ACS Omega
·
2018
·
IF 0
Chunming Xiong,Falin Wei,Weitao Li,Pingde Liu,Yong Wu,Mingli Dai,Jun Chen
A gel system composed of acrylamide (AM), N,N′-methylenebisAM (BIS), and ammonium persulfate ((NH4)2S2O8) was developed and applied extensively in reservoirs to reduce water cut and increase oil production in mature fields. However, this gel system suffers from thermal stability loss and syneresis at high temperatures that reduces its ability to control water flow. It has been widely accepted that the loss of gel thermal stability can be explained via three aspects: the rupture of polymer chains, the breakage of cross-linker chains, and hydrolysis of polymer. The mechanism of hydrogel syneresis through polymer hydrolysis has been investigated extensively in other publications. However, research on the other two mechanisms is quite limited. In this article, we conduct a series of experiments to demonstrate how the rupture of polymer and cross-linker chains leads to the hydrogel instability at high temperatures. Viscosity and energy-dispersive system measurements suggested that polyAM chains were disrupted by the oxidation reactions involving free radicals. The method to measure the cross-linking degree was established and in combination with X-ray photoelectron spectroscopy measurements, the results showed that cross-linker chains were broken as a result of weaker C–N bond resulting from positively charged mesomethylene carbon and hydrolysis of amide groups on the cross-linker. Because of the application of deionized water in the experiments, nuclear magnetic resonance and FTIR measurements showed that the hydrolysis degree of polymer was weak. Hence, our results verified that breakage of polymer and cross-linker chains led to the rupture of the gel network at high temperature. Besides, cross-linker chains may play a more important role in the thermal stability of the gel, which explains some work into high-temperature-resistant gels.
研究领域:
石油工程
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材料科学
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化学工程
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产品关联
DOI
PubMed
Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Xianni Song,Junhua Zhang
Polyvinyl alcohol (PVA) is a kind of refractory organic polymer with high COD and low BOD. Efficient treatment of PVA wastewater has always been a challenging subject especially for ultra-high concentration (UHC). In this paper, based on our previous work, a sequential combination process method including NaClO chain breakage followed by Cu x O activated carbon catalytic oxidation was developed to efficient treat UHC PVA wastewater. The sequential combination system was optimized by monitoring the treatment performance with different key parameters (such as oxidant dosage, Cu loading and catalyst dosage, two-stage reaction time, pH value, etc.). And the COD of PVA wastewater declined from the initial 206,240.00 mg/L to 557.78 mg/L (removal rate 99.73 %), the PVA concentration decreased from the initial 171,325.00 mg/L to 19.94 mg/L (removal rate 99.99 %) under the optimal conditions. Through the discussion of the combined processes, it was found that both chain breakage and catalytic oxidation were necessary and indispensable to achieve efficient degradation of PVA wastewater. Additionally, the free radical scavenging experiments show that the combined oxidation process was mainly controlled by the catalytic oxidation process, and followed the free radical reaction mechanism with·OH as the main oxidant. Based on this, it is recommended that subsequent researchers focus on the combined process for the treat of refractory organic wastewater.
研究领域:
环境科学
·
化学工程
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DOI
高影响因子
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
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2021
·
IF 5.471
Jincheng Lei,Ziqian Li,Shuai Xu,Zishun Liu
Fracture is a highly nonlinear problem, especially under a large deformation in cross-linked elastomers. Existing constitutive theories and fracture models fail to predict the fracture behavior of cross-linked elastomers because of the absence of the random polymer network structure. Meanwhile, few numerical methods can present the realistic fracture process of a polymer network. In this study, we propose a mesoscopic network mechanics method to present the entire large deformation and fracture process of the polymer network in cross-linked elastomers. The microstructure of a cross-linked elastomer is abstracted as a polymer network model where nodes are referred to as crosslinkers and connections between nodes are referred to as polymer chains. A hybrid total energy form of the network model is proposed including the free energy of polymer chains and volumetric deformation energy. In addition, using a proposed stretch criterion of polymer chains to realize chain scission, this mesoscopic network mechanics method is numerically implemented by coding. Two-dimensional network models with uniform and randomly distributed chain lengths, as well as models with different types of pre-cracks, are constructed and simulated under uniaxial tension tests using our method. Our method reproduces the entire hyper-elastic large deformation and fracture process of polymer network models. The random network models show a lower Young's modulus and a less significant strain-hardening stage, indicating that the structural randomness is the primary cause of accuracy degradation for existing hyperelastic constitutive models under large deformations. The results also reveal that the structural randomness of the polymer network is a primary reason for the ductile fracture and the low notch sensitivity of cross-linked elastomers.
