添加剂对非离子表面活性剂AEO9浊点的影响

研究了不同添加剂如无机盐、有机醇、有机酸和离子型表面活性剂对非离子表面活性剂AEO9浊点的影响。结果表明，通过盐析性的无机盐与胶束争夺水分子，使非离子表面活性剂分子从水中析出，从而降低了非离子表面活性剂的浊点；而如NaI这样的盐溶性无机盐则相反，由于其可使自由水分子增加，从而导致AEO9的浊点升高。极性有机物对AEO9浊点的影响表明，与水无限混溶的极性有机物升高了浊点，而在水中部分溶解的极性有机物降低了浊点。这是因为前一类有机物通过改变溶剂水的结构，降低了介质的极性，同时部分有机物吸附在胶束-水界面，通过其溶剂化作用使AEO9的胶团化作用受到了限制，浊点升高；而后一类有机物分子由于增溶于胶束栅栏层中，导致胶束体积膨胀，从而降低了AEO9的浊点。在非离子表面活性剂溶液中加入离子型表面活性剂，如十二烷基硫酸钠SDS、十二烷基苯磺酸钠SDBS和十六烷基三甲基溴化铵CTAB，由于离子型表面活性剂能与非离子表面活性剂形成混合胶束，胶束表面电荷密度增大，胶束间电荷斥力增大，使体系稳定，从而其浊点显著升高。加入极少量的离子表面活性剂即可使浊点显著上升，当加入的离子表面活性剂达到其临界胶束浓度（cmc）时，浊点将发生突跃。

EFFECT OF ADDITIVES ON THE CLOUD POINT OF NONIONIC SURFACTANT AEO9 IN AQUEOUS SOLUTION

The effects of additives, such as salts, alcohols, carboxylic acids and ionic surfactants on the cloud point (CP) of aqueous solution of nonionic surfactant dodecylpolyoxyethylene ether AEO_9 (C_(12)H_(25)O(CH_2CH_2O)_9H) were studied. It was found that salting-out electrolytes lowered the cloud point of nonionic surfactant AEO_9 due to the dehydration and then the precipitation of surfactant molecules, while salting-in electrolyte such as NaI works the opposite way. The addition of the polar organic additives being infinitely miscible with water increased the cloud point of AEO_9, whereas the addition of the polar organic additives being partially soluble in water decreased the cloud point of AEO_9. The former additives could change the structure of water molecules, then lower the polarity of solution, and some of additive molecules were adsorbed on the surface of micelles to inhibit the micellization, resulting in the increase of CP, while the molecules of the latter could be solubilized in the layer of micelles to lead the micelles swell, resulting in the decrease of CP. When ionic surfactants such as sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulphonate (SDBS) and cetyltrimethylammonium bromide (CTAB) were added into the solution of nonionic surfactants, the CP of the solution increases since ionic surfactants formed mixed micelles with nonionic surfactant and the charge repulsion between micelles increased, leading to the system stable. If the concentration of the added ionic surfactant reached its cmc, the CP of the solution will jump.