Abstract: The polymerization of ethylene with late transition metal complexes typically provides highly branched amourphous poly(ethylene)s through a chain-walking mechanism, while the chain-straightening polymerization of α-olefins gives semicrystalline polymers. Herein, we report the polymerization of 1-hexene, 1-octene, and 1-dodecene catalyzed by an α-diimine Ni(II) complex in combination with diethylaluminum chloride. The effect of monomer chain length and monomer concentration on the productivity, polymerization “livingness”, selectivity of monomer insertion, and polymer structure/properties is investigated. The polymerization results indicate the possibility of precise microstructure control, depending on the monomer employed and monomer feedstock concentration, which in turn strongly affects the physical polymer properties. Additionally, di- and triblock copolymers were successfully fabricated in an easy, high-yielding route, at room temperature. The synthesis was accomplished through the sequential monomer...

Abstract: The migration and transport of polymerization initiators are problematic for commercially used polymerization procedures. For example, UV printing of packaging generates products with potentially harmful components that come in contact with food. Enlarging the size of the initiator is the only way to prevent contamination, e.g., by gas phase transport. In this manuscript, the synthesis and advanced and full analyses of novel nanoparticle-based types of non-migration, fragmenting and non-fragmenting photo-initiators will be presented in detail. This study introduces non-fragmenting/“Norrish type II” and fragmenting/“Norrish type I” ZnO nanoparticle-based initiators and compares them with two commercial products, a “Norrish type I” initiator and a “Norrish type II” initiator. Therefore, inter alia, the recently developed analysis involves examining the solidification by UV-vis and the double bond content by Raman. Irradiation is performed using absolute and spectrally calibrated xenon flash lights. A novel procedure for absolute and spectral calibration of such light sources is also presented. The non-optimized “Norrish type II” particle-based initiator is already many times faster than benzophenone, which is a molecular initiator of the same non-fragmenting type. This experimentally observed difference in reactive particle-based systems without co-initiators is unexpected. Co-initiators are normally an additional molecular species, which leads to migration problems. The discovery of significant initiation potential resulting in a very well-dispersed organic–inorganic hybrid material suggests a new field of research opportunities at the interface of physical chemistry, polymer chemistry and engineering science, with enormous value for human health.

Abstract: A one-step method that converts soybean oil into (acryloylamino)ethyl soyate, a new vinyl monomer of free radical polymerization, was developed. The synthesized monomer combines a vinyl double bond (acryloyl functional group) and nonconjugated (isolated) double bonds of fatty acids. The double bond of the acryloyl group is reactive in a free radical chain polymerization that yields linear macromolecules containing isolated double bonds in side chains. Monomer reactivity ratios (r1, r2) in copolymerization of the new soybean oil-based acrylic monomer (SBA) with styrene, methyl methacrylate, and vinyl acetate, as well as the Q–e parameters of the SBA, were determined. The obtained results indicate that copolymerization can be described with the classical Mayo–Lewis equation. In terms of polymerizability, the SBA can be classified as an acrylic monomer. The double bonds of the fatty acid chains remain mainly unaffected during the free radical polymerization. The remaining unsaturated fragments in the side ch...

Abstract: The molecularly imprinted polymer (MIP) based on methacrylic acid functionalized β-cyclodextrin (MAA-β-CD) monomer was synthesized for the purpose of selective recognition of benzylparaben (BzP). The MAA-β-CD monomer was produced by bridging a methacrylic acid (MAA) and β-cyclodextrin (β-CD) using toluene-2,4-diisocyanate (TDI) by reacting the -OH group of MAA and one of the primary -OH groups of β-CD. This monomer comprised of triple interactions that included an inclusion complex, π-π interaction, and hydrogen bonding. To demonstrate β-CD performance in MIPs, two MIPs were prepared; molecularly imprinted polymer-methacrylic acid functionalized β-cyclodextrin, MIP(MAA-β-CD), and molecularly imprinted polymer-methacrylic acid, MIP(MAA); both prepared by a reversible addition fragmentation chain transfer polymerization (RAFT) in the bulk polymerization process. Both MIPs were characterized using the Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and Brunauer-Emmett-Teller (BET). The presence of β-CD not only influenced the morphological structure, it also affected the specific surface area, average pore diameter, and total pore volume of the MIP. The rebinding of the imprinting effect was evaluated in binding experiments, which proved that the β-CD contributed significantly to the enhancement of the recognition affinity and selective adsorption of the MIP.