研究领域:
材料科学
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力学
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DOI
高影响因子
Matter
·
2022
·
IF 19.967
Zhihao Wang,Yunlong Wang,Zhiqing Ge,Yuan Tian,Meixing Ai,Shuiyan Cao,Mozhen Wang,Shuao Wang,Jun Ma
The development of power-free, wide-range, and real-time visible radiation dosimeters is highly desirable but challenging. Here, we report a new dosimetry concept based on the continuous and linear Bragg wavelength shift of photonic crystals in response to X-ray or γ-ray radiation. As a proof of concept, three distinct photonic crystal dosimeters with high spatial resolution and tunable responsive range from 0 up to 225 kGy were demonstrated based on the decrease of lattice distance caused by chain scission or crosslinking of polymer networks. Compared with the conventional radiochromic dosimeters, this design possesses more flexibility in composition or microstructure and exceptional pre-irradiation stability against light and temperature. In addition, their uniqueness leads to convenient device-free readout techniques through naked-eye color-strip calibration and cell phone-based measurement using hue value detection. In conclusion, our work presents the necessary dosimeters for more direct and effective dose verification in industrial and medical applications.
研究领域:
材料科学
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医学物理
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放射生物学
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DOI
高影响因子
Materials Today Communications
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2024
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IF 3.7
Le Yang,Yin Qin,Yang Li,Bangsheng Wang,Huabi Chen,Zhu Luo
Polylactic acid (PLA) is known for its degradative properties. Since PLA possesses a long chain macromolecular structure, its degradation behavior and characteristics have been the focus of research. In the presence of Lewis acid, the carbonyl oxygen in the ester group of PLA molecular chain can coordinate with it and be activated, so as to break the ester group and cause PLA degradation. However, there is still a lack of research strategies on the evolution of the remote structure of PLA chains, and there were few studies on the long-range degradation of PLA molecular chain in the effect of Lewis acid. In this work, a statistical method, combined with molecular weight testing, was proposed to investigate the long-range degradation behavior of PLA molecular chains. Results showed that in the presence of nano-ZnO, the long-range degradation of PLA molecular chain in solution was initially carried out in the form of terminal group biting-back and exchanging within 4 hours, and the molecular chain with new terminal-group was still long enough after degradation, gradually shortened over time. PLA began to degrade obviously after 8 h reaction. This chain scission method can provide a reaction platform for some reactions such as long-chain branching, which can be utilized to prepare PLA with special molecular chain topology and explore the mechanism of PLA chain structure transformation.
研究领域:
材料科学
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高分子化学
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降解研究
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产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 40
·31365-31374
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IF 3.84
Ruiwei Guo,Pengbo Mei,Qing Zhong,Yuan Yao,Qian Su,Jianhua Zhang
The effective preparation of photoresponsive polymers with precisely controlled location and number of photolabile units in the main chain is essential for their applications. In this study, a series of photocleavable well-defined triblock copolymers with the photocleavable middle block of poly(phenyl vinyl ketone) (PPVK) were readily synthesized by RAFT polymerization. The chain structure and chemical composition of copolymers were characterized by 1HNMR, FTIR and GPC. The well-controlled molecular weights and low polydispersity (<1.30) demonstrated the excellent controllability and living characteristics of the RAFT process for the polymerization of PVK. Then the photocleavage mechanism and kinetics of PPVK-functionalized copolymers were systematically investigated by tracking, fractionating and quantifying the photolysis products using gradient polymer elution chromatography (GPEC). The results not only confirmed the rapid photocleavability of PPVK-based polymers, but also firstly provided direct evidence for the proposed Norrish type reaction mechanism of the chain scission of PPVK. Moreover, the investigation of the effect of the PPVK chain on the photolysis kinetics demonstrated that the photodegradation rate of PPVK-based polymers can be controlled by adjusting the PPVK chain length in block copolymers. As a preliminary application study, the self-assembled micelles of the obtained PPVK-based amphiphilic polymers under light irradiation were found to undergo photo-triggered rapid disassembly and exhibited photo-controllable emulsifiability. In sum, the incorporation of the highly photolabile PPVK into block copolymers by RAFT polymerization provides a promising strategy for the construction of complex polymeric architectures or nanostructures with controllable photocleavability.
