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dissipative particle dynamics Simulation of Microscopic Properties in Diblock Copolymer Films

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Chinese Journal of Chemical Physics 2010年第3期23卷 274-280,I0001页

作者：徐毅宋小瑜张彰王勇陈捷朱宪上海大学环境与化学工程学院化工系上海200444 华东理工大学化学与分子工程学院上海200237

Mean-square bond length, root-mean-square end-to-end distance and gyration radius in diblock copolymer films have been studied by dissipative particle dynamics simulations. Results show evident linear trends of any property separately with the thickness of film, the interaction between particles of different types, the repulsion between particle and boundary, except for the dependence of the variations of mean-square bond length on the thickness of film, which exhibits as a wave trend. What＇s more, the varying trends of mean-square bond length and root-mean-square end-to-end distance can correspond to each other. The density distribution of either component in diblock copolymer film can be controlled and adjusted effectively through its interaction with boundary.

关键词： Diblock copolymer film Microscopic property dissipative particle dynamics

dissipative particle dynamics thermostat: a novel thermostat for molecular dynamics simulation of liquid crystals with Gay–Berne potential

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Science China Chemistry 2015年第4期58卷 694-707页

作者： Yuting Ouyang Liang Hao Yanping Ma Hongxia Guo Beijing National Laboratory for Molecular Sciences (BNLMS) State Key Laboratory for Polymer Physics and ChemistryInstitute of Chemistry Chinese Academy of Sciences

The Gay-Berne （GB） model has been proved to be highly successful in the simulation of liquid crystal phases via both molec- ular dynamics （MD） and nonequilibrium molecular dynamics （NEMD）. However, the conventional thermostats used in the simulations of GB systems, such as Nose-Hoover and Langevin thermostats, have serious shortcomings especially in NEMD simulations. Recently, dissipative particle dynamics （DPD） has established itself as a useful thermostat for soft matter simulations, whereas the application of DPD thermostat in （NE）MD simulations is limited to the spherically isotropic potential models, such as the Lennard-Jones model. Considering the virtues of the DPD thermostat, that is, local, momentum conserved, and Galilean invariant, we extend the DPD thermostat to the non-spherical GB model. It is interesting to find that the translational DPD and rotational DPD thermostats can be used in the GB system independently and both can achieve the thermostatting effects. Also, we compared the performance of the DPD thermostat with other commonly used thermostats in NEMD simulations by investigating the streaming velocity profiles and the dynamics of phase separation in a typical but simple binary GB mixture under shear field. It is revealed that the known virtues of DPD thermostats, such as Galilean invariant, shear velocity profile-unbiased, and unscreened hydrodynamic interactions, are still intact when applying to GB systems. Finally, the appro- priate parameters for the DPD thermostat in the GB system are identified for future investigations.

关键词： molecular dynamics simulation liquid crystal thermostat dissipative particle dynamics Gay-Berne potential

dissipative particle dynamics Simulation of Onion Phase in Star-block Copolymer

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Chemical Research in Chinese Universities 2013年第1期29卷 171-176页

作者： WUShao-gui DU Ting-ting College of Chemistry and Materials Sciences Sichuan Normal University Chengdu 610068 P. R. China

A dissipative particle dynamics simulation technique was used to investigate the effect of molecular architecture of star-block copolymer on the patterned structure in a nanodroplet. With increasing the ratio of solvophilic to block length to solvophobic block length（RwT）, solvophobic sphere, ordered hexagonal phase, onion phase, perforated onion phase and flocculent phase are formed, respectively. Since onion phase has potential application in controlled drug release, it has received wide attention experimentally and theoretically. Our simulation indicates onion phase forms at a certain RH/T（close to but less than 1）. A star-block copolymer molecule has two conformations in onion phase： either fully located in a shell or shared by two neighboring shells. Central structure affects onion＇s final shape. The molecular number of the copolymer in each shell is a quadratic function of the shell＇s radius. The arm number of star-block copolymer has little influence on onion＇s structure, but slightly affects the solvent content. Additionally, we studied the influence of arm length on onion＇s structure.

