Abstract: Anionic polymerization of 4-methacryloyloxy-TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidin-1-oxyl) was successfully carried out using methyl methacrylate-capped 1,1-diphenylhexyllithium (DPHLi/MMA), of which nucleophilicity is moderate enough to suppress the side reaction between the nitroxide radical of TEMPO moiety and the carbanion of DPHLi, to yield the radical polymer with well-controlled molecular weight, narrow polydispersity index (PDI 95%), and almost 1.0 radicals per monomer unit.

Abstract: A para-substituted bis(3-aminopropyl)hexaisobutyl-polyhedral oligomeric silsesquioxane (POSS) was successfully synthesized via a selective corner-opening reaction of 3-aminopropylheptaisobutyl-POSS...

Abstract: The present work deals with kinetic studies of copolymerization of methyl methacrylate and styrene using ultrasound assisted semibatch emulsion copolymerization in the presence of sodium dodecyl sulfate (emulsifier) and potassium persulfate (external initiator). The effect of temperature, acoustic intensity, initiator loading, surfactant concentration and monomer concentration on the extent of conversion has been investigated. The extent of polymerization was observed to increase with an increase in the temperature, and concentrations of initiator, monomer and surfactant. Further, the initial polymerization rate increased with an increase in the acoustic intensity from 11.2 to 23.1 W cm−2 and then it was found to decrease with a further increase to 33.80 W cm−2. The novelty of this work lies in the fact that there have been only limited kinetic studies for the approach of ultrasound assisted emulsion copolymerization. It has been also established in the present work that the formation of fine and stable monomer droplets, due to the cavitational activity at/near the interface of immiscible monomer phase and subsequent disruption by micro jets, leads to the smaller final polymer particle size and under optimized conditions, it was found to be about 40 nm.

Abstract: The acid–base catalytic system based on N,N-dimethyl-4-aminopyridine (DMAP) and a protic acid that has already been revealed to be efficient for the ring-opening polymerization (ROP) of L-lactide in solution at room temperature was tested for the same polymerization in bulk at 100 °C. As observed in solution, the presence of the DMAP·HX (X = Cl, CH3SO3, CF3SO3) salt enhanced yields. Linear and star-like polylactides with 3 and 4 branches were prepared. Polylactides were thus easily prepared reaching high molar masses (up to 75 000 g mol−1 for linear PLLA and 140 000 g mol−1 for star-like PLLA) with good control in less than 1 h. In all cases, the appearance of transesterification reactions was shown to occur only at very high yield. The ROP of lactones (e-caprolactone and δ-valerolactone) was also investigated with the same catalytic systems in bulk conditions. In contrast to lactide polymerization, only the DMAP/DMAP·HOTf allowed lactone polymerization with a slower rate. However, the control over the molar masses remained very good. Block copolymers were also synthesized.

Abstract: Polystyrene-reduced graphene oxide (PSTY/RGO) composites were prepared via the in situ bulk polymerization method using two different preparation techniques. The general approach is to use microwave irradiation (MWI) to enhance the exfoliation and the dispersion of RGO nanosheets within the PSTY matrix. In the first approach, a mixture of GO and styrene monomers (STY) were polymerized using a bulk polymerization method facilitated by microwave irradiation (MWI) to obtain R-(GO-PSTY) composites. In the second approach, a mixture of RGO and STY monomers were polymerized using a bulk polymerization method to obtain RGO-(PSTY) composites. The two composites were characterized by FTIR, 1 H-NMR, XRD, SEM, HRTEM, TGA and DSC. The results indicate that the composite obtained using the first approach, which involved MWI, had a better morphology and dispersion with enhanced thermal stability, compared with the composites prepared without MWI. Moreover, DSC results showed that the Tg value of the composites after loading the RGO significantly increased by 24.6 ° C compared to the neat polystyrene.

