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Autogenous healing mechanism of cement-based materials

结构与土木工程前沿:英文版 2023年第6期17卷 948-963页

作者： Desheng LI Hao ZHENG Kang GU Lei LANG Shang SHI Bing CHEN Department of Civil Engineering School of ScienceNanjing University of Science and TechnologyNanjing210094China School of Transportation Science and Engineering Harbin Institute of TechnologyHarbin150090China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai200240China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsWuhan430071China

Autogenous self-healing is the innate and fundamental repair capability of cement-based materials for healing cracks.Many researchers have investigated factors that influence autogenous healing.However,systematic research on the autogenous healing mechanism of cement-based materials is lacking.The healing process mainly involves a chemical process,including further hydration of unhydrated cement and carbonation of calcium oxide and calcium hydroxide.Hence,the autogenous healing process is influenced by the material constituents of the cement composite and the ambient environment.In this study,different factors influencing the healing process of cement-based materials were investigated.Scanning electron microscopy and optical microscopy were used to examine the autogenous healing mechanism,and the maximum healing capacity was assessed.Furthermore,detailed theoretical analysis and quantitative detection of autogenous healing were conducted.This study provides a valuable reference for developing an improved healing technique for cement-based composites.

关键词： autogenous healing cement-based materials healing mechanism aggregation effect

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The aggregation effects on the two-photon absorption properties of para-nitroaniline polymers by hydrogen-bond interactions

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Chinese Physics B 2010年第4期19卷 288-292页

作者：孙元红李晶赵珂王传奎 Fundamental Division of Shandong Police College College of Physics and Electronics Shandong Normal University

This paper has theoretically designed a series of aggregate polymers on the basis of several para-nitroaniline monomers by hydrogen-bond interactions. At the level of time-dependent hybrid density functional theory, it has optimized their geometrical structures and studied their two-photon absorption （TPA） properties by using analytical response theory. The calculated results exhibit that the aggregation effects not only bring out the conaiderable red shift of the excited energies but also greatly enhance the TPA intensities of the aggregate polymers in comparison with the para-nitroaniline monomer. The aggregate configurations also have an important influence on the TPA abilities of the polymers; the trimer has the largest TPA cross section. The electron transitions between the molecular orbits involving the strong TPA excitations of the trimer are depicted to illuminate the relationship between the intermolecular charge transfer and the TPA property.

关键词： two-photon absorption aggregation effect analytical response theory

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Fluorination strategy enables greatly improved performance for organic solar cells based on polythiophene derivatives

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Chinese Chemical Letters 2021年第7期32卷 2274-2278页

作者： Chenyi Yang Shaoqing Zhang Junzhen Ren Pengqing Bi Xiaotao Yuan Jianhui Hou School of Chemistry and Biology Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Polymer Physics and Chemistry Beijing National Laboratory for Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China

The power conversion efficiencies(PCEs)of organic solar cells(OSCs)have reached 18%recently,which have already met the demand of practical application.However,these outstanding results were generally achieved with donor-acceptor(D-A)type copolymer donors,which can hardly fulfill the low-cost largescale production due to their complicated synthesis processes.Therefore,developing polymer donors with simple chemical structures is urgent for realizing low-cost OSCs.Polythiophene(PT)derivatives are currently regarded as promising candidates for such kind of donor materials,which has been illustrated in many works.In this work,two new alkylthio substituted PT derivatives,P301 and P302,were synthesized and tested as donors in the OSCs using Y5 as the accepto r.In comparison,the introduction of fluorine atoms on the backbone of P302 can not only downshift the energy levels,but also greatly improve the phase separation morphologies of the active layers,which is ascribed to the enhanced aggregation effect and the reduced miscibility with the non-fullerene acceptor.As a result,the P302:Y5-based OSC exhibits a significantly improved PCE of 9.65%than that of P301:Y5-based one,indicating the important role of fluorination in the construction of efficient PT derivative donors.

关键词： Organic solar cells Polythiophene derivatives Fluorination aggregation effect Miscibility

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Structural, photophysical and nonlinear optical limiting properties of sandwich phthalocyanines with different rare earth metals

Structural, photophysical and nonlinear optical limiting pro...

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中国稀土学会2020学术年会暨江西(赣州)稀土资源绿色...

作者： Caixia Ou Weixia Lv Jun Chen

Four sandwich phthalocyanines with different rare earth metals (La,Y,Yb and Sc) are synthesized to investigate the influence of aggregation on nonlinear optical limiting effect.Hyperchem fitting results show that the distance between the phthalocyanine rings of the four phthalocyanine compounds is 2.81,2.69,2.56 and 2.38?for LaPc (Tetra-β-(4-nitro) lanthanum phthalocyanine),YPc (Tetra-β-(4-nitro) yttrium phthalocyanine),YbPc (Tetra-β-(4-nitro) ytterbium phthalocyanine) and ScPc (Tetra-β-(4-nitro) scandium phthalocyanine),respectively.As the radius of rare earth ions decreases,the interlayer spacing between phthalocyanine rings decreases,which greatly increases the degree of aggregation between phthalocyanine rings.As a result,the photophysical and nonlinear absorption coefficients of different rare-earth phthalocyanines also show regular changes.The nonlinear absorption coefficients of the four rare-earth phthalocyanines were LaPc (β=1.86ⅹ10 m/W),YPc (β=9.78ⅹ10 m/W),YbPc (β=6.63ⅹ10 m/W),ScPc(β=7.43ⅹ10 m/W),respectively,indicating that the degree of aggregation between phthalocyanine rings gradually increases as the radius of rare earth metals changes from La,Y,Yb,to Sc,which inhibits the reverse saturable absorption process of the triplet states,resulting in a gradual decrease of the nonlinear absorption coefficient.The experimental results fully reveal the effect of the aggregation effect between phthalocyanine rings on photophysical and nonlinear optical properties,and would provide a theoretical basis for the design of high-performance nonlinear optical materials.

关键词： phthalocyanine rare earth metal aggregation effect nonlinear absorption optical limiting

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