En-Xiang Liang

Photo-induced atom transfer radical polymerization in ionic liquid

The photo-induced atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was successfully carried out in ionic liquid at ambient temperature with ethyl 2-bromoisobutyrate as initiator and CuBr2/N,N,N′,N′,N″-pentamethyldiethylenetriamine as the complex catalyst system. In this system, TiO2 was used as photocatalyst. The well-controlled poly(methyl methacrylate) (PMMA) was obtained, as evidenced by the controlled molecular weights of the obtained. The prepared PMMA had narrow molecular weight distributions. The polymerizations were manipulated by turning on/off the light. The chemical structure of the obtained PMMA was characterized by 1H NMR. Chain extension experiment with bromine-atom-ended PMMA as macroinitiator was carried out successfully to verify the living nature of photo-induced ATRP of MMA.

Photoinduced ATRP of acrylonitrile with aniline as photoinitiator

ABSTRACT Photo-mediated atom transfer radical polymerization (ATRP) of acrylonitrile (AN) was carried out at 25°C in N,N-dimethyl formamide (DMF) with aniline as photoinitiator. Polyacrylonitrile (PAN) with predictable average molecular weight and narrow molecular weight distribution was synthesized with 2-Bromopropionitrile (BPN) as ATRP initiator and FeCl3·6H2O/Triphenylphosphine (PPh3) as the catalyst. The obtained kinetics showed that the photoinduced Fe-mediated ATRP of AN provided a route to synthesize well defined PAN with narrow molecular weight distribution (Mw/Mn). The living character of photoinduced Fe-mediated ATRP of AN was verified by the linear increase of molecular weights with monomer conversion and the molecular weights are in good agreement with the theoretic values. In addition, the chain extension experiments were successfully conducted under the same conditions. The periodic light on-off process was investigated for the photoinduced Fe-mediated ATRP of AN. The obtained PAN was characterized by 1H nuclear magnetic resonance and gel permeation chromatography. The brominated PAN was used to perform chain-extension with AN as macroinitiator in order to verify the living nature of photoinduced ATRP of AN-Br.

Perylene as a visible light photoredox catalyst for photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization of MMA

AbstractThe organic photocatalyst, perylene, was used to mediate photoinduced electron transfer (PET) reversible addition-fragmentation chain transfer polymerization (RAFT) of methyl methhacrylate ...

Living radical polymerization of polyacrylamide with submicrometer size by dispersion polymerization

Abstract Atom transfer radical dispersion polymerization of acrylamide was successfully performed in ethyl acetate/ethanol with 2,2-azobisisobutyronitrile/FeCl2/succinic acid as the initiating system. Polyvinylpyrrolidone was used as the stabilizer. The “living” characteristics of the polymerization were studied. A linear relationship of ln([M]0/[M]) vs. polymerization time was obtained. Furthermore, the molecular weight increased with monomer conversion and agreed well with the theoretical values with a narrow molecular weight distribution (<1.5). Size-controlled submicrometer polyacrylamide (PAM) was obtained and characterized by transmission electron microscopy. The chemical structure of the obtained PAM was characterized by 1H NMR. The living characteristics were confirmed by chain extension experiment.