Reverse atom‐transfer radical polymerization of acrylonitrile catalyzed by FeCl3/iminodiacetic acid

FeCl₃ coordinated by iminodiacetic acid (IMA) was Changed used for the first time as the catalyst in azobisisobutyronitrile‐initiated reverse atom‐transfer radical polymerization (ATRP) of acrylonitrile (AN). An FeCl₃ to IMA ratio of 1:2 not only gave the best control of molecular weight and its distribution but also provided a rather rapid reaction rate. The effects of solvents on the polymerization of AN were also investigated. The rate of the polymerization in N,N‐dimethylformamide (DMF) was faster than in propylene carbonate or toluene. The molecular weight of polyacrylonitrile agreed reasonably well with the theoretical molecular weight in DMF. The rate of polymerization increased with increasing polymerization temperature and the apparent activation energy was calculated to be 54.8 kJ mol⁻¹. The reverse ATRP of AN did not show obvious living characteristics with CuCl₂ instead of FeCl₃. Copyright © 2005 Society of Chemical Industry     

ATRP of acrylonitrile catalyzed by FeCl2/succinic acid under microwave irradiation

A single‐pot atom‐transfer radical polymerization (ATRP) under microwave irradiation was first used to successfully synthesize polyacrylonitrile. This was achieved by using FeCl₂/succinic acid as the catalyst and 2‐chloropropionitrile as the initiator. Using the same experimental conditions, the apparent rate constant under microwave irradiation was found to be higher than that under conventional heating. The FeCl₂/succinic acid ratio of 1 : 2 not only gives the best control of molecular weight and its distribution but also provides rather rapid reaction rate. When FeCl₂ was replaced with CuCl, ATRP of AN does not show an obvious living characteristics. To demonstrate the active nature of the polymer chain end, the polymers were used as macroinitiators to proceed the chain‐extension polymerization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1598–1601, 2006     

An iron‐based reverse ATRP process for the living radical polymerization of acrylonitrile

A hexa‐substituted ethane thermal iniferter, diethyl‐2,3‐dicyano‐2,3‐di(p‐tolyl) succinate (DCDTS), was firstly used as the initiator in the reverse atom transfer radical polymerization (RATRP) of acrylonitrile. FeCl₃ coordinated by isophthalic acid (IA) was used as the catalyst in this system. The polymerization in N,N‐dimethylformamide not only shows the best control of molecular weight and its distribution but also provides rather rapid reaction rate with the ratio of [AN] : [DCDTS] : [FeCl₃] : [IA] at 500 : 1 : 2 : 4. The polymers obtained were end‐functionalized by chlorine atom, and they were used as macroinitiators to proceed the chain extension polymerization in the presence of FeCl₂/IA catalyst system via a conventional ATRP process and polyacrylonitrile obtained was with M_n = 39,260, PDI = 1.25. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Atom transfer radical polymerization of acrylonitrile

Iron(II) chloride coordinated by succinic acid was first used as the catalyst in 2‐chloropropionitrile‐initiated atom transfer radical polymerization (ATRP) of acrylonitrile. N,N‐dimethylformamide was used as a solvent to improve the solubility of the ligand. An iron(II) chloride to succinic acid ratio of 0.5 not only gives the best control of molecular weight and its distribution but also provides rather rapid reaction rate. Effects of solvent on polymerization of acrylonitrile were also investigated. The induction period is shorter in N,N‐dimethylformamide than in propylene carbonate and toluene and the rate of the polymerization in N,N‐dimethylformamide is fastest. The molecular weight of polyacrylonitrile agrees reasonably well with the theoretical molecular weight of N,N‐dimethylformamide. The rate of polymerization increases and the induction period becomes shorter with increasing polymerization temperature, and the apparent activation energy was calculated to be 56.5 kJ mol^?1. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1050–1054, 2006     

Reverse ATRP of acrylonitrile with diethyl 2,3-dicyano-2,3-diphenyl succinate/FeCl3/iminodiacetic acid

