Abstract
Self-assembled multilayers (SAMs) of poly (amide amine) generation 4.0 dendrimer, coded as the PAMAM G4.0 SAMs, were prepared successfully via a simple approach. The resulting SAMs were characterized by means of ellipsometry, contact angle measurement, X-ray photoelectron spectroscopy, and atomic force microscopy. Their micro-tribological behavior was evaluated using a reciprocal ball-on-disc test rig, while their nano-tribological behavior was evaluated using an atomic force microscope. Results of ellipsometry indicate that the thickness of the PAMAM G4.0 SAMs increased with increasing deposition time, which corresponds well to the enhanced intramolecular hydrogen bonding of the PAMAM as evidenced by the corresponding X-ray photoelectron spectroscope data. The thickness of the PAMAM G4.0 SAMs is an important factor affecting their tribological properties. The long wear-life in a micro-tribotest can be attributed to the interior cavities and flexible carbon chain of the PAMAM molecules.
Acknowledgment
The financial support from the Innovation Group Fund of National Natural Science Foundation of China (Grant No. 50421502) and the Ministry of Science and Technology of China (in the name of National Major Fundamental Research plan, Grant No. A1320060604) is gratefully acknowledged. We would like to express our gratitude to Phillip H. Geil from University of Illinois for his polishing of this manuscript.