Photoinduced ATRP of acrylonitrile with aniline as photoinitiator

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 (M_w/M_n). 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.     

AGET ATRP of acrylonitrile using 1,1,4,7,10,10‐hexamethyltriethylenetetramine as both ligand and reducing agent

Atom transfer radical polymerization using activators generated by electron transfer (AGET ATRP) of acrylonitrile (AN) initiated by ethyl 2‐bromoisobutyrate was approached for the first time using 1,1,4,7,10,10‐hexamethyltriethylenetetramine (HMTETA) and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) as both ligand and reducing agent. AGET ATRP of AN with HMTETA as both ligand and reducing agent was better controlled than with PMDETA as both ligand and reducing agent under the same experimental conditions. With an increase content of HMTETA, the polymerization provided an accelerated reaction rate and a broader polymer molecular weight distribution. The rate of polymerization with DMF as solvent was faster than with acetonitrile, cyclohexanone, toluene, and xylene as solvents. The polymerization apparent activation energy was calculated to be 45.7 kJ mol^?1. The end functionality of polyacrylonitrile (PAN) was confirmed by ¹H NMR spectroscopy. The living feature of PAN was verified by chain extensions of PAN with methyl methacrylate and AN. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 128–133, 2010     

Synthesis of polyacrylonitrile by single‐electron transfer‐living radical polymerization using Fe(0) as catalyst and its adsorption properties after modification

Fe(0) was firstly used as single‐electron transfer‐living radical polymerization catalyst for acrylonitrile polymerization using carbon tetrachloride as initiator, hexamethylenetetramine as N‐ligand, and N,N‐dimethylformamide as the solvent at 65 °C. First‐order kinetic studies indicated that this polymerization proceeded in a “living”/controlled manner. The living nature of the polymerization was also confirmed by chain extension of methyl methacrylate with polyacrylonitrile (PAN) as macroinitiator. Furthermore, PAN was modified with NH₂OH·HCl to generate amidoxime groups for extraction of heavy metal ions (Hg²⁺) from aqueous solutions. Fourier transformed infrared spectroscopy was performed to characterize chemical composition and structure. The adsorption property of Hg²⁺ was investigated at different pH values of aqueous solutions and distilled water. The maximal saturated adsorption capacity of Hg²⁺ was 4.8 mmol g^?1. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Reverse Atom Transfer Radical Polymerization of Acrylonitrile Catalyzed by FeCl3/Lactic Acid

Reverse atom transfer radical polymerization (RATRP) of acrylonitrile (AN) was carried out using azobisisobutyronitrile (AIBN) as initiator, ferric trichloride anhydrous (FeCl₃)/lactic acid (LA) as catalyst system; a ratio of FeCl₃/LA was 1:2 gave the best control. RATRP of AN with N,N-dimethylformamide (DMF) as solvent gave the moderate polymerization rate and the narrowest polydispersity index (PDI). When FeCl₃ was replaced by CuBr₂, RATRP of AN showed a longer induction period. When Cu was added to the CuBr₂-based catalyst system, the induction period was reduced. ¹H-NMR spectra of PAN verified the possibility of controlled/living polymerization for future chain extension.     

β-CYCLODEXTRIN REGULATED STEREOREGULARITY AND MOLECULAR WEIGHT IN INCLUSION POLYMERIZATION OF ACRYLONITRILE

Polyacrylonitrile (PAN) polymers were prepared by inclusion polymerization of the monomer using various molar equivalents of β-cyclodextrin (β-CD). Stereoregular (isotactic, atactic and syndiotactic) distributions of the prepared PAN polymers were determined from terminal model Bernoullian statistics using ¹³C-NMR data. With an increase in acrylonitrile (AN): β-CD ratios, the proportion of isotactic polymers increased. Also, T_g increased along with degradation temperature at higher AN: β-CD ratios. However, molecular weight of the polymers prepared was lower at an AN: β-CD ratio of 10:1, but was found to be larger than the control at an AN: β-CD ratio of 20:1.     

2‐Cyanoprop‐2‐yl dithiobenzoate mediated reversible addition–fragmentation chain transfer polymerization of acrylonitrile targeting a polymer with a higher molecular weight

The reversible addition–fragmentation chain transfer (RAFT) polymerization of acrylonitrile (AN) mediated by 2‐cyanoprop‐2‐yl dithiobenzoate was first applied to synthesize polyacrylonitrile (PAN) with a high molecular weight up to 32,800 and a polydispersity index as low as 1.29. The key to success was ascribed to the optimization of the experimental conditions to increase the fragmentation reaction efficiency of the intermediate radical. In accordance with the atom transfer radical polymerization of AN, ethylene carbonate was also a better solvent candidate for providing higher controlled/living RAFT polymerization behaviors than dimethylformamide and dimethyl sulfoxide. The various experimental parameters, including the temperature, the molar ratio of dithiobenzoate to the initiator, the molar ratio of the monomer to dithiobenzoate, the monomer concentration, and the addition of the comonomer, were varied to improve the control of the molecular weight and polydispersity index. The molecular weights of PANs were validated by gel permeation chromatography along with a universal calibration procedure and intrinsic viscosity measurements. ¹H NMR analysis confirmed the high chain‐end functionality of the resultant polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1272–1281, 2007     

