Graft copolymerization of methyl methacrylate onto sago starch using ceric ammonium nitrate and potassium persulfate as redox initiator systems

The graft copolymerization of methyl methacrylate (MMA) onto sago starch was carried out in aqueous media by different initiators of ceric ammonium nitrate (CAN) and potassium persulfate (PPS) and under a nitrogen gas atmosphere. Using CAN as an initiator, the maximum percentage of grafting (%G) was ascertained to be 246% at the following optimum conditions: a 70°C reaction temperature, a 2‐h reaction period, 2.0 mmol of CAN, 0.4 mmol of nitric acid, and 141 mmol of MMA. The maximum %G achieved with PPS as the initiator was 90%. The optimum conditions were a 50°C reaction temperature, a 1.5‐h reaction period, 47 mmol of monomer, and 1.82 mmol of PPS. The grafting of MMA onto sago starch was confirmed by the IR spectra of pure sago starch, MMA, and MMA grafted sago starch. This material may have application as a biodegradable plastic. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1375–1381, 2001     

Graft copolymerization of acrylamide–methylacrylate comonomers onto cellulose using ceric ammonium nitrate

The graft copolymerization of acrylamide–methylacrylate comonomers was carried out using ceric ammonium nitrate as initiator in the presence of nitric acid at 25 ± 1°C. The effects of feed molarity, feed composition, reaction time, and temperature on graft yield (%G) and other grafting parameters were investigated. The determination of rate of ceric (IV) ions disappearance as a function of feed molarity and reaction time was useful in the determination of the rate of ceric (IV) ions consumption during graft copolymerization. The graft yield (%G) in the presence of acrylamide increases because of the synergistic effect of acrylamide comonomer. The composition of the grafted chains (F_AAm) varies on varying the feed composition and reaction temperature but is almost constant during feed molarity variation. The Mayo and Lewis method was used to determine the reactivity ratios of acrylamide (r₁) and methylacrylate (r₂), which are 0.65 and 1.07, respectively. The product of reactivity ratio (r₁ r₂) is less then unity; hence, an alternate arrangement of comonomer blocks in the grafted copolymer chain is proposed. The rate of graft copolymerization of comonomers onto cellulose is second power to the concentration of comonomers and square root to the concentration of ceric ammonium nitrate. Suitable reaction steps for graft copolymerization of comonomers onto cellulose are proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2631–2642, 2002     

Graft copolymerization of 4‐vinyl pyridine onto konjac glucomannan initiated by ammonium persulfate

The grafting of 4‐vinyl pyridine (4‐VP) onto konjac glucomannan (KGM) by ammonium persulfate (APS) as the initiator was studied in an acid aqueous solution under an inert atmosphere. The grafting ratio (G%) and grafting efficiency (E%) were evaluated comparatively. The dependence of these parameters on the initiator concentration, sulfuric acid concentration, ratio of monomer to KGM, temperature, and reaction time was also investigated. Under conditions of [KGM] = 1.00 g/L, [APS] = 1.00 × 10^?2 mol/L, [4‐VP] = 9.32 × 10^?2 mol/L, [H⁺] = 5.00 × 10^?2 mol/L, temperature = 35°C, and time = 120 min, the optimum G% and E% were 307.27 and 52.75%, respectively. The proof of grafting was obtained from thermogravimetric analysis and infrared spectra. Preliminary research of the graft's adsorption capacity for heavy‐metal ions [Cr(VI), Cu(II), Pb(II), and Cd(II)] was done. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Graft copolymerization of water‐soluble monomers containing quaternary ammonium group on poly(vinyl alcohol) using ceric ions

