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Hierarchical structures,surface morphology and mechanical elasticity of lamellar crystals dominated by halogen effects
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作者 Chuanxin Wei Jianfeng Wang +7 位作者 Yanni Zhang Xuehua Ding Yanze Jiang Qiang Zhao Jinyi Lin Jianfeng Zhao Linghai Xie Wei Huang 《Chinese Chemical Letters》 SCIE CAS CSCD 2023年第8期337-342,共6页
To understand the deformation mechanism of molecular crystals under mechanical forces will accelerate the molecular design and preparation of deformable crystals.Herein,the relationship between structural halogenation... To understand the deformation mechanism of molecular crystals under mechanical forces will accelerate the molecular design and preparation of deformable crystals.Herein,the relationship between structural halogenation and molecular-level stacking,micro/nanoscale surface morphology,and macroscopic mechanical properties are investigated.Elastic crystals of halo-pyrimidinyl carbazoles(CzM-Cl,CzM-Br and CzM-I)with lamellar structure and brittle crystal(CzM-F)were quantitatively analyzed by crystal energy framework(CEF)providing the inter/intralayer interaction energy(Inter/Intra-IE).It is revealed that the elastic crystals bend under external force as a result from stronger Intra-IE to prevent cleavage and weaker Inter-IE for the short-range movement of molecules on the slip plane.This research will provide an insight for the molecular design of flexible crystals and facilitate the development of next-generation smart crystal materials. 展开更多
关键词 HALOGEN lamellar crystal ELASTICITY Crystal energy framework(CEF) Inter/intralayer interaction energy (Inter/Intra-IE)
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Preparation and characterization of monodisperse zirconia spherical nanometer powder via lamellar liquid crystal template method
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作者 何伟艳 刘进荣 +2 位作者 曹珍珠 李彩虹 高艳芳 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第10期1721-1727,共7页
Cubic phase spherical zirconia nano-powder was prepared by a direct template route in the lamellar liquid crystal formed by polyoxyethylene tert-octylphenyl ether(Triton X-100)/sodium dodecyl sulfate(SDS)/H_2O.The pre... Cubic phase spherical zirconia nano-powder was prepared by a direct template route in the lamellar liquid crystal formed by polyoxyethylene tert-octylphenyl ether(Triton X-100)/sodium dodecyl sulfate(SDS)/H_2O.The precursor powder and zirconia powder were characterized by XRD,FT-IR,TG/DSC,TEM,and SEM methods.Results show that the stability of the lamellar liquid crystal is controlled by NH_3·H_2O concentration.The size of nanoparticles is greatly affected by NH_3·H_2O and ZrOCl_2·8H_2O concentrations.The zirconia nanoparticles show narrow particle size distribution of 10-30 nm. 展开更多
关键词 ZIRCONIA Spherical nanometer powder lamellar liquid crystal template
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A Modified Phase-Field Model for Polymer Crystal Growth 被引量:3
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作者 杨斌鑫 张晨辉 王芳 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2017年第5期538-546,I0001,共10页
The irrationality of existing phase field model is analyzed and a modified phase-field model is proposed for polymer crystal growth, in which the parameters are obtained from real materials and very simple to use, and... The irrationality of existing phase field model is analyzed and a modified phase-field model is proposed for polymer crystal growth, in which the parameters are obtained from real materials and very simple to use, and most importantly, no paradoxical parameters appeared in the model. Moreover, it can simulate different microstructure patterns owing to the use of a new different free energy function for the simulation of morphologies of polymer. The new free energy function considers both the cases of T〈Tm and T≥Tm, which is more reasonable than that in published literatures that all ignored the T≥Tm case. In order to show the validity of the modified model, the finite difference method is used to solve the model and different crystallization morphologies during the solidification process of isotactic polystyrene are obtained under different conditions. Numerical results show that the growth rate of the initial secondary arms is obviously increased as the anisotropy strength increases. But the anisotropy strength seems to have no apparent effect on the global growth rate. The whole growth process of the dendrite depends mainly upon the latent heat and the latent heat has a direct effect on the tip radius and tip velocity of side branches. 展开更多
关键词 Phase-field method Polymer crystallization Numerical simulation Dendritic lamellar
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Insights from polymer crystallization: Chirality, recognition and competition 被引量:1
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作者 Jun Xu Shujing Zhang Baohua Guo 《Chinese Chemical Letters》 SCIE CAS CSCD 2017年第11期2092-2098,共7页