研究领域:
高分子化学
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材料科学
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产品关联
DOI
高影响因子
Science of Advanced Materials
·
2022
·Vol. 14
·期 5
·911-919
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IF 1.067
Zhu Chunxia,Ming Shenqiu,Qiu Bin,Zhong Hui
FePt nanoparticles were in this study prepared at varied concentrations to assess their mechanism in regulating DNA injury and inactivation of Hela cells through mitogen-activated protein kinase (MAPK) signal pathway. The cells were divided into following 5 group sets: 1st, 2nd, 3rd,
4th and 5th, which were randomly intervened by following varied concentrations of FePt nanoparticles; 0, 5, 10, 15 and 20 μg/mL. Their action on cellular toxicity, proliferation and inactivation of cells was detected with CCK-8 method, while apoptotic condition was detected with
flow cytometry (FCM). The degree of DNA double chains fracture was detected with neutral single cell gel electrophoresis and immunofluorescence staining. The protein expressions of of EKR1/2, p-ERK1/2, p38 MAPK and p-p38 MAPK in every set were detected with Western Blot assay, while proliferative
activity in the 4th and 5th sets was lower than in the 1st set, and inhibiting action in the 4th set was best. There was no notable difference between 4th and 5th sets, and apoptotic rate in the 1st set was lower than in the other sets. The DNA percentage in the Hela cells was reduced and
Tial length was lengthened along with increased concentration of adopted FePt nanoparticles. The proliferation of Hela cells was restrained by FePt nanoparticles through restraining of the MAPK signal pathway, but growth of Hela cells was not affected, and DNA double-strand break (DSB) was
increased. The FePt nanoparticles could therefore be adopted as one kind of effective anti-tumor drug through increased DNA DSB in tumor cells based on killing effect of tumor cells and good compatibility for normal cells.
研究领域:
纳米技术
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癌症生物学
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细胞信号传导
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毒理学
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE
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2023
·
IF 3.4
Binbo Wang,Yi Wang,Falin Li,Shuai Du,Jin Zhu,Songqi Ma
Thermoplastic polyurethane (TPU), as one of the most widely used elastomers, has received rapid development, and its recycling becomes increasingly urgent. In this work, a TPU is upcycled to PU covalent adaptable networks (CANs) via chain breaking-crosslinking strategy of being extruded with polyol and isophorone diisocyanate (IPDI) on a micro twin-screw extruder. The carbamate exchange between the polyol and TPU breaks the chain of TPU and introduces plenty of reactive hydroxyl groups, which activates the TPU chain. Long-chain-branched TPU with hydroxyl groups is obtained during the chain-breaking step and then crosslinked with IPDI to obtain highly crosslinked networks. PU-CANs exhibit improved mechanical properties and elastic recovery rate, which is propitious to elastomers. Moreover, the crosslinked network greatly enhances the creep resistance and solvent resistance of the material. PU-CANs maintain favorable reprocessability, suitable for screw extrusion and hot-press processing. This work provides a simple and efficient method to upcycle TPU into reprocessable highly-crosslinked polymers and improve the properties of polymers. Graphical
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
高影响因子
Journal of Environmental Sciences
·
2023
·
IF 6.9
Yunjin Zhong,Lebing Zhuo,Wangyang Lu
Microplastic pollution has become one of the most concerned focuses in the world. Among many treatment methods, photocatalysis is considered to be one of the most environmentally friendly methods. In this work, the photodegradation behavior of polyamide microplastics is studied by using polyamide 6 PA6) as model microplastics and FeCl 3 as catalyst. It is hoped that the PA6 fiber can be effectively degraded by utilizing the strong oxidizing active species that can be produced after FeCl 3 is irradiated in water. The results shows that PA6 fiber can be almost completely degraded after 10 days of irradiation in FeCl 3 aqueous solution, indicating that it is promising to use this new method to solve the problem of PA6 type microplastics. In addition, the chain scission mechanism and degradation process of PA6 are analyzed in detail by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS), which provides a new insight for the study of polymer degradation mechanism.
