Polymer bristles: a SANS study

King, Stephen M.; Washington, C.; Attwood, David; Booth, Charles L.; Mai, Shao-Min; Yang, Yisu; Cosgrove, Terence

doi:10.1107/s0021889899013266

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…However, in reality the volume fraction of polymer would probably decay with increasing distance from the surface. For spherical particles, it is possible to interpret the scattering in terms of a volume fraction profile ,, that decays with increasing distance from the surface, instead of a “block” profile that corresponds to a core−shell model. An interpretation of SANS from coated disk-shaped particles of this aspect ratio (or other anisotropic shapes, e.g., rods), in terms of a continuously decaying profile, has not yet been developed; however, one possible approach may be the use of multiple shells.…”

Section: Discussionmentioning

confidence: 99%

A Small-Angle Neutron Scattering Study of Adsorbed Poly(ethylene oxide) on Laponite

2004

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The adsorption of poly(ethylene oxide) (PEO) on synthetic anisotropic clay particles (Laponite) has been investigated as a function of the molecular weight. Contrast variation small-angle neutron scattering (SANS) measurements were used to characterize the distribution and adsorbed amount of polymer on the particles. These experiments show not only that polymer is present on the face of the clay particle but that it also extends or "wraps" over the edges. The edge layer was thicker than the face layer for all the molecular weights studied. The polymer layers are unusually thin, with a thickness and adsorbed amount that show little variation with molecular weight.

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Section: Discussionmentioning

confidence: 99%

A Small-Angle Neutron Scattering Study of Adsorbed Poly(ethylene oxide) on Laponite

2004

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“…[21][22][23][24] PEO block copolymers with short hydrocarbon blocks, known as hydrophobically modified PEO block copolymers (HMPEOs), are also associative polymers. [25][26][27][28] These molecules have also been used as adsorbing molecules at the interface of microemulsions [29][30][31] in order to better understand how surfactant and block copolymer molecules arrange themselves at interfaces in colloidal systems and their influence on the phase behavior. The Brij 700 surfactant (C 18 EO 100 ) used in the present study can also be regarded as a HMPEO due to its relatively large PEO block and small hydrocarbon chain.…”

Section: Introductionmentioning

confidence: 99%

Structure and Interactions of Block Copolymer Micelles of Brij 700 Studied by Combining Small-Angle X-ray and Neutron Scattering

Sommer

Pedersen

Garamus³

2005

Langmuir

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Spherical micelles of the diblock copolymer/surfactant Brij 700 (C(18)EO(100)) in water (D(2)O) solution have been investigated by small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS). SAXS and SANS experiments are combined to obtain complementary information from the two different contrast conditions of the two techniques. Solutions in a concentration range from 0.25 to 10 wt % and at temperatures from 10 to 80 degrees C have been investigated. The data have been analyzed on absolute scale using a model based on Monte Carlo simulations, where the micelles have a spherical homogeneous core with a graded interface surrounded by a corona of self-avoiding, semiflexible interacting chains. SANS and SAXS data were fitted simultaneously, which allows one to obtain extensive quantitative information on the structure and profile of the core and corona, the chain interactions, and the concentration effects. The model describes the scattering data very well, when part of the EO chains are taken as a "background"contribution belonging to the solvent. The effect of this becomes non-negligible at polymer concentrations as low as 2 wt %, where overlap of the micellar coronas sets in. The results from the analysis on the micellar structure, interchain interactions, and structure factor effects are all consistent with a decrease in solvent quality of water for the PEO block as the theta temperature of PEO is approached.

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Solution Structure of the Tn3 Resolvase-Crossover Site Synaptic Complex

Nöllmann

Byron

et al. 2004

Molecular Cell

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Tn3 resolvase is a site-specific DNA recombinase, which catalyzes strand exchange in a synaptic complex containing twelve resolvase subunits and two res sites. Hyperactive mutants of resolvase can form a simpler complex (X synapse) containing a resolvase tetramer and two shorter DNA segments at which strand exchange takes place (site I). We have solved the low-resolution solution structure of the purified, catalytically competent X synapse from small-angle neutron and X-ray scattering data, using methods in which the data are fitted with models constructed by rigid body transformations of a published crystallographic structure of a resolvase dimer bound to site I. Our analysis reveals that the two site I fragments are on the outside of a resolvase tetramer core and provides some information on the quaternary structure of the tetramer. We discuss implications of our structure for the architecture of the natural synaptic complex and the mechanism of strand exchange.

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Polymer bristles: a SANS study

Cited by 3 publications

References 5 publications

A Small-Angle Neutron Scattering Study of Adsorbed Poly(ethylene oxide) on Laponite

A Small-Angle Neutron Scattering Study of Adsorbed Poly(ethylene oxide) on Laponite

Structure and Interactions of Block Copolymer Micelles of Brij 700 Studied by Combining Small-Angle X-ray and Neutron Scattering

Solution Structure of the Tn3 Resolvase-Crossover Site Synaptic Complex

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