Graft copolymerization of water‐soluble monomers containing quaternary ammonium onto PVA was studied in an aqueous medium using ceric ammonium nitrate‐nitric acid as the redox initiator. To optimize the reaction conditions for obtaining a maximum percent of grafting, the concentrations of methacryloxyethyl trimethylammonium chloride (DMC) monomer, ceric ammonium nitrate, and temperature were varied, and the effects on the grafting copolymerization were discussed. Under optimum conditions, a series of water‐soluble monomers containing quaternary ammonium, such as methacryloxyethyl trimethylammonium chloride (DMC), DMAEMA^˙C₂H₅Br, DMAEMA^˙C₄H₉Br, DMAEMA^˙C₁₆H₃₃Br, and DMAEMA^˙C₇H₇Cl, were successfully grafted onto PVA. The resulting grafted PVA were characterized with IR, NMR, and viscosity measurements. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2186–2191, 2005     

Graft copolymerization of methyl acrylate onto sago starch using ceric ammonium nitrate as an initiator

The graft copolymerization of methyl acrylate onto sago starch was carried out by a free radical initiating process. The free radicals were produced by the chemical initiation method in which ceric ammonium nitrate was used as an initiator. It was found that the percentages of grafting, grafting efficiency, and rate of grafting were all dependent on the concentration of ceric ammonium nitrate (CAN), methyl acrylate (MA), sago starch (AGU), mineral acid (H₂SO₄), and reaction temperature and period. The variables affecting the graft copolymerization were thoroughly examined. The optimum yield of grafting was obtained when the concentration of CAN, MA, AGU, and H₂SO₄ were used at 8.77 × 10⁻³, 0.803, 0.135, and 0.175 mol L⁻¹, respectively. The optimum reaction temperature and period were 50°C and 60 min, respectively. The rate of graft polymerization was explored on the basis of experimental results and reaction mechanism. The evidence of grafted copolymers was investigated by using FTIR spectroscopy, TG, and DSC analysis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 516–523, 2000     

Graft copolymerization of acrylamide onto cellulose in presence of comonomer using ceric ammonium nitrate as initiator

The graft copolymerization of acrylamide (AAm) and ethylmethacrylate (EMA) monomers onto cellulose has been carried out using ceric ammonium nitrate (CAN) as initiator in presence of nitric acid at (25 ± 1)°C and varying feed molarity from 7.5 × 10^?2 mol dm^?3 to 60.0 × 10^?2 mol dm^?3 at fixed feed composition (f_AAm = 0.6). The graft yield (%G_Y) has shown a linear increasing trend upto a feed molarity of 37.5 × 10^?2 mol dm^?3. The composition of grafted copolymer chains was found to be constant (F_AAm = 0.56) during feed molarity variation but shown variations with feed composition (f_AAm) and reaction temperature. The grafting parameters have shown increasing trends up to 7.5 × 10^?3 mol dm^?3 concentration of ceric (IV) ions and decreased on further increasing the concentration of ceric (IV) ions beyond 7.5 × 10^?3 mol dm^?3. The IR and elemental analysis data were used to determine the composition of grafted chains (F_AAm) and reactivity ratio of acrylamide (r₁) and ethylmethacrylate (r₂) comonomers. The reactivity ratio for acrylamide (r₁) and ethylmethacrylate (r₂) has been found to be 0.7 and 1.0 respectively, which suggested for an alternate arrangement of average sequence length of acrylamide (mM?₁) and ethylmethacrylate (mM?₂) in grafted chains. The rate of graft copolymerization of comonomers onto cellulose was found to be proportional to square concentration of comonomers and square root to the concentration of ceric (IV) ions. The energy of activation (ΔEa) of graft copolymerization was found to be 9.57 kJ mol^?1 within the temperature range of 20–50°C. On the basis of experimental findings, suitable reaction steps have been proposed for graft copolymerization of selected comonomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2546–2558, 2006     

Synthesis and characterization of butyl acrylate graft sodium salt of partially carboxymethylated starch

