KEY ENGINEERING MATERIALS
·
2017
·
IF 0
Dong Han Li,Ming Yi Liao
Preparation of telechelic hydroxyl low molecular weight fluoropolymers by reduction reaction was presented. The telechelic carboxyl low molecular weight fluoropolymers were chosen as raw materials which were prepared by oxidative degradation method. The molecular weights of telechelic carboxyl low molecular weight fluoropolymers were about 3700. Then, using lithium aluminum hydride reacted with carboxyl groups to prepare the telechelic hydroxyl low molecular weight fluoropolymers. The effects of reaction temperatures, reaction times, contents of solvent and lithium aluminum hydride were investigated in detail. The structures, Mn and dynamic viscosity of low molecular weight fluoropolymers were analyzed by FTIR, 1H-NMR, GPC and viscometer respectively. Finally telechelic hydroxyl low molecular weight fluoropolymers were prepared. The conversion rate of that reduction reaction was about 95%. The product was a viscous fluid with a dynamic viscosity of 48Pa·s at 50°C.
研究领域:
材料化学
·
高分子化学
✓ 已验证
产品关联
DOI
ACS Omega
·
2021
·
IF 3.512
Xufei Shao,Xiaotong Li,Jinzhu Ma,Runduo Zhang,Hong He
Ozone is a poisonous gas, so it is necessary to remove excessive ozone in the environment. Catalytic decomposition is an effective way to remove ozone at room temperature. In this work, 10%Ag/nano-Al2O3 and 10%Ag/AlOOH-900 catalysts were synthesized by the impregnation method. The 10%Ag/nano-Al2O3 catalyst showed 89% ozone conversion for 40 ppm O3 for 6 h under a space velocity of 840 000 h–1 and a relative humidity of 65%, which is superior to 10%Ag/AlOOH-900 (45% conversion). The characterization results showed Ag nanoparticles to be the active sites for ozone decomposition, which were more highly dispersed on nano-Al2O3 as a result of the greater density of terminal hydroxyl groups. The understanding of the dispersion and valence of silver species gained in this study will be beneficial to the design of more efficient supported silver catalysts for ozone decomposition in the future.
研究领域:
环境催化
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材料化学
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纳米催化
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大气污染控制
·
表面化学
✓ 已验证
DOI
高影响因子
ACS Central Science
·
2023
·
IF 18.2
Xinyu Yin,Yuanyang Yan,Xiangning Zhang,Bin Bao,Pihui Pi,Yahong Zhou,Xiufang Wen,Lei Jiang
Superhydrophobic surfaces are suggested to deal with hydrate blockage because they can greatly reduce adhesion with the formed hydrates. However, they may promote the formation of fresh hydrate nuclei by inducing an orderly arrangement of water molecules, further aggravating hydrate blockage and meanwhile suffering from their fragile surfaces. Here, inspired by glass sponges, we report a robust anti-hydrate-nucleation superhydrophobic three-dimensional (3D) porous skeleton, perfectly resolving the conflict between inhibiting hydrate nucleation and superhydrophobicity. The high specific area of the 3D porous skeleton ensures an increase in terminal hydroxyl (inhibitory groups) content without damaging the superhydrophobicity, achieving the inhibition to fresh hydrates and antiadhesion to formed hydrates. Molecular dynamics simulation results indicate that terminal hydroxyls on a superhydrophobic surface can inhibit the formation of hydrate cages by disordering the arrangement of water molecules. And experimental data prove that the induction time of hydrate formation was prolonged by 84.4% and the hydrate adhesive force was reduced by 98.7%. Furthermore, this porous skeleton still maintains excellent inhibition and antiadhesion properties even after erosion for 4 h at 1500 rpm. Therefore, this research paves the way toward developing novel materials applied in the oil and gas industry, carbon capture and storage, etc.
