The addition of different types of polymer additives can significantly affect the membrane properties and efficiency in removing contaminants from water in polymer-based membranes for water treatment. These additives can alter the membrane's surface properties, porosity, hydrophilicity, and mechanical strength, which in turn influence the membrane's performance in terms of permeability, selectivity, and fouling resistance. Some common types of polymer additives include:1. Hydrophilic additives: These additives, such as polyethylene glycol PEG , polyvinylpyrrolidone PVP , and polyacrylic acid PAA , can increase the hydrophilicity of the membrane surface. A more hydrophilic surface can reduce fouling by minimizing the adsorption of organic contaminants and other foulants, leading to improved permeability and selectivity.2. Porogens: Porogens, such as inorganic particles, organic solvents, or other polymers, can be added to the polymer solution to create pores in the membrane during the phase inversion process. The size, shape, and distribution of these pores can be controlled by adjusting the type and concentration of porogens, which can influence the membrane's permeability and selectivity. For example, larger pores can enhance permeability but may reduce selectivity for certain contaminants.3. Crosslinking agents: Crosslinking agents, such as glutaraldehyde, epichlorohydrin, or polyfunctional isocyanates, can be used to form covalent bonds between polymer chains, increasing the membrane's mechanical strength and chemical resistance. This can improve the membrane's stability and durability under various operating conditions, but excessive crosslinking may reduce permeability.4. Surface-modifying agents: These additives, such as surfactants, nanoparticles, or functional polymers, can be used to modify the membrane surface properties, such as charge, roughness, or chemical functionality. This can enhance the membrane's selectivity for specific contaminants, improve fouling resistance, or promote specific interactions with target contaminants for enhanced removal.5. Antifouling agents: Antifouling agents, such as biocides, enzymes, or zwitterionic polymers, can be incorporated into the membrane to reduce biofouling or organic fouling. These agents can either kill or inhibit the growth of microorganisms or reduce the adsorption of organic foulants, leading to improved membrane performance and longer service life.In summary, the addition of different types of polymer additives can significantly influence the membrane properties and efficiency in removing contaminants from water in polymer-based membranes for water treatment. The choice of additives and their concentrations should be carefully optimized to achieve the desired balance between permeability, selectivity, fouling resistance, and mechanical stability for a specific water treatment application.