Abstract: The free-radical redox-initiated aqueous solution polymerization of fully and partially neutralized acrylic acid was carried out at room temperature under full exposure to air The effect of neutralization degree on the polymerization rate and product properties was studied Increasing neutralization of the reaction mixture with sodium hydroxide resulted in greater conversion of acrylic acid to sodium acrylate The rate of polymerization, determined from a gravimetric off-line water removal technique, was shown to decrease significantly with decreasing degree of neutralization Molecular weight also decreased with decreasing degree of neutralization The glass transition temperature and hydrophilicity of the polymer product decreased with increasing degree of neutralization In-line infrared monitoring was also used to monitor the reaction progress and was shown to be an effective tool for this purpose

Abstract: A series of (±)- and (R,R)-tridentate diamino, ortho/para disubstituted phenolate proligands H(NNOR) with various phenolate substituents was synthesized and used to prepare indium dichloride complexes (NNOR)InCl2via salt metathesis of the deprotonated ligands with indium trichloride. These complexes are dinuclear in the solid state, in contrast to previously reported complexes with t-butyl or methyl phenolate substituents. Solution state 1H and PGSE NMR spectroscopy suggests that a fast exchange between the monomeric and dimeric forms of these complexes may exist in solution and is likely influenced by the chirality of the complexes undergoing aggregation. The indium dichloride complexes were utilized to synthesize dinuclear indium ethoxide complexes via salt metathesis with sodium ethoxide. These complexes were active for the polymerization of lactide. In situ and bulk polymerization data confirmed differences in the activity and selectivity of these systems based on the phenolate substituents as well as the ligand chirality.

Abstract: Dipalladium complexes of a cyclic bis(diimine) ligand with a double-decker structure catalyze polymerization of ethylene and α-olefins and copolymerization of ethylene with 1-hexene. The polymerization of 1-hexene yields a polymer that is mainly composed of the hexamethylene unit formed by 2,1-insertion of the monomer into the palladium-carbon bond, followed by chain-walking (6,1-insertion). The polymerization of 4-methyl-1-pentene proceeds by 2,1-insertion with a selectivity of 92-97 %, and affords the polymer with methyl and 2-methylhexyl branches. 2,1-Insertion occurs selectively in all of the polymerization reactions of α-olefins catalyzed by the dipalladium complexes. Ethylene polymerization with the catalyst at 100 °C lasts over 24 h, whereas the monopalladium-diimine catalyst loses its activity within 8 h at 60 °C. Polyethylene obtained by the dipalladium catalyst is less-branched and has a higher molecular weight compared to that of the monopalladium catalyst under the same conditions. Copolymerization of ethylene with 1-hexene affords solid products with melting points and molecular weights that vary depending on the polymerization time, suggesting formation of a block and/or gradient copolymer.

Abstract: Stable white-emitting down-converted LEDs are straightforwardly prepared by bulk polymerization of an organic dye doped polymethyl-methacrylate (PMMA) shell directly on top of a highly efficient commercial blue-emitting InGaN LED. Our optimized polymerization procedure allows for extending the form factor of achievable luminescence converter (LUCO) material beyond the conventional thin film form and to directly produce devices with light bulb design. The selected organic dyes, the blue-emitting Coumarin 30 and a red-emitting diketopyrrolopyrrole derivative, exhibit high compatibility with the free radical polymerization reaction of the PMMA matrix and ensure high stability of the final hybrid device. The control of both the thickness of the PMMA shell and the concentration of the dopant dyes allow for fine tuning of the emission color of the LUCO LED and to obtain white light with CIE chromatic coordinates x = 0.32 and y = 0.33, with rendering index as high as 80. This simple and versatile procedure is not dye-exclusive and is therefore extendable to other molecular systems for color-tunable efficient solid-state lighting sources.

