Composite film and preparation method thereof

In general, the present invention relates to a composite membrane for use in filtration. The invention also relates to a method of making the composite membrane, and a filtration method using the composite membrane as disclosed herein. The method for preparing the composite membrane comprises the following steps: contacting a perfluorinated polymer solution with the surface of a polymer layer; and, at a relative humidity of less than 20%, drying the perfluorinated polymer solution to form a perfluorinated polymer layer that is physically adsorbed on the surface of the polymer layer. 整体上讲，本发明涉及一种用在过滤中的复合膜。本发明还涉及一种制备复合膜的方法，以及使用如所本文公开的复合膜的过滤方法。所述制备复合膜的方法包括：使全氟化聚合物溶液与聚合物层的表面接触；和，在小于20％的相对湿度下，对所述全氟化聚合物溶液进行干燥以形成物理吸附在所述聚合物层的所述表面上的全氟化聚合物层。