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Mechanical and thermal properties of mesogen-jacketed liquid crystalline polymer/epoxy resin composites

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Science China Chemistry 2015年第6期58卷 1021-1026页

作者： Chunpeng Chai Fangfang Yin Guoping Li yunjun luo School of Material Science and Engineering Beijing Institute of Technology

The effects of mesogen-jacketed liquid crystalline polymer poly(dipropyl vinylterephthalate)(PDPVT) on the mechanical and thermal properties of diglycidyl ether of bisphenol-A(DGEBA) epoxy resin were investigated by impact test, tensile test and thermogravimetric analysis(TGA). The mechanism underlying the enhancement of mechanical properties of epoxy resin was studied using 1D wide-angle X-ray diffraction(WAXD) and scanning electron microscope(SEM). It was found that the mechanical properties of 1 wt%–5 wt% PDPVT/DGEBA composites were significantly improved compared to neat epoxy resin. Especially, the epoxy resin with 3 wt% PDPVT had the greatest increase in mechanical properties, with the impact strength, tensile strength and elongation while breaking increased by 87%, 59% and 174%, respectively. The increased mechanical strength was due to the fact that PDPVT maintained liquid crystalline phase in cured PDPVT/DGEBA composites, which would blunt the crack tip and prevent crack propagation. Moreover, PDPVT had slight effect on the thermal stability properties of epoxy resin.

关键词： mesogen-jacketed liquid crystalline polymer epoxy resin mechanical properties thermal stability properties

Fabrication and thermal decomposition of glycidyl azide polymer modified nitrocellulose double base propellants

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Science China Chemistry 2016年第4期59卷 472-477页

作者： Benbo Zhao Tianfu Zhang Zhen Ge yunjun luo School of Materials Science and Engineering Beijing Institute of Technology

Glycidyl azide polymer （GAP） with the advantages of non-volatility and excellent thermal stability is a candidate as a re- placement for nitroglycerine （NG） in a double base propellant. The GAP-NC double base propellants were formulated with GAP and nitrocellulose （NC） fibers. Tensile test and SEM characterization indicated that GAP-NC propellants had a homoge- neous structure. Thermogravimetric analysis of GAP-NC propellants revealed that the onset decomposition temperature reached a high level ranging from 192.9 to 194.6 ℃, which indicated that the substitution of NG with GAP contributed to the safe storage and process operations for double base propellant. The result analysis of decomposition products of GAP-NC propellants showed that the main gas decomposition products of the propellants were NO, NO〉 CO, CO2, NH3, CH4, HCN, N2 CH20 and C2H40. The thermal decomposition process of the specimens was proposed.

关键词： glycidyl azide polymers (GAP) nitrocellulose double base propellant nitroglycerine thermal decomposition

Amphiphilic Block Copolymer Micelles for Gene Delivery

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Chemical Research in Chinese Universities 2022年第6期38卷 1368-1379页

作者： LI Qin JIN Bixin luo yunjun LI Xiaoyu School of Material Science and Engineering Beijing Institute of TechnologyBeijing100081P.R.China Key Laboratory of High Energy Density Materials Ministry of EducationBeijing Institute of TechnologyBeijing100081P.R.China Experimental Centre of Advanced Materials Beijing Institute of TechnologyBeijing100081P.R.China

Gene therapy is a promising method to treat acquired and inherited diseases by introducing exogenous genes into specific recipient *** micelles with different nanoscopic morphologies and properties hold great promise for gene delivery *** cationic polymers,poly(ethyleneimine)(PEI),poly(L-lysine)(PLL),poly(2-dimethylaminoethyl methacrylate)(PDMAEMA)and novel cationic polymers poly(2-oxazoline)s(POxs),have been incorporated into block copolymers and decorated with targeting moieties to enhance transfection *** order to minimize cytotoxicity,nonionic block copolymer micelles are utilized to load gene through hydrophilic and hydrophobic interactions or covalent conjugations,*** our perspective,properties(shape,size,and mechanical stiffness,etc.)of block copolymer micelles may significantly affect cytotoxicity,transfection efficiency,circulation time,and load capacity of gene vectors in vivo and in *** review briefly sums up recent efforts in cationic and nonionic amphiphilic polymeric micelles for gene delivery.