研究领域:
环境科学
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分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2025
·
IF 8.5
Xin Wang,Binbo Wang,Rong Huang,Tao Jiang,Yi Wang,Shuai Du,Falin Li,Jin Zhu,Songqi Ma
Poly (butylene adipate- co -terephthalate) (PBAT)/starch composites have captured great attentions due to their favorable biodegradability and cost-effectiveness. However, it is still a challenge to prepare PBAT/starch composites with superior mechanical performance, solvent and creep resistance, and gas barrier. This study used a chain breaking-crosslinking strategy to prepare covalent adaptable network (CAN) composites from PBAT and unmodified starch via reactive extrusion. In the chain breaking stage, dipentaerythritol was used to break PBAT via transesterification and capped more hydroxyl groups on PBAT, achieving favorable compatibility with unmodified starch, which is confirmed via infrared spectroscopy analysis and scanning electron microscopy among other experimental methods. In the crosslinking stage, the hydroxyl groups of chain broken PBAT and starch were reacted with styrene-maleic anhydride copolymer (SMA) to form CAN composites. The superior compatibility and network feature gave the composites excellent thermal properties, strength and modulus, creep resistance, solvent resistance and gas barrier performance. Moreover, fast stress relaxation can be achieved based on the transesterification, allowing for extrusion processing and thermal compression molding, demonstrating excellent reprocessing recyclability of the PBAT/starch CAN composites. Overall, this work provides a simple, green and efficient method for preparing high-performance PBAT/starch CAN composites, which should also be suitable for other polymer/filler composites.
研究领域:
材料科学
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高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
·
2024
·
IF 6.2
Cong Ma,Kaiqin Hu,Xueke Zhang,Yaru Yu,Zuying Xu,Tian Ma,Hongzhen Ruan,Yingying Zhang,Jiajia Wang,Xinyu Yue,Chunmei Liang,Huifen Xiang,Rui Guo,Yunxia Cao,Zhiming Ding
Arsenic is a pollutant that can cross the placenta; however, research on the effects of arsenic exposure during pregnancy on the fertility of female offspring is limited. To address this gap, we developed a mouse model to investigate the relationship between arsenic exposure during pregnancy and fertility in female offspring. Our fertility assessment revealed that gestational exposure to 1 mg/kg arsenic or higher (10 mg/kg) resulted in reduction in litter size, ovarian volume, and multistage-follicle number in female offspring. By assessing the in vitro developmental capacity of oocytes and zygotes, we confirmed that the reduced fertility was due not to impaired oocyte quality but rather to a reduction in oocyte quantity. Arsenic exposure impedes synapsis formation in MPI and compromises homologous recombination-mediated repair of double-strand breaks, resulting in fewer crossovers. This disruption activates the pachytene-checkpoint, hindering the progression of the MPI and resulting in the elimination of defective oocytes through p-Chk2 activation. Our study reveals for the first time the detrimental effects of arsenic exposure during pregnancy on the fertility of female offspring, underscoring the urgent need to prevent such exposure to safeguard reproductive health.
研究领域:
生殖生物学
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毒理学
·
遗传学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2014
·
IF 2.235
Qinzhuo Zhou,Suyun Jie,Bo-Geng Li
Hydroxyl-terminated polybutadiene (HTPB) with high cis-1,4 content (>95.0%) has been prepared via a two-step method by taking commercial butadiene rubber (BR9000) as a starting material, including the one-pot synthesis of aldehyde-group-terminated polybutadiene (ATPB) in high efficiency and the subsequent reduction reaction. The double bonds distributed in linear polybutadiene were first epoxidized and then cleaved at the exact epoxidized sites. The epoxidation reaction by 3-chloroperbenzoic acid and chain-cleavage reaction by periodic acid are controllable, highly efficient, selective, and quantitative. Along with an epoxy percent increase, the molecular weight of ATPB prepared via a one-pot method decreased with a relatively narrow polydispersity index. The aldehyde groups in the chain ends were reduced by NaBH4 to produce HTPB, in which the high cis-1,4 content of BR was retained.
研究领域:
化学工程
·
材料科学
✓ 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）