The reverse atom transfer radical polymerization (RATRP) technique using FeCl₃/iminodiacetic acid (IMA) complex as a catalyst was applied to the living radical polymerization of acrylonitrile (AN). A hexa-substituted ethane thermal initiator, diethyl 2,3-dicyano-2,3-diphenylsuccinate (DCDPS), was firstly used as the initiator in this iron-based RATRP system. The polymerization in N,N-dimethylformamide not only shows the best control of molecular weight and its distribution but also provides rather rapid reaction rate with the ratio of [AN]:[DCDPS]:[FeCl₃]:[IMA] at 500:1:2:4. The rate of polymerization increases with increasing the polymerization temperature and the apparent activation energy was calculated to be 49.9 kJ mol⁻¹. The polymers obtained were end-functionalized by chlorine atom, and they were used as macroinitiators to proceed the chain extension polymerization in the presence of FeCl₂/IMA catalyst system via a conventional ATRP process. The resultant polyacrylonitrile fibers were obtained with the fineness at 1.16 dtex and the tenacity at 6.01cN dtex⁻¹.     

Synthesis of polyacrylonitrile via reverse atom transfer radial polymerization (ATRP) initiated by diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate,FeCl3, and triphenylphosphine

The reverse atom transfer radical polymerization (RATRP) technique using FeCl₃/triphenyl‐phosphine (PPh₃) complex as a catalyst was applied to the living radical polymerization of acrylonitrile (AN). A hexa‐substituted ethane thermal iniferter, diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS), was first used as the initiator in this iron‐based RATRP initiation system. A FeCl₃ to PPh₃ ratio of 1:3 not only gives the best control of molecular weight and its distribution but also provides a rather rapid reaction rate. The rate of polymerization increases with increasing the polymerization temperature and the apparent activation energy was calculated to be 54.9 kJ mol^?1. Because the polymers obtained were end‐functionalized by chlorine atoms, they were used as macro‐initiators to proceed the chain extension polymerization in the presence of an FeCl₂/PPh₃ catalyst system via a conventional ATRP process. Copyright © 2005 Society of Chemical Industry     

Reverse atom transfer radical polymerization of acrylonitrile under microwave irradiation

Reverse atom transfer radical polymerization was first used to successfully synthesize polyacrylonitrile under microwave irradiation. FeCl₃, coordinated by isophthalic acid, was used as the catalyst, and 2,2′‐azobisisoheptonitrilewas used as the initiator. N,N‐Dimethylformamide was used as the solvent to improve the solubility of the ligand. Under the same experimental conditions, the apparent rate constant under microwave irradiation was higher than that under conventional heating. The polymerization not only showed the best control of the molecular weight and its distribution but also provided a rather rapid reaction rate with the [acrylonitrile]/[2,2′‐azobisisoheptonitrile]/[FeCl₃]/[isophthalic acid] ratio of 300 : 1 : 1 : 2. The polymers obtained were used as macroinitiators to initiate the chain extension and successfully synthesize acrylonitrile polymers with a molecular weight higher than 50,000 and a narrow polydispersity as low as 1.30. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Fe‐mediated ICAR ATRP of styrene and acrylonitrile in polyethylene glycol

In this contribution, random copolymers of p(styrene‐co‐acrylonitrile) via initiators for continuous activator regeneration (ICAR) in atom transfer radical polymerization (ATRP) (ICAR ATRP) of styrene and acrylonitrile (SAN) were synthesized at 90°C in low molecular weight polyethylene glycol (PEG‐400) using CCl₄ as initiator, FeCl₃·6H₂O as catalyst, succinic acid as ligand and thermal radical initiator azobisisobutyronitrile (AIBN) as thermal free radical initiator. In this system, well‐defined copolymer of SAN was achieved. The kinetics results showed that the copolymerization rate obeyed first‐order kinetics model with respect to the monomer concentration, and a linear increase of the molecular weights with the increasing of monomer conversion with narrow molecular weight distribution was observed in the range of 1.1–1.5. The conversion decreased with increasing the amount of FeCl₃·6H₂O and increased with increasing the molar ratio of [St]₀/[AN]₀/[CCl₄]₀ and temperature. AIBN has a profound effect on the polymerization. The activation energy was 55.67 kJ mol^?1. The living character of copolymerization was confirmed by chain extension experiment. The resultant random copolymer was characterized by ¹H‐NMR and GPC. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40135.     