关键词： Polymeric micelle Block copolymer Gene delivery

Precise and Controllable Assembly of Block Copolymers

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Chinese Journal of Chemistry 2023年第1期41卷 93-110页

作者： Bixin Jin Yiqi Chen yunjun luo Xiaoyu Li School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory of High Energy Density Materials Ministry of EducationBeijing Institute of TechnologyBeijing 100081China

With the development of nanotechnology,the precise synthesis of nanoparticles with nicely-defined dimensions and structures has been well-developed,and the functionalization and subsequent applications of the resultant nanostructures are becoming increas-ingly *** to inorganic nanoparticles,the nanostructures based on soft matters,especially block copolymer as-semblies,are much lower in cost,easier to fabricate and richer in ***,the dimensional control over the block co-polymer assemblies is not as *** in recent decade,with the discovery of living Crystallization-Driven Self-Assembly(CDSA)by Manners and Winnik,researchers become able to precisely tune the sizes of block copolymer assemblies in a relatively wide *** discovery has inspired tremendous research effort in the self-assembly field,and considerable progress has been made *** review summarizes the main progress in the precise and controllable self-assembly field in the past five years,and is mostly fo-cused on four aspects,including in-depth understanding of the assembly methods,extension of this method to two-dimensional nanostructures,utilization of this method to fabricate hierarchical structures,and the potential applications of these well-defined *** hope not only to make a periodic systematic summary of previous studies,but also to provide some useful thinking for the future development of this field.

关键词： Nanostructures Micelles Nanotechnology Self-assembly Precise assembly

Preparation and characterization of Al/B/Fe_2O_3 nanothermites

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Science China Chemistry 2014年第6期57卷 797-802页

作者： SHEN LianHua LI GuoPing luo yunjun GAO Kun GE Zhen School of Materials and Engineering Beijing Institute of Technology

A sol-gel synthetic approach combined with an ultrasonic method was utilized to prepare Al/B/Fe2O3 *** structure and properties of the prepared nanothermites were characterized by thermogravimetric analysis,differential scanning calorimetry,scanning electron microscopy,X-ray diffraction,and an impact sensitivity *** results verified that the nano-aluminum and the micro-boron were uniformly dispersed in the pores of the iron oxide *** heat of the prepared Al/B/Fe2O3 nanothermites was 1.3 times that of the simple physically mixed *** addition,the heat of the combustion test showed that these materials were indeed ***-scale safe experiments also showed that the prepared materials through sol-gel were relatively insensitive to standard impact.

关键词： sol-gel nanothermites energetic materials properties

A new fluorocarbon adhesive:Inhibiting agglomeration during combustion of propellant via efficient F-Al_(2)O_(3) preignition reaction

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Carbon Energy 2024年第6期6卷 292-305页

作者： Qifa Yao Min Xia Chao Wang Fanzhi Yang Wei Yang yunjun luo School of Materials Science and Engineering Beijing Institute of TechnologyBeijingChina Key Laboratory of High Energy Density Materials Ministry of EducationBeijing Institute of TechnologyBeijingChina School of Aerospace Engineering Beijing Institute of TechnologyBeijingChina Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijingChina

Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid *** this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking *** FTPE was applied in aluminum-based propellants for the first *** to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 *** reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the *** results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.

关键词： agglomeration characteristics aluminum particles combustion fluorine alcohol compounds HTPE propellants

Plasma‐oxidized 2D MXenes subnanochannel membrane for high‐performance osmotic energy conversion

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Carbon Energy 2024年第8期6卷 178-191页

作者： Zhengmao Ding Tiancheng Gu Rui Zhang Shouyi Sun Kaiqiang Wang Hanli Zhang Jinjin Li yunjun luo State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijingChina Key Laboratory of High Energy Density Materials Ministry of EducationBeijing Institute of TechnologyBeijingChina Department of Engineering Mechanics Northwestern Polytechnical University(Chang'an Campus)Xi'anChina

