Alternating copolymerization of 2-methyl-2-oxazoline with α-chloro- and α-bromoacrylic acids: 3. Synthesis,characterization and kinetics

New 1:1 alternating copolymers of 2-methyl-2-oxazoline with (i) α-chloroacrylic acid and (ii) α-bromoacrylic acid were synthesized and characterized by i.r., n.m.r. and the products of alkaline hydrolysis. The copolymerization occurred at a temperature of 60°C without any added catalyst or initiator. The copolymerization kinetics were studied and the order with respect to each monomer was found to be unity. A scheme for the copolymerization involving a zwitterion intermediate is proposed.     

Kinetic study of copolymerization of acrylonitrile with ammonium acrylate

Ammonium acrylate was first used to successfully copolymerize with acrylonitrile. Kinetics of copolymerization of acrylonitrile with ammonium acrylate was investigated in a H₂O/dimethylsulfoxide (DMSO) mixture. The rate of copolymerization and particle size were measured. Kinetic equation of the copolymerization was obtained. Effect of copolymerization systems on monomer apparent reactivity ratios for acrylonitrile/ammonium acrylate copolymers was studied in comparison. Values of monomer apparent reactivity ratios were calculated by Kelen‐Tudos method. It has been found that monomer apparent reactivity ratios in water‐rich reaction medium [H₂O/DMSO>80/20] are approximately equivalent to those in aqueous suspension polymerization system. In DMSO‐rich reaction medium (DMSO/H₂O > 80/20), apparent reactivity ratios are similar to those in solution polymerization system. With an increase in polarity of solvent, values of apparent reaction ratios both decrease. The values of apparent reaction ratios gradually tend to 1 with increase in the copolymerization temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4679–4683, 2006     

Peroxydiphosphate–metal ion–cellulose thiocarbonate redox system‐induced graft copolymerization of vinyl monomers onto cotton fabric

The grafting of methacrylic acid (MAA) and other vinyl monomers onto cotton cellulose in fabric form was investigated in an aqueous medium with a potassium peroxydiphosphate–metal ion–cellulose thiocarbonate redox initiation system. The graft copolymerization reaction was influenced by peroxydiphosphate (PP) concentration, the pH of the reaction medium, monomer concentration, the duration and temperature of polymerization, the nature of vinyl monomers, and the nature and concentration of metallic ions (activators). On the basis of a detailed investigation of these factors, the optimal conditions for the grafting of MAA onto cotton fabric with the said redox system were as follows: [Fe²⁺] = 0.1 mmol/L, [PP] = 2 mmol/L, [MAA] = 4%, pH‐2, grafting time = 2 h, grafting temperature = 70°C, and material/liquor ratio = 1 : 50. Under these optimal conditions, the graft yields of different monomers were in the following sequence: MAA ? acrylonitrile > acrylic acid > methyl acrylate > methyl methacrylate. The unmodified cellulosic fabric (the control) had no ability to be grafted with MAA with the PP–Fe²⁺ redox system. The percentage of grafting onto the thiocarbonated cellulosic fabric was more greatly enhanced in the presence of iron salts than in their absence. This held true when the lowest concentrations of these salts were used separately. A suitable mechanism for the grafting processes is suggested, in accordance with the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1879–1889, 2003     

Synthesis of ethylene/1‐octene copolymers with controlled block structures by semibatch living copolymerization

A kinetic model was developed for the living copolymerization of ethylene/1‐octene using the fluorinated FI‐Ti catalyst system, bis[N‐(3‐methylsalicylidene)‐2,3,4,5,6‐pentafluoroanilinato] TiCl₂/dried methylaluminoxane is presented. The model was first validated by batch polymerization experiments. Kinetic parameters were estimated from the model correlations with online ethylene consumption rates and end‐of‐batch copolymer molecular weight. The model was then used to calculate the microstructural properties of ethylene/1‐octene copolymers with controlled composition profiles (uniform, diblock, and step triblock), which were synthesized using sequential comonomer feeding policies in semibatch copolymerization. The synthesized block copolymers had the exact composition distributions and molecular weights as the model simulated. It was demonstrated that the polymer chain microstructure in the living copolymerization of olefins could be precisely regulated by using semibatch comonomer feeding policies. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4686–4695, 2013     