Graft copolymers were synthesized by graft copolymerization of butyl acrylate (BA) onto sodium salt of partially carboxymethylated starch (Na‐PCMS). Ceric ammonium nitrate (CAN), a redox initiator, was used for initiation of graft copolymerization reaction. All the experiments were run with Na‐PCMS having degree of substitution, DS = 0.35. The grafting reaction was characterized by parameters such as % total conversion (%Ct), % grafting (%G), % grafting efficiency (%GE), and % add‐on. Graft copolymers were characterized by infrared spectral analysis and scanning electron microscopy. Variables affecting graft copolymerization reaction such as nitric acid concentration, reaction time, reaction temperature, and ceric ion concentration were investigated. The results revealed that 0.3M CAN as initiator, 0.3M HNO₃, with reaction time 4–4.5 h at 25–30°C were found as suitable parameters for maximum yield of graft copolymerization reaction. © 2006 Wiley Periodicals, Inc. JAppl Polym Sci 102: 3334–3340, 2006     

硝酸铈铵改性纳米TiO2的合成及其光催化活性研究

以四氯化钛为钛源,硝酸铈铵为改性原料,采用非水体系溶胶-凝胶法制备了二氧化钛催化剂。采用XRD、UV-Vis和SEM等测试技术对样品进行了表征。结果显示:硝酸铈铵的添加抑制了TiO2晶粒的生长,可使其对可见光吸收增强并且改变了其形貌及尺寸。以苯酚为模型,考察了样品的催化性能。结果表明,在n(Ce)∶n(Ti)为0.3%的条件下,于550℃下焙烧的TiO2催化剂的催化活性最好。3 h光照后,苯酚降解率为93.1%。     

Graft copolymerization of methyl acrylate onto poly(vinyl alcohol) initiated by potassium diperiodatoargentate(III)

The graft copolymerization of methyl acrylate onto poly(vinyl alcohol) (PVA) using potassium diperiodatoargentate(III) [Ag(III)]–PVA redox system as initiator was studied in an alkaline medium. Some structural features and properties of the graft copolymer were confirmed by Fourier‐transfer infrared spectroscopy, scanning electron microscope, X‐ray diffraction and thermogravimetric analysis. The grafting parameters were determined as a function of concentrations of monomer, initiator, macromolecular backbone (X?_n = 1750, M? = 80 000 g mol^?1), reaction temperature and reaction time. A mechanism based on two single‐electron transfer steps is proposed to explain the formation of radicals and the initiation profile. Other acrylate monomers, such as methyl methacrylate, ethyl acrylate and n‐butyl acrylate, were also used to produce graft copolymerizations. It has been confirmed that grafting occurred to some degree. Thermogravimetric analysis was performed in a study of the moisture resistance of the graft copolymer. Copyright © 2004 Society of Chemical Industry     

Graft polymerization of vinyl acetate onto silica

The free‐radical graft polymerization of vinyl acetate onto nonporous silica particles was studied experimentally. The grafting procedure consisted of surface activation with vinyltrimethoxysilane, followed by free‐radical graft polymerization of vinyl acetate in ethyl acetate with 2,2′‐azobis(2,4‐dimethylpentanenitrile) initiator. Initial monomer concentration was varied from 10 to 40% by volume and the reaction was spanned from 50 to 70°C. The resulting grafted polymer, which was stable over a wide range of pH levels, consisted of polymer chains that are terminally and covalently bonded to the silica substrate. The experimental polymerization rate order, with respect to monomer concentration, ranged from 1.61 to 2.00, consistent with the kinetic order for the high polymerization regime. The corresponding rate order for polymer grafting varied from 1.24 to 1.43. The polymer graft yield increased with both initial monomer concentration and reaction temperature, and the polymer‐grafted surface became more hydrophobic with increasing polymer graft yield. The present study suggests that a denser grafted polymer phase of shorter chains was created upon increasing temperature. On the other hand, both polymer chain length and polymer graft density increased with initial monomer concentration. Atomic force microscopy–determined topology of the polymer‐grafted surface revealed a distribution of surface clusters and surface elevations consistent with the expected broad molecular‐weight distribution for free‐radical polymerization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 300–310, 2003     

