This title appears in the Scientific Report :
2012
Please use the identifier:
http://dx.doi.org/10.1021/jp209458a in citations.
Dynamics of 1,3-diphenylpropane tethered to the interior pore surfaces of MCM-41
Dynamics of 1,3-diphenylpropane tethered to the interior pore surfaces of MCM-41
The diffusive motions of covalently tethered 1,3-diphenylpropane (DPP) via a silyl-aryl-ether linkage in the mesopores of MCM-41 were studied by quasielastic neutron scattering. The geometric effect of pore radius was investigated with samples having pores that ranged from 1.6 to 3.0 nm in diameter...
Saved in:
Personal Name(s): | Kintzel, E.J. |
---|---|
Kidder, M.K. / Buchanan, A.C. / Britt, P.F. / Mamontov, E. / Zamponi, M. / Herwig, K.W. | |
Contributing Institute: |
Neutronenstreuung; ICS-1 Neutronenstreuung; JCNS-1 JCNS-FRM-II; JCNS-FRM-II |
Published in: |
The @journal of physical chemistry |
Imprint: |
Washington, DC
Soc.
2012
|
Physical Description: |
923 - 932 |
DOI: |
10.1021/jp209458a |
Document Type: |
Journal Article |
Research Program: |
Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung |
Series Title: |
Journal of Physical Chemistry C
116 |
Subject (ZB): | |
Publikationsportal JuSER |
The diffusive motions of covalently tethered 1,3-diphenylpropane (DPP) via a silyl-aryl-ether linkage in the mesopores of MCM-41 were studied by quasielastic neutron scattering. The geometric effect of pore radius was investigated with samples having pores that ranged from 1.6 to 3.0 nm in diameter and highest achievable DPP grafting density. The effect of molecular crowding was investigated in 3.0 rim diameter pores for surface coverage ranging from 0.60 to 1.61 DPP/nm(2). Temperature dependence was determined for large pore diameter samples from 240 to 370 K. As the DPP molecules remain attached over this entire temperature range, data were analyzed in terms of a model of localized diffusion inside a sphere. Only the motions of the DPP hydrogen atoms were considered because of the high sensitivity of neutron scattering to the presence of hydrogen. As atoms far from the attachment point have a greater range of motion than those nearer the tether, the radius of the sphere limiting the motion of individual hydrogen atoms was allowed to increase based on the atom's distance from the tether point Both smaller pore diameters and higher DPP grafting density resulted in larger amplitude motion while the diffusion coefficient was greatest in the largest pores at highest DPP density. These observations support a model where the DPP molecules prefer an orientation allowing close proximity to the MCM-41 pore surface and are forced into the pore interior by either the steric effect of small pore diameter or by increased competition for surface area at high molecule surface coverage. |