SET‐LRP of acrylonitrile catalyzed by tin powder

Sn(0)‐mediated single electron transfer‐living radical polymerization (SET‐LRP) of acrylonitrile (AN) with carbon tetrachloride (CCl₄) as initiator and hexamethylenetetramine (HMTA) as ligand in N, N‐dimethylformamide (DMF) was studied. The polymerization obeyed first order kinetic. The molecular weight of polyacrylonitrile (PAN) increased linearly with monomer conversion and PAN exhibited narrow molecular weight distributions. Increasing the content of Sn(0) resulted in an increase in the molecular weight and the molecular weight distribution. Effects of ligand and initiator were also investigated. The block copolymer PAN‐b‐polymethyl methacrylate with molecular weight at 126,130 and polydispersity at 1.36 was successfully obtained. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A copper‐based reverse atom‐transfer radical polymerization process for the living radical polymerization of polyacrylonitrile

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). A hexasubstituted ethane thermal iniferter, diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS), was firstly 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 57.4 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. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 226–231, 2006     

Samarium powder as catalyst for SET‐LRP of acrylonitrile in 1,1,1,3,3,3‐hexafluoro‐2‐propanol for control of molecular weight and tacticity

Samarium powder was applied as a catalyst for single electron transfer‐living radical polymerization (SET‐LRP) of acrylonitrile (AN) in 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) with 2‐bromopropionitrile as initiator and N,N,N′,N′‐tetramethylethylenediamine as ligand. First‐order kinetics of polymerization with respect to the monomer concentration, linear increase of the molecular weight with monomer conversion, and the highly syndiotactic polyacrylonitrile (PAN) obtained indicate that the SET‐LRP of AN could simultaneously control molecular weight and tacticity of PAN. An increase in syndiotacticity of PAN obtained in HFIP was observed compared with that obtained by SET‐LRP in N,‐N‐dimethylformamide (DMF). The syndiotacticity markedly increased with the HFIP volume. The syndiotacticity of PAN prepared by SET‐LRP of AN using Sm powder as catalyst in DMF was higher than that prepared with Cu powder as catalyst. The increase in syndiotacticity of PAN with Sm content was more pronounced than the increase in its isotacticity. The block copolymer PAN‐b‐polymethyl methacrylate (52,310 molecular weight and 1.34 polydispersity) was successfully prepared. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Copper(0)‐mediated living radical polymerization of acrylonitrile: SET‐LRP or AGET‐ATRP

Cu(0)‐mediated living radical polymerization was first extended to acrylonitrile (AN) to synthesize polyacrylonitrile with a high molecular weight and a low polydispersity index. This was achieved by using Cu(0)/hexamethylated tris(2‐aminoethyl)amine (Me₆‐TREN) as the catalyst, 2‐bromopropionitrile as the initiator, and dimethyl sulfoxide (DMSO) as the solvent. The reaction was performed under mild reaction conditions at ambient temperature and thus biradical termination reaction was low. The rapid and extensive disproportionation of Cu(I)Br/Me₆‐TREN in DMSO/AN supports a mechanism consistent with a single electron transfer‐living radical polymerization (SET‐LRP) rather than activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). ¹H NMR analysis and chain extension experiment confirm the high chain‐end functionality of the resultant polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of high molecular weight and narrow molecular weight distribution poly(acrylonitrile) via RAFT polymerization

Well‐defined polyacrylonitrile (PAN) of high viscosity‐average molecular weight (M_η = 405,100 g/mol) was successfully synthesized using reversible addition‐fragmentation chain transfer polymerization. The polymerization exhibits controlled characters: molecular weights of the resultant PANs increasing approximately linearly with monomer conversion and keeping narrow molecular weight distributions. The addition of 0.01 equiv (relative to monomer acrylonitrile) of Lewis acid AlCl₃ in the polymerization system afforded the obtained PAN with an improved isotacticity (by 8%). In addition, the influence of molecular weights and molecular weight distributions of PANs on the morphology of the electrospun fibers was investigated. The results showed that, under the same conditions of electrospinning, average diameter (247–1094 nm) of fibers increased with molecular weights of PANs, and it was much easier to get “uniform” diameter fibers while using PANs with narrow molecular weight distributions as the precursor of electrospinning. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

