Synthesis of sulfonated polyethylene terephthalate via melt polycondensation

Polyethylene terephthalate (PET) is an essential thermoplastic polyester that used in many industrial applications. The synthesis of PET has two pathways, which are the esterification of terephthalic acid (TPA) and ethylene glycol (EG) or transesterification of dimethyl terephthalate (DMT) and EG. PET can be produced via melt polymerization to obtain low to medium molecular weight. High molecular weight PET requires one additional step, solid-state polymerization (SSP). PET has distinctive properties such as high mechanical strength and solvent resistance. The hydrophobic nature of PET restricts its use in some applications, such as textile, dyeing, adhesion, and water absorption, in which polarity is necessary. Modifying the surface of the PET is necessary to enhance its wettability. In this study, to alter the hydrophobic nature of PET and introduce hydrophilicity, the effect of incorporation of the ionic monomers, SM_1 and SM_2, was investigated. The copolymers were synthesized via melt polycondensation, and their wettability were investigated by using contact angle measurements. The impact of incorporating additional monomers such as diethylene glycol (DEG) and triethylene glycol (TEG) on PET hydrophilicity was studied. Sulfonated copolymers of PET were synthesized on a large scale. Surface modification of PET with sulfonated monomers, DEG and TEG exhibited better hydrophilic properties than the pure PET.