reversibility of the acetal structure endowed green polyurethane materials with the ability of reprocessing, self-repairing and closed-loop recycling.
研究领域:
材料科学
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高分子化学
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可持续材料
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产品关联
DOI
高影响因子
JOURNAL OF FOOD COMPOSITION AND ANALYSIS
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2025
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IF 4.6
Wei Dai,Wenjun Tan,Xuepeng Chen,Jilei Wang,Yougui Yu,Qing Zheng
This study investigates the interconversion between acetaldehyde and its acetal derivatives during the aging process of Baijiu. Acetaldehyde imparts a pungent aroma, while acetal contributes soft fruity and sweet notes to Baijiu. The dynamic equilibrium between these two compounds, mediated by a reversible reaction, significantly influences the aromatic balance and overall flavor harmony of the liquor. By analyzing aging data from Baijiu samples of different alcohol contents (62°, 52°, and 38° ABV) and aromatic types ( Nong , Jiang , Feng , Jian ), we calculated the apparent equilibrium constant (K) and developed a model predicting the simplified equilibrium constant as a function of alcohol content. Results revealed that reduced alcohol content shifts the equilibrium toward acetaldehyde formation, diminishing acetal-derived aromas. This study pioneers a thermodynamic quantitative model for acetaldehyde-acetal interconversion in Baijiu, elucidates the regulatory role of alcohol content in reaction equilibrium through solvent effects. These findings contribute significantly to the scientific understanding of Baijiu aging and offer practical solutions for flavor optimization in Baijiu production, particularly for low-alcohol Baijiu.
研究领域:
食品化学
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风味科学
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物理化学
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热力学
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酿造技术
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产品关联
DOI
高影响因子
Catalysis Science & Technology
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2015
·Vol. 6
·期 11
·3854-3861
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IF 5.426
Peng Wang,Huan Liu,Yong-Qi Li,Xiao-Li Zhao,Yong Lu,Ye Liu
A series of ionic phosphonium-based aminophosphines L1–L3 were prepared and fully characterized, in each of which the involved bifunctional moieties of the phosphine fragment and Lewis acidic phosphonium were linked together by stable chemical bonds and bridged by one N-atom. The molecular structure of the L2-ligated Rh-complex (Rh-L2) indicated that such bifunctionalities were well retained without incompatibility problems. Investigations on co-catalysis over L1–L3 showed that L3 exhibited the best sequential catalysis for both hydroformylation and acetalization. The phosphine fragment in L3 was responsible for hydroformylation together with the Rh-complex and the phosphonium acted as the Lewis acidic catalyst in charge of acetalization. The L3–Rh(acac)(CO)2 system also exhibited good generality to hydroformylation–acetalization of a wide range of olefins in different alcohols.
研究领域:
有机化学
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催化化学
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DOI
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
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2024
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IF 3.3
Rui Sun,Junyi Wang,Haoran Liang,Shuo Li,Xiao Yang
A facile and novel N-heteroarenium iodide-catalyzed hydroalkoxylation of enamides has been described. The protocol provides easy access to N,O-acetals, which proved to be a versatile synthetic synthon. The hydrosulfonylation, hydroamination, and hydrophosphorylation products of enamide could be indirectly provided from N,O-acetals. The reaction mechanism was further investigated, which indicated that the hydroalkoxylation of enamides was driven by weak coordination between enamide and the contact ion pair of N-heteroarenium iodide.
研究领域:
有机化学
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合成化学
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DOI
PubMed
高影响因子
SOUTH AFRICAN JOURNAL OF BOTANY
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2018
·
IF 1.442
J.J. Nair,J. Van Staden
Cancer is a leading cause of death worldwide. This, in spite of the tremendous gains made in cancer chemotherapies over the past several decades. The identification and development of new targets with greater structural diversities and better potencies are at the forefront of drug discovery endeavors across disciplines. Plants have afforded a significant number of successful anticancer drugs, several of which manifest their activities by inducing apoptosis (or programmed cell death) in cancer cells. The Amaryllidaceae alkaloids have similarly distinguished themselves as potent antiproliferative agents, some at the nanomolar level, with selective apoptosis inducing effects demonstrated in a wide variety of cancer cells. The proteolytic enzymes caspases are the key effectors of the apoptotic pathways, the main function of which is, in turn, the activation of caspases. Once activated caspases set in motion an intricately choreographed cascade of events leading to eventual cell death and phagocytosis. The lycorane and crinane group of alkaloids were amongst the first of the Amaryllidaceae for which apoptosis and attendant caspase inducing effects were discovered. These have been central in ongoing efforts to unravel the mechanistic basis to the cytotoxicity of these alkaloids. This review focuses on the various caspases which have been shown to be integral in apoptosis signaling pathways mediated by lycorane and crinane alkaloids.
研究领域:
药理学
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植物化学
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肿瘤学
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产品关联
DOI
高影响因子
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2014
·
IF 2.129
Na Li,Jiang-Kun Dai,Hong-Tao Du,Mao-Sen Yuan,Ji-Wen Zhang,Jun-Ru Wang
A novel sensing system based on the β -carboline core has been designed and synthesized for Hg 2+ detection in water. We have demonstrated that a straight forward methodology can provide rapid, sensitive and selective recognition (cross-contamination experiments) for Hg 2+ over a wide pH range. The vivid fluorescence change from blue to colorless can be clearly discriminated by the naked eye. Furthermore, there is a good negative correlation between the fluorescent intensity and the concentration of Hg 2+ in the range 1.0 × 10 −6 M–7.0 × 10 −6 M. β -Carboline as a fluorophore synthesized via this route also provides a new strategy for the design of novel fluorescence probes and fluorochromes.
研究领域:
分析化学
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
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2017
·
IF 2.323
Midong Shi,Gaoyin He,Fan Gan,Xuemin Yu,Qingsong Li
In order to reduce the energy consumption of distillation and decomposition of methylal in water, the experimental liquid–liquid equilibria (LLE) data of water + methylal + cyclohexane and water + methylal + n-heptane systems were measured in this work at different temperatures: 303.15 and 313.15 K under atmospheric pressure. The reliability of the tie-line data obtained by this present work was determined using the Othmer–Tobias and Hand equations. Moreover, the LLE data were correlated by nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) models with good results in both systems.
研究领域:
化学工程
·
分离技术
✓ 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）