Mang Lu

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.

Photo-induced single-electron transfer living radical polymerization (SET-LRP) of MMA in the presence of ZnO

In this study, the photo-induced single-electron transfer living radical polymerization (SET-LRP) of methyl methacrylate (MMA) was successfully performed in N,N-dimethylformamide (DMF) with ethyl α-bromoisobutyrate(EBiB)/Fe(0)/tetramethylethylenediamine(TMEDA)/[ZnO] as the initiating system. ZnO was used as the inorganic photoinitiator. The living nature of the photo-induced SET-LRP of MMA was confirmed by kinetic studies in the presence or absence of air. The plot of ln([M]0/[M]) versus polymerization reaction time was linear, and the molecular weight distribution (MWD) of the resulting PMMA was narrow. The effects of the amounts of Fe(0)/TMEDA, EBiB, ZnO, and light intensity on the photo-induced SET-LRP of MMA were investigated. The conversion increased with increasing the amounts of Fe(0)/TMEDA, EBiB, and ZnO. Increasing the light intensity resulted in a higher polymerization reaction rate. The catalyst and ZnO played important roles in the photo-induced SET-LRP of MMA. The polymerization proceeded in an uncontrollable fashion when the molar ratio of Fe(0)/TMEDA was 0:0.1, and no reaction took placed in the absence of ZnO. In comparison with other SET-LRP of MMA in bulk or conventional solvents, the photo-induced SET-LRP of MMA proceeded periodically when the light was turned on or off under the mild experimental conditions. The polymerization did not take place when the light was turned off. However, the polymerization was very fast when the light was turned on. The chemical structure of resulting PMMA was characterized by 1HNMR. The living characteristics were demonstrated by chain extension experiment.

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.

Photo-induced metal-free ATRP of MMA with 2,7-bi-(N-penothiazinyl)fluorenone as photocatalyst

ABSTRACT In this study, 2,7-bi-(N-penothiazinyl)fluorenone was employed as photocatalyst (PC), ethyl α-bromophenylacetate (EBP) as atom transfer radical polymerization (ATRP) initiator, and photo-induced metal-free ATRP of methyl methacrylate (MMA) was performed at 25°C under blue light irradiation. PMMAs with well-defined architectures and precisely controlled chain lengths were synthsized. The kinetics results confirmed that molecular weights increased linearly with monomer consumption. The molecular weight distributions (Mw/Mn) of the resultant PMMA were narrow. The polymerization was activated and deactivated by periodic light control process. 1H nuclear magnetic resonance spectrometer (NMR) and gel permeation chromatography (GPC) were used to characterize the obtained PMMAs. The living characters of the polymerization system were further confirmed by chain extension of from the PMMA-Br macroinitiator.

Controlling/living polymerization of MMA with RGO/BiVO4 as photoinitiator

ABSTRACT In this study, reduced grapheme oxide (RGO)/BiVO4 composite was prepared and characterized by FT-IR, XRD, and UV spectrum. Photo-chemically-mediated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was successfully performed at 25°C in N,N-dimethylformamide (DMF) with RGO/BiVO4 as photoinitiator, FeCl3·6H2O/triphenylphosphine (PPh3) as catalyst, and ethyl 2-bromoisobutyrate as ATRP initiator. MMAs were polymerized in a controlled manner under ultraviolet (UV) light and sunlight conditions. The results show that a first-order kinetics model was obeyed up to higher conversion. The reaction gave well-controlled PMMA with Mn,GPC close to the theoretical value and a narrow MWD (Mw/Mn<1.5). The experiments of light on and off reveal the photoredox cycle between Fe(III) and Fe(II) species. The living character was further verified by the chain extension experiments.

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.

“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.