| Language: | English |
|---|---|
| Type: | Article |
| Authors: | Katsuya Funayama, Toyoko Imae, Hideki Seto, Keigo Aoi, Kaname Tsutsumiuchi, Masahiko Okada, Michihiro Nagao and Michihiro Furusaka |
| Journal: | Journal of Physical Chemistry B |
| ISSN: | 1520-6106 |
| Volume: | 107 |
| Number: | 6 |
| Month: | 2 |
| Year: | 2003 |
| Actual year: | 2003 |
| Pages: | 1353-1359 |
| doi: | 10.1021/jp0269874 |
| Abstract: | Neutron spin-echo (NSE) experiments were performed at room temperature on D2O solutions of fifth generation poly(amido amine) (PAMAM) dendrimers with different types of end groups. Intermediate correlation functions I(Q,t)/I(Q,0) at different scattering vectors Q as a function of time t show different dynamics for dendrimer concentrations of 1.0 and 10 wt %, while the dynamics was independent of the chemical species of the end groups, hydroxyl or glucopeptide. The NSE results for a 10 wt % solution followed a single-exponential decay. With increasing Q, the evaluated effective diffusion coefficients D-eff decreased and converged to the translational diffusion coefficient D-0, which was obtained from dynamic light scattering. It is assumed that the Q-dependence of D-eff is caused by the dendrimer-dendrimer interaction, which is observed as the inter-dendrimer structure factor on small-angle neutron scattering. On the other hand, NSE results for a 1.0 wt % solution were well-fitted to a double-exponential function with two decay rates (fast and slow modes). It was observed that the diffusion coefficient of the slow mode corresponds to D-0. The fast mode originates from the motion of amido-amine segments in the dendrimer, which is a common internal unit for the two dendrimers. |
Katsuya Funayama, Toyoko Imae, Hideki Seto, Keigo Aoi, Kaname Tsutsumiuchi, Masahiko Okada, Michihiro Nagao and Michihiro Furusaka, Journal of Physical Chemistry B, 107, 1353-1359 (2003)