Preparation and characterization of hyperbranched polyacrylate copolymers by self‐condensing vinyl copolymerization (SCVCP)

A series of hyperbranched polyacrylate copolymers have been synthesized by self‐condensing vinyl copolymerization (SCVCP) of 2‐(2‐bromopropionyloxy)‐ethyl acrylate (BPEA) and methyl acrylate (MA) in the presence of CuBr and bipyridine. The structures and properties of the polymers obtained are characterized by NMR and SEC/RALLS/DV/RI measurements. The effects of reaction conditions on molecular weight (MW), molecular weight distribution (MWD) and degree of branching (DB) are investigated. © 2002 Society of Chemical Industry     

Water-soluble copolymers: 21. Copolymers of acrylamide with 2-acrylamido-2-methylpropanedimethylammonium chloride: Synthesis and characterization

The copolymerization of acrylamide (AM) with 2-acrylamido-2-methylpropanedimethylammonium chloride (AMPDAC) has been studied in the range from 40 to 90% AM in the feed. The value of r₁r₂ has been determined to be 0.19 for the AM-AMPDAC pair. The copolymer compositions have been determined from elemental analysis and ¹³C n.m.r. The molecular weights of the copolymers were measured by low-angle laser light scattering, and ranged from 1.7–3.6 × 10⁶. Furthermore, the molecular weights were found to be relatively unaffected by monomer feed ratios. The copolymer microstructures, including run numbers and sequence distributions, were calculated from the reactivity ratios. These model structures are utilized for assessment of structure/dilute solution property relationships reported in a subsequent paper in this series.     

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     

Studies on the radical copolymerization of methylacrylate with styrene using ZnCl2 as an accelerator

The kinetic investigation of the radical copolymerization of methylacrylate (MA) with styrene (Sty) using zinc chloride (ZnCl₂) as an accelerator was carried out at 60 ± 0.1 °C for 120 min. The rate of polymerization was proportional to the concentrations of ZnCl₂ and monomers. The energies of activation in the presence and absence of the complex are 34 and 89 kJ mol^?1, respectively.     

Kinetic studies on the dilatometric‐free radical copolymerization of new modified laser dye monomer with methyl methacrylate and characterization of the obtained copolymer

The synthesis of the new modified laser dye from fluorescein ester (II) and acryloyl chloride was performed. The structure of the new monomer 2‐(6‐acryloyloxy‐3‐oxo‐3H‐xanthene‐9‐yl)‐benzoic acid ethyl ester [AOXBE] was confirmed by ¹HNMR, IR, ¹³CNMR, mass spectroscopy, and elemental analysis. Free radical copolymerization of AOXBE with methyl methacrylate (MMA) was discussed using dilatometric technique. The effect of different solvents on the rate of copolymerization reaction was carried out. The rate equation was found to be R_p = [Initiator]^0.5473 [Monomer]^1.5. It was also noticed that the increase of AOXBE concentration in the monomer feed has an inhibition effect on the rate of copolymerization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Superabsorbent resin of acrylic acid/ammonium acrylate copolymers synthesized by ultraviolet photopolymerization

