Poly(methyl methacrylate)s (PMMA)s and poly(methyl acrylate)s (PMA)s are prepared by atom transfer radical polymerization (ATRP) or single electron transfer‐living radical polymerization (SET‐LRP) using methyl dichloroacetate (MDCA) and ethyl dibromoacetate (EDBA) as bifunctional initiators. The chain‐end functionality is determined by MALDI‐TOF mass spectrometry. The target PMMA (Mn = 2000 g mol?1) and PMA (Mn = 2000 g mol?1) samples obtained by ATRP of MMA and MA with MDCA as initiator have 12 and 81 mol% bis‐chloro end groups, respectively; those prepared by SET‐LRP have 57 and 100 mol% bis‐chloro end groups, respectively. The PMMAs obtained by ATRP or SET‐LRP with EDBA have no bromine end groups.
The controlled radical polymerization of 2‐vinylpyridine is reported using commercial blue light‐emitting diodes as visible light source in the presence of S‐1‐dodecyl‐S′‐(α,α′‐dimethyl‐α″‐aceticacid) trithiocarbonate without exogenous initiators or photocatalysts. With this system, poly(2‐vinylpyridine) with well‐regulated molecular weight and narrow dispersity (?) (? = 1.13) and a conversion efficiency of 84.9% is obtained after 9 h irradiation. The polymerization can be instantly switch “on” or “off” in response to visible light while maintaining a linear increase in molecular weight with conversion and first order kinetics. These results demonstrate the simplicity and efficiency of the photocatalysts‐free, visible light mediated reversible addition fragmentation chain transfer polymerization as a platform to achieve well‐defined poly(2‐vinylpyridine) under mild conditions.
Coordinated ionic liquid (IL) monomers provide many of the benefits of conventional ILs in radical polymerization with the advantage of relatively simple synthesis and recovery of the polymer product. Previous studies have reported high solubilities of lithium bistriflimide in polar organic monomers such as methyl methacrylate (MMA), 1‐vinylimidazole (VIm) and others. Here, coordinated IL monomers are formed comprising a variety of alkali and alkaline earth Mn+(Tf2N−)n salts with MMA and VIm, and polymerization behavior is investigated using real‐time attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT‐IR). The size and valency of the coordinated Mn+ cations are observed to strongly influence monomer reactivity, as evidenced by significant changes in FT‐IR spectra. This work further demonstrates that the bulky, delocalized [Tf2N]− anion allows for facile introduction of a wide range of Mn+ cations into organic polymers without phase separation, which may open opportunities for new composite materials.
Poly(methyl methacrylate)‐block‐poly(4‐vinylpyridine), polystyrene‐block‐poly(4‐vinyl pyridine), and poly(ethylene glycol)‐block‐poly(4‐vinylpyridine) block copolymers are synthesized by successive atom transfer radical polymerization (ATRP), single‐electron‐transfer nitroxide‐radical‐coupling (SET‐NRC) and nitroxide‐mediated polymerization (NMP). This paper demonstrates that this new approach offers an efficient method for the preparation of 4‐vinylpyridine‐containing copolymers.
Monomer conversion versus time profiles for the radical polymerization of ionized acrylic acid (AA), 0.6 to 0.8 mol L?1 in aqueous solution, are measured at 50 °C via inline near‐infrared spectroscopy mostly on fully ionized AA, i.e., of alkali acrylates. Ionization reduces polymerization rate with the size of this effect being dependent on the type and on the concentration of the alkali counter cation, which is varied from lithium to rubidium. Polymerization rate becomes very small upon shielding the cation by complexation, whereas an enhancement of cation concentration, by addition of alkali chloride, may enhance polymerization rate such as to even reach the high rates observed with the radical polymerization of nonionized AA.
A new method is developed to synthesize organic microsphere‐supported polymer brushes for affinity separation of saccharides and glycoproteins. In the first step, crosslinked polymer microspheres are synthesized using atom transfer radical polymerization (ATRP). The terminal ATRP initiators on the microspheres are used to graft polymer brushes from propargyl acrylate and N‐isopropyl acrylamide. The microsphere‐supported polymer brushes are conjugated with an azide‐tagged phenylboronic acid to complete the material synthesis. The microsphere‐supported, boronic acid‐containing polymer brushes are able to bind not only low molecular weight cis‐diol compounds but also glycoproteins. The synthetic procedure developed in this work provides a convenient means for preparing all‐organic microsphere‐supported polymer brushes that have high alkaline stability. Using the surface‐attached polymer brushes to immobilize a catalytic glycoprotein (horseradish peroxidase), it is possible to retain on‐particle enzyme activity due to the open structure of the polymer brushes and the oriented immobilization.
