ABSTRACT:The reaction of dye with toluene diisocyanate and dimethyldichlorosilane in the presence of other additives to form a colored siloxane-based polyurethane (PU) ionomer has been proven to occur by infrared spectra. In aqueous solution, the numberaverage particle size for the colored siloxane-based PU ionomer was found to increase with an increase in the NCO-to-OH ratio, dye concentration, and dimethyldichlorosilane concentration, as a result of increased free volume of the ionomer molecules. It is worthy to note that the amount of air diffusing into the film cast from colored siloxanebased PU ionomer was found to increase with an increase in the concentration of dimethyldichlorosilane instead of raising the ratio of NCO to OH or the concentration of dye, as a result of the formation of more porosities. In addition, the tensile strength of this film will be strengthened by raising the NCO/OH ratio or the concentration of dimethyldichlorosilane, whereas the elongation, on the other hand, can be substantially increased with increasing the concentration of dye instead of increasing the concentration of dimethyldichlorosilane for use in the PU ionomer system.