STUDIES ON THE BRANCHING ATOM TRANSFER RADICAL POLYMERIZATION USING DIFFERENT DIVINYL MONOMERS AS THE BRANCHING AGENT

The branching atom transfer radical polymerization (ATRP) of styrene has been studied using different divinyl monomers as the branching agent. The divinyl monomers used are triethylene glycol dimethacrylate (tri-EGDMA) with electron-poor double bonds and divinyl benzene (DVB) with electron-rich double bonds. The polymerization kinetics was studied using gas chromatography (GC). The consumption of the pendent double bond was analyzed using proton nuclear magnetic resonance (H-1-NMR). The changes in molecular weight and polydispersity of the resulting copolymers, the development of branching and the formation mechanism of branched copolymers throughout the copolymerization and the characteristics of the resulting copolymers were analyzed using triple detection size exclusion chromatography (TD-SEC). As expected, the conversion of styrene (St) is almost the same in the two reaction systems. However, the conversion of tri-EGDMA is increased much faster than that of DVB at the same conversion of styrene, which is due to the interaction of the donor and the acceptor between St and tri-EGDMA. Since St and tri-EGDMA are typical monomers with electron-rich and electron-poor double bonds, respectively, while St and DVB are both monomers of electron-rich double bonds. The interactions of the donor and the acceptor between St and tri-EGDMA lead to high tri-EGDMA consumption rate, high reactivity of the tri-EGDMA pendent double bond, hence high development rate of the branched chain in the St and tri-EGDMA reaction system, high weight content of the branched chain and high molecular weight of the branched chain at the same styrene conversion. The Zimm branching factors of the branched chains at the same molecular weight from two reaction systems are almost the same, suggesting the branching agents do not affect the branch architecture of the obtained copolymers seriously.