Abstract: The in situ generation of an anionic initiator X– obtained by the deprotonation of various secondary amides with tBuP4 phosphazene base was tested as possible way to initiate the polymerization of 1,2-epoxybutane. The initiation efficiency of different amide-containing molecules was investigated. Particular attention was given to the detection of eventual transfer or side reactions, especially due to nucleophilic attacks on the initiator moiety at the α-chain end. In all cases, the initiation of the polymerization by the amidate anion was effective. And in most cases, the polymerization proceeded in a controlled manner to afford amide end-capped poly(butylene oxide) with narrow molar mass distribution and expected molar masses.

Abstract: Mizoroki-Heck coupling polymerization of 1,4-bis[(2-ethylhexyl)oxy]-2-iodo-5-vinylbenzene (1) and its bromo counterpart 2 with a Pd initiator for the synthesis of poly(phenylenevinylene) (PPV) was investigated to see whether the polymerization proceeds in a chain-growth polymerization manner. The polymerization of 1 with tBu3PPd(Tolyl)Br (10) proceeded even at room temperature when 5.5 equiv of Cy2NMe (Cy = cyclohexyl) was used as a base, but the molecular weight distribution of PPV was broad. The polymerization of 2 hardly proceeded at room temperature under the same conditions. In the polymerization of 1, PPV with H at one end and I at the other was formed until the middle stage, and the polymer end groups were converted into tolyl and H in the final stage. The number-average molecular weight (Mn) did not increase until about 90% monomer conversion and then sharply increased after that, indicating conventional step-growth polymerization. The occurrence of step-growth polymerization, not catalyst-transfer chain-growth polymerization, may be interpreted in terms of low coordination ability of H-Pd(II)-X(tBu3P) (X = Br or I), formed in the catalytic cycle of the Mizoroki-Heck coupling reaction, to π-electrons of the PPV backbone; reductive elimination of H-X from this Pd species with base would take place after diffusion into the reaction mixture. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 543–551

Abstract: We couple UV–vis and FT–NIR spectroscopy for the real-time monitoring of polymerization reactions, allowing the simultaneous tracking of the rates of light absorption and initiator/monomer consumption, from which dynamic and previously difficult-to-measure parameters are calculated: quantum yields of initiator consumption, initiation and polymerization, photosensitivity, and residual content of leachable chromophore. Estimating these parameters from one set of experiments is not possible with any other probing technique. We demonstrate the potential of this technique using the free radical initiating system including camphorquinone as photoreducible chromophore and amines as reductants for the visible-light-triggered bulk polymerization of methacrylate monomers, important for dental and biomaterials. Photoinitiation by camphorquinone/amine pairs in two dimethacrylates serves to show the importance of obtaining quantum yields in the polymerizing medium instead of using inert solvents. Additionally, the oft...

Abstract: Heterogeneous polymer brushes on surfaces can be easily formed from a binary initiator on a silicon oxide substrate where two different types of polymers can be grown side-by-side. Herein, we designed a new Y-shaped binary initiator using straightforward chemistry for “grafting from” polymer brushes. This initiator synthesis takes advantage of the Passerini reaction, a multicomponent reaction combining two initiator sites and one surface linking site. This Y-shaped binary initiator can be synthesized in three steps with a higher yield than other similar initiators reported in the literature, and can be performed on a multigram scale. We were able to attach the initiator to a silicon oxide substrate and successfully grow polymer brushes from both initiators (separately and in combination), confirmed by NEXAFS, AFM, and contact angle.

Abstract: Provided is a method for producing water-absorbent resin particles suitable for use in absorbent article and the like, the water-absorbent resin particles having better water-absorbent performance, a suitable particle size, and a narrow particle-size distribution. A method for producing water-absorbent resin particles by reversed-phase suspension polymerization of a water-soluble ethylenic unsaturated monomer in a carrier fluid, wherein the method for producing water-absorbent resin particles comprises conducting the reversed-phase suspension polymerization reaction in the presence of an organic acid monoglyceride.