An amphiphilic penta‐telechelic polyhedral oligomeric silsesquioxane (POSS)‐containing inorganic/organic hybrid poly(acrylic acid), (Glu‐PAA‐POSS5), is prepared by hydrolysis of penta‐telechelic poly(tert‐butyl acrylate) (Glu‐PtBA‐POSS5), synthesized by the combination of atom transfer radical polymerization (ATRP) and a “click” reaction. The self‐assembly behavior of Glu‐PAA‐POSS5 in aqueous solution at pH 8.5 is investigated by using transmission electron microscopy (TEM), scanning electronic microscopy (SEM), atomic force microscopy (AFM), and dynamic light scattering (DLS). The results show that Glu‐PAA‐POSS5, with a long poly(acrylic acid) (PAA) chain, can self‐assemble in water into giant capsules, which provides an optional approach in the construction of capsules.
The thermally induced spontaneously initiated autopolymerization of methyl methacrylate (MMA) upon air exposure in amide‐type polar solvents at 75–90 °C is unexpectedly observed and then investigated. By using iodometric analysis, it is confirmed that oligo(MMA peroxide)s in situ form at a moderate rate via thermally induced interpolymerization of MMA with O2 diffusing from air above 70 °C and give rise to an equivalent concentration above 10?4 mol L?1 in 2–4 h in N,N‐dimethylacetamide, N,N‐dimethylformamide, and N‐methyl‐2‐pyrrolidinone (in a descending order of the formation rate). Simultaneously, oligo(MMA peroxide) undergoes thermally induced homolytic decomposition into alkyloxyl radicals to initiate polymerization of MMA in the above solvents at a rate comparable to those initiated by chemical initiators. Thus, the thermally induced in situ O2 activation into peroxides via interpolymerization accounts for the spontaneous initiation of the autopolymerization of MMA in these solvents at moderate temperature.
Polymer electrolyte membranes (PEMs) are synthesized via in situ polymerization of vinylphosphonic acid (VPA) within a poly(2,5‐benzimidazole) (ABPBI) matrix. The characterization of the membranes is carried out by using Fourier transform infrared (FTIR) spectroscopy for the interpolymer interactions, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for the thermal properties, and scanning electron microscopy (SEM) for the morphological properties. The physicochemical characterizations suggest the complexation between ABPBI and PVPA and the formation of homogeneous polymer blends. Proton conductivities in the anhydrous state (150 °C) measured by using impedance spectroscopy are considerable, at up to 0.001 and 0.002 S cm?1 for (1:1) and (1:2) molar ratios, respectively. These conductivities indicate significant improvements (>1000×) over the physically blended samples. The results shown here demonstrate the great potential of in situ preparation for the realization of new PEM materials in future high‐temperature and non‐humidified polymer electrolyte membrane fuel cell (PEMFC) applications.
N‐(2‐methylpropyl)‐N‐(1‐diethylphosphono‐2,2‐dimethylpropyl)‐O‐(2‐carboxyprop‐2‐yl) hydroxylamine (BlocBuilder MA) is, among the commercially available alkoxyamines, one of the most efficient for nitroxide‐mediated polymerization (NMP). However, recent results have shown that it does not perform well for the NMP of isoprene. The occurrence of intramolecular hydrogen bonding (IHB) between the carboxylic function and the diethoxyphosphoryl group has been proposed as the reason for its low efficiency. In this article, the presence of this IHB is confirmed using IR, 31P NMR, 31P‐1H HOESY, and DFT calculation results. The solvent effect on this IHB and consequently on kd values is also investigated. However, combining kinetic analysis and rate measurements in various solvents, the influence of this IHB on the C? ON bond homolysis and reformation in alkoxyamine is shown to be very weak.
Triple hydrophilic asymmetric poly(2‐hydroxyethyl acrylate)‐b‐poly(ethylene oxide)‐b‐poly(2‐hydroxyethyl acrylate) (PHEA‐b‐PEO‐b‐PHEA) triblock copolymers are obtained by copper(0) catalyzed reversible deactivation radical polymerization (RDRP). Copper wire catalyzed polymerization of HEA from large PEO (Mn = 35 000 g mol?1) macroinitiator in dimethylsulfoxide or in water fails to reach high monomer conversion in a controlled manner contrary to what is previously published with a shorter PEO macroinitiator. Catalysis by nascent Cu(0) particles generated by disproportionating CuBr in water allows rapid polymerization and high monomer conversion with a rather good control of both dispersity and HEA block length. Model disproportionation experiment shows that HEA influences the disproportionation/comproportionation equilibrium. Larger quantities of HEA lead to higher apparent rate constants and less disproportionation of CuBr which is in agreement with the supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) mechanism and not with the single electron transfer–living radical polymerization (SET‐LRP) mechanism.