Abstract: A Lewis acid-free initiating system for cationic polymerization of alkyl vinyl ethers (VEs) was developed using CF3SO3H and tetraalkylammonium halides (nBu4NX; X = I, Br, or Cl). The reaction of CF3SO3H, nBu4NX, and an alkyl VE generated a VE–hydrogen halide adduct. The labile carbon–halogen bond, such as a carbon–iodine bond, cleaved without a Lewis acid catalyst to induce the living cationic polymerization of VEs. Combining halide anions with suitable nucleophilicities according to monomer reactivity was indispensable for controlled polymerization. Another prerequisite was that the polymerization be conducted at a suitable temperature. After the initiation step, the polymerization probably proceeded via the mechanisms similar to those for the previously reported systems using hydrogen halide and an ammonium salt with a noncoordinating anion. The present system was also useful as a facile method for the synthesis of VE–hydrogen halide adducts without the use of harmful gaseous hydrogen halides. The adduc...

Abstract: The ring-opening polymerization behavior of five-membered lactones fused to a cyclohexane ring (that is, the trans- and cis-hexahydro-2(3H)-benzofuranone denoted T6L and C6L, respectively) was investigated under various conditions. The potassium tert-butoxide (tBuOK)-initiated anionic polymerization of T6L yields polymers with number-average molecular weight (Mn) values of 5000. However, no polymeric products were obtained via cationic and coordination polymerization. Among the anionic initiators, a base stronger than an alkoxide initiated the polymerization of T6L. In contrast, cis-isomer C6L did not polymerize regardless of the initiator species used, which implied an increase in the ring strain of the lactone ring by the trans-fused cyclohexane. The anionic polymerization of T6L was reversible, and the thermodynamic parameters characterizing the polymerization of T6L were estimated to be ΔHp°=−18 kJ·mol−1 and ΔSp°=–65 J·K−1mol−1 on the basis of the measurement of the equilibrium monomer concentration. The ring-opening polymerization behavior of five-membered lactones fused to a cyclohexane ring, T6L and C6L, was investigated under various conditions. The t-BuOK-initiated anionic polymerization of T6L produces polymers having Mn values of 5000. In remarkable contrast, C6L did not polymerize at all, implying the increase in ring strain of the lactone ring by trans-fused cyclohexane. The anionic polymerization of T6L was reversible, and the thermodynamic parameters characterizing the polymerization of T6L were estimated to be ΔHp°=−18 kJ·mol−1 and ΔSp°=–65 J·K−1mol−1.

Abstract: In this study, we found that acid-catalyzed ring-opening polymerization (ROP) of γ-butyrolactone, which showed difficulty progressing in general ROP, took place under high-pressure conditions. The ...

Abstract: The RAlCl2 × OiPr2-co-initiated (R = iBu or Et) cationic polymerization of isobutylene in the presence of externally added water (0016–01 mM) in nonpolar n-hexane at 10 °C and high monomer concentration ([IB] = 58 M) has been investigated It was shown that the sequence of H2O introduction into the system had the crucial effect on the polymerization rate, saturated monomer conversion, and, to a lesser extent, the content of exo-olefin end groups Particularly, the highest polymerization rate (>70% of monomer conversion in 10 min) and acceptable exo-olefin end groups content (∼83%) were observed when iBuAlCl2 × 08OiPr2 reacted with suspended in n-hexane H2O before the monomer addition Better functionality can be obtained when H2O is introduced into the system in the course of the polymerization (after 3–10 min since the initiation of reaction) Under these conditions, highly reactive polyisobutylenes (exo-olefin content is 86–89%) with desired low molecular weight (Mn = 1000–2000 g mol−1) in a high yield (75–90% of monomer conversion in 20 min) were readily synthesized © 2014 Wiley Periodicals, Inc J Polym Sci, Part A: Polym Chem 2014, 52, 2386–2393

Abstract: The copolymerization of butyl methacrylate and butyl acrylate initiated by CuBr2/tris[(2-pyridyl)methyl]amine/ethyl 2-bromoisobutyrate, with tin(II) 2-ethylhexanoate as reducing agent, is studied experimentally and using kinetic Monte Carlo simulations at 70 and 90 °C under batch activator regenerated by electron transfer atom transfer radical polymerization conditions in anisole at low Cu levels (down to 35 ppm Cu on a molar basis with respect to monomer). With increasing initial butyl acrylate content, the initiator efficiency is improved with an accompanying increase in polymer dispersity due to oligomer formation. The addition of reducing agent during the polymerization, i.e. a semi-batch approach, allows an increase in polymerization rate and initiator efficiency, driving the polymerization towards full conversion and allowing for better initiator consumption. © 2013 Society of Chemical Industry