Ceric‐initiated free radical graft copolymerization of acrylonitrile onto kappa carrageenan

The polysaccharide, kappa carrageenan (kC), was modified using ceric‐initiated graft copolymerization of acrylonitrile (AN) under inert atmosphere in a homogeneous aqueous medium. Grafting was confirmed using FTIR spectroscopy, solubility test, elemental analysis, acid hydrolysis, and thermogravimetric analysis (TGA). kC‐graft‐poly(AN) products had a higher thermal stability than kC as revealed by TGA analysis. The polyacrylonitrile branches were isolated by acidic degradation of the carrageenan main chains and characterized by size exclusion chromatography (SEC). Residual monomers were not found by HPLC in graft copolymers stored even for longer periods. The effect of various factors affecting on grafting, i.e., concentration of the initiator, monomer, and polysaccharide as well as the reaction time and temperature were studied by conventional methods to achieve the optimum grafting parameters. The graft copolymerization reactions were kinetically investigated using semi‐empirical expressions and a suitable rate expression has been derived. According to the empirical rates of the polymerization and the graft copolymerization of AN onto kC backbone, the overall activation energy of the graft copolymerization reaction was estimated to be 20.96 kJ/mol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Graft mechanism of acrylonitrile onto starch by potassium permanganate

The graft mechanism of acrylonitrile (AN) onto starch under the initiation of potassium permanganate was investigated. The relationships of the grafting rate and the concentrations of potassium permanganate, AN, and backbone starch, as well as the reaction temperature, were established. On this basis, the equation for the rate of the graft copolymerization was derived, and the apparent activation energy for the graft copolymerization was obtained. Through the study of the oxidation reaction of starch with manganic ions, the valence changes of manganic ions during the graft copolymerization, and the grafting ability of different starch derivatives, together with electron spin resonance analysis, the grafting mechanism for the graft copolymerization of AN onto starch under the initiation of potassium permanganate was determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 146–152, 2003     

Graft copolymerization of methyl acrylate onto poly(vinyl alcohol) initiated by potassium diperiodatonickelate(IV)

The graft copolymerization of methyl acrylate onto poly(vinyl alcohol) (PVA) with a potassium diperiodatonickelate(IV) [Ni(IV)]–PVA redox system as an initiator was investigated in an alkaline medium. The grafting parameters were determined as functions of the temperature and the concentrations of the monomer and initiator. The structures of the graft copolymers were confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The Ni(IV)–PVA system was found to be an efficient redox initiator for this graft copolymerization. A single‐electron‐transfer mechanism was proposed for the formation of radicals and the initiation. Other acrylate monomers, such as methyl methacrylate, ethyl acrylate, n‐butyl acrylate, and n‐butyl methacrylate, were used as reductants for graft copolymerization. These reactions definitely occurred to some degree. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 529–534, 2003     

改性淀粉-醋酸乙烯酯的接枝共聚反应研究

提出了以高替代率的淀粉醋酸酯与醋酸乙烯酯接枝共聚制备生物降解淀粉塑料的新工艺 ,研究了不同工艺条件对共聚反应的影响。结果表明当选用过硫酸铵作引发剂、且其浓度为 0 0 1mol/L ,单体浓度为 2 1mol/L ,反应温度 45℃ ,聚合时间1 30min时 ,淀粉醋酸的接枝率与接枝效率较高 ,大大改善了纯淀粉接枝的工艺效率     

Graft copolymerization of acrylonitrile onto poly(vinyl alcohol) in presence of air using ceric ammonium nitrate‐natural gums

