Thin organic layers of polyamidoamine (PAMAM) dendrimers on poly(dimethylsiloxane) (PDMS) films were prepared, and their transport properties were evaluated. The surface of the PDMS film was plasma-modified either in air or in maleic anhydride (MAH) vapor. In the case of the MAH-plasma-treated surface, the majority of anhydride groups were maintained during the plasma treatment. Stable dendrimer layers were deposited by simple loading of amine-terminated PAMAM dendrimer solutions on the air-plasma-treated PDMS film to make PDMS-dendrimer membranes and were formed by reacting amine groups of the PAMAM dendrimers with anhydride groups on the MAH-plasma-treated surface to prepare PDMS-anhydride-dendrimer composite membranes. The dendrimer layers were characterized using XPS, ATR FT-IR spectrometry, and contact-angle and gas permeance measurements. Both PDMS-anhydride and PDMS-anhydride-dendrimer composite films showed facilitated transport of propylene when coordinated with silver salts. The propylene permeance and ideal separation factor over propane were 34 GPU and 340, respectively, at high silver loading.