Non-transition metal-catalyzed living radical polymerization of vinyl chloride initiated with iodoform in water at 25°C

Non-transition metal-catalyzed living radical polymerization (LRP) of vinyl chloride (VC) in water at 25-35 degreesC is reported. This polymerization is initiated with iodoform and catalyzed by Na2S2O4. In water, S2O42- dissociates into SO2-. that mediates the initiation and reactivation steps via a single electron transfer (SET) mechanism. The exchange between dormant and active propagating species also includes the degenerative chain transfer to dormant species (DT). In addition, the SO2 released from SO2-. during the SET process can add reversibly to poly(vinyl chloride) (PVC) radicals and provide additional transient dormant similar toSO(2)(.) radicals. This novel LRP proceeds mostly by a combination of competitive SET and DT mechanisms and, therefore, it is called SET-DTLRP. Telechelic PVC with a number-average molecular weight (M-n) = 2,000-55,000, containing two active similar toCH(2)-CHCII chain ends and a higher syndiotacticity than the commercial PVC were obtained by SET-DTLRP. This PVC is free of structural defects and exhibits a higher thermal stability than commercial PVC. SET-DTLRP of VC is carried out under reaction conditions related to those used for its commercial free-radical polymerization. Consequently, SET-DTLRP is of technological interest both as an alternative commercial method for the production of PVC with superior properties as well as for the synthesis of new PVC-based architectures. (C) 2004 Wiley Periodicals, Inc.