A new method of synthesizing a superabsorbent resin (SAR) from an acrylic acid/ammonium acrylate copolymer by direct UV photopolymerization was studied. The effects of the degree of neutralization of acrylic acid, the photoinitiators, the crosslinking agents, and the UV‐light exposure time on the water absorbency (Q) were investigated. The results showed that Q of an SAR based on Irgacure 1700 or Irgacure 1800 and Irgacure 651 was high, reaching about 1200 mL/g, but under the same conditions, Q was low for an SAR based on other photoinitiators. The UV absorption spectrum proved that the photoinitiators matched the UV light source. Among the crosslinking agents, N,N′‐methylene bisacrylamide was more efficient than the others at a small concentration and a high value of Q. ¹³C‐NMR spectrometry was used to identify the mechanism of the crosslinking reaction through the esterification of hydroxyethyl acrylate (HEA) and 2‐hydroxypropyl acrylate with carboxylic acid group in acrylic acid/ammonium acrylate copolymerization, but the efficiency of the crosslinking reaction by esterification was lower than that of the copolymerization of vinyl groups in the crosslinking agent. Q of the acrylic acid/ammonium acrylate copolymer for the SAR reached 1255 mL/g under certain conditions (degree of neutralization of acrylic acid = 75%, Irgacure 651 concentration = 0.2 wt %, [HEA] = 0.2 wt %, exposure time = 10 min). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 546–555, 2005     

New syntheses of graft copolymers using the DPE-technique: ATRP graft copolymerization

Summary A new one-step synthesis of a set of macroinitiators for atom transfer radical polymerization (ATRP) via controlled radical polymerization is presented. The macroinitiators consist of methacrylate and p-chloromethylstyrene (CMS) and were synthesized by controlled radical polymerization in the presence of l,l-diphenylethylene (DPE) using azobisisobutyronitrile (AIBN) as initiator. The resulting macroinitiators were used for the ATRP of different methacrylates yielding graft copolymers which were characterized by SEC and NMR. Received: 25 July 2002/Revised version: 28 October 2002/ Accepted: 28 October 2002 Correspondence to Oskar Nuyken     

Kinetics of ylide-initiated radical copolymerization of 4-vinylpyridine and methyl methacrylate

The ylide-initiated radical copolymerization of 4-vinylpyridine (4-VP) with methyl methacrylate (MMA) at 60°C using carbon tetrachloride as inert solvent yields non-alternating copolymers. The kinetic parameters, average rate of polymerization (R_p) and orders of reaction with respect to monomers and initiator, have been evaluated and the kinetic equation is found to be R_pα[ylide]^0.94 [MMA]^1.0 [4-VP]^1.5. The values of the energy of activation and k_p²/k_t are 48 kJ mol^?1 and 6.6 × 10^?5 litre mol^?1s^?1, respectively. The copolymers have been characterized by IR and NMR spectroscopy.     

Graft copolymerization of N‐vinyl‐2‐pyrrolidone onto sodium carboxymethylcellulose with azobisisobutyronitrile as the initiator

Graft copolymers of sodium carboxymethylcellulose with N‐vinyl‐2‐pyrrolidone were prepared in aqueous solutions with azobisisobutyronitrile as the initiator. The graft copolymers [sodium carboxymethylcellulose‐g‐poly(N‐vinyl‐2‐pyrrolidone)] were characterized with Fourier transform infrared spectroscopy, elemental analysis, nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The grafting parameters, including the graft yield of the graft copolymer and the grafting efficiency of the reaction, were evaluated comparatively. The effects of reaction variables such as the time, temperature, and monomer and initiator concentrations on these parameters were studied. The graft yield and grafting efficiency increased and then decreased with increasing concentrations of N‐vinyl‐2‐pyrrolidone and azobisisobutyronitrile and increasing polymerization temperatures. The optimum temperature and polymerization time were 70°C and 4.30 h, respectively. Further changes in the properties of grafted sodium carboxymethylcellulose, such as the intrinsic viscosity, were determined. The overall activation energy for the grafting was also calculated to be 10.5 kcal/mol. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 936–943, 2007     

Enhanced stability of gold nanoparticles capped with double hydrophilic block copolymers synthesized by eATRP

