Abstract: A simple, inexpensive, and convenient catalyst system consisting of supporting ligand-free MgnBu2 in combination with an alcohol, isopropanol (iPrOH), benzyl methanol (PhCH2OH), diphenylmethanol (Ph2CHOH), or triphenylmethanol (Ph3COH), generates a convenient catalyst system to promote the polymerization of l-LA. In particular, the binary system MgnBu2/Ph2CHOH demonstrates an unprecedentedly high activity in the presence of a large excess amount of Ph2CHOH with the [OH]0/[Mg]0 ratio varying from 2 to 500, producing up to 500 polylactide (PLA) chains per Mg center and thus showing a typical nature of immortal polymerization. The molecular weights of the obtained PLAs with a broad range of monomer-to-metal ratios ([l-LA]0/[Mg]0 = 200–5000) are rather accurately controlled by the Ph2CHOH loading, relative to [Mg]0, while the molecular weight distributions remain nearly constant with polydispersity index (PDI) = 1.08–1.18. Moreover, the active polymerization intermediate has been isolated from the stoichiomet...

Abstract: Atomic transfer radical polymerization (ATRP) of acrylamide has been accomplished in aqueous media at room temperature. By using methyl 2-chloropropionate (MeClPr) as the initiator and tris[2-(dimethylamino)ethyl]amine (Me6TREN)/copper halogenide (CuX) as the catalyst system, different linear polyacrylamides with apparent molecular weights up to >150 000 g/mol were synthesized with dispersities as low as 1.39. The molecular weights agreed well with the theoretical ones at relatively low-medium monomer/initiator ratios (<700:1). Initial chain extension experiments (isolated macroinitiator) resulted in a polymer with bimodal distribution. However, in situ chain extension experiments, carried out by addition of a second fresh batch of monomer to the reaction mixture, confirmed the living nature of the polymerization. By adding a fresh batch of monomer to a linear macroinitiator (Mn = 22 780 g/mol, PDI = 1.42) in solution, an increase in the molecular weight up to 30 220 g/mol (PDI = 1.64) was observed. In ad...

Abstract: We report the unprecedented controlled radical polymerization of 4-vinylimidazole (4VIM). Reversible addition–fragmentation chain transfer (RAFT) of 4VIM in glacial acetic acid afforded homopolymers with well-defined molecular weights and narrow polydispersity indices (PDIs). The polymerizations in acetic acid mediated with 4-cyano-4-(ethylsulfanylthiocarbonylsulfanyl)pentanoic acid (CEP) displayed linear pseudo-first-order kinetics and linear molecular weight growth with monomer conversion. Systematic variation of numerous polymerization parameters included solvent composition, initiator concentration, monomer concentration, and the calculated degree of polymerization. Aqueous size exclusion chromatography (SEC) confirmed linear molecular weight growth to number-average molecular weights (Mn) of 65 000 g/mol with low PDIs (<1.20). Subsequent monomer addition confirmed the presence of the trithiocarbonate functionality at the chain ends, which provided further evidence of controlled polymerization conditi...

Abstract: Zinc alkyl cations supported by N,N-BIAN-type bidentate ligands were found to be highly active in the immortal ROP of e-caprolactone to yield narrowly disperse and chain length-controlled poly(e-caprolactone), whether in solution or bulk polymerization conditions.

Abstract: Most of conjugated microporous polymers (CMPs) prepared to date are poorly processable, intractable solids. The immobilization of CMPs onto various surfaces is strongly desirable for many applications, such as for gas storage and separation, heterogeneous catalysis, and so forth. However, the preparation of thin porous films remains a challenging task. This Letter reports Ni-catalyzed surface-initiated Kumada catalyst-transfer polycondensation of a tetrafunctional thiophene-based (AB) 2-monomer from organosilica microparticles leading to microparticles covered by thin-film (∼30 nm) layers of the CMP. A sample of unbound CMP was also prepared by a bulk polymerization of the same monomer. Thus-obtained CMP possesses a relatively high specific surface area of 463 m2 g–1. The porosity of the immobilized polymer is somewhat lower with a specific surface area of 123 m2 g–1.

