“All-PVC” Flexible Poly(vinyl Chloride): Nonmigratory Star-Poly(vinyl Chloride) as Plasticizers for PVC by RAFT Polymerization

Xanthate-mediated RAFT polymerization has been used to prepare 3-star and 4-star-poly­(vinyl chloride) (star-PVC) with a number average molar mass (M_n) in the range of 1 to 7 kg mol^–1. The T_g of star-PVC reduces with molar mass and with the number of arms. The star-PVC have substantially lower glass-transition temperatures (T_g) than that of linear PVC of similar M_n, with the T_g of low-molar mass 4-star-PVC being −7.4 °C. The star-PVC are effective in lowering the T_g of blends with commercial PVC when added at 10–30 wt % PVC. When added even at 10 wt %, they are effective in improving the ductility of PVC with an elongation at break (EB) of ∼350% (4-star-PVC) and ∼300% (3-star-PVC) relative to commercial PVC, which is substantially higher than that for PVC conventionally plasticized with 30 wt % dioctyl phthalate under similar conditions (EB ∼160%). Importantly, the star-PVC, despite their low molar mass, do not migrate from the PVC blends when tested under standard conditions. The performance of the star-PVC as non-migratory plasticizers for PVC demonstrates the potential for an “all-PVC” flexible PVC.