A simple and environmentally friendly method for the preparation of composite cathode materials from cost‐effective waste‐product elemental sulfur and sustainable, nonhazardous vegetable oils is presented. High sulfur contents of up to 80 wt% are achieved. Scanning electron microscopy reveals that the composite materials consist of micrometer sized sulfur particles which are embedded in a crosslinked polymeric network. The polymeric network formed upon copolymerization of the fatty acid residues and elemental sulfur is similar to factice. For the first time factice‐like sulfur containing composites are utilized successfully as the active cathode material in Li–S batteries. Upon employment, high initial specific capacities up to 880 mAh g−1, good capacity retention abilities (63% after 100 cycles) as well as high coulombic efficiencies are achieved, suggesting reasonable suppression of polysulfide diffusion as a consequence of the embedment.
The grafting of well‐defined polystyrene to graphene oxide (GO) using nitroxide‐mediated polymerization (NMP) is demonstrated by a two‐step reaction. In the first step, GO is functionalized with glycidyl methacrylate (GMA) to yield GO‐GMA. Polystyrene (PS), previously synthesized via SG1‐based NMP, is then grafted to GO‐GMA by a simple reaction between the SG1 end group and the GMA double bond to yield GO‐GMA‐g‐PS. 1H, heteronuclear single‐quantum correlation (HSQC), nuclear magnetic resonance (NMR), X‐ray photoelectron spectroscopy (XPS), Raman, Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and thermogravimetric analysis (TGA) are consistent with attachment of the GMA group to the GO surface and with polystyrene being grafted to the GO surface to form the GO‐GMA‐g‐PS nanocomposite (NC). GPC analysis shows a number‐average molecular weight of 3330 g mol?1 for the PS with molecular weight dispersity (Ð) of 1.13. Up to 28 mass% of PS has been introduced into the GO NC. The present “grafting‐to” methodology holds promise for the facile and clean synthesis of graphene oxide polymer NCs.
A novel polymerization system with activators generated by electron transfer for atom transfer radical polymerization (ATRP) for sustainable catalyst/ligand separation and recycling in situ is developed based on thermoregulated phase transfer catalysis in organic/aqueous biphasic system. Herein, a typical iniferter agent 1‐cyano‐1‐methylethyldiethyldithiocarbamte is used as the initiator, and CuBr2, monomethoxy poly(ethylene glycol)‐350‐supported substituted dipicolylamine (L350), ascorbic acid, and methyl methacrylate are employed as the catalyst, thermoresponsive ligand, reducing agent, and the model monomer, respectively. The “living” nature of the system is confirmed by polymerization kinetics with recycled catalyst complex aqueous solution and chain‐extension experiments via iniferter and ATRP mechanism, respectively. In addition, the catalyst residue in polymers is less than 2 ppm and the recycling efficiency of catalyst complex in water kept more than 95% even after 5 times of recovery experiments while keeping narrow molecular weight distribution (Mw/Mn < 1.33).
Hydrophilic naphthalene diimide based acceptor polymers are prepared by the incorporation of triethylene glycol or poly(ethylene glycol) side chains in the monomers and subsequent nitroxide‐mediated polymerization (NMP). The kinetic investigation of the polymerization reveals a controlled chain growth as well as a narrow molar mass distribution. Due to the utilization of a functional NMP initiator, a single Ru(II) photosensitizer unit is readily attached at the polymers chain terminus by a modular approach to construct water soluble photoredox‐active acceptor–photosensitizer dyads. The analysis of the optical properties by steady‐state absorption and emission spectroscopy reveals preserved optical absorption properties of the individual building blocks, and, more importantly, an efficient quenching of the Ru(II) emission assigned to intramolecular charge transfer from the complex to the acceptor polymer. The results demonstrate the versatility of side chain modifications to prepare water‐processible photoredox‐active architectures under preservation of the modular character known from hydrophobic systems.
