Polymer brushes   总被引：1，自引：0，他引：1  

Milner ST 《Science (New York, N.Y.)》1991,251(4996):905-914

Polymers attached by one end to an interface at relatively high coverage stretch away from the interface to avoid overlapping, forming a polymer "brush." This simple picture may serve as the basis for models in diverse interfacial systems in polymer science, such as polymeric surfactants, stabilized suspensions of colloidal particles, and structures formed by block copolymers. The structure and dynamics of polymer brushes have been the subject of considerable theoretical and experimental activity in recent years. An account is given of recent advances in theoretical understanding of stretched polymers at interfaces, and the diverse experimental probes of systems modeled by brushes are briefly reviewed.  相似文献   

Polymers     

Brauman JI 《Science (New York, N.Y.)》1991,251(4996):853

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Language without cognition     

Gleason JB 《Science (New York, N.Y.)》1991,252(5008):1016-1020

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Ventures in popularization     

Nye MJ 《Science (New York, N.Y.)》1991,252(5008):980-981

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How the retinoblastoma gene may onhibit cell growth     

M J 《Science (New York, N.Y.)》1991,252(5012):1492

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Toujours gaia     

Coyne J 《Science (New York, N.Y.)》1991,252(5012):1472-1474

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Atomic force microscopy of atomic-scale ledges and etch pits formed during dissolution of quartz     

Gratz AJ  Manne S  Hansma PK 《Science (New York, N.Y.)》1991,251(4999):1343-1346

The processes involved in the dissolution and growth of crystals are closely related. Atomic force microscopy (AFM) of faceted pits (called negative crystals) formed during quartz dissolution reveals subtle details of these underlying physical mechanisms for silicates. In imaging these surfaces, the AFM detected ledges <1 nanometer (nm) high that were spaced 10 to 90 nm apart. A dislocation pit, invisible to optical and scanning electron microscopy measurements and serving as a ledge source, was also imaged. These observations confirm the applicability of ledge-motion models to dissolution and growth of silicates; coupled with measurements of dissolution rate on facets, these methods provide a powerful tool for probing mineral surface kinetics.  相似文献   

Auger electron angular distributions from surfaces: direct comparison with isoenergetic photoelectrons     

Terminello LJ  Barton JJ 《Science (New York, N.Y.)》1991,251(4998):1218-1220

Angular distribution patterns of Auger electrons and of photoelectrons from a Cu (001) surface were measured at the same electron kinetic energy. These measurements reveal that the low kinetic energy angular distributions for Cu Auger electrons and Cu 3p(3/2) photoelectrons differ substantially. This direct comparison between the photoelectron and Auger electron angular distributions demonstrates that, in some circumstances, the Auger process produces a complicated source wave whose nature must be explored before Auger angular distributions can be used for surface structure analysis.  相似文献   

Atomic-resolution electrochemistry with the atomic force microscope: copper deposition on gold     

Manne S  Hansma PK  Massie J  Elings VB  Gewirth AA 《Science (New York, N.Y.)》1991,251(4990):183-186

The atomic force microscope (AFM) was used to image an electrode surface at atomic resolution while the electrode was under potential control in a fluid electrolyte. A new level of subtlety was observed for each step of a complete electrochemical cycle that started with an Au(111) surface onto which bulk Cu was electrodeposited. The Cu was stripped down to an underpotential-deposited monolayer and finally returned to a bare Au(111) surface. The images revealed that the underpotential-deposited monolayer has different structures in different electrolytes. Specifically, for a perchloric acid electrolyte the Cu atoms are in a close-packed lattice with a spacing of 0.29 +/- 0.02 nanometer (nm). For a sulfate electrolyte they are in a more open lattice with a spacing of 0.49 +/- 0.02 nm. As the deposited Cu layer grew thicker, the Cu atoms converged to a (111)-oriented layer with a lattice spacing of 0.26 +/- 0.02 nm for both electrolytes. A terrace pattern was observed during dissolution of bulk Cu. Images were obtained of an atomically resolved Cu monolayer in one region and an atomically resolved Au substrate in another in which a 30 degrees rotation of the Cu monolayer lattice from the Au lattice is clearly visible.  相似文献   

Leon Lederman's Quest: Double Science Funding     

Palca J 《Science (New York, N.Y.)》1991,251(4990):153-154

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