Nanofluidic channels inspired by electric eels open a new era of efficient harvesting of clean blue osmotic energy from salinity *** by less charge and weak ion selectivity of the raw material itself,energy conversion through nanofluidic channels is still facing considerable ***,a facile and efficient strategy to enhance osmotic energy harvesting based on drastically increasing surface charge density of MXenes subnanochannels via oxygen plasma is *** plasma could break Ti–C bonds in the MXenes subnanochannels and effectively facilitate the formation of more Ti–O,C═O,O–OH,and rutile with a stronger negative charge and work function,which leads the surface potential of MXenes membrane to increase from 205 to 430 *** significant rise of surface charge endows the MXenes membrane with high cation selectivity,which could make the output power density of the MXenes membrane increase by 248.2%,reaching a high value of 5.92Wm^(−2) in the artificial sea‐river water ***,with the assistance of low‐quality heat at 50℃,the osmotic power is enhanced to an ultrahigh value of 9.68Wm^(−2),which outperforms those of the state‐of‐the‐art two‐dimensional(2D)nanochannel *** exciting breakthrough demonstrates the enormous potential of the facile plasma‐treated 2D membranes for osmotic energy harvesting.

关键词： ion transport MXenes membranes osmotic energy harvesting plasma two‐dimensional nanochannels

STUDY OF NANOSIZED SILICA GRAFIED WITH HYPERBRANCHED POLY(AMINE-ESTER)

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Chinese Journal of Reactive Polymers 2006年第1期15卷 86-89页

作者： ZHAO Hui YANG Shu luo yunjun School of Mater. Sci. ＆ Eng. Beijing Institute of Technology Beijing 100081.China Kaifeng University Kaifeng 475001 China

A new method to chemically modify the surface of nanosized-SiO2 was studied in this ***-SiO2 was grafted with hyperbranched poly(amin ester)through one-spot polycondensation between AB2 monomer and active hydroxyl on silica surface in present of *** with the results of FTIR and TEM,it is found hyperbranched poly(amin ester)is successfully grafted on the surface of nanosized-SiO2 and the surface properties have been changed with an expected *** results indicate that nanosized-SiO2 grafted with hyperbranched poly(amin ester)has better dispersion in the ethanol or chloroform than that unmodified.

关键词： Hyperbranched poly(amin-ester) Nanosized Silica Surface Modification dispersion stability.

高分子模板对CdS量子点制备及其光催化性能的影响

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化学学报 2010年第19期68卷 1971-1976页

作者：丛日敏罗运军于怀清北京理工大学材料科学与工程学院北京100081 山东理工大学材料科学与工程学院淄博255049

分别以球形聚酰胺-胺(PAMAM)树形分子和线形聚乙烯吡咯烷酮(PVP)两种结构不同的高分子为模板,原位制备了分散良好的CdS量子点(CdSQDs),并以甲基橙为降解对象,研究了高分子模板结构对CdS量子点的制备和光催化性能的影响.结果表明,以PAMA... 详细信息

分别以球形聚酰胺-胺(PAMAM)树形分子和线形聚乙烯吡咯烷酮(PVP)两种结构不同的高分子为模板,原位制备了分散良好的CdS量子点(CdSQDs),并以甲基橙为降解对象,研究了高分子模板结构对CdS量子点的制备和光催化性能的影响.结果表明,以PAMAM树形分子为模板制备的CdS量子点(CdSQDs/PAMAM)比以PVP为模板制备的CdS量子点(CdSQDs/PVP)的尺寸分布更窄,激子吸收峰更明显,光致发光(PL)强度更高;并且在量子点尺寸接近的情况下,CdSQDs/PAMAM的催化效率明显高于CdSQDs/PVP.这是由于PAMAM树形分子独特的结构有利于生成尺寸均匀的CdS量子点,且不易钝化量子点表面的活性位点;而线性的PVP分子量分布较宽,使制备的量子点的尺寸分布较宽,且PVP分子链缠绕在CdS量子点表面,钝化了部分活性位点,降低催化效率.此外,CdSQDs/PAMAM的催化能力随粒径减小而增大.

关键词： CdS量子点 PAMAM树形分子聚乙烯吡咯烷酮光催化甲基橙