关键词： Star-block copolymer dissipative particle dynamics Onion phase

dissipative particle dynamics Study on Aggregation of MPEG- PAE-PLA Block Polymer Micelles Loading Doxorubicine

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Chinese Journal of Chemistry 2012年第9期30卷 1980-1986页

作者：杨楚芬孙尧章莉娟朱国典张灿阳钱宇 School of Chemistry and Chemical Engineering South China University of TechnologyGuangzhouGuangdong 510640China Faculty of Chemical Engineering&Light Industry Guangdong University of TechnologyGuangzhouGuangdong 510006China

To guide the molecular design of the pH-sensitive triblock amphiphilic polymer MPEG-PAE-PLA and the for- mula design of its doxorubicine （DOX）-loaded micelles, dissipative particle dynamics （DPD） simulations are em- ployed to investigate the aggregation behaviors of the DOX-loaded micelles. The simulation results showed that the aggregate morphologies of micelles and DOX distribution are influenced by degree of polymerization of blocks, and the proposed structure of polymer is MPEG44-PAE3-PLA4. With different contents of polymer or DOX, differ- ent aggregate morphologies of the micelles, like microsphere, spindle/column, reticulation or lamella are observed. To prepare the micro-spherical DOX-loaded micelles, the polymer content is proposed as 10%--15%, and the DOX content less than 10%.

关键词： dissipative particle dynamics pH-sensitive polymer amphiphilic polymer drug-loaded micelles

Effect of shear on the symmetric diblock copolymer/nanorod mixture:A dissipative particle dynamics study

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Chinese Physics B 2012年第8期21卷 549-559页

作者：何林李张瑞芬季永运 Department of Physics Wenzhou University

The phase behaviours of a lamellar diblock copolymer/nanorod composite under steady shear are investigated using dissipative particle dynamics. We consider a wide range of nanorod concentrations, where the nanorods each have a preferential affinity to one of the blocks. Our results suggest that shear not only aligns the orientations of the diblock eopolymer templates and nanorods towards flow direction, but also regulates the distribution of the nanorods within the polymer matrix. Meanwhile, the shear-induced reorientation and morphology transitions of the systems also significantly depend on the nanorod concentration. At certain nanorod concentrations, the competitions between shearinduced polymer thinning and nanorods dispersion behaviours determine the phase behaviours of the composites. For high nanorod concentrations, no morphology transition is observed, but reorientation is present, in which the sheared nanorods are arranged into hexagonal packing arrays. Additionally, the orientation behaviour of nanorods is determined directly by the applied shear, also interfered with by the shear-stretched copolymer molecules.

关键词： dissipative particle dynamics shear nanocomposites orientation

Statics,dynamics and Linear Viscoelasticity from dissipative particle dynamics Simulation of Entangled Linear Polymer Melts

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Chinese Journal of Polymer Science 2023年第9期41卷 1392-1409,I0007页

作者： Fan Wang Lu-Kun Feng Ye-Di Li Hong-Xia Guo Beijing National Laboratory for Molecular Sciences Joint Laboratory of Polymer Sciences and MaterialsState Key Laboratory of Polymer Physics and ChemistryInstitute of ChemistryChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China

dissipative particle dynamics(DPD)with bond uncrossability shows a great potential in studying entangled polymers,however relatively little is known of applicability range of entangled DPD model to be use as a model for ideal chains and properly describe the full dynamics of entangled ***,we perform a comprehensive study on structure,dynamics and linear viscoelasticity of a typical DPD entangled model system,semiflexible linear polymer *** polymers obey Flory's ideality hypothesis in chain dimensions,but their local structure exhibits nonideal behavior due to weak correlated hole *** monomer motion and viscoelasticity relaxation reproduce the full pictures as predicted by reptation *** stronger chain length dependent diffusion coefficient and relaxation time as well as dynamic moduli are in close agreement with predictions of modern tube model that accounts for additional relaxation mechanisms besides chain ***,an anomalous sub-diffusive center of mass motion is observed both before and after the intermediate reptation regime and the cross-correlation between chains is not negligible even these polymers obey stress-optical law,indicating limitations of the reptation *** semiflexible linear entangled DPD model can correctly describe statics and dynamics of entangled polymer melts.