ICAR ATRP of methyl methacrylate catalyzed by FeCl3·6H2O/succinic acid

In this work, methyl methacrylate (MMA) was polymerized by initiator for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) method to obtain low molecular weight living polymers. The ATRP initiator was ethyl 2‐bromoisobutyrate, the catalyst ligand complex system was FeCl₃·6H₂O/succinic acid, and the conventional radical initiator 2,2′‐azobisisobutyronitrile was used as a thermal radical initiator. Polymers with controlled molecular weight were obtained with ppm level of Fe catalyst complex at 90°C in N,N‐dimethylformamide. The polymer was characterized by nuclear magnetic resonance (NMR). The molecular weight and molecular weight distribution of the obtained poly (methyl methacrylate) were measured by gel permeation chromatography method. The kinetics results indicated that ICAR ATRP of MMA was a “living”/controlled polymerization, corresponding to a linear increase of molecular weights with the increasing of monomer conversion and a relatively narrow polydispersities index. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of DMF on the polymerization of tert‐butyl acrylate initiated by 4‐oxo‐TEMPO‐capped polystyrene macroinitiator

BACKGROUND: In a number of studies it has been shown that 2,2,6,6‐tetramethylpiperidinooxy (TEMPO)‐mediated polymerization of acrylates is not facile. Therefore, the object of the study reported here was to prepare poly[styrene‐block‐(tert‐butyl acrylate)] (PS‐b‐PtBA) block copolymers using 4‐oxo‐TEMPO‐capped polystyrene macroinitiator as an initiator, in the presence of small amounts of N,N‐dimethylformamide (DMF). The kinetic analysis and the effect of DMF on the reaction mechanism are also discussed. RESULTS: PS‐b‐PtBA block copolymer was prepared through polymerization of tert‐butyl acrylate (tBA) initiated by 4‐oxo‐TEMPO‐capped polystyrene macroinitiator at 135 °C. The polymerization rate of tBA could be increased by adding a small amount of DMF, and the number average molecular weight of the PtBA block in PS‐b‐PtBA reached 10 000 g mol^?1 with narrow polydispersity. The activation rate constant k_act?tBA of alkoxyamine increased and the recombination rate constant k_rec?tBA decreased with increasing DMF concentration. CONCLUSION: DMF was shown to be a rate‐enhancing additive for the polymerization of tBA using a 4‐oxo‐TEMPO‐capped polystyrene macroinitiator. From the kinetic analysis, it was concluded that the improvement of polymerization with the addition of DMF was due to an increase in k_act?tBA and a decrease in k_rec?tBA. Copyright © 2008 Society of Chemical Industry     

Kinetic study of the atom transfer radical polymerization of n‐docosyl acrylate

The atom transfer radical polymerization (ATRP) of n‐docosyl acrylate (DA) was studied at 80°C in N,N‐dimethylformamide using the carbon tetrabromide/FeCl₃/2,2′‐bipyridine (bpy) initiator system in the presence of 2,2′‐azobisisobutyronitrile (AIBN) as the source of reducing agent. The rate of polymerization exhibits first‐order kinetics with respect to the monomer. The linear relationship between the molecular weight of the resulting poly(n‐docosyl acrylate) with conversion and the narrow polydispersity of the polymers indicates the living characteristics of the polymerization reaction. The significant effect of AIBN on the ATRP of DA was studied keeping [FeCl₃]/[bpy] constant. A probable reaction mechanism for the polymerization system is postulated to explain the observed results. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2147–2154, 2005     

Synthesis of polyacrylonitrile via reverse atom transfer radical polymerization initiated by 1,1,2,2‐tetraphenyl‐1,2‐ethanediol/FeCl3/triphenylphosphine

FeCl₃ coordinated by triphenylphosphine was first used as the catalyst in the 1,1,2,2‐tetraphenyl‐1,2‐ethanediol‐initiated reverse atom transfer radical polymerization of acrylonitrile. A FeCl₃/triphenylphosphine ratio of 0.5 not only gave the best control of the molecular weight and its distribution but also provided a rather rapid reaction rate. The rate of polymerization increased with increasing polymerization temperature, and the apparent activation energy was calculated to be 62.4 kJ/mol. When FeCl₃ was replaced with CuCl₂, the reverse atom transfer radical polymerization of acrylonitrile did not show prominent living characteristics. To demonstrate the active nature of the polymer chain end, the polymers were used as macroinitiators to advance the chain‐extension polymerization in the presence of a CuCl/2,2′‐bipyridine catalyst system via a conventional atom transfer radical polymerization process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4041–4045, 2007     

