Adding value to polystyrene waste by chemically transforming it into sulfonated polystyrene

Polystyrene (PS), one of the most used polymers in everyday life, has a low recycling rate due to itsinexpensive virgin resin. In order to make polystyrene waste (WPS) recycling advantageous, it is possible tochange it chemically, introducing heteroatoms in the polymer chain thus transforming the waste into amaterial with more added value. In this work, sulfonation reactions of polystyrene waste (disposable cupsand expanded polystyrene - EPS) with different degrees of sulfonation were carried out by homogeneoussulfonation using acetylsulfate as a sulfonating agent, originating polystyrene sulfonate (PSS). Thecharacterization of the products was done using Fourier Transformed Infrared Spectroscopy (FTIR),solubility tests and inductively coupled plasma optical emission spectroscopy (ICP-OES). Infraredspectroscopy revealed that the reaction was efficient and all the starting materials tested were successfullysulfonated and transformed into PSS. There was no distinction between the residues tested, revealing that it\u27spossible to carry the reaction without sorting the waste. EPS was chosen as the substrate for further reactionsvarying the degree of sulfonation. Solubility and ICP-OES tests have shown that, by changing the synthesisconditions, it is possible to achieve different degrees of products sulfonation. As a result of the studiedreactions it was found that varying the degree of sufonation it is possible to use polystyrene residues toproduce PSS for different applications.Keywords: Polystyrene, Waste, Sulfonated polystyrene, Sulfonation, Recycling, Expanded polystyrene