Abstract: A Monte Carlo approach has been developed to simulate the miniemulsion polymerization of n-butyl acrylate with a water-soluble monomer, 2-hydroxyethyl methacrylate. The proposed simulation takes into account all the reactions in the aqueous and organic phases, as well as the entry of oligoradicals into the polymer particles by absorption and precipitation. The effect of the water-soluble monomer on the polymerization rate and on the molecular weight distribution of the polymer in the aqueous and organic phases has been studied. The addition of the water-soluble monomer retards the polymerization, though it had no significant effect on the molecular weight of the polymer produced in the particles; however, it increased the concentration of water-soluble polymer and its molecular weight. By this approach, it is possible to extract detailed information of polymer in the aqueous phase, such as the copolymer composition distribution.

Abstract: In this study, the preparation of poly(acrylamide)/nanoclay organic-inorganic hybrid nanoparticles via surfactant-free inverse emulsion polymerization by using organically modified clay platelets as stabilizers was discussed. Colloidally stable inverse Pickering emulsions of aqueous acrylamide solution in cyclohexane (solvent) stabilized by hydrophobic Cloisite 20A (MMT20) were prepared. Polymerization was carried out via 2,2′-azobis(isobutyronitrile) and composite particles with an average size of ∼250 nm were obtained. The effect of initiator and solvent type on the stability, size, size distribution, and morphology of the produced composite particles was examined. It was observed that in the presence of xylene as solvent, particles with bigger sizes and broader size distribution were obtained. Furthermore, using an ionic initiator resulted in a slight coagulation during polymerization and smaller particles. Moreover, the effect of various polymerization conditions such as temperature, initiator, and crosslinking agent concentration and clay content on the polymerization rate was evaluated. The experimental results showed that polymerization rate increases with an increase in polymerization temperature, crosslinking agent concentration, and initiator content. However, increasing in clay content results in a lower polymerization rate.

Abstract: Uniformly sized polymeric molecularly imprinted microspheres have been synthesized by membrane emulsification and suspension polymerization of methyl methacrylate and ethyl glycol dimethacrylate in the presence of bisphenol A as a template. At the beginning the best monomer compositions were selected by bulk polymerization of eight different mixtures of monomer and crosslinking agent. For the selected compositions that had the highest affinity to bisphenol A, a two-step process composed of membrane emulsification and suspension polymerization was used. Materials prepared by the two-step process showed the higher efficiency to the bisphenol A removal than their analogues prepared by bulk polymerization. The best material was synthesized from a mixture of methyl methacrylate and ethylene glycol dimethacrylate as 4:6 in the presence of n-octane as a solvent, and with 3 wt.% of bisphenol A. The logKBPA value for this sample was 4.9. The experimental sorption isotherms were fitted by Scatchard plots and hetero...

Abstract: A simple model discrimination method for RAFT polymerization mechanism, proposed on a theoretical basis, is applied to the polystyryl dithiobenzoate-mediated styrene polymerization. It is confirmed that the intermediate termination (IT) is the major reason for the rate retardation. The method utilizes the theoretical finding that the IT model shows a significantly larger polymerization rate in miniemulsion compared with the corresponding bulk polymerization, while the slow fragmentation model does not change the polymerization rate. The miniemulsion polymerization rate increases as the droplet size is made smaller, which agrees reasonably well with the theoretical prediction. The present model discrimination method is easy to apply, and would provide great insight into both basic and applied research in RAFT polymerization.

