Ridell Annika, Evertsson Hans, Nilsson Stefan
Physical Pharmaceutical Chemistry, Uppsala Biomedical Centre, Uppsala University, Box 580, Uppsala, S-751 23, Sweden.
J Colloid Interface Sci. 2002 Mar 15;247(2):381-8. doi: 10.1006/jcis.2001.8151.
Fluorescence probe techniques together with microcalorimetry and dye solubilization were used to study the interaction between nonionic polymers and anionic surfactants with different monovalent counterions in order to examine the effects of the counterion. The polymers used were the cellulose ethers hydroxypropyl methyl cellulose (HPMC) and ethyl hydroxyethyl cellulose (EHEC). The surfactants were dodecyl sulfates with potassium, sodium, and lithium as counterions (KDS, NaDS, LiDS). The counterion influenced the interaction start concentration as well as the nature of the mixed aggregates formed. The interaction start, according to surfactant concentration, was found to be in the order KDS < NaDS < LiDS for both polymers as well as in aqueous solution. From fluorescence measurements it was found that the KDS-polymer aggregates shield pyrene from water better than the other surfactants, indicating larger aggregates with a more fluid interior. The microcalorimetry measurements confirm that the adsorption of the surfactants onto the polymer is endothermic and entropy driven at the start and as more clusters are formed on the polymer chains the process converts to being exothermic and driven by both enthalpy and entropy.
采用荧光探针技术结合微量热法和染料增溶法，研究了非离子聚合物与带有不同单价抗衡离子的阴离子表面活性剂之间的相互作用，以考察抗衡离子的影响。所用聚合物为纤维素醚羟丙基甲基纤维素（HPMC）和乙基羟乙基纤维素（EHEC）。表面活性剂为以钾、钠和锂作为抗衡离子的十二烷基硫酸盐（KDS、NaDS、LiDS）。抗衡离子影响相互作用起始浓度以及形成的混合聚集体的性质。根据表面活性剂浓度，发现两种聚合物以及在水溶液中，相互作用起始顺序均为KDS < NaDS < LiDS。通过荧光测量发现，KDS - 聚合物聚集体比其他表面活性剂能更好地使芘免受水的影响，表明形成了更大且内部更具流动性的聚集体。微量热法测量证实，表面活性剂在聚合物上的吸附在开始时是吸热且由熵驱动的，随着聚合物链上形成更多簇，该过程转变为放热且由焓和熵共同驱动。
