Zhao-Hui Hou

Photoirradiated Fe-Mediated AGET ATRP of Methyl Methacrylate in the Presence of Alcohol

In this study, photoirradiated Fe-mediated AGET (activators generated by electron transfer) atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was investigated at ambient temperature in N,N-dimethylformamide (DMF) using carbon tetrachloride as initiator, FeCl3·6H2O/bipyridine (Bpy) as catalyst complex, and alcohol as reducing agent. Linear semi-logarithmic plot of conversion vs. time was obtained from the kinetic experiments, and the number-average molecular weight increased linearly with monomer conversion and corresponded to the theoretic values with molecular weight distributions (Mw/Mn) as low as 1.25, which agreed with the character of controlled/living polymerization. The kinds of alcohol played an important role in photoirradiated Fe-mediated AGET ATRP of MMA. The living characteristics were demonstrated through chain extension experiment. The obtained polymer was characterized by proton nuclear magnetic resonance (NMR) and gel permeation chromatography.

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.

Homogeneous Fe-Mediated AGET ATRP of Methyl Methacrylate in PEG-400 in the Presence of Na2CO3

The activator generated by electron transfer (AGET) atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was successfully carried out in poly(ethylene glycol) (PEG-400) with CCl4/FeCl3·6H2O/N,N,N′,N′-tetramethyl-1,2-ethanediamine (TMEDA) as the initiating system in the presence of Na2CO3. The living nature of the polymerization was confirmed by kinetic studies, end-group analysis and chain extension. The molecular weight distribution (MWD) of the polymer obtained was quite narrow (MWD = 1.10–1.40). The effects of ligand and temperature on polymerization were investigated. Based on the slope of the plot of ln (kapp) vs. (1/T), the apparent activation energy (Eapp) of 34.1 kJ mol−1 was calculated. The recovering and recycling of PEG-400 were first investigated. After the polymerization and isolation of PMMA, the mixture containing catalysts and PEG-400 was shown to be recoverable and recyclable without further treatment.

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.

“Nascent” Fe(0)-mediated living radical copolymerization of styrene and acrylonitrile

Abstract In this work, we reported the synthesis of copolymers of poly(styrene-co-acrylonitrile) via single-electron transfer-living radical polymerization using CCl4 as an initiator and Zn(0)/2,2′-bipyridine (Bpy)/FeCl2 as catalyst complexes. The polymerization was carried out at 25°C. The polymerization proceeded in a living fashion based on “nascent” Fe(0) as the source of the transition metal, which was prepared by Zn(0)/FeCl2 in situ. The kinetic experimental results showed that the copolymerization is first-order kinetics. The molecular weights increased linearly with respect to monomer conversion, and narrow polydispersity index values were obtained. The effect of the molar ratio of [Zn(0)]0/[FeCl2]0 on polymerization was investigated. In addition, the polymerization carried out in different solvents was also investigated. The obtained random copolymer was characterized by 1H NMR and gel permeation chromatography. The living characteristic was demonstrated by chain extension experiment.