STUDY ON THE POLYMERIZATION OF ACRYLONITRILE INITIATED BY POLYPROPYLENE-BASED VANADYL POLYIMIDODIACETATE——THIOUREA REDOX SYSTEM

The present paper deals with the kinetics of polymerization of acrylonitrile (AN) initialed by the redox system of polypropylene-based vanadyi polyimidodiacetate (PV)-thiourea (TU)in aqueous sulfuric acid in the temperature range from 25 to 40℃. The polymerization rate was measured by varying the concentrations of monomer, vanadyl polyimidodiacetate, thiourea and sulfuric acid. The overall rate of polymerization was summarized asRp=2.2×10~5e~(-6.560/RT) [AN]~(1.0)[PV]~(0.50)[TU]~(1.5)[H_2SO_4]~(2.0)The molecular weight of polyacrylonitrile based on the experimental data was:(?)=k 1/T [pv]~(0.50)[TU]~(1.5)[H_2SO_4]~(2.0)These results indicated that the chain radicals are terminated by combination and/or disproportionation rather than chain transfer. The cooperation effect of carboxylic groups and the macromolecular field effect of polymer supporter are the characters of vanadyl polyimidodiacetate such as the case reported in early paper.     

Indication Ion Square Wave Voltammetric Determination of Thiamine and Ascorbic Acid

Abstract

Cd²⁺ ion was used as an electrochemical indicator to detect V_B1 or Vc using square ware voltammetry (SWV) at a mercury film‐coated glassy carbon (GC) electrode. At pH=10 NH₃‐NH₄Cl buffer, a new cathodic peak was found at ?0.360 V (vs.SCE) by addition of thiamine, and the peak current of SWV was linear with the concentration of thiamine in the range of 1×10^?6 to 4×10^?3 M. On the other hand, the SWV peak current of Cd²⁺ at ?0.856 V linearly decreased with addition of ascorbic acid in the range of 6×10^?6～10^?3 M. The effects of interference, such as citric acid, DL‐malic acid, and calcium panlothenate, on thiamine or ascorbic acid determination were investigated. This method was successfully applied to the determination of thiamine or in pharmaceutical preparation.     

Uranium and lead adsorption onto bentonite and zeolite modified with polyacrylamidoxime

Polyacrylonitrile (PAN) and bentonite (B)/zeolite (Z)-PAN composites were prepared by direct polymerization of acrylonitrile (AN) and AN adsorbed onto B and Z. PAN and the composites were subjected to amidoximation procedure to obtain polyacrylamidoxime (PAO), B-PAO and Z-PAO compositions. The structural features were evaluated by FT-IR, XRD and SEM analysis. The adsorption dependency of the materials on ion concentration, temperature and time were investigated for Pb²⁺ and UO₂ ²⁺. The adsorption capacities of B/Z-PAO composites were higher than those of pure PAO. The values of enthalpy and entropy changes were positive. The kinetics of the adsorption was well defined by the pseudo second order rate model. For the use of 1 M HCl as a regenerative effluent, the composites were reusable for five sequential treatments without any change in their structures whereas PAO completely gelled in the first use.     

KINETICS OF POLYMERIZATION OF ACRYLONITRILE INITIATED BY VANADIUM(V)-THIOUREA REDOX SYSTEM

The kinetics of polymerization of acrylonitrile (AN) initiated by quinquevalent vanadium (V~(5+))-thiourea (TU) redox system has been investigated in aqueous nitric acid in the temperature range from 30 to 50℃. The polymerization rate (R_p) can be expressed as follows: In the copolymerization of acryionitrile with methyl acrylate (MA), the reactivity ratios were found to be 1.0 and 1.1, respectively. The experimental observations suggest that the initiating species is probably a complex consisting of a central ion of Lewis acid-VO_2~+ and the ligands of Lewis bases-acrylonitrile, thiourea, and nitrate anions, while the initiating system in lower concentration, the polymerization of acrylonitrile does not occur if the thiourea is acidified prior to its reaction with quinquevalent vanadium. This indicates that the primary radicals (or the monomeric radicals in the present article) are produced by associated thiourea rather than isothlourea.     

ARGET ATRP of acrylonitrile with ionic liquid as reaction media and 1,1,4,7,7‐pentamethyldiethylenetriamine as both ligand and reducing agent in the presence of air

