Role of Cyclic Ketene Dithioacetals in Free Radical Polymerization of Vinyl Chloride

The role of the sulfur analog of cyclic ketene acetals in the synthesis of polyvinyl chloride is examined in this study. In this context, whether 2-methylene-1,3-dithiolane (S-CKA5), 2-methylene-1,3-dithione (S-CKA6), and 2-methylene-1,3-dithiepane (S-CKA7) monomers are involved in the radical polymerization of vinyl chloride through the ring opening reaction is examined by quantum chemical methods. In light of calculations at the M06-2X/6-31+G(d) level, it is concluded that, in general, S-CKAs undergo little or no ring-opening and form block copolymers, mainly with the homopolymerization of S-CKAs and their ring-retaining step. It is determined that S-CKA7 is the most prone to ring-opening reaction and inserting dithioate links to the polymer backbone. However, the radical ring-opening of S-CKA7 is strongly reversible, as in other S-CKAs. This is a quantum chemical study on sulfur analogs of 5, 6, and 7-membered cyclic ketene acetals (S-CKA) and analysis to synthesize biodegradable polyvinyl chloride (PVC). This study shows that radical polymerization of vinyl chloride in the presence of 7-membered S-CKA presents improved biodegradability of PVC. image