High‐molecular‐weight polyacrylonitrile by atom transfer radical polymerization

A single‐pot atom transfer radical polymerization was used for the first time to successfully synthesize polyacrylonitrile with a molecular weight higher than 80,000 and a narrow polydispersity as low as 1.18. This was achieved with CuBr/isophthalic acid as the catalyst, 2‐bromopropionitrile as the initiator, and N,N‐dimethylformamide as the solvent. The effects of the solvent on the polymerization of acrylonitrile were also investigated. The induction period was shorter in N,N‐dimethylformamide than in propylene carbonate and toluene, and the rate of the polymerization in N,N‐dimethylformamide was fastest. The molecular weight of polyacrylonitrile agreed reasonably well with the theoretical molecular weight in N,N‐dimethylformamide. When chlorine was used in either the initiator or the catalyst, the rate of polymerization showed a trend of decreasing, and the molecular weight deviated from the theoretical predication significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3372–3376, 2006     

Organic–inorganic composite materials as photoinitiator for controlling/living polymerization

Titanium dioxide (TiO₂)/graphitic carbon nitride (g‐C₃N₄) composites were first used as photoinitiator for photochemically mediated controlled/living polymerization of methyl methacrylate. The polymerization was successfully carried out in polyethylene glycol at room temperature with FeCl₃·6H₂O/N,N,N ′,N ′,N ″‐pentamethyldiethylenetriamine as complex catalyst and ethyl 2‐bromoisobutyrate as initiator in this case. A pseudo‐first‐order dependence of the monomer concentration on the polymerization time was observed. TiO₂/g‐C₃N₄ was verified to be an efficient photoinitiator. The polymerization was controlled to produce poly(methyl methacrylate) with narrow molecular weight distribution and controlled number average molecular weight (M_n,GPC). The M_n,GPC matched well with the theoretical values when using both UV and sunlight irradiation as light source. The effects of reaction conditions on the polymerization were investigated. The polymerization could be started and stopped through periodically switching on/off the light. The living nature was further supported by the chain extension experiments. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42891.     

Effect of reaction medium on radical copolymerization of acrylonitrile with vinyl acids

Radical polymerization of acrylonitrile (AN) with methacrylic acid (MAA) and itaconic acid (IA) was carried out in a mixture of dimethylformamide (DMF) and water at 70°C using α, α′‐azobisisobutyronitrile (AIBN) as an initiator. Monomer feed in the polymerization vessel was 98:2 (AN:MAA/IA) in the molar ratio, and the DMF:H₂O ratio was varied between 20:80 and 80:20 (w/w). Copolymers were characterized by FTIR, carbon, hydrogen, nitrogen elemental CHN analysis, ¹H‐ and ¹³C‐NMR, and viscometry. The rate of polymerization (R_p) was found to decrease with an increase in DMF concentration in the reaction medium, that is, in 20% DMF for AN–MAA system, the R_p is 1.23% min⁻¹ in 1 h of polymerization, while in 80% DMF, R_p is reduced to 0.37% min⁻¹. The nature of the vinyl acid also affects the R_p. It has been shown that the rate of polymerization is higher for an AN–MAA system as compared to an AN–IA system (R_p = 1.0% min⁻¹) and the methacrylic or itaconic acid content in the copolymer increases with an increase in the DMF concentration. The MAA content in the poly(AN–MAA) polymer produced in 20% DMF is 3.2 mol %, which increases to 6.1 mol % (calculated through FTIR spectra) when DMF is increased to 80% in the reaction medium. The intrinsic viscosity [η] of the poly(AN–IA) and poly(AN–MAA) copolymers in DMF was found to be in the range of 0.67–2.90 dLg⁻¹ depending on the reaction medium. In determining the intrinsic viscosity, a definite deviation from rectilinearity of the concentration dependence in the high‐dilution region is observed, thereby demonstrating the polyelectrolyte behavior of these polymers. Through FTIR and NMR spectral studies, PAN homopolymer and other copolymers have shown the formation of a small quantity of acrylamide units. In addition copolymer P₁₀, which contains 10.1 mol % IA, has shown anhydride formation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1640–1652, 2001     

Synthesis of poly(octadecyl acrylate‐b‐styrene‐b‐octadecyl acrylate) triblock copolymer by atom transfer radical polymerization

