Preparation of highly flexible cellulose acetate membranes modified by hyperbranched poly(amine ester)-epoxidized soybean oil and evaluation of its filtration properties

Cellulose acetate (CA) is considered as one of the first materials used in membrane technology. However, CA membranes suffered finding their way for widespread commercial applications due to low mechanical stability and sensitivity to bio-fouling. In this study a green procedure was developed to overcome some of CA drawbacks in membrane applications. For this purpose 2nd generation of hyperbranched poly(amine ester) (HBPAE-G2), was synthesized using methyl 3-[bis(2-hydroxyethyl)amino]propanoate and triethanolamine through a pseudo one-pot polycondensation, reacted with soybean oil fatty acid, and then double bonds epoxidized by H₂O₂/formic acid to acquire hyperbranched poly(amine ester)-epoxidized soybean oil (HBPAE-ESBOFA). Finally, this reactive additive was blended with CA membrane dope solution to obtain simultaneously plasticized and cross-linked structure. Synthesis procedures were monitored by FTIR and NMR techniques, and membrane samples were investigated using ATR-FTIR, FE-SEM (top and cross-sectional), TGA and DSC. Filtration properties were studied by determining pure water flux, water contact angle, bio-fouling, water content, mean pore size and solute rejection tests. Permeability tests showed decline in water flux, but fouling resistance, salt rejection and thermal properties improved. Moreover, modified samples showed fascinating flexibility and mechanical stability enhanced dramatically.