Abstract: The aim of this study was to analyze the unreacted monomers of four commonly used composite resins, which were released after curing with different polymerization conditions. Four composite resins, consisting of two hybrid types and two flowable types from two manufacturers, were photopolymerized using different curing times and curing distances. After polymerization, samples were extracted for analysis at different time points up to 24 h. Released monomers were analyzed by reversed-phase liquid chromatography at UV 210 nm. Longer curing times and shorter curing distances resulted in higher polymerization rates and decreased release of TEGDMA and UDMA, but changes in curing time and distance had no significant effect on Bis-GMA. Release of BPA increased with increase in curing time or decrease in curing distance, in contrast to the results of TEGDMA and UDMA. Polymerization conditions need to be differently applied according to both monomer and resin types.

Abstract: The copolymer of styrene and methylmethacrylate containing reduced graphene oxide/silver nanoparticles (PS-PMMA/RGO/AgNPs) nanocomposite were prepared via in situ bulk polymerization method using two different preparation techniques. In the first approach, a mixture of graphene oxide (GO), styrene (S) and methylmethacrylate monomers (MMA) were polymerized using a bulk polymerization method with a free radical initiator. After the addition silver nitrate (AgNO3), the product was reduced via microwave irradiation (MWI) in presence of the reducing agent hydrazine hydrate (HH), to obtain R-(GO-(PS-PMMA))/AgNPs nanocomposite. This nanocomposite was then used to create a material that had antimicrobial properties to be used in medical devices or medical related implants.

Abstract: An initiating system composed of GaCl3 and an alkylbenzene was demonstrated to be highly effective for the controlled cationic polymerization of a plant-derived monomer, β-pinene. Alkylbenzenes such as pentamethylbenzene and hexamethylbenzene were shown to function as suitable additives for the polymerization of β-pinene, an alkene monomer with low reactivity, although the alkylbenzenes are much less basic than conventional additives such as esters and ethers for base-assisting living cationic polymerization. For example, when two equivalents of hexamethylbenzene were added to GaCl3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, cationic polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction, i.e., control of an active–dormant equilibrium, was attributed to the formation of a complex between GaCl3 and the alkylbenzene, as confirmed by UV–vis and 71Ga NMR analyses. An initiating system composed of GaCl3 and an alkylbenzene was demonstrated to be highly effective for the controlled cationic polymerization of a plant-derived monomer, β-pinene. When two equivalents of hexamethylbenzene were added to GaCl3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, cationic polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction was attributed to the formation of a complex between GaCl3 and the alkylbenzene, as confirmed by UV–vis and 71Ga NMR analyses.

Abstract: A convenient real-time monitoring of monomer concentration during living cationic ring-opening polymerizations of tetrahydrofuran (THF) initiated with methyl triflate (MeOTf) has been developed for kinetic investigation and determination of equilibrium monomer concentration ([M]e) via in situ FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance (ATR) immersion probe. The polymerization rate was first order with respect to monomer concentration and initiator concentration from the linear slope of ln([M]0-[M]e)/([M]-[M]e) versus polymerization time at different temperatures in various solvents. [M]e decreased linearly with initial monomer concentration while increased exponentially with increasing polymerization temperature. The equilibrium also strongly depends on solvent polarity and its interaction with monomer. The equilibrium polymerization time (te) decreased with increasing solvent polarity and decreased linearly with increasing [M]0 in three solvents with different slopes to the same point of bulk polymerization in the absence of solvent. Equation of Mn,e = 72.1/(0.14-0.04[M]e) has been established to provide a simple and effective approach for the prediction for the number-average molecular weight of polyTHFs at equilibrium state (Mn,e) in the equilibrium living cationic ring-opening polymerization of THF at 0 °C.

