Vaynberg KA, Wagner NJ, Sharma R, Martic P
Department of Chemical Engineering, University of Delaware, Newark, Delaware, 19716
J Colloid Interface Sci. 1998 Sep 1;205(1):131-40. doi: 10.1006/jcis.1998.5640.
The extent and structure of the adsorbed layer of gelatin onto colloidal particles is measured using dynamic light scattering, small-angle neutron scattering, and dilution viscometry. Adsorption isotherms are measured using solution depletion of fluorescein-5-isothiocyanate tagged gelatin. The results show that the adsorbed gelatin layer at saturation on acrylic-based latex (pH 6.5, 0.01 M sodium acetate) has approximately twice the average density of the free gelatin in solution, while for the adsorption onto polystyrene latex (pH 8.7, deionized water), it has nearly the same average density. The energetics of gelatin affinity is calculated from the temperature dependence of the adsorption equilibrium constant. It was found that the enthalpy of adsorption of a net negatively charged gelatin onto a negatively charged surface is favorable. An additional, favorable entropy of adsorption is measured for the polystyrene latex, for which hydrophobic interactions are important. Selective, competitive adsorption of nonionic and anionic surfactants confirms the specific source of the adsorption interactions. Copyright 1998 Academic Press.
利用动态光散射、小角中子散射和稀释粘度测定法来测量明胶在胶体颗粒上吸附层的范围和结构。采用异硫氰酸荧光素标记的明胶溶液耗尽法来测量吸附等温线。结果表明，在丙烯酸基乳胶（pH 6.5，0.01 M醋酸钠）上达到饱和时，吸附的明胶层平均密度约为溶液中游离明胶的两倍，而对于在聚苯乙烯乳胶（pH 8.7，去离子水）上的吸附，其平均密度几乎相同。根据吸附平衡常数的温度依赖性计算明胶亲和力的能量学。结果发现，带净负电荷的明胶吸附到带负电荷表面上的吸附焓是有利的。对于聚苯乙烯乳胶，测量到了额外的有利吸附熵，其中疏水相互作用很重要。非离子和阴离子表面活性剂的选择性竞争吸附证实了吸附相互作用的具体来源。版权所有1998年学术出版社。