The synthesis of triblock copolymer poly(octadecyl acrylate‐b‐styrene‐b‐octadecyl acrylate), using atom transfer radical polymerization (ATRP), is reported. The copolymers were prepared in two steps. First, polystyrene was synthesized by ATRP using α,α′‐dichloro‐p‐xylene/CuBr/bpy as the initiating system; Second, polystyrene was further used as macroinitiator for the ATRP of octadecyl acrylate to prepare ABA triblock copolymers in the presence of FeCl₂·4H₂O/PPh₃ in toluene. Polymers with controlled molecular weight (M_n = 17,000–23,400) and low polydispersity index value (1.33–1.44) were obtained. The relationship between molecular weight versus conversion showed a straight line. The effect of reaction temperature on polymerization was also investigated, showing a faster polymerization rate under higher temperature. The copolymers were characterized by FTIR, ¹H‐NMR, DSC, and GPC and the crystallization behavior of the copolymers was also studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1539–1545, 2004     

Photo‐Induced atom transfer radical polymerization with nanosized α‐Fe2O3 as photoinitiator

Photo‐induced atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was achieved in poly(ethylene glycol)‐400 with nanosized α‐Fe₂O₃ as photoinitiator. Well‐defined poly(methyl methacrylate) (PMMA) was synthesized in conjunction with ethyl 2‐bromoisobutyrate (EBiB) as ATRP initiator and FeCl₃·6H₂O/Triphenylphosphine (PPh₃) as complex catalyst. The photo‐induced polymerization of MMA proceeded in a controlled/living fashion. The polymerization followed first‐order kinetics. The obtained PMMA had moderately controlled number‐average molecular weights in accordance with the theoretical number‐average molecular weights, as well as narrow molecular weight distributions (M_w/M_n). In addition, the polymerization could be well controlled by periodic light‐on–off processes. The resulting PMMA was characterized by ¹H nuclear magnetic resonance and gel permeation chromatography. The brominated PMMA was used further as macroinitiator in the chain‐extension with MMA to verify the living nature of photo‐induced ATRP of MMA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42389.     

Synthesis of polyacrylonitrile via reverse ATRP initiated by 1,1,2,2‐tetraphenyl‐1,2‐ethanediol/CuCl2/2,2′‐bipyridine

The reverse atom‐transfer radical polymerization (RATRP) technique using CuCl₂/2,2′‐bipyridine (bipy) complex as a catalyst was applied to the living‐radical polymerization of acrylonitrile (AN). 1,1,2,2‐Tetraphenyl‐1,2‐ethanediol (TPED) was first used as the initiator in this copper‐based RATRP initiation system. A CuCl₂ to bipy ratio of 0.5 not only gives the best control of molecular weight and its distribution, but also provides rather rapid reaction rate. The rate of polymerization increases with increasing the polymerization temperature, and the apparent activation energy was calculated to be 53.2 kJ mol^?1. Because the polymers obtained were end‐functionalized by chlorine atoms, they were used as macroinitiators to proceed the chain extension polymerization in the presence of CuCl/bipy catalyst system via a conventional ATRP process. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3529–3533, 2007     

‘Living’ radical polymerization of styrene with AIBN/FeCl3/PPh3 initiating system via a reverse atom transfer radical polymerization process

Well‐defined polystyrenes with an α‐C(CH₃)₂(CN) and an ω‐chlorine atom end‐groups, and narrow polydispersity (M_n = 3000–4000 g mol⁻¹, M_w/M_n = 1.3–1.4) have been synthesized by a radical polymerization process using 2,2′‐azobisisobutyronitrile(AIBN)/FeCl₃/PPh₃ initiation system. When the ratio of [St]₀:[AIBN]₀:[FeCl₃]₀:[PPh₃]₀ is 200:1:4:12 at 110 °C, the radical polymerization is ‘living’, but the molecular weight of the polymers is not well‐controlled. The polymerization mechanism belongs to a reverse atom transfer radical polymerization (ATRP). Because the polymer obtained is end‐functionalized by a chlorine atom, it can then be used as a macroinitiator to perform a chain extension polymerization in the presence of CuCl/2,2′‐bipyridine catalyst system via a conventional ATRP process. The presence of a chlorine atom as an end‐group was determined by ¹H NMR spectroscopy. © 2000 Society of Chemical Industry