scholarly journals Structural Characterization of a Polymer Substituted Fullerene (Flagellene) by Small Angle Neutron Scattering

1994 ◽  
Vol 359 ◽  
Author(s):  
K.A. Affholter ◽  
G.J. Bunick ◽  
J.M. Desimone ◽  
M.O. Hunt ◽  
Y.Z. Menceloglu ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Virial Coefficient ◽  
Scattering Length ◽  
Second Virial Coefficient ◽  
Radius Of Gyration ◽  
Polystyrene Sample ◽  
Negative Scattering Length

ABSTRACTSmall-angle neutron scattering (SANS) can structurally characterize fullerenes1in solvents with strong SANS contrast (e.g. CS2). Deuterated solvents (e.g. toluene-d8) have a high scattering length density (SLD), which is close to that of C60and C70moieties. Hence, there is virtually no SANS contrast with the solvent and these particles are practically “invisible” in such media. On the other hand, the negative scattering length of hydrogen means that the SLD of H1-containing materials is much lower, so they have strong contrast with toluene-d8. Thus, SANS makes it possible to study the size and shapes of modified buckyballs such as the polymer-substituted fullerenes, or flagellenes2. These consist of C60cores to which 1-4 polystyrene chains (with a molecular weight, MW ≃ 2000) are attached. The extrapolated cross section at zero angle of scatter [dΣ/dΩ(0)]s is a function of the number of pendant chains, so SANS can be used to assess the number of “arms” which are covalently attached to the fullerene “sphere”. Close agreement (± 4%) between the measured and calculated values of dΣ/dΩ(0) along with independent estimates of the radius of gyration (Rg) and second virial coefficient (A2) for a calibration linear polystyrene sample serves as a cross check on the validity of this methodology.

Real-space interpretation of spin-echo small-angle neutron scattering

2003 ◽  
Vol 36 (1) ◽  
pp. 117-124 ◽  
Author(s):  
Timofei Krouglov ◽  
Ignatz M. de Schepper ◽  
Wim G. Bouwman ◽  
M. Theo Rekveldt
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Spin Echo ◽  
Scattering Length ◽  
Structural Parameters ◽  
Pair Correlation ◽  
Real Space ◽  
Radius Of Gyration ◽  
Solid Spheres

Spin-echo small-angle neutron scattering (SESANS) is a novel real-space scattering technique. SESANS measures a correlation-like functionG(Z), the meaning of which was unknown until now. Here a direct real-space interpretation ofG(Z) through the particle scattering density and pair correlation function is given. One-dimensional and two-dimensional SESANS are compared. The case of non-interacting particles is considered in detail with an explicit geometrical interpretation. General methods for the calculation of structural parameters, such as the total scattering length and the radius of gyration, are developed. Analytical expressions ofG(Z) for non-interacting solid spheres, hollow spheres and Gaussian coils are derived. The case of solid spheres is compared with experimental data.

Small-Angle Neutron Scattering Study of Poly(oxyethylene)-block-poly(oxypropylene)-block-poly(oxyethylene) in Aqueous Solutions

1993 ◽  
Vol 58 (10) ◽  
pp. 2428-2436 ◽  
Author(s):  
Herman Pospíšil ◽  
Josef Pleštil ◽  
Zdeněk Tuzar
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Structural Parameters ◽  
Second Virial Coefficient ◽  
Scattering Data ◽  
Radius Of Gyration ◽  
Deuterated Water ◽  
Neutron Scattering Study ◽  
Copolymer Poly

Solutions of a triblock copolymer, poly(oxyethylene)-block-poly(oxypropylene)-block-poly(oxyethylene) (POE-POP-POE), in deuterated water were studied by small-angle neutron scattering (SANS) in the temperature range from 20 to 45 °C. Radius of gyration, molecular weight, second virial coefficient for both unimers and micelles, critical micelle concentration and unimer concentration were determined from the scattering data. Under assumption of the spherical core/shell micellar model structural parameters were estimated. Degree of swelling of the micellar core was evaluated from the mean-square fluctuation of scattering density.

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