Thin-layer composite forward osmosis membrane and preparation method thereof

The invention provides a preparation method of a thin-layer composite forward osmosis membrane. On the basis of maintaining the original advantages, the prepared forward osmosis membrane can effectively reduce the polarization of internal concentration difference so as to greatly improve the water flux, can greatly improve the compounding strength of a screen supporting layer and an interface polymerized cortex, can improve the durability of the forward osmosis membrane, prolong the service life and can solve the bottleneck problem of the forward osmosis application. Dopa and/or dopamine is adopted for chemically modifying and decorating a screen, so that not only can the original excellent supporting layer structure of the screen be maintained, but also the hydrophilia and reaction property of the screen can be improved, and the compatibility between the screen and the cortex can be improved. In addition, long chain/hyperbranched macromolecules and surface active agent are added to polyamine aqueous solution, so that not only can the quantity of active groups be increased, but also the space structure of the macromolecule can be enlarged, the complete pavement of the aqueous solution on the surface of the screen can be facilitated, the cortex completeness can be improved, and a purpose of adjusting the cross-linking structure of the cortex can be realized.