Copolymerization of carbon dioxide (CO2) and propylene oxide (PO) is employed to generate amphiphilic polycarbonate block copolymers with a hydrophilic poly(ethylene glycol) (PEG) block and a nonpolar poly(propylene carbonate) (PPC) block. A series of poly(propylene carbonate) (PPC) di‐ and triblock copolymers, PPC‐b‐PEG and PPC‐b‐PEG‐b‐PPC, respectively, with narrow molecular weight distributions (PDIs in the range of 1.05–1.12) and tailored molecular weights (1500–4500 g mol?1) is synthesized via an alternating CO2/propylene oxide copolymerization, using PEG or mPEG as an initiator. Critical micelle concentrations (CMCs) are determined, ranging from 3 to 30 mg L?1. Non‐ionic poly(propylene carbonate)‐based surfactants represent an alternative to established surfactants based on polyether structures.
A convenient one‐pot method for the controlled synthesis of polystyrene‐block‐polycaprolactone (PS‐b‐PCL) copolymers by simultaneous reversible addition–fragmentation chain transfer (RAFT) and ring‐opening polymerization (ROP) processes is reported. The strategy involves the use of 2‐(benzylsulfanylthiocarbonylsulfanyl)ethanol (1) for the dual roles of chain transfer agent (CTA) in the RAFT polymerization of styrene and co‐initiator in the ROP of ε‐caprolactone. One‐pot polymerizations using the electrochemically stable ROP catalyst diphenyl phosphate (DPP) yield well‐defined PS‐b‐PCL in a relatively short reaction time (≈4 h; = 9600?43 600 g mol?1; / = 1.21?1.57). Because the hydroxyl group is strategically located on the Z substituent of the CTA, segments of these diblock copolymers are connected through a trithiocarbonate group, thus offering an easy way for subsequent growth of a third segment between PS and PCL. In contrast, an oxidatively unstable Sn(Oct)2 ROP catalyst reacts with (1) leading to multimodal distributions of polymer chains with variable composition.
Reverse iodine transfer polymerization (RITP) of 1,1,2,2‐tetrahydroperfluorodecyl acrylate (FDA) is successfully performed in supercritical carbon dioxide (scCO2) at 70 °C under a CO2 pressure of 300 bar. PolyFDA (PFDA) of increasing molecular weights (from 10 000 to 100 000 g mol?1) is synthesized with good agreement between theoretical, 1H NMR spectroscopy and and size exclusion chromatography/refractive index/right‐angle laser‐light scattering/differential viscometer (SEC/RI/RALLS/DV)‐estimated molecular weights (). Furthermore, the increase of goes with a decrease of the dispersity of the polymers (? from 2.06 to 1.33), which is consistent with a controlled radical polymerization (CRP). Lastly, the structure of final PFDA and therefore the RITP process are confirmed by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) analyses.
Synthesis of multiarm star polymers via “core first” method but possibly through two different chain growth fashions has been described. Two distinct styrenyl‐TEMPO‐based G3 and G4 dendritic unimolecular initiators have been used for this method. Polymerization of styrene using these core‐cum‐initiators at 125 °C varying the monomer to initiator ratio and polymerization time yields multiarm star polymers with molecular weight (Mw) in the range of 1.71 × 105 to 4.75 × 105 g mol?1 and polydispersity in the range of 1.34–1.46. Hydrolysis leading to degradation of inner polyurethane core yields highly narrow dispersed—PDI 1.00 to 1.04—polystyrene chains, and the SEC‐MALLS data of these chains confirm the accurate control on predetermination in the number of arms up to 48 of star polymers. The specific refractive index increment (dn/dc) of the polymers is found to be decreased with decreasing weight fraction of core. The transmission electron microscope (TEM) and atomic force microscopy (AFM) images and hydrodynamic radius of chosen polymers confirm the two different chain growth fashions leading to the formation of star polymers as discrete nanoparticle in the case of initiator in which TEMPO is anchored and formation of peripherally low entangled short chains in the case of initiators in which TEMPO is end‐capped.
A novel Janus compound containing azo‐based thermal initiator and bromo‐based atom transfer radical polymerization (ATRP) initiator group is synthesized. Such compound can be applied in the living radical polymerization of alkyl methacrylate monomers, such as methyl methacrylate, tert‐butyl methacrylate, and 2‐(N,N‐dimethylamino) ethyl methacrylate. Polymers with controlled molecular weights and narrow molecular weight distributions are obtained. The structure of polymers is identified by 1H NMR spectroscopy and matrix‐assisted laser desorption ionization time‐of‐flight mass spectrum. A modified initiator for continuous activator regeneration ATRP mechanism is proposed according to the polymerization behavior, hydrolysis of chain backbone, and end group identification.
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