COMPUTERIZED DESIGN OF SURFACTANTS 249 Table I Properties of Novel Carboxylates Measured in the Testing Program a. Ross-Miles Foam Height b. Surface Activity (Surface Tension) c. Lime Soap Dispersion Activity d. Draves Wetting e. Cationic Interference f. Solubility g. HLB h. Detergency CONTOURING AND THE PREDICTIVE MODE The properties listed in Table I were measured for each of 44 compounds, in many instances over several concentrations, temperature, and pH ranges. Upon completion, the resultant data, properly formatted and coded, were subjected to computer manipulation to give mathematical models of the behavior or performance of the product system in the form of functions of the specified variables given in Table II. These models were then utilized to generate representatives of selected performance ranges in chosen values of the variables listed above. One useful type of representation is the contour map. Figure 1 shows the contour map of surface tension at pH 10, 0.01% active concentra- tion under the constraints indicated. Also given is the regression equation for the optimization program. Figure 1 is keyed to Table II. Depicted in terms of another coordinate system, Figure 2 shows the three dimensional graphics for surface tension under these conditions. Shown in these two 16- Z14- 12- 10 1.00 Surface Tension {0.01%, pH 10) = 161.1 -- 10.67a -- 4.00b -72.31c -- 8.66d -- 0.46e + 0.33a 2 -- 0.13ab +0.23b 2 + 2.94ac 47.5 +1.74bc + 18.21c • +0.50ad + 0.04be :, 4.o.o / / 5,00 • 0,00 • •,00 20.00 Total •lkox•l•tion Figure 1. Surface tension response surface in dynes/cm at: 0.01% concentration pH = 10 PO block position = 3 percent PO = 40% and percent conversion = 22.0%.

250 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table II Structural Design Variables of Novel Carboxylates a. Carbon Number in Hydrophobe b. Total Alkoxylation c. VO/(VO + EO) I d. Block Position (of PO) e. Percent Methylcarboxylation •Propylene Oxide/(Propylene Oxide + Ethylene Oxide) figures, for pH 10 and 0.01% active concentration, maximum surface activity is predicted to be achieved by the structure: C10 H21 O(EO), (PO)3.95 CH 2 COOH, (III) where: PO/PO + EO = 0.80 PO + EO=4.95 % methylcarboxylation = 44%. Predicted surface tension for a 0.01% solution at pH 10 at ambient temperature is 24.86 dynes/cm. AAAOCS. NRF {PO/PO+EO - 0.80000 {BLOCK POS - 5.0000 {CONV - 44.000 Figure 2. Three-dimensional graphics for surface tension as shown under the conditions of Figure 1.