SYNTHESIS AND CHARACTERIZATION OF PES Copolymers With Carboxyl ans sulfonic units

Aromatic polyethersulfone (PES) is one of the most used polymeric material for many technological applications. This material possesses a high hydrophobicity, which leads to accumulation phenomena on the surface of membranes (biofouling). In order to prepare materials with an optimal balance of hydrophobic and hydrophilic character, a series of aromatic polyethersulfones containing different percentages of 4,4-Bis(4-hydroxyphenyl) pentanoic acid (DPA) units (10, 20, 25, 50, 70 mol%) in the main chains was synthesized. The structure of these polymers was investigated by 1H-NMR and MALDI-TOF techniques. The results obtained show a random distribution of the units along the chains, in accordance with a statistical model which was used to verify the molar composition of the copolymers. The thermal characterization was carried out by TGA, DSC, DMA and pyrolysis analysis. In particular, DSC shows the Tg value decrease as increases the amount of DPA units along the chains. To extend the application of this materials as membranes for fuel cells or to metal chelation, it is necessary to increase the hydrophilic character of these copolymers, in order to increases their swelling properties in presence of water and/or methanol. Therefore, sulfonate PES macromers (up to 2K g/mol) were grafted to PES-DPA chains by using carboxyl groups as reactive sites. The new sulfonated graft-PES copolymers present a totally hydrophobic main chain and hydrophilic pendant moieties.