Abstract: The invention relates to a preparation method of a slow-release solid polycarboxylic acid water reducing agent, which comprises the following steps: pretreating carboxylic acid small monomer containing unsaturated double bond by using amine organic small molecule; and after heating to melt the pretreated unsaturated acrylic small monomer and unsaturated polyethenoxy ether big monomer, dropwisely adding unsaturated ester small monomer to perform mass polymerization reaction under the action of an initiator and a chain-transfer agent in a water-free organic-solvent-free environment. The slow-release solid polycarboxylic acid water reducing agent prepared by the mass polymerization process in the water-free solvent-free environment has the advantages of simple and controllable technique, transportation cost saving, environment friendliness, no pollution and the like, achieves the goal of slow release and keeping the slump for 3-4 hours without loss in concrete, and has wide market application prospects.

Abstract: The synthesis of sub-100 nm polymeric nanoparticles in a surfactant-free form is currently very challenging due to the oil nanoemulsion instability in polar solvents and in the absence of stabilizers. Here we report for the first time the surfactant-free synthesis method of poly(styrene-co-divinylbenzene) nanoparticles in an aqueous environment using ultrasonic radiation. This method involves emulsification of the monomers mixture in water, followed by free-radical polymerization under pulsed or continuous acoustic fields. The local energy produced in water by cavitation effects was sufficient to: (1) generate and stabilize the monomer nanoemulsion due to mechanical forces, and (2) drive the radical polymerization due to the heat generated. The average size of the final polymer nanoparticles obtained depended: (i) inversely on the monomer/water interfacial energy, emulsification power, and (ii) directly on temperature, amount of initiator and monomer solubility. The polymer nanoparticle size distribution and shape was considerably improved upon the addition of a co-polymerizable surfactant.

Abstract: The comparison between methyl methacrylate (MMA) and styrene (St) RAFT emulsion polymerization using oligo(methacrylic acid41-b-methyl methacrylate8) RAFT agent (oligo(MAA41-b-MMA8) RAFT) as surfactant is investigated in order to gain a better understanding on RAFT emulsion polymerization of MMA. It is found that the colloidal stability during MMA emulsion polymerization is much more sensitive to the initiator concentrations and temperature than that of St polymerization. The coagulum-free latex of highly living PMMA can be achieved only at 80 °C and low initiator concentrations. The final PDI is higher in RAFT emulsion polymerization of MMA than that of St. It is revealed that about 40% acid groups of oligo(MAA41-b-MMA8) RAFT should be buried within the final particles of PMMA, indicating that particle coagulation should occur in the very beginning of the polymerization. The poorer performance of the MMA polymerization could be well explained by the homogeneous nucleation mode of particles combined with relatively slow transporting rate of oligo(MAA41-b-MMA8) RAFT molecules from the partly frozen micelles to the newly-born particles.

Abstract: A new ion-imprinted polymer (IIP) was synthesized by bulk polymerization from 2-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (EGDMA; the cross-linker), 2, 2′- azobisisobutyronitrile (the initiator), diphenylcarbazone (the ligand), and nickel nitrate (the template ion) in acetonitrile solution. The prepared IIP was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, and studied for the preconcentration and determination of trace nickel ion from aqueous solutions using inductive couple plasma optical emission spectroscopy. The optimal pH value for the quantitative preconcentration was 6.0 and maximum sorbent capacity was 3.26 mg g−1. Under the optimized conditions, the method had a linear analytical range from 0.5 to 50 μg L−1. The detection limit, relative standard deviation, and recovery of the method were evaluated as 0.38 μg L−1, 3.6% and 95–98%, respectively. The developed method was successfully applied to the selective extractio...

Abstract: Titanium complexes with dialkanolamine (1, 2) and salen ligands (3), as well as titanium alkoxide containing two fragments of an unsaturated alcohol (cis-but-2-ene-1,4-diol) ase-ligands (4), were studied in the anionic ring-opening bulk polymerization of ɛ-caprolactone (CL) at 80–130 °,C. All the catalysts involved initiate controlled polymerization and afford polyesters with a number-average molecular weight up to Mn = 20 000 g mol−1, which can be regulated by adjusting the [monomer]: [catalyst] ratio. Among the catalysts studied, complex 2 is most efficient in CL polymerization and affords polyesters with the narrowest molecular weight distribution (Mw/Mn < 1.2). In addition, complex 2 initiates the controlled polymerization of d,l-lactide (LA) and is effective in the synthesis of random and block copolymers of CL and LA.