Structural characterization of a polymer substituted fullerene (flagellene) by small angle neutron scattering
- Oak Ridge National Lab., TN (United States)
- North Carolina Univ., Chapel Hill, NC (United States). Dept. of Chemistry
Small-angle neutron scattering (SANS) can structurally characterize fullerenes in solvents with strong SANS contrast (e.g. CS{sub 2}). Deuterated solvents (e.g. toluene-d{sub 8}) have a high scattering length density (SLD), which is close to that of C{sub 60} and C{sub 70} moieties. 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 H{sup 1}-containing materials is much lower, so they have strong contrast with toluene-d{sub 8}. Thus, SANS makes it possible to study the size and shapes of modified buckyballs such as the polymer-substituted fullerenes, or flagellenes. These consist of C{sub 60} cores to which 1-4 polystryene chains (with a molecular weight, MW {approx_equal} 2000) are attached. The extrapolated cross section at zero angle of scatter [d{Sigma}/d{Omega}(0)] 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 ({plus_minus}4%) between measured and calculated values of d{Sigma}/d{Omega}(0) along with independent estimates of the radius of gyration (R{sub g}) and second virial coefficient (A{sub 2}) for a calibration linear polystyrene sample serves as a cross check on the validity of this methodology.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); Department of Defense, Washington, DC (United States); National Science Foundation, Washington, DC (United States); North Carolina Univ., Chapel Hill, NC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 101160
- Report Number(s):
- CONF-941144--168; ON: DE95014590; CNN: Air Force Contract F3361-90-C-5813
- Country of Publication:
- United States
- Language:
- English
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