聚乙二醇、聚丙二醇和环氧乙烷-环氧丙烷嵌段共聚物在固液界面上的吸附——Ⅱ.硅胶/水界面

测定了25℃时硅胶自水溶液中吸附五种聚乙二醇(PEG)、一种聚丙二醇(PPG)和三种环氧乙烷(EO)-环氧丙烷(PO)嵌段共聚物的吸附等温线。除PPG的等温线为S型外,其余的均为Langmuir型的。计算结果表明,对于PEG系列和EO-PO嵌段共聚物系列都可得到极限吸附时的分子面积(A)与分子中所含EO数(n_(EO))的关系为不通过原点的曲线。当PEG分子量大到一定程度后,此A-n_(EO)关系即成近似于通过原点的直线。根据所得结果的分析,以及考虑了吸附水的影响,初步可得出分子是以平躺的方式被吸附的结论。文中还计算了吸附直由能,并对计算结果作了初步的解释。

ADSORPTION OF POLYETHYLENE GLYCOLS,POLYPROPYLENE GLYCOL AND POLYOXYETHYLENEPOLYOXYPROPYLENE BLOCK CO-POLYMERS ON SOLID/LIQUID INTERFACES——Ⅱ. SILICA GEL/WATER INTERFACE

The adsorption isotherms Of polyethylene glycols (PEG, molecular weights of 400, 1000, 3350, 6000 and 20000), one polypropylene glycol (PPG) and polyoxyethylene-polyoxypropylene block co-polymers (L61, L64 and F68) from water onto silica gel have been determind (at 25℃). Except polypropylene glycol,all the other isotherms can be represented by the Langmuir equation. The calculated results show that for PEG and EO-PO co-polymer the molecular area at limiting adsorption (A) versus the number of EO in the polymer molecules (n_(EO)) is a curve which does not through the origin, If the PEG molecular weight>3000, the A-n_(EO)) curve is approximately a straight line through the origin. On the basis of these results and the cosideration of adsorption of water, it is suggested that the adsorbed molecules lies flat on the surface of silica gel.