Electrically Conducting Dendrimers
详细信息 查看全文
- 作者：Larry L. Miller ; Robert G. Duan ; David C. Tully ; and Donald A. Tomalia
- 刊名：Journal of the American Chemical Society
- 出版年：1997
- 出版时间：February 5, 1997
- 年：1997
- 卷：119
- 期：5
- 页码：1005 - 1010
- 全文大小：231K
- 年卷期：v.119,no.5(February 5, 1997)
- ISSN：1520-5126
文摘
Generations 1-5 of poly(amidoamine) (PAMAM) dendrimers wereperipherally modified with cationicallysubstituted naphthalene diimides. Reduction with sodium dithionitein water or formamide formed anion radicalson the diimide moieties. Evaporation of water under argon producedpowders of the reduced dendrimers that wereelectrically conductive. Using formamide as solvent, films werecast of reduced generation-3 modified dendrimers.Fully reduced films (1.1 e/diimide) gave conductivities underambient conditions of about 10-3 S/cm.Films formedfrom these dendrimers that were half-reduced (0.55 e/diimide) gave 
chars/sigma.gif" BORDER=0 >= 10-2 S/cm. Near-infrared (NIR)spectra onthe films showed the formation of chars/pi.gif" BORDER=0 >-stacks with maximum absorbancebeyond 2000 nm. The wavelength and intensityof this absorbance correlated with the conductivity. Theconductivity increased with increased humidity above thefilms reaching values as high as 18 S/cm at 90% relative humidity.The conductivity was in all cases electronic andisotropic. The conductivity-humidity effect was probed by NIRspectroscopy, X-ray powder diffraction, and quartzcrystal microbalance measurements. These studies suggest that theamorphous films absorb water from the air andat high humidity they are plasticized, allowing faster stack-to-stackelectron hopping and increased conductivity.
chars/sigma.gif" BORDER=0 >= 10-2 S/cm. Near-infrared (NIR)spectra onthe films showed the formation of chars/pi.gif" BORDER=0 >-stacks with maximum absorbancebeyond 2000 nm. The wavelength and intensityof this absorbance correlated with the conductivity. Theconductivity increased with increased humidity above thefilms reaching values as high as 18 S/cm at 90% relative humidity.The conductivity was in all cases electronic andisotropic. The conductivity-humidity effect was probed by NIRspectroscopy, X-ray powder diffraction, and quartzcrystal microbalance measurements. These studies suggest that theamorphous films absorb water from the air andat high humidity they are plasticized, allowing faster stack-to-stackelectron hopping and increased conductivity.