0000000000424700

AUTHOR

Avraham Halperin

showing 3 related works from this author

3D Conformations of Thick Synthetic Polymer Chains Observed by Cryogenic Electron Microscopy.

2019

The backbone conformations of individual, unperturbed synthetic macromolecules have so far not been observed directly in spite of their fundamental importance to polymer physics. Here we report the dilute solution conformations of two types of linear dendronized polymers, obtained by cryogenic transmission electron stereography and tomography. The three-dimensional trajectories show that the wormlike chain model fails to adequately describe the scaling of these thick macromolecules already beyond a few nanometers in chain length, in spite of large apparent persistence lengths and long before a signature of self-avoidance appears. This insight is essential for understanding the limitations o…

chemistry.chemical_classificationQuantitative Biology::BiomoleculesMaterials scienceScatteringGeneral EngineeringGeneral Physics and Astronomy02 engineering and technologyPolymerElectron010402 general chemistry021001 nanoscience & nanotechnology01 natural sciences0104 chemical scienceslaw.inventionCondensed Matter::Soft Condensed MatterchemistryChemical physicslawPolymer physicsGeneral Materials ScienceElectron microscope0210 nano-technologyScalingSelf-avoiding walkMacromoleculeACS nano
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The Largest Synthetic Structure with Molecular Precision: Towards a Molecular Object

2010

Pushing the limits: A 200A - 10 Da structurally defined, linear macromolecule (PG5) has a molar mass, cross-section dimension, and cylindrical shape that are comparable to some naturally occurring objects, such as amyloid fibrils or certain plant viruses. The macromolecule is resistant against flattening out on a surface; the picture shows PG5 embracing the tobacco mosaic virus (TMV).

Macromolecular SubstancesPolymersStereochemistryviruses02 engineering and technologyMicroscopy Atomic Force010402 general chemistry01 natural sciencesCatalysisFlatteningPlant virusScattering Small AngleTobacco mosaic virus[SDV.IB.BIO]Life Sciences [q-bio]/Bioengineering/BiomaterialsComputingMilieux_MISCELLANEOUSMESH: Scattering Small Anglechemistry.chemical_classificationMESH: Microscopy Atomic ForceMolar mass010405 organic chemistryMacromolecular SubstancesGeneral ChemistryPolymerMESH: Macromolecular SubstancesGeneral Medicine021001 nanoscience & nanotechnologyAmyloid fibrilMESH: Polymers0104 chemical sciencesTobacco Mosaic ViruschemistryChemical physicsMESH: Tobacco Mosaic Virus0210 nano-technologyMacromoleculeAngewandte Chemie
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Micelles of Polysoaps:  The Role of Bridging Interactions

1996

Polysoaps, hydrophilic polymers incorporating amphiphilic monomers, form intrachain micelles in aqueous media. The micelles are similar to those formed by monomeric amphiphiles but are also endowed with a swollen, starlike corona formed by the spacer chains joining the amphiphiles. Long polysoaps form strings comprising many intrachain micelles. Exchange of amphiphiles between such micelles may give rise to bridging attraction, resulting in the adoption of a collapsed configuration in which the swollen micelles are close packed into a spherical globule. Upon addition of free amphiphiles, this structure unravels in a highly nonlinear fashion. Titration by surfactants, and the resulting swell…

Aqueous solutionPolymers and PlasticsAqueous mediumOrganic ChemistryMicelleInorganic Chemistrychemistry.chemical_compoundMonomerHydrophilic polymersChemical engineeringchemistryPulmonary surfactantIntermolecular interactionAmphiphileMaterials ChemistryOrganic chemistryMacromolecules
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