Abstract: A novel reactive phosphorus- and sulfur-containing flame-retardant monomer [di(allyloxybisphenol sulfone) phenoxy phosphonate, DASPP] was successfully synthesized and well characterized. Various amounts of DASPP were incorporated into the unsaturated polyester by radical bulk polymerization. The thermal properties and flammability of the flame-retardant unsaturated polyester resin (FR-UPR) samples were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), limiting oxygen index (LOI) measurements, and cone calorimetry. The results showed that the introduction of DASPP into unsaturated polyester resin (UPR) can substantially improve its fire resistance and high-temperature stability. Interestingly, a linear increase in the glass transition temperature (Tg) with increasing incorporated DASPP content was observed by DSC. Scanning electron microscopy (SEM) and Raman spectroscopy studies revealed that DASPP can effectively improve the microstructure of UPR char residue and i...

Abstract: A novel, ester-free initiator for surface-initiated free radical polymerization has been synthesized and tested. The structurally non-symmetrical azo-based initiator features a chemically stable alkane linker between the initiating group and the silane anchoring group, setting it apart from the majority of surface initiators that are linked by hydrolyzable moieties, such as esters. The novel design of the initiator is bolstered by an original synthetic approach, leading to a greater yield and a dramatic reduction in cyanide usage relative to previous methods. Here we demonstrate the capability of this novel initiator for surface-initiated free radical polymerization (SI-FRP), reverse ATRP, and RAFT, noting that Arrhenius behavior of SI-FRP differs significantly from that of FRP in the bulk. Furthermore, we show that polymer brushes formed from the novel initiator are more stable than those formed from ester-based initiators.

Abstract: The disclosure relates to methods of making polymer particles, said methods including the steps of: making an aqueous gel reaction mixture; forming an emulsion having dispersed aqueous phase micelles of gel reaction mixture in a continuous phase; adding an initiator oil comprising at least one polymerization initiator to the continuous phase; and performing a polymerization reaction in the micelles. Further, the initiator oil is present in a volume % relative to a volume of the aqueous gel reaction mixture of between about 1 vol % to about 20 vol %. The disclosure also relates to methods of making nucleic acid polymer particles having the same method steps and wherein the aqueous gel reaction mixture includes a nucleic acid fragment, such as a primer.

Abstract: Several methods for polymerizing 4-methyl-2-oxetanone (β-butyrolactone, BL) were developed allowing the controlled synthesis of polymers with molar masses up to 100 kDa. Although new catalytic systems have been described for the living anionic polymerization of BL, no detailed studies have been published on the influence of the monomer purity on the polymerization reaction. In the present study, nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) are used for assessing monomer purity. These techniques indicate that an additional reaction of BL with an oxidizing agent such as potassium permanganate produces a monomer of higher purity as demonstrated by the higher rate of BL polymerization and improved control over the polymerization process that is initiated with either tetrabutylammonium acetate or carboxylic acid/phosphazene base (P1-t-Bu, P2-t-Bu and P4-t-Bu) systems.

Abstract: A method of making polymer particles includes making an aqueous gel reaction mixture; forming an emulsion comprising dispersed aqueous phase micelles of gel reaction mixture in a continuous phase at a temperature less than about 10°C; and performing a polymerization reaction in the micelles. Further, the emulsion comprises at least one polymerization initiator in the micelles of gel reaction mixture. The gel reaction mixture can be maintained at a temperature less than about 10°C when it comprises the polymerization initiator.

Abstract: BACKGROUND: There are few reports on erythromycin molecularly imprinted polymers (MIPs) used as HPLC stationary phase and solid phase extraction matrices. These imprinted polymers are prepared by bulk polymerization, which is tedious and time-consuming, and they are irregular and possess poor reproducibility and low binding capacity. In this study, molecularly imprinted microspheres for erythromycin were prepared by aqueous suspension polymerization for the first time.

Abstract: To understand if either of two controversial models for the retardation by RAFT agents is applicable, styrene polymerization using dithiobenzoate as the RAFT agent is carried out in both bulk and miniemulsion systems with the same rates of radical generation and the same RAFT agent concentrations. Miniemulsion polymerization with average diameters of the miniemulsion droplets of ≈107 nm is by far faster than in bulk, and the obtained rate of polymerization agrees well with the calculated results assuming a bimolecular termination between propagating radical and intermediate radical, generated by the addition reaction of propagating radical to the RAFT agent, which shows that the intermediate termination is the major reason for rate retardation by the RAFT agent.

Abstract: Solid-state polycondensation (SSP) comprises a bulk polymerization technique industrially applied to step-growth polymers. It involves heating the starting material (crystalline monomer or prepolymer) in an inert atmosphere or in vacuo , at a temperature below its melting point, permitting the initiation and propagation of typical polymerization reactions. Both chemical and physical steps occur during an SSP process, namely chemical reaction, reactive-chain end diffusion in the amorphous phase, and removal of low-molecular-weight condensate through diffusion. These phenomena are herewith discussed with an emphasis on polyamide (PA) 66, poly(ethylene terephthalate) (PET), and poly(lactic acid) (PLA), revealing important mechanistic aspects.

