摘要:

Transport of nano‐sized colloidal particles in a dilute lyotropic lamellar phase of a nonionic surfactant has been studied by AC electrophoretic light scattering. The frequency dispersion of complex electrophoretic mobility shows two relaxation processes at about 1kHz (HF relaxation) and a few Hz (LF relaxation). These relaxations are originated from the hindrance of diffusion of particles in characteristic local structures of lamellar phase. The HF relaxation is found to relate the local deformation of membranes induced by particles. The LF one relates the confinement of a particle within persistence length of lamellar orientation. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764072

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The segregation phenomena of binary granular mixtures in a horizontal rotating cylinder are investigated. For the sake of simplicity, the glass cylinder which is a half‐filled with binary mixture of glass particles is adopted. The mixture consists of the same volumes of small size (diameter:0.2mm) and large size (diameter:0.6mm) glass particles. The rotation speed dependence of the long time scale segregation phenomena is studied. In a low rotation speed region, the initial narrow bands, which consist of small particles, gradually combined with each other and finally form one large band. On the other hand, in a high rotation speed region the initial narrow bands never combine with each other. The segregation phenomena in our case is thought to be caused by the drift motion of small particles along a inner axial core.We propose a new type model for numerical simulation which is able to take account of both effects of surface flow and inner drift of small particles. This model can reproduce the consecutive segregation phenomena obatained in our experiments. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764073

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

A highly charged polyelectrolyte, sodium polystyrenesulfonate, was investigated in various quality of solvent by using dynamic light scattering and viscosity measurements. As the solvent quality was lowered, the relaxation dynamics by the scattering measurements exhibited a drastic change from two relaxations to single one. Furthermore, an obvious reduction of zero‐shear viscosity coincided with the transition. These results indicate that the polyelectrolyte solution system in the solvent region has formed mono‐disperse micelles by strong segregation. The micelle size was estimated to be about 20 nm by Einstein‐Stokes relation. This micelle formation of polyelectrolyte solution system has been achieved experimentally for the first time despite theoretical predicts so far. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764074

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The formation of liquid droplets, which were generated at the confluence of two‐microchannels, was nvestigated in the microchip. Tributyl phosphate (TBP)‐droplets were formed precisely and continuously at 90–200 &mgr;m‐diameter at the range of 5–55 mm/s in the main‐channel and 47–370 mm/s in the other‐channel and a variation in the formation of TBP‐droplet was observed in a microchannel. And, the extraction of Aluminum‐DHAB chelate (DHAB=2,2′‐dihydroxyazobenzen) was studied by the laser‐induced fluorescence. The fluorescence intensity of Al3+‐DHAB chelate in the droplet was gradually increased with the distance from the confluence of two‐channel. The extraction using droplet in the microchannel has finished for 18 second. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764075

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

In this study we investigated the morphology transition of microemulsion droplet induced by polymer confinement using a small angle neutron scattering (SANS) technique. By confining the polymer chain strongly the scattering profiles showed the following changes; 1) a characteristic scattering peak corresponding to the size of droplet shifts to the higherqside, and 2) the scattering intensity in the lowqregion increases considerably. These changes of the scattering profiles can be described by a rod (or sphero‐cylinder) model. Thus, the strong confinement of polymer chains in droplets induces the morphological transition from spherical to rod‐like droplet. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764076

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We incorporated amphiphilic triblock copolymer into a lyotropic lamellar system and studied the effects of the hydrophilic chain length on the elastic nature of the lamellar membranes. The triblock copolymer consists of a hydrophobic chain (PPO) bounded by two identical hydrophilic chains (PEO). The hydrophobic chain anchors in the lamellar membranes and the hydrophilic chain decorates the membrane. We estimated the layer compression modulus by combining a small angle x‐ray scattering (SAXS) and a neutron spin echo (NSE) technique. The increase of the hydrophilic chain length changes the bending rigidity of membrane and enhances the repulsive forces between membranes. We discuss the results in terms of the entropic undulation interaction of lamellar membranes and comformational entropy of the hydrophilic chains. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764077

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

We report a novel method to assemble colloidal particles to an ordered structure. Individual DNA molecules folded by a sticky condensing agent can be prefabricated into a linear micrometer‐sized pearling chain under trapping field with a focused IR laser. Using this method, the macromolecules are assembled in a sequential order, and then a complex structure is fabricated by arraying them on a solid substrate. This approach may be useful for the further development of micro‐manufacture using macromolecules as nano‐elements. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764078

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Curious light scattering occurs during continuous elevation of temperature of supercooled liquid films on metal substrates. The phenomenon is observed for ethylbenzene and some related compounds when the temperature of the sample prepared by vapor deposition on cold substrate was raised to the point a little above the glass‐transition temperature but still below the temperature where spontaneous crystallization takes place. The relaxation time of particular Fourier components of structural inhomogeneity that gives the light scattering is well related to the viscosity of the sample. Surface undulation of viscous liquid is suggested to occur being caused by the difference between the thermal‐expansion coefficients of the supercooled liquid and metal substrate. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764079

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The nature of fluctuation modes of lamellar structure in a nonionic surfactant/water system has been investigated using a small angle x‐ray scattering and a neutron spin echo technique. Approaching temperature from lamellar phase to double‐gyroid phase, a diffuse scattering peak appears in the small angle scattering profile prior to the transition. This diffuse scattering is originated from the least stable fluctuation modes of lamellar structure predicted by Qi and Wang. The intermediate scattering profiles of the lamellar phase can be described by an undulation fluctuation mode and a least stable fluctuation mode of the lamellar structure. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764080

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

By using a new system that combines a confocal scanning laser microscope (CSLM) and a rheometer, we observed the structural change and measured the shear stress simultaneously in an immiscible polymer blend. The blend used is composed of a liquid crystalline plolymer (LCP) and a petroline mineral oil (PMO). When subjected to an external electric field, we observed a change from an LCP‐droplet‐dispersed structure to a network structure, corresponding to an increase of the shear stress. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1764081

出版商:AIP    

年代:1904

数据来源: AIP