Crystallization of flexible polymer chains reveals distinct characters compared to small molecules, which provides a platform to study molecular self-assembly and morphogenesis. In this review, some examples, e.g., tw... Crystallization of flexible polymer chains reveals distinct characters compared to small molecules, which provides a platform to study molecular self-assembly and morphogenesis. In this review, some examples, e.g., twisting chirality of polymer lamellar crystals, recognition of different chain units and competitive nucleation of different polymorphs and different lamellar thicknesses are briefly discussed. It is shown that the polymer crystallization process far from equilibrium is in practically minimization of the system free energy in local space and finite time, leading to formation of twisted crystals, metastable polymorphism and lamellar crystals with finite thickness. Though each molecule is blind to others, the peculiar ordered configurations with stronger long-range interactions are chosen from the enormous random trials. At the end, we list some remaining questions and outlook the perspectives. 展开更多
关键词 Polymer crystallization Chiral growth lamellar twisting Polymorphism Competitive nucleation lamellar thickness lamellar width
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SOLUTION CRYSTALLIZATION BEHAVIOR OF LINEAR AND STAR-SHAPED POLY(ETHYLENE GLYCOL)-b-POLY(ε-CAPROLACTONE) BLOCK COPOLYMERS
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作者 Ting Yu Jian-qiang Zhang +5 位作者 Ya Lia Su-dan Shen Wen-feng Wei Peng Chen 王宗宝 顾群 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2013年第12期1717-1724,共8页
Lamellar crystals of diblock, triblock and four-arm poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL) crystalline-crystalline copolymers were successfully obtained from their solution. Morphology and str... Lamellar crystals of diblock, triblock and four-arm poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL) crystalline-crystalline copolymers were successfully obtained from their solution. Morphology and structure of lamellar crystals of crystalline-crystalline copotymers were investigated using tapping-mode atomic force microscopy (AFM) and selected area electron diffraction (SAED). All of these samples showed the truncated-lozenge multilayer basal shapes with central screw dislocation or central stack, which were all obtained simultaneously from the oil bath. The diffraction pattern of PEG block lamellar crystal is attributed to the (120) diffracting planes and the pattern of PCL block lamellar crystal is attributed to the (1 I0) diffracting planes and (200) diffracting planes according to the SAED results. Four (110) crystal growth planes and two (200) crystal growth planes are discovered for the PCL blocks, but the (120) crystal growth planes of PEG blocks are hided in the figure of AFM. The crystalline structure of the four-arm copolymers (FA) is more disorder and confused than that of the diblock (DI) copolymer and the striated fold surface structures of lamellar crystals of four-arm copolymers (FA) are smoother than these of linear analogues, owing to the confused crystallization of blocks caused by the mutual restriction of blocks and the hindrance of the dendritic cores. In addition, the aspect ratio of FA is greater than that of the others. It is hypothesized that there are two reasons for the change of aspect ratios. First, the (200) diffracting planes of PCL crystals grew slowly compared to their (110) diffracting planes because of difference in the energy barrier. Secondly, edge dislocations on the (200) diffracting planes are also responsible for the variation of the aspect ratio. Consequently, the crystalline defects are augmented by the competing blocks crystallized simultaneously and the hindrance of the dendritic cores. 展开更多
关键词 lamellar crystal Topological structure PEG-b-PCL Edge dislocation Aspect ratio.
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Location of ethanol in sodium dodecyl sulfate aggregates
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作者 刘天晴 于卫里 郭荣 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2000年第1期18-24,共7页
The hexagonal liquid crystalline phase of SDS (Sodium dodecyl sulfate)/H2O system changes into lamellar liquid crystal and the effective length of surfactant molecule d0/2 in the lamellar liquid crystal decreases with... The hexagonal liquid crystalline phase of SDS (Sodium dodecyl sulfate)/H2O system changes into lamellar liquid crystal and the effective length of surfactant molecule d0/2 in the lamellar liquid crystal decreases with the addition of ethanol. The micellar aggregation number N of SDS decreases and the micellar diffusion coefficient increases with the added ethanol. Under a constant concentration of SDS, the molecule number ratio of ethanol to SDS in the micelle increases with the concentration of ethanol and even exceeds 10 when ethanol concentration is 1. 085 mol/L. All these results show that ethanol, even though a short chain alcohol and soluble in water, can partly exist in the interphase of the amphiphilic aggregates showing some properties of co-surfactant. 展开更多
关键词 ETHANOL hexagonal liquid crystal lamellar liquid crystal MICELLE aggregation number diffusion coefficient
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