Dow Cyclotene 4026 surfaces were treated by downstream ammonia cold plasma with and without argon plasma pretreatments. The modified polymer surfaces were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared-attenuated total reflection, and atomic force microscopy (AFM). A 2(IV)(4-1) fractional factorial design was developed to identify the optimal processing parameters. Further experimental investigation has also been conducted to optimize the operating conditions. The combined results show that the extent of surface amination of Cyclotene grows with increase of power, pressure, and temperature of ammonia plasma treatments both with and without argon plasma pretreatments. For the treatment time effect, the results indicate that N/C (nitrogen/carbon) ratios increase with time and then start to slightly decrease at the similar to 4-min point, which may be tentatively explained by a competition between the modification process and the degradation process on the polymer surfaces. AFM results suggest that the upper limit of the operating condition to obtain a desirable surface topography is 175 degrees C. Based on all the results from Design of Experiment, experimental data, and AFM analysis, the optimum processing parameters have been suggested. Finally, the aging effect of aminated surfaces is discussed; further investigation of this effect is still underway. (c) 2005 Wiley Periodicals, Inc.