Factors influencing the C?ON bond strength of the alkoxyamines in the styrene–acrylonitrile–TEMPO copolymerization system

Homolytic bond dissociation energy (BDE) of the (C? ON) bond for several N‐alkoxyamines derived from 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and the corresponding (C? H) bonds were determined from quantum‐mechanical calculations including the B3‐LYP6‐31G(d), B3‐LYP/6‐311++G(2df,p), UB3‐LYP/6‐311+G(3df,2p), and integrated IMOMO (G3:ROMP2/6‐31G(d)) method. The investigated N‐alkoxyamines were considered as models for dormant forms of propagating chains in the radical copolymerization process of styrene with acrylonitrile in the presence of TEMPO according to the terminal and penultimate model. The substituent effect on BDE was investigated. Radical stabilization energies (RSE) for radicals created from homolysis of the investigated N‐alkoxyamines were calculated according to Rüchardt's method. Polar, steric, and stabilization effects on C? ON alkoxyamine bond homolysis were studied. A dramatically weakened C? ON bond in the alkoxyamine‐containing two consecutive styrene units in the propagating chain was ascribed to geometric parameters characterizing energetically unfavorable conformation of the substituents. These phenomena can be regarded as the penultimate effect in the radical living/controlled copolymerization system of styrene with acrylonitrile. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1165–1177, 2008     

Professor Takeo Saegusa is Awarded Mark Medal

Abstract

Probability theory has been used to derive equations for the terminal model for free radical terpolymerization, showing how the polymer composition and triad fractions are related to the reactivity ratios and monomer composition. These relationships have been used to analyze the monomer-polymer composition data for the acrylonitrile-styrene-2,4,6-tri-bromophenyl acrylate system using a nonlinear least-squares method. The “best values” of the reactivity ratios which describe the polymerization have been used to calculate the triad fractions for each monomer.     

Carbonization of electrospun poly(acrylonitrile) nanofibers containing multiwalled carbon nanotubes observed by transmission electron microscope with in situ heating

Composite nanofibers with 5% w/w multiwalled carbon nanotubes (MWCNTs) in polyacrylonitrile (PAN) were fabricated using the electrospinning technique. Morphological development during the carbonization process was characterized by transmission electron microscopy (TEM) with in situ heating. It was found that the orientation of graphitic layers increases with temperature and does not change significantly with time during our TEM measurement, except the 750 °C. In the heating stage at 750 °C noticeable enhancement of orientation with time was observed. The presence of embedded CNTs enhances the order of the formed graphitic structures even when the CNTs are irregular or entangled. The results indicate that embedded MWCNTs in the PAN nanofibers nucleate the growth of carbon crystals during PAN carbonization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Synthesis of well‐defined copolymer of acrylonitrile and maleic anhydride via RAFT polymerization

Well‐defined copolymer of acrylonitrile (AN) and maleic anhydride (MAn) has been successfully synthesized via reversible addition‐fragmentation chain transfer polymerization. The polymerization kinetics and “living”/controlled features were thoroughly studied and confirmed. The thermal properties and spinnability of the prepared copolymers were investigated via differential scanning calorimetry, thermogravimetric analyzer, and electrospinning subsequently. When PAN‐co‐PMAn was used as precursors, nonwoven with “crosslinked” structures was obtained during electrospinning. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5263–5269     

Living radical polymerization of acrylonitrile catalyzed by copper with a high concentration of radical initiator and its application in removal of Ag(I) after modification

In this study, we reported the synthesis of polyacrylonitrile (PAN) via living radical polymerization in N, N‐dimethylformamide using carbon tetrachloride as initiator, copper(II) chloride (CuCl₂)/hexamethylenetetramine as catalyst system, and 2,2‐azobisisobutyronitrile as a high concentration of thermal radical initiator. The polymerization proceeded in controlled/living manner as indicated by first‐order kinetics of the polymerization with respect to the monomer concentration, linear increase of the molecular weight with monomer conversion and narrow polydispersity. Higher polymerization rate and narrower molecular weight distributions were observed with CuCl₂ less than 50 ppm. The rate of polymerization showed a trend of increase along with temperature. The modified PAN containing amidoxime group was used for extraction of Ag(I) ions from aqueous solutions. The adsorption kinetics data indicated that the adsorption process followed pseudo‐second‐order rate model. The isotherm adsorption process could be described by the Freundlich isotherm model. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Novel acrylonitrile-based copolymers containing phospholipid moieties: synthesis and characterization

Novel acrylonitrile-based copolymers containing phospholipid moieties were synthesized by a three-step process, which included the copolymerization of acrylonitrile and 2-hydroxyethyl methacrylate (HEMA) in water and the reaction of the resulting poly[acrylonitrile-co-(2-hydroxyethyl methacrylate)]s (PANCHEMA) with 2-chloro-2-oxo-1,3,2-dioxaphospholane (COP) followed by the ring-opening reaction of COP with trimethylamine. The chemical structure of PANCHEMA and the phospholipid-containing acrylonitrile-based copolymers (PLCANCP) was analyzed with FT-IR spectroscopy, (1)H and (31)P NMR, and XPS. Surface properties of the studied copolymers were evaluated by the pure water contact angle, protein adsorption and platelets adhesion measurements. The water contact angle measured by sessile drop method decreased for the polymers in the following sequence: PAN, PANCHEMA, and PLCANCP. The adsorption amount of bovine serum albumin and the adhesive number of platelet followed the same decline sequence. These results demonstrate that the biocompatibility of the acrylonitrile-based copolymer membranes could be improved efficiently by the introduction of phospholipid moieties.     

The formation of acrylonitrile over solid base catalysts

The reaction of methanol and acetonitrile to form acrylonitrile has been studied over solid base catalysts derived from MgO. High surface area MgO produced the best yields of acrylonitrile and propionitrile, but higher specific activity was achieved by impregnating the MgO support with chromium oxide. This revised version was published online in June 2006 with corrections to the Cover Date.     

Preparation and performance analysis of PE-supported P(AN-co-MMA) gel polymer electrolyte for lithium ion battery application

Copolymer, poly(acrylonitrile-co-methyl methacrylate) (P(AN-co-MMA)), was synthesized by solution polymerization with different mole ratios of monomers, acrylonitrile (AN) and methyl methacrylate (MMA). Polyethylene (PE) supported copolymer and gel polymer electrolyte (GPE) were prepared with this copolymer and their performances were characterized with FTIR, TGA, SEM, and electrochemical methods. It is found that the GPE using the PE-supported copolymer with AN to MMA = 4:1 (mole) exhibits an ionic conductivity of 2.06 × 10⁻³ S cm⁻¹ at room temperature. The copolymer is stable up to 270 °C. The PE-supported copolymer shows a cross-linked porous structure and has 150 wt% of electrolyte uptake. The GPE is compatible with anode and cathode of lithium ion battery at high voltage and its electrochemical window is 5.5 V (vs. Li/Li⁺). With the application of the PE-supported GPE in lithium ion battery, the battery shows its good rate and initial discharge capacity and cyclic stability.     

Cu－Cr_2O_3催化合成丙烯酰胺中铬的助催化作用

Ｃｕ－Ｃｒ_２Ｏ_３催化合成丙烯酰胺中铬的助催化作用李晶明，杨博，周贵林，谢筱帆，李圭甲（中国科学院长春应用化学研究所长春１３００２２）关键词Ｃｕ－Ｃｒ＿２Ｏ＿３催化剂，丙烯腈，丙烯酰胺，催化水合，反应机理在还原铜催化剂中加铬可提高丙烯腈（ＡＮ）催化水...