研究领域:
材料科学
·
能源工程
·
表面科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
REACTIVE & FUNCTIONAL POLYMERS
·
2025
·
IF 5.1
Alaaddin M.M. Saeed,Gui-Ping Cao,Mustapha Sani Shehu,Ahmed S. Al-Fatesh,Salwa B. Alreshaidan,Hui Lv,Xiao-Tian Han,Jun-Yang Yan
This study synthesized a novel double-ended hydroxyl-terminated poly(cyclohexyl ethylene) (HO-PCHE-OH), and investigated the individual and interactive effects of reaction temperature, time, and stirring speed on the synthesis of double-ended hydroxyl terminated polystyrene (HO-PS-OH) via the anionic polymerization of styrene, employing sodium-naphthalene as the initiator. A central composite design (CCD) combined with response surface methodology (RSM) was utilized for experimental design, process modelling, and optimization. The optimal reaction conditions were determined to be a temperature of 17.9 °C, a reaction time of 46.7 min, and a stirring speed of 189.1 rpm, yielding a styrene conversion of 91.1 %. The synthesized HO-PS-OH was subsequently subjected to catalytic hydrogenation to enhance its properties, achieving complete hydrogenation within 4 h at 170 °C. The successful transformation of HO-PS-OH into double-ended hydroxyl-terminated poly(cyclohexyl ethylene) (HO-PCHE-OH) was confirmed through nuclear magnetic resonance ( 1 H NMR and 13 C NMR) spectroscopy and Fourier transform infrared (FTIR) analysis. Therefore, the complete saturation of the 6-member carbon ring in HO-PCHE-OH was chemically and photochemically inert. Furthermore, the thermogravimetric analysis revealed that HO-PS-OH exhibited thermal resistance, with a degradation onset temperature of 420.85 °C, while HO-PCHE-OH demonstrated a higher degradation onset temperature of 431.55 °C.
研究领域:
高分子化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2020
·Vol. 10
·期 18
·10932-10938
·
IF 3.119
Yunfei Chang,Mingyi Liao,Xueyan Li
Using a simple one-pot method, the reduction of liquid terminated-carboxyl fluoroelastomers (LTCFs) by sodium borohydride and samarium chloride (NaBH4/SmCl3) was successfully realized and liquid terminated-hydroxyl fluoroelastomers (LTHFs) were obtained. The structure and functional group content of LTCFs and LTHFs were analyzed by FTIR, 1H-NMR, 19F-NMR and chemical titration. The results showed that –CC– and carboxyl groups of LTCFs were reduced efficiently, the reduction rate reached 92% under optimum reaction conditions. Compared with other frequently-used metal chlorides, SmCl3 with a high coordination number could increase the reduction activity of NaBH4 more effectively and the reduction mechanism was explored.
研究领域:
材料化学
·
有机化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING
·
2013
·Vol. 39
·期 1
·43-51
·
IF 0.385
Ahmad Nadeem,Khan M. B.,Ma Xiaoyan,Ul-Haq Noaman
Cross-linked and chain-extended polyurethane networks based on hydroxyl-terminated polybutadiene are synthesized by one-step reaction with isophorone diisocyanate. The degree of cross-linking is controlled by varying the triol to diol ratio. Chain extension is optimized by appropriate adjustment in the concentration of the diols. The influence of cross-linking agents and chain-extenders on mechanical properties of cured elastomers is investigated. IR-spectroscopy is employed to observe the curing reaction and inter-segment hydrogen bonding. It is demonstrated that the chain-extended polymer is phase segregated at sub-micron level and registers far better mechanical properties as compared to cross-linked polymer. Incorporation of 1,4 butanediol yields the maximum tensile strength, elongation and modulus. The polymer fabricated with trimethylolpropane is stronger than that of hexanetriol but exhibits lower stretching properties. However, butanediol exhibits superior mechanical properties in comparison to hexanediol. Equilibrium swelling behaviour follows the expected norm; degree of swelling varies inversely with the cross-link density. The chain-extended polymers show reduced degree of swelling due to plausible association between the hard segment domains formed in the micro-phase segregated structures.