Abstract: Molecular imprinting is a method for making artificial receptor sites in a polymer. This article reports the direct nanolayer immobilization of molecularly imprinted polymers (MIPs) on hydroxyl-functionalized multiwalled carbon nanotubes (MWCNTs) without any binder to improve their characteristics. MIPs were formed for hydrochlorothiazide (HCT) as a template on the surface of the MWCNTs with methacrylic acid (functional monomer) and ethylene glycol dimethacrylate (crosslinking agent) with a thermal polymerization technique. The morphology and stability of the immobilized molecularly imprinted polymers on the surface of multiwalled carbon nanotubes (MIPCNTs) was characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The resulting MIPCNTs demonstrated favorable selectivity, good stability, and a higher adsorption capacity for the template molecule (93.0 μg/mg) compared to products created by bulk polymerization. The adsorption kinetics of HCT at the surface of the MIPCNTs was in agreement with the second-order rate equation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Abstract: A series of hyperbranched polyglycerols (HPGs) have been synthesized using glycol as an initiator in the presence of potassium counterion ([K+]0/[−OH]0 = 0.75) and employing batch monomer addition (BMA) to obtain insight into the kinetics of the polymerization. The first-order time–conversion plots show that the polymerization is fast up to ∼200 min, and the rate decreases substantially with increasing reaction time. Size exclusion chromatography of the HPGs during the polymerization indicates the presence of two living species in the reaction: a large fraction that grows into oligomers ( 140 000 g/mol). 13C NMR of the oligomer HPG shows signals corresponding to epoxy ring headgroup at 45.1 and 52.0 ppm and confirms the formation of epoxy anion, an inimer, via intermolecular proton transfer from glycidol. Self-condensing ring-opening polymerization of epoxy i...

Abstract: The surface of waste rubber powder (WRP) was graft-modified with styrene (St) by bulk polymerization method. The effects of styrene content, initiator mass, time of reaction, and temperature on the graft efficiency were investigated. The results showed that the graft efficiency (%) was highest when 89 wt% styrene and 0.11 g of initiator were added for reaction time of 25 h at 85 °C. The surface of graft-modified rubber powder was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive X-ray (EDXS) analysis, and thermogravimetric (TG/DTG) analysis. The results showed that polystyrene (PS) was grafted onto waste rubber powder, which formed a WRP/PS core–shell structure.

Abstract: In this work, living radical polymerizations of a water-soluble monomer poly(ethylene glycol) monomethyl ether methacylate (PEGMA) in bulk with low-toxic iron catalyst system, including iron chloride hexahydrate and triphenylphosphine, were carried out successfully. Effect of reaction temperature and catalyst concentration on the polymerization of PEGMA was investigated. The polymerization kinetics showed the features of “living”/controlled radical polymerization. For example, Mn,GPC values of the resultant polymers increased linearly with monomer conversion. A faster polymerization of PEGMA could be obtained in the presence of a reducing agent Fe(0) wire or ascorbic acid. In the case of Fe(0) wire as the reducing agent, a monomer conversion of 80% was obtained in 80 min of reaction time at 90 °C, yielding a water-soluble poly(PEGMA) with Mn = 65,500 g mol−1 and Mw/Mn = 1.39. The features of “living”/controlled radical polymerization of PEGMA were verified by analysis of chain-end and chain-extension experiments. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Abstract: The surface of silica nanoparticles is modified using the “grafting from” technique. A multi-step reaction is conducted to modify their surface properties. (3-glycidoxypropyl) trimethoxysilane (GPS) is used as the coupling agent for the fixation of atom transfer radical polymerization (ATRP) initiator. The grafting efficiency of GPS mixed with aqueous suspension of silica nanoparticles is studied, followed by the coupling efficiency towards ATRP initiator. The bromide concentration of ATRP initiator is kept constant for comparative kinetic studies of styrene and MMA polymerizations. The consequences at high conversions and the particle size distribution are studied. The behaviour of the glass transition temperature of either polymer-modified particles and the nature of dispersion of polymer-coated silica particles are analyzed.

