No abstract

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

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

Polyacrylonitrile (PAN) was grafted from surfaces of chloro‐modified silica‐gel with their surface chlorines as initiation sites, using an iron (III)‐mediated surface‐initiated atom transfer radical polymerization (ATRP) with activators regenerated by electron transfer (SI‐ARGET ATRP) method. The graft reaction exhibits first‐order kinetics with respect to the polymerization time in the low‐monomer‐conversion stage. The conversion of monomer (C%) and the percentage of grafting (PG%) increased with increasing of the polymerizing time and reached 23 and 730% after a polymerizing time of 24 hr, respectively. Hydroxylamine (NH2OH·HCl) was used to modify the cyano groups of SG‐g‐PAN to obtain amidoxime (AO) groups. The AO SG‐g‐PAN was used to remove Hg2+. The adsorption kinetics indicated that the pseudo‐second‐order model was more suitable to describe the adsorption kinetics of AO SG‐g‐PAN for Hg2+. The adsorption isotherms demonstrated that Langmuir model was much better than Freundlich model to describe the isothermal process. Copyright © 2010 John Wiley & Sons, Ltd.

Crosslinked polyacrylonitrile (PAN) was synthesized with divinylbenzene as the crosslinker with an iron(III)-mediated atom transfer radical polymerization method with activators regenerated by electron transfer. The polymerization exhibited first-order kinetics with respect to the polymerization time. Hydroxylamine hydrochloride (NH 2 OHÁHCl) was used to modify the cyano groups of the crosslinked PAN to obtain amidoxime (AO) groups. The AO-crosslinked PAN was used to remove Hg(II). The optimum pH, adsorption kinetics, and adsorption isotherms were investigated.