研究领域:
高分子材料科学
·
功能高分子
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聚合物化学
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材料力学
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软物质物理
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2024
·Vol. 31
·期 7
·1-11
·
IF 2.6
Zhang Jingxuan,Huang Yeming,Wang Xin,Wang Dunju
3,4-Dinitrofurazanfuroxan (DNTF) is widely used in fusion-cast-based explosive carriers owing to its low melting point, high energy, and excellent stability. To reduce the susceptibility of DNTF and improve the thermal properties, core–shell composites (DNTF@PDA@HTPB) were synthesized using the oxidative self-polymerization reaction of dopamine. The results showed that hydroxyl-terminated polybutadiene (HTPB) was tightly coated on the surface of DNTF@PDA crystals, and the crystal structure of the high-energy crystals did not experience any significant changes during the encapsulation process. Compared with the raw DNTF, the thermal decomposition of DNTF in the DNTF@PDA and DNTF@PDA are delayed by 13.3℃ and 17.1℃, respectively. This phenomenon indicates that the thermal stability of DNTF@PDA and DNTF@PDA@HTPB composites is improved. The ignition speed of DNTF@PDA@HTPB is faster, and the flame activity is more vigorous. Meanwhile, the friction susceptibility of DNTF@PDA@HTPB is reduced by 44% compared to DNTF, and the impact susceptibility is significantly reduced by 75%. This study provides a new idea to improve fused-cast explosives' structure and combustion performance.
研究领域:
材料科学
·
爆炸物化学
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产品关联
DOI
高影响因子
Nature Communications
·
2023
·Vol. 14
·期 1
·1-8
·
IF 16.6
Fang Zizheng,Shi Yunpeng,Mu Hongfeng,Lu Runzhi,Wu Jingjun,Xie Tao
Delicate geometries and suitable mechanical properties are essential for device applications of polymer materials. 3D printing offers unprecedented versatility, but the geometries and mechanical properties are typically fixed after printing. Here, we report a 3D photo-printable dynamic covalent network that can undergo two independently controllable bond exchange reactions, allowing reprogramming the geometry and mechanical properties after printing. Specifically, the network is designed to contain hindered urea bonds and pendant hydroxyl groups. The homolytic exchange between hindered urea bonds allows reconfiguring the printed shape without affecting the network topology and mechanical properties. Under different conditions, the hindered urea bonds are transformed into urethane bonds via exchange reactions with hydroxyl groups, which permits tailoring of the mechanical properties. The freedom to reprogram the shape and properties in an on-demand fashion offers the opportunity to produce multiple 3D printed products from one single printing step.
研究领域:
材料科学
·
化学工程
·
高分子科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Research Express
·
2022
·Vol. 9
·期 2
·025302
·
IF 2.025
Xing Wu,Fengmei Ren,Haihong Ma,Zhengfa Zhou,Weibing Xu
In this paper, end-hydroxy fumaryl chloride-diol copolyesters (EHFDCP) with different double bond contents were prepared by the reaction of fumaryl chloride and diols. The molecular weight of the target hydroxy polyesters was controlled to be essentially the same, EHFDCP prepared from 1,8-octanediol, 1,5-pentanediol and ethylene glycol named EHFDCP-1, EHFDCP-2 and EHFDCP-3, respectively. The UV-induced adhesion-reducing adhesives (ARA) were prepared with EHFDCP, isophorone diisocyanate (IPDI), chain extender and photoinitiator. The ARA-1, ARA-2 and ARA-3 were produced by EHFDCP-1, EHFDCP-2 and EHFDCP-3, respectively. After UV curing, all the surfaces of ARA-1, ARA-2, and ARA-3 had a high number of concave and convex areas, which helped to reduce the contact area between the adhesive and the substrate surface. The surface roughness of ARA-2 is the highest and the adhesion reduction effect is the most significant. The higher surface roughness of ARA-2 came from moderate double bond content and crosslinking density. With the increasing photoinitiator content, the 180° peel strength after UV curing decreased. The 180° peel strength of ARA-2 was reduced to 0.16 N/25 mm at 4 wt% of photoinitiator content, and it also had a high initial 180° peel strength of 18.55 N/25 mm due to the absence of small molecule polyfunctional monomers.