Abstract: Initiators for continuous activator regeneration atom transfer radical polymerization technique was first accessed to acrylonitrile by using CuBr2/2,2′-bipyridine as the catalyst, ethyl 2-bromoisobutyrate as the halogen initiator, and azobis(isobutyronitrile) as the free radical initiator. The key to success is ascribed to the facile achievement of the rapid equilibrium between active species and dormant species. Effects of ligand, catalyst concentration, free radical initiator concentration, and reaction temperature on the polymerization reaction and molecular weight (MW) as well as polydispersity index (PDI) were investigated in detail. The polymerization proceeded in a controlled/living fashion even though the concentration of copper catalyst decreased to 50 ppm, which is evident in pseudo first-order kinetics of polymerization, linear increase of molecular weight, low PDI, and high chain-end functionality of the generated polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Abstract: The invention relates to a novel selective water shutoff agent for oil well water shutoff, belonging to the technical field of tertiary oil recovery. The water shutoff agent is a composite system of gel particles with the mass concentration of 0.5-5% and a cross-linking agent with the mass concentration of 1-2%, which is prepared by using oilfield injection water; and the water shutoff agent is applicable to water plugging of an oil well at a temperature of 60-120 DEG C. The gel particles are formed by an acrylamide monomer or compounding the acrylamide monomer with a temperature resistant and salt-resistant auxiliary monomer and a cross-linking monomer through copolymerization; the cross-linking monomer is an ester monomer which has a double-bond structure and is easy to resolved when being heated, the expanding and resolving time of the cross-linking monomer at different temperatures can be controlled through adjusting the concentration of the cross-linking monomer, and bulk polymerization or inverse emulsion polymerization is adopted as a polymerization method. In the invention, basically no gel is formed on an oil layer, and high-strength gel can be formed on a water layer, thus defects in the prior art are overcome, the error shutoff phenomenon easily caused by the traditional polymer bulk gel in the oil layer is reduced to the greatest extent, and the capacity of an oil well suffering from water shutoff is ensured.

Abstract: This article first reports a fast and controlled living radical polymerization (LRP) of acrylonitrile, evidenced by 81.3% monomer conversion within 40 min and well-defined the polymers with a narrow polydispersity index (PDI) range of 1.14−1.38. This was achieved by utilizing azobis(isobutyronitrile) as radical initiator with a high concentration up to 190 mM and CuBr2 as catalyst with a very low concentration down to 50 ppm. The polymerization displayed typical LRP characteristics, including pseudo first-order kinetics of polymerization, the linear increase of number-average molecular weights (MWs), low PDI values. The influence of various experimental components, radical initiator concentration, catalyst concentration, and reaction temperature, on the polymerization reaction and MW as well as PDI has been investigated in detail. 1H NMR and gel permeation chromatography analyses as well as chain extension reaction confirmed the very high chain-end functionality of the resultant polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Abstract: The effect of monomer feeding rate on particle size, molar masses, glass transition and tacticity of poly(n-butyl methacrylate) (PBMA) nanoparticles synthesized by semi-continuous heterophase polymerization under monomer-starved conditions is reported. Three feed rates were examined. Highly monomer-starved conditions at the two slower addition rates were confirmed by the low amount of residual monomer throughout the reaction and by the fact that the instantaneous polymerization and feeding rates became similar at later stages of the reaction. Under these conditions, polymer particles in the nanometer range (30 to 35 nm) were obtained. Glass transition temperatures are substantially higher than those reported for commercial PBMA. Polymers tacticity was determined by 13C-NMR spectroscopy. NMR measurements confirm that the syndiotactic content of the PBMA synthesized here is larger than those of the commercial ones made by free-radical polymerization. Molar masses are much lower than those expected from term...

Abstract: Cationic polymerization of L,L-lactide (LA) in the presence of trifluoromethane- sulfonic acid (TfA) has been studied. It was found that propagation proceeds mainly accord- ing to the activated monomer (AM) mechanism. Hydroxyl groups required for this type of propagation are formed as a result of the ring opening of protonated lactide. Thus, part of the acid (acting as an initiator) is consumed for the generation of hydroxyl groups, and part (act- ing as a catalyst) is involved in the protonation of monomer molecules forming secondary oxonium ions which are then able to react with the hydroxyl groups. A dual role of the pro- tic acid is reflected in the kinetic results and in the dependence of experimental degree of polymerization on theoretical values. The structure of active species responsible for polymer chain growth was determined by phosphorus ion-trapping method. The evidence that in the cationic ring-opening polymerization (ROP) of LA initiated by protic acids, both hydroxyl groups and secondary oxonium ions are present throughout the polymerization (as required for polymerization proceeding by the AM mechanism) was found on the basis of changes of the averaged proton chemical shift in 1 H NMR spectra of LA polymerizing mixture.