Diffusion of Dextran Probes in a Self-Assembled Fibrous Gel Composed of Two-Dimensional Arborols

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• 作者：Jirun Sun ; Bethany F. Lyles ; Keunok Han Yu ; Jaime Weddell ; John Pople ; Max Hetzer ; Daniel De Kee ; Paul S. Russo
• 刊名：Journal of Physical Chemistry B
• 出版年：2008
• 出版时间：January 10, 2008
• 年：2008
• 卷：112
• 期：1
• 页码：29 - 35
• 全文大小：216K
• 年卷期：v.112,no.1(January 10, 2008)
• ISSN：1520-5207

文摘

Two-dimensional arborols are bolaform amphiphiles in which a central, hydrophobic spacer separates twinhydrophilic ends. Under appropriate conditions, these relatively small molecules assemble into very longfibers; subsequently, the system gels if the arborol concentration is sufficiently high. The diffusion of linearor slightly branched dextran probes in 3 and 6% arborol gels, as determined by fluorescence photobleachingrecovery, resembles that of dextrans in water, suggesting a highly open network structure. Melting the gelsproduces almost no change in diffusion of the dextran probes. Small-angle X-ray scattering (SAXS) of wetarborol gels at different concentrations and temperatures reveals the diameter of the repeating unit of thefibers to be 8.26 ± 0.68 nm. This dimension, which is independent of concentration and temperature, exceedsthe length of a single arborol molecule by about a factor of 3. Rheological investigation identifies the linearresponse regime of the gels and permits an examination of the weak correlation between dextran probe diffusionand gel viscoelasticity.