In this study, the gold nanoparticles (Au NPs) are capped with a novel, well-defined double hydrophilic block copolymer, poly (ethylene glycols)-block-poly(mono-2-(methacryloyloxy) ethyl succinate) (PEG-b-PSEMA). The PEG-b-PSEMA, with long side chains and relatively narrow dispersity index, is successfully prepared by aqueous electrochemically mediated atom transfer radical polymerization using a PEG-Br macroinitiator (M_n≈2000 g mol⁻¹). By simply mixing PEG-b-PSEMA and Au precursor before adding reductants, coulombic interactions occur between the Au precursor and the carboxylate group of the PSEMA, as a result dense Au NPs are formed. This enables the Au NPs to remain dispersed even in the presence of temperature variations, pH adjustments, and incubation in organic solvents. Au NPs were endowed by PEG-b-PSEMA with more remarkable catalytic activity in organic solvents of 4-nitrophenol into 4-aminophenol than by sodium citrate (Au@citrate) and MeO-PEG-OH (Au@PEG). In addition, PEG-b-PSEMA-stabilized Au NPs (Au@PEG-b-PSEMA) were also tested for the dye degradation property against Rhodamine-B in only pH 10 basic solution, and over 99% of dye degradation can be achieved in 9 min. PEG-b-PSEMA induces coulombic interactions with Au NPs, providing outstanding stability for catalytic applications in organic or specific acidic-base environments.     

乙烯和环烯烃共聚用有机金属催化剂

配位催化共聚是制备环烯烃共聚物的主要方法,目前商品化的环烯烃共聚物主要由乙烯与降冰片烯或者四环十二碳烯共聚得到。共聚单体及其含量是决定环烯烃共聚物性能的关键因素,而决定共聚单体含量的最核心因素是催化剂。本文从催化剂结构的角度出发,综述了乙烯和降冰片烯/四环十二碳烯共聚用有机金属催化剂,从双茂有机金属催化剂、单茂有机金属催化剂、非茂有机金属催化剂、后过渡金属催化剂等部分进行论述,同时论述了催化剂结构及关键聚合工艺（如温度、压力、单体浓度等）对催化活性及共聚单体插入量的重要影响。此外,由于乙烯与四环十二碳烯共聚活性低,未来针对该共聚反应的研究会继续进行。合成更多新结构的配体、开发更高活性的催化剂、构建更经济有效的反应体系将会是新的研究重点。     

Synthesis of N-acryloxysuccinimide copolymers by RAFT polymerization, as reactive building blocks with full control of composition and molecular weights

The reversible addition-fragmentation chain transfer (RAFT) polymerization process was used to synthesize well-defined N-acryloxysuccinimide (NAS) based copolymers, very useful reactive building blocks for various applications. Kinetic studies of RAFT copolymerization of NAS with a bi-substituted acrylamide derivative, N-acryloylmorpholine (NAM), were performed in the presence of tert-butyl dithiobenzoate (tBDB). An excellent control was reached with very high conversions (>95%), molecular weights (MW) up to 80?000 g mol⁻¹ and very narrow molecular weight distributions (MWD) (polydispersity indices, PDI<1.1), as determined by aqueous size exclusion chromatography with on-line light scattering detector (SEC/LS). In addition, the comparison of RAFT and conventional NAM/NAS free radical copolymerization indicated that the apparent reactivity ratios in RAFT are similar to the reactivity ratios determined from conventional copolymerization. An identical azeotropic composition (60/40 NAM/NAS molar ratio) was obtained providing perfectly random poly(NAM-co-NAS) copolymers with full control of composition and MW. These copolymer chains with regularly-distributed reactive functions can be integrated into more complex architectures. As an example, poly[(NAM-co-NAS)-b-NAM] block copolymers with length-varying poly(NAM) block were synthesized with a very efficient control over MW, MWD and composition.     

Green polycarbonates prepared by the copolymerization of CO2 with epoxides

Polycarbonates can be prepared by the copolymerization of epoxides with carbon dioxide as an inexpensive, abundant, nontoxic, and renewable feedstock. This review covers the synthesis, the physicochemical properties, and the growing applications of this class of green polymers. The review has been conceived to provide a useful tool for the researchers who are new to this field, as well as to offer an updated overview for those who are already actively working on this topic. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41141.