ASSOCIATION REACTIONS OF POLYETHYLENE GLYCOLS TABLE 1.--CLouD POINTS OF POLYETHYLENE OXIDE PRODUCTS As 0.5 PER CENT AQUEOUS SOLVTXONS 2O3 Compound Ethylene Oxide % of Total Weight of Compound Cloud Point, øC. Tergitol© NPX 68 60-65 Tergitol© NP-35 75 96-100 Carbowax© 6000 100 100 Polyox© WSR-301 100 99 TABLE 2.--EFFECT OF SODIUM BICARBONATE ON CLOUD POINT øF. •--Cloud Point for 1% Solution. i•ergitol(• Per Cent Tergitol© NaHCO3 NP-35 NPX 0 212-3- 148 2 202 131 4 186 120 6 173 108 8 160 95 10 146 75 © Registered Trademark of Union Carbide Corporation. Just as the addition of salt to aqueous solutions of many types of organic compounds results in the "salting out" of those compounds, it is found that salt addition to polyethylene oxide products decreases their solubility. The incremental addition of sodium salts to aqueous solutions of typical polyoxide products decreases the cloud point in a regular manner, as shown in Table 2. In this instance, the competition of the salt ions for water effectively reduces the amount of "free water" available for solubilizing the product, and correspondingly less heat must be applied to sever the remaining water links. POLYVALENT ION COMPLEX FORMATION While the preceding explanation serves well for the effect of many inor- ganic salts, the inevitable exceptions are found that require an entirely different explanation. It is found, for example, that a number of poly- valent cation salt solutions, when mixed with the typical polyethylene oxide products, have relatively little effect on solubility or the solubility is even enhanced. This "salting in" effect produced by some polyvalent cations in contrast to the "salting out" effect of monovalent cations was observed and reported by Doscher, Myers and Arkins (1) with a number of nonionic surface-active agents. These workers isolated a definite crystalline complex from an aqueous mixture of $ per cent Renex (tall oil ethoxylate Atlas Chemical Industries, Inc.) in a 30 per cent calcium chlo- ride solution. After purification by recrystallization from isopropanol, the molar ratios of the components in the complex were found to be 3 CaCb.: 15 H20:l Renex. X-ray diffraction studies of this product led Doscher

204 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 9O 80 7O 3O 2o % -'"' EFFECT OF_S_•_CT tNoC, •ND coot,)ON • CLOUD POINT OF 0.5'/. 'TERGITOL" , NON,ON,C •PX I I I I I I I I i IO 20 30 40 50 60 70 80 90 GRAMS SALT PER I00 ML SOLUTION Figure 2. !00 IlO I00 9o •J8o •L m?O J 060 5O 4O [ i [ i , i ! i i EFFECT OF SALT (NoCI AND CoCI2) ON CLOUD POINT OF 0,5% CARBOWAX POLYETHYLENE GLYCOL 6000 I I I I I I I I I 2 4 6 8 I0 12 14 16 18 GRAMS SALT PER I00 ML OF SOLUTION Figure 3. 2o