Preparation of monodisperse hydrophilic polymer microspheres with N,N′‐methylenediacrylamide as crosslinker by distillation precipitation polymerization

Highly crosslinked cauliflower‐like poly(N,N′‐methylenebisacrylamide) particles were prepared by distillation precipitation polymerization in neat acetonitrile with 2,2′‐azobisisobutyronitrile as initiator. Monodisperse hydrophilic polymer microspheres with various functional groups, such as amide, pyrrolidone and carboxylic acid, with a spherical shape and smooth surface in the size range 120–600 nm were prepared by distillation precipitation copolymerizations of functional comonomers including N‐isopropylacrylamide, N‐vinylpyrrolidone, methacrylic acid with N,N′‐methylenebisacrylamide as crosslinker. The polymer particles were formed and precipitated out from the reaction medium during the distillation of the solvent from the reaction system through an entropic precipitation manner. The effects of the solvent and the degree of crosslinking on the morphology and the loading capacity of the functional groups of the resultant polymer particles were investigated. The resulting polymer particles were characterized with scanning electron microscopy, transmission electron microscopy, dynamic light scattering and Fourier transform infrared spectroscopy. Copyright © 2007 Society of Chemical Industry     

Synthesis and characterization of poly(N-(2-(thiophen-3-yl)methylcarbonyloxyethyl)maleimide) and its spectroelectrochemical properties

A new monomer; N-(2-(thiophen-3-yl)methylcarbonyloxyethyl) maleimide (NMT) was synthesized. The chemical structure of the monomer was characterized by Nuclear Magnetic Resonance (¹H-NMR) and Fourier Transform Infrared (FTIR) Spectroscopy. Electrochemical polymerization of NMT was performed in acetonitrile (AN)/borontrifloride ethylether (BFEE) solvent mixture (1:1, v/v) where tetrabutylammonium tetrafluoroborate (TBAFB) was utilized as the supporting electrolyte. The resulting conducting polymer was characterized by Fourier Transform Infrared (FTIR) Spectroscopy, thermal analyses and Scanning Electron Microscopy (SEM). Electrical conductivity was measured by the four-probe technique. The spectroelectrochemical behavior and switching ability of P(NMT) film were investigated by UV–Vis spectrophotometry. P(NMT) revealed color changes between yellow and blue in the reduced and oxidized states respectively.     

Functionalized polystyrene latex particles as substrates for ATRP: Surface and colloidal characterization

In this work, the process for producing polystyrene particles surface functionalized with a thin shell of ATRP initiator polymerized alone or along with styrene and a crosslinker, is presented. Copolymerization of styrene and acrylic end-capped ATRP initiator to generate a thin shell on the fully polymerized core particles suffered from secondary nucleation owing to their possible incompatibility with the core particles and their own colloidal stability. One step functionalization processes, where the shell forming monomers are added directly to the 70% polymerized core particles, lead to significant changes in the resulting particle morphologies. The shot addition of these monomers led to a very uniform surface morphology without any secondary nucleation owing to quick coalescence of the secondary particles on the soft surface of the seed particles. Addition of crosslinker to the system helped in effectively eliminating the smaller particles generated due to secondary nucleation along with the chemical networking.     

The mechanism of the oxidative polymerization of aniline and the formation of supramolecular polyaniline structures

Polyaniline is one of the most important conducting and responsive polymers. A molecular mechanism for the oxidation of aniline is proposed. This mechanism explains the specific features of aniline oligomerization and polymerization in various acidity ranges. The formation of polyaniline precipitates, colloids and thin films is reviewed and discussed on the basis of the chemistry of aniline oxidation. The generation of nanostructures, i.e. granules, nanotubes, nanowires and microspheres, is also considered. Oligomers containing phenazine constitutional units play an important role in self‐assembly to form templates. Polyaniline chains then grow from these templates and produce the various individual morphologies. Copyright © 2008 Society of Chemical Industry     

Structural reorganization of the PPy/DBS films caused by the reduction branch of potentiodynamic polymerization

Polypyrrole/dodecylbenzenesulfonate (PPy/DBS) films were synthesized in aqueous solution by cyclic voltammetry. The polymerization carried out at slow scan rates produces two cathodic peaks on the reduction branch. A single reduction peak was obtained at scan rates higher than 50 mV s⁻¹. Two different polymeric structures have been proposed to explain the observed cathodic splitting. Structure I was associated with the organization reached by slow rate electropolymerization processes. Structure II was obtained when I was permanently modified by electrochemical reduction. Under electrogeneration by potential cycling a constant amount of I is generated on every cycle, providing a constant reduction peak A charge. However, the charge involved in peak B, where structure II is reduced, increases with the cycling. Structure I has a lower energetic content than structure II: it is reduced at lesser cathodic potentials than II. Voltammetric and EDX measurements indicated that a main cationic transport occurred during the redox process of the PPy/DBS. However, a certain amount of Na⁺ cations was not interchanged, since they were stabilized inside the polymer, forming ion pairs with an extra quantity of DBS⁻ anions trapped in the polymer matrix during the polymerization process.     

Reversible addition–fragmentation chain transfer polymerization of styrene using a novel thiophene dithioester as the reversible addition–fragmentation chain transfer agent

Benzyl thiophene‐2‐carbodithioate and 2‐methyl‐2‐(4‐methylcyclohex‐3‐enyl)propyl thiophene‐2‐carbodithioatewere synthesized. The reversible addition–fragmentation chain transfer polymerizations of styrene with benzyl thiophene‐2‐carbodithioate and 2‐methyl‐2‐(4‐methylcyclohex‐3‐enyl)propyl thiophene‐2‐carbodithioate as chain‐transfer agents and with 2,2′‐azobisisobutyronitrile as an initiator were carried out. The polymerization kinetics were investigated. An ab initio calculation method was used to explore the differences between benzyl thiophene‐2‐carbodithioate and benzyl benzodithioate. The structure of the obtained polymers was characterized with ¹H‐NMR. Chain‐extension experiments of the obtained polymer with styrene were carried out. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

间规1,2—聚丁二烯合成的实验室研究

报道了使用Ｃｏ－Ａｌ－Ｐ－Ｈ２Ｏ催化体系实验室合成间规１，２－取丁二烯的研究结果，详细讨论了催化组分的加料顺序，老化条件及聚合工艺条件对聚合反应的影响，在此基础上得到最佳工艺条件，进行了模试放大，所得聚合物的基本性能与ＪＳＲ ＲＢ８２０相近。     

Kinetics and mechanism of radical polymerization of methylmethacrylate using p-acetylbenzylidene triphenylarsonium ylide (p-ABTAY) as an initiator

Solution polymerization of methylmethacrylate (MMA) initiated by p-acetylbenzylidene triphenylarsonium ylide in dioxane was carried out at 60±0.2 °C up to 10 hrs. in a polymerization tube under a nitrogen atmosphere. The values of the initiator and the monomer exponent were computed as 0.46 and 1.03, respectively. The overall activation energy and kp²/k_t were calculated as 53 KJ/mole and 1.19 × 10⁻² L/mol·s, respectively for the polymerization.