In an attempt to overcome the problem of polymerization of vinyl monomers in presence of oxygen, polymerization was done by using some plant gums. The effect of some plant gums were studied on the graft copolymerization of acrylonitrile (AN) on to poly(vinyl alcohol) using ceric ammonium nitrate (CAN) as initiator in presence of air. Percent of grafting was determined as a function of nitric acid, concentration of monomer, time, and temperature. The rate of polymerization and maximum grafting (151%) were high compared with those in absence of the gum both in air of even in an inert atmosphere. Thus, it was definitely observed that the graft copolymerization is affected by the gum. From the differential scanning calorimetric (DSC) studies the glass‐transition temperature Tg of polyacrylonitrile (PAN) is found to be 56°C. Thermal stabilities were checked by thermogravimetric analysis (TGA) and this indicated that the grafted copolymers were resistant to moisture absorption. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1586–1590, 2000     

Effects of ceric ammonium nitrate (CAN) additive in HNO3 solution on the electrochemical behaviour of ruthenium for CMP processes

In order to develop a new chemical mechanical polishing process for ruthenium (Ru), the present work deals with the effect of a ceric ammonium nitrate (CAN) additive on the electrochemical behaviour of physical vapour deposited Ru films in a 1 M HNO₃ solution employing electrochemical methods and surface analytical techniques. By adding CAN to HNO₃ solution, the polarisation curves showed an increase in the corrosion potential and current, suggesting that Ru is anodically polarised by CAN as an oxidising additive. To characterise the influence of CAN, open-circuit potential (OCP) and potentiostatic anodic current transient curves were examined in CAN-containing HNO₃ solution and the resulting surfaces were then characterised by scanning electron microscopy and X-ray photoelectron spectroscopy. It is proposed that Ru is oxidised to heterogeneous Ru₂O₃ and RuO₂ films on the Ru surface in CAN-containing HNO₃ solution and galvanic corrosion occurs at grain boundaries, caused by the difference in OCP between the grain interiors and boundaries. The grain boundaries are oxidised to RuO₄, a volatile species, resulting in a roughened and porous structure.     

Graft copolymerization of itaconic acid onto sodium alginate using ceric ammonium nitrate as initiator

Graft copolymers of sodium alginate (NaAlg) with itaconic acid (IA) were prepared in aqueous solution using ceric ammonium nitrate (CAN) as the redox initiator under N₂ atmosphere. The carboxylic acid groups of IA were neutralized with sodium hydroxide before grafting process. Grafted copolymers as sodium salts (NaAlg‐g‐PIA) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, intrinsic viscosity measurement, differential scanning calorimetry, and thermogravimetric analysis. The graft yield (GY %) of the graft copolymer and the grafting efficiency (GE %) of the reaction were evaluated comparatively. The effects of the reaction variables such as the reaction time, temperature, percentage of NaAlg, monomer and initiator concentrations on these parameters were studied. It was observed that GY% and GE% increased and then decreased with increasing concentrations of IA and polymerization temperature. The optimum grafting conditions for maximum GY were obtained with a reaction time of 5 h, reaction temperature of 30°C, IA concentration of 0.23 M, CAN concentration of 9.12 × 10^?2 M and percentage of NaAlg 0.5 g/dL. The overall activation energy for the grafting was also calculated to be 1135 cal/mol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thiocyanation of aromatic and heteroaromatic compounds using polymer-supported thiocyanate ion as the versatile reagent and ceric ammonium nitrate as the versatile single-electron oxidant

Indoles, pyrrole aniline derivatives and aromatic amino compounds undergo smooth thiocyanation with cross-linked poly (4-vinylpyridine) supported thiocyanate ion, [P₄-VP]SCN in the presence of ceric ammonium nitrate (CAN) as a versatile single-electron oxidant in ethanol at room temperature to afford the corresponding 3-indolyl 2-pyroyl and 4-aryl thiocyanates, respectively, in high to excellent yields with excellent selectivity in a short reaction time. The use of [P₄-VP]SCN/CAN makes it quite simple, more convenient, and practical. The present procedure offers advantages such as short reaction time, simple reaction work-up, and the polymeric reagents can be regenerated and reused for several times without significant loss of their activity.