关键词： Entangled polymer melts dynamics Linear viscoelasticity dissipative particle dynamics

Pickering emulsion transport in skeletal muscle tissue:A dissipative particle dynamics simulation approach

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Chinese Journal of Chemical Engineering 2024年第4期68卷 65-75页

作者： Xuwei Liu Wei Chen Yufei Xia Guanghui Ma Reiji Noda Wei Ge State Key Laboratory of Mesoscience and Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China Division of Environmental Engineering Science Graduate School of Science and TechnologyGunma University1-5-1 Tenjin-choKiryuGunma 376-8515Japan State Key Laboratory of Biochemical Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing 100190China

Lymph node targeting is a commonly used strategy for particulate vaccines,particularly for Pickering ***,extensive research on the internal delivery mechanisms of these emulsions,especially the complex intercellular interactions of deformable Pickering emulsions,has been surprisingly *** gap in knowledge holds significant potential for enhancing vaccine *** study aims to address this by summarizing the process of lymph-node-targeting transport and introducing a dissipative particle dynamics simulation method to evaluate the dynamic processes within cell *** transport of Pickering emulsions in skeletal muscle tissue is specifically investigated as a case *** factors impacting the transport process are explored,including local cellular tissue environmental factors and the properties of the Pickering emulsion *** simulation results primarily demonstrate that an increase in radial repulsive interaction between emulsion particles can decrease the transport ***,larger intercellular gaps also diminish the transport efficiency of emulsion droplet particles due to the increased motion complexity within the intricate transport space compared to a single *** study sheds light on the nuanced interplay between engineered and biological systems influencing the transport dynamics of Pickering *** insights hold valuable potential for optimizing transport processes in practical biomedical applications such as drug ***,the desired transport efficiency varies depending on the specific *** instance,while a more rapid transport might be crucial for lymph-node-targeted drug delivery,certain applications requiring a slower release of active components could benefit from the reduced transport efficiency observed with increased particle repulsion or larger intercellular gaps.

关键词： Pickering emulsion Skeletal muscular cells Transport phenomena dissipative particle dynamics Drug delivery

The Paraffin Crystallization in Emulsified Waxy Crude Oil by dissipative particle dynamics

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Frontiers in Heat and Mass Transfer 2024年第1期22卷 129-139页

作者： Ruiqiong Wang Tiantian Du Jinchen Cao Guoqiang Wang Power China Chongqing Engineering Co. Ltd.Chongqing400060China College of Electrical Engineering Xinjiang UniversityUrumqi830017China Key Laboratory of Low-Grade Energy Utilization Technologies and Systems Ministry of EducationSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China

With the advancement of oilfield extraction technology,since oil-water emulsions in waxy crude oil are prone to be deposited on the pipe wall,increasing the difficulty of crude oil *** this paper,the mesoscopic dissipative particle dynamics method is used to study themechanism of the crystallization and deposition adsorbed on *** results show that in the absence of water molecules,the paraffin molecules near the substrate are deposited on themetallic surface with a horizontalmorphology,while the paraffin molecules close to the fluid side are arranged in a vertical column *** the emulsified system,more water molecules will be absorbed on the metallic substrate than paraffin molecules,which obstructed the direct interaction between paraffin molecules and solid ***,the addition of watermolecules hinders the crystallization of wax near the ***,on the fluid side,water molecules promote the formation of paraffin *** research in this paper reveals the crystallization mechanism of paraffin wax in oil-water emulsions in the pipeline from the microscopic scale,which provides theoretical support for improving the recovery of wax-containing crude oil and enhancing the transport efficiency.

关键词： Emulsified waxy crude oil paraffin crystal deposition dissipative particle dynamics

Temperature dependence of microscopic properties in diblock copolymer films:A dissipative particle dynamics simulation

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Journal of Shanghai University(English Edition) 2010年第4期14卷 255-261页

作者：徐毅冯剑宋小瑜王勇陈捷朱宪 School of Environmental and Chemical Engineering Shanghai University Department of Chemistry and Life Science Chuzhou University School of Chemistry and Molecular Engineering East China University of Science and Technology

Temperature dependence of microscopic properties in diblock copolymer films has been investigated by dissipative particle dynamics simulations. Results show the relation between mean-square bond length （MSBL） and system temperature can be described as a quadratic curve. The root-mean-square radius of gyration （RMSGR） and end-end distance （RMSED） increase gradually as the temperature rises and composition fraction changes from 0.1 to 0.5, in which the effect of the former is primary. Especially, the relation between RMSGR and temperature is nearly linear in the confinement-introduced direction. Density distribution of each component in the films can be controlled and adjusted effectively by its interaction with other components and boundaries. Moreover, the changes of system temperature and composition fraction can both affect the density distributions to a certain extent.

关键词： diblock copolymer films microscopic properties dissipative particle dynamics