[C₁₂mim][BF₄], [C₈mim][BF₄], and [C₄mim][BF₄] were first applied as reaction media for atom transfer radical polymerization using activators regenerated by electron transfer (ARGET ATRP) of acrylonitrile (AN) with 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) as both ligand and reducing agent in the presence of air. The rate of polymerization in [C₁₂mim][BF₄] was considerably faster than in [C₈mim][BF₄] and [C₄mim][BF₄]. ARGET ATRP of AN in [C₁₂mim][BF₄] were better controlled than in [C₈mim][BF₄] and [C₄mim][BF₄] under the same experimental conditions. With an increase in the content of PMDETA, the polymerization provided an accelerated reaction rate and a broader polymer molecular weight distribution. A slow polymerization rate and a broad polydispersity index were observed using TMEDA instead of PMDETA as both ligand and reducing agent. There was an obvious induction period with CuCl₂ instead of CuBr₂ as catalyst. Well‐defined PAN‐b‐PMMA with higher molecular weight at 104,560 and relatively broader distribution at 1.35 was successfully prepared with PAN as macroinitiator via ARGET ATRP in [C₁₂mim][BF₄] in the presence of air. The resultant fibers were obtained with the fineness at 1.17dtex and the tenacity at 6.03cN · dtex^?1. Copyright © 2010 John Wiley & Sons, Ltd.     

Isotactic poly(acrylonitrile) via ultraviolet irradiation of acrylonitrile-urea canal complex

Isotactic poly(acrylonitrile) (PAN) has been prepared by means of a conventional ultraviolet (UV) irradiation apparatus without γ-ray sources; an acrylonitrile-urea canal complex was directly formed at the surface of the UV (Hg) emission tube at low temperatures (～ ?78°C). When the complex was UV-irradiated at this temperature, a stereoregular polymer was formed in the canal. The ¹³C-NMR analyses indicate that (1) these PAN are rich in isotactic configuration, (2) the extent of the isotactic triad is in the range of 56?71%, and (3) the penultimate unit effect, 4 (mm) (rr)/(mr)², is linearly correlated with the ultimate unit effect, (mm)/(rr). From the plots of log{4(mm)(rr)/(mr)²} vs log{(mm)/(rr)}, the anomaly in the polymerization of AN is discussed. The molecular characteristics of the UV canal PAN such as molecular weight, etc., were briefly noted. © 1995 John Wiley & Sons, Inc.     

A minimal amount of acrylonitrile turns the nitroxide‐mediated polymerization of methyl methacrylate into an almost ideal controlled/living system

Nitroxide‐mediated controlled/living free‐radical polymerization of methyl methacrylate initiated by the SG1‐based alkoxyamine BlocBuilder was successfully performed in bulk at 80–99 °C with the help of a very small amount of acrylonitrile (AN, 2.2–8.8 mol %) as a comonomer. Well‐defined PMMA‐rich P(MMA‐co‐AN) copolymers were prepared with the number‐average molar mass, M_n, in the 6.1–32 kg mol^?1 range and polydispersity indexes as low as 1.24. Incorporation of AN in the copolymers was demonstrated by ¹H and ¹³C NMR spectroscopy, and its effect on the chain thermal properties was evaluated by DSC and TGA analyses. Investigation of chain‐end functionalization by an alkoxyamine group was performed by means of ³¹P NMR spectroscopy and chain extensions from a P(MMA‐co‐AN)‐SG1 macroinitiator. It demonstrated the very high proportion of SG1‐terminated polymer chains, which opened the door to block copolymer synthesis with a high quality of control. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 34–47, 2010     

Samarium(III)-based AGET ATRP of Acrylonitrile Using Ascorbic Acid as Reducing Agent

Atom transfer radical polymerization using activators generated by electron transfer (AGET ATRP) of acrylonitrile (AN) initiated by ethyl 2-bromoisobutyrate (EBiB) was approached for the first time in the absence of oxygen and in the presence of air, using a novel catalyst system based on SmBr₃·6H₂O/isophthalic acid complexes and using ascorbic acid (VC) as a reducing agent. Both the polymerization in the absence of oxygen and in the presence of air proceeded in a well-controlled manner as evidenced by kinetic studies. Compared with the polymerization in the absence of oxygen, the polymerization in the presence of air provided rather slow reaction rate and showed better control of molecular weight and its distribution under the same experimental conditions. The polymerization apparent activation energies in the absence of oxygen and in the presence of air were calculated to be 47.1 and 51.3 kJ·mol^?1, respectively. A slow polymerization rate and a broad polydispersity index were observed using anisole and toluene instead of DMF as solvent. Polyacrylonitrile obtained was successfully used as a macroinitiator to proceed the chain extension polymerization of styrene via AGET ATRP in the presence of air.     

POLYMERIZATION OF ACRYLONITRILE WITH ORGANOLANTHANIDES AS SINGLE-COMPONENT CATALYSTS

 Ind₂Y(μ-Et)₂AlEt₂ and Ind₂LnN(i-Pr)₂ (Ln = Y, Yb) were used as a single-component catalyst for the polymerization of acrylonitrile (AN) respectively. The regularity of polymerization of AN and stereoregularity of polyacrylonitrile (PAN) were also studied in both cases. Both catalysts can produce PAN with molecular weight from I0,000to 30,000. In addition, the catalytic activity and molecular weights were increased by the addition of PhONa.