Semi-permeable membranes and production methods thereof

A semi-permeable membrane comprising:

• a support layer including a first surface and an opposing second surface;
• the support layer having a porous structure including a polymer and an amount of at least one metal oxide or metalloid oxide in the porous structure of the support layer;
• the at least one metal oxide or metalloid oxide including at least one of silicon, titanium, zirconium, and aluminum;
• the amount of the at least one metal oxide or metalloid oxide having a concentration gradient that increases with decreasing distance moving towards the first surface of the support layer and moving away from the second surface of the support layer;
• and an amount of the metal or the metalloid element of the at least one metal oxide or metalloid oxide in the first surface of the support layer being greater than or equal to about 10% based on a total weight of all elements constituting the polymer and the metal oxide or metalloid oxide in the first surface as measured by a scanning electron microscope—electron dispersive X-ray spectroscopy analysis of the semi-permeable membrane;
• and
• an active layer in contact with the first surface of the support layer.