研究领域:
材料科学
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高分子化学
·
粘合技术
✓ 已验证
产品关联
DOI
高影响因子
CHEMBIOCHEM
·
2022
·Vol. 23
·期 9
·e202200063
·
IF 3.461
Ya-Li Dong,Gang-Gang Chong,Chun-Xiu Li,Qi Chen,Jiang Pan,Ai-Tao Li,Jian-He Xu
Graphical Make activation of C-H bond feasible : Cytochrome P450 monooxygenases (P450s) catalyze the terminal hydroxylation of fatty acids to form ω-hydroxy fatty acids. To date, available P450s for the terminal hydroxylation of fatty acids stalls at CYP153A subfamily members, which have the limitation of low activity and poor thermostability. We, therefore, adopted directed evolution to generate P450pyr mutants with higher catalytic efficiency toward medium-chain fatty acids. The results show that mutants toward C6−C12 fatty acids display improved analytical yields of ω-hydroxy fatty acids. The P450-mediated terminal hydroxylation of non-activated C−H bonds is a chemically challenging reaction. CYP153A7 monooxygenase, discovered in Sphingomonas sp. HXN200, belongs to the CYP153A subfamily and shows a pronounced terminal selectivity. Herein, we report the significantly improved terminal hydroxylation activity of CYP153A7 by redesign of the substrate binding pocket based on molecular docking of CYP153A7−C 8:0 and sequence alignments. Some of the resultant single mutants were advantageous over the wild-type enzyme with higher reaction rates, achieving a complete conversion of n- octanoic acid (C 8:0, 1 mM) in a shorter time period. Especially, a single-mutation variant, D258E, showed 3.8-fold higher catalytic efficiency than the wild type toward the terminal hydroxylation of medium-chain fatty acid C 8:0 to the high value-added product 8-hydroxyoctanoic acid.
研究领域:
生物化学
·
酶学
·
生物催化
·
蛋白质工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
POLYMER TESTING
·
2021
·
IF 4.282
Lingxiao Ma,Xiuzhong Zhu,Wanbin Zhang,Haitao Zhang,Jianyong Wang,Jianbo Qu
Hydroxy-terminated oligomers with narrow molecular weight distribution using as soft segment of polyurethane can significantly increase the modulus, tensile strength, and elongation at break of the polyurethane. Thus, design and synthesis of new hydroxy-terminated oligomers having narrow molecular weight distribution can improve the properties of polyurethane and further expand the use range of polyurethane. A set of side-chain hydroxyl-terminated polybutadiene (HTPB) derivatives were successfully synthesized by anionic polymerization and blue light photocatalytic thiol-ene reaction. Firstly, HTPB with narrow molecular weight distribution was synthesized via anionic polymerization using mono-lithium based initiator and followed by de-protection. Then, HTPB derivatives with different side-chains such as butyl, ethyl acetate, or myristyl, namely HTPB but , HTPB eac and HTPB tet , were obtained by blue light photocatalytic thiol-ene reaction using Ru(bpy) 3 Cl 2 as photoredox catalyst and HTPB as matrix polymer. Similar with HTPB, those HTPB derivatives also have narrow molecular weight distribution. Polyurethane elastomers (PUs) were synthesized with HTPB or HTPB derivatives as soft segment, toluene diisocynate (TDI) as hard segment, and 1, 4-butanediol as chain extender. Compared study the performances of polymers, the results showed that glass transition temperature ( T g ) and viscosity of HTPB derivatives were increased when short-chain side groups were introduced. But instead, T g and viscosity of HTPB derivatives was reduced following long-chain side groups being grafted. Through comparing research of properties for PUs, tensile strength is reduced and elongation at break is augmented, when side groups were introduced in HTPB backbone. Research on the contact angle tests of PUs indicated that the contact angle of PUs using HTPB, HTPB but or HTPB eac as soft segment, is similar, and PUs using HTPB tet as soft segment has a larger contact angle about 137.2 °C.
研究领域:
高分子科学
·
材料科学
·
化学工程
✓ 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）