Abstract: In this report, a novel method for the synthesis of polyaniline in aqueous medium, based on a G-quadruplex DNAzyme-catalyzed oxidation and polymerization of aniline by hydrogen peroxide in the presence of a polyanionic template, is described. The synthesis is simple and the experimental conditions are mild. The polymerization of aniline is carried out in an acidic aqueous medium with a catalytic amount of the DNAzyme. It was found that aniline polymerization occurs in a pH range from 2.0 to 5.0 with an optimal pH of 3.0. The polymerization kinetics can be described by the classical Michaelis–Menten reaction mechanism. Comparing to the horseradish peroxidase-catalyzed polymerization of aniline, the advantages of using the DNAzyme as the catalyst in the polymerization of aniline are cost-effectiveness and greater tolerance to the acidity of the reaction solution and high concentrations of hydrogen peroxide.

Abstract: Controlled radical polymerization (CRP) such as atom transfer radical polymerization (ATRP) is often conducted in solution processes and stopped at medium monomer conversions to yield well controlled polymer samples. A great challenge lies in running bulk CRP up to high conversions but still retaining system livingness and molecular weight control. In this work, we demonstrate the achievement of good living and well controlled high-conversion bulk ATRP by means of design and optimizing polymerization thermal histories. The initiator-for-continues-activator-regeneration (ICAR) ATRP of methyl methacrylate (MMA) is used as a model system. Employing step functions in temperature, MMA conversions are pushed up to 98% and the PMMA samples possess polydispersities <1.3. Chain extension experiments confirm good livingness of synthesized polymers collected at high conversions.

Abstract: The semi-continuous heterophase polymerization (SHP) under monomer-starved conditions of methyl methacrylate and hexyl methacrylate is reported, at various monomer addition rates to elucidate the effect of monomer solubility on the mechanism of particle nucleation and growth. Polymer particles in the nanometer range from both monomers were obtained, which decreased in size as monomer addition rate was decreased. Molar masses of both polymers also diminished as monomer addition rate was slowed down. The propagation rate constant dictates how fast the starved condition is achieved rather than the monomer solubility in the aqueous phase. A slow particle rate of growth helps to obtain a narrower PSD.

Abstract: In this work, seeded dispersion polymerization of styrene was carried out in the presence of various types of seed particles. We found that in the case of polystyrene and poly(methyl methacrylate) seeds, the shape of the resulting particles remained spherical. For styrene/poly(nbutyl methacrylate) (PnBMA) and styrene/poly(lauryl methacrylate) seeding particles, raspberry like particles were produced along with those of occluded morphology. We studied the effects of various polymerization factors such as concentrations of a stabilizer, an initiator, and a monomer, a weight ratio of methanol to water, a type of initiator, weight ratio of styrene to Pn-BMA seed particles, and polymerization temperature on the formation of these raspberry-like particles. The experimental results showed that the increase of concentrations of the initiator and the stabilizer as well as that of methanol favors the formation of such particles by increasing their surface roughness. An increase of the temperature of polymerization had the same effect on the morphology of resulting product. We hypothesized that the nucleation and growth of specifically fine-structured polystyrene domains on the surface of the Pn-BMA particles guides the formation of non-linear morphology during seeded polymerization in colloidal solution.

Abstract: Poly(3,3-bis(difluoroaminomethyl)oxetane/tetrahydrofuran), poly(3-difluoroaminomethyl-3-methyloxetane/tetrahydrofuran), and poly(3,3-bis(difluoroaminomethyl)oxetane/3-difluoroaminomethyl-3-methyloxetane/tetrahydrofuran) were synthesized via cationic bulk polymerization using boron trifluoride etherate/polyol mixture as catalyst system. Thermal decomposition behaviors of these polymers were investigated by thermogravimetric analysis/differential scanning calorimetry. Kinetics of thermolysis was studied by a model-free method. All of these polymers exhibited a two-stage mass-loss process. The elimination of HF with the activation energy at 95–110 kJ mol−1 dominated the first stage, while the second stage contained the thermolysis of the remaining polymer chain with monofluoroimino and cyano groups. Fourier transform infra red spectra of the degradation residues showed that the difluoroamino groups decomposed in a two-step HF loss at different temperatures. The existence of monofluoroimino groups was responsible for the two-stage thermolysis process.