Iodo functionalized polyethylene (PE‐I), prepared by the addition of iodine after catalyzed polyethylene chain growth on magnesium, is demonstrated to be an efficient macroinitiator for thermally induced, controlled free radical polymerization using dimanganese decacarbonyl (Mn2(CO)10). The free radical polymerization of methyl methacrylate is initiated by thermal homolysis of (Mn2(CO)10) at 80 °C, forming reactive manganese pentacarbonyl radical species [?Mn(CO)5] capable of activating the C?I bond of PE‐I. The metal catalyzed radical generation and degenerative iodine processes yielded polyethylene‐b‐poly(methyl methacrylate) (PE‐b‐PMMA) block copolymers with relatively low dispersities. The end group functionality of the block copolymer is confirmed by the successful thermal polymerization of styrene by using PE‐b‐PMMA as a macroinitiator in the described process. This work conclusively provides a new approach for combining polyethylene with vinyl polymers via manganese chemistry in a simple and efficient pathway of importance in synthetic polymer chemistry and other related applications.
Alternating copolymers of an oligopeptide (N3‐GVGV‐N3, where G: glycine; V: valine) and an oligothiophene (5,5′‐bis(ethynyl)‐3,3'‐dioctyltetrathiophene) are prepared by click chemistry. The experimental results discover that these copolymers exhibit strong molecular‐weight‐dependent self‐assembly behaviors. The copolymer P1 with the lowest weight‐average molecular weight ( = 7400 g mol?1), assembles into well‐ordered fibrous nanostructures. P3 ( = 16 980 g mol?1) assembles into nanoballs. P2, which has the medium between P1 and P3, ( = 14 800 g mol?1), exhibits more‐complicated self‐assembly behaviors, more like a transition state between the other two. All of the results suggest the self‐assembly ability of these oligopeptide segments might be the major reason for the nano‐structure evolution.
A family of novel (X‐TATAT)n‐type conjugated polymers based on the carbazole (X), thiophene (T), and benzoxadiazole (A) moieties is designed and explored as electron‐donor materials for organic bulk heterojunction solar cells. Incorporation of the branched side chains of different size and shape affects significantly the optoelectronic properties of the materials, particularly frontier energy levels of polymers translated to the open circuit voltages of the photovoltaic cells. The revealed unprecedented correlation between the parameters of the solar cells (V OC, fill factor (FF), J SC) and bulkiness of the alkyl side chains provides useful guidelines for rational design of novel materials for organic photovoltaics.
A new synthetic pathway for the polymerization of furan based polyesters is reported in this work. First, poly(butylene 2,5‐furandicarboxylate) cyclic oligoesters (COEs) are chemically synthesized by semi‐batch esterification. The structure of the COEs is confirmed by infrared spectroscopy, 1H, and 13C‐NMR, while the molecular weight distribution of the COEs is determined by matrix‐assisted laser desorption/ionization time of flight mass spectroscopy. The cyclic oligoesters are then successfully polymerized via ring‐opening polymerization using tetrakis(2‐ethylhexyl)‐titanate as catalyst. Differential scanning calorimetry and 1H‐NMR analysis unambiguously proves the formation of polymeric species. Both end‐group analysis from 1H‐NMR spectrum and calculation through Flory–Fox equation give comparable estimates of the number average molecular weight: 5.8 × 103 g mol?1 and 7.8 × 103 g mol?1, respectively.
A novel strategy for the preparation of hybrid particles of optically active polymer and silica is developed via combination of chemoenzymatic transesterification, reversible addition‐fragmentation chain transfer (RAFT) polymerization, and click reaction for the first time. During this procedure, Novozym 435 is employed to catalyze the transesterification between 2,2,2‐trifluoethyl methacrylate monomer and 2‐octanol to form the target monomer (R)‐OMA, which synchronously participates in RAFT polymerization to obtain a new polymer with transformed optically active side groups. Compared with RAFT polymerization, the transesterification reaction is much faster, with conversion ratio reaching 93% after 7 h; subsequently, the polymerization is nearly homo‐polymerization of (R)‐OMA. The molar fraction of (R)‐OMA in the final polymer is about 97.8% with controlled molecular weight (Mn ≈ 6840 g mol?1) and a narrow polydispersity index (≈1.25). Finally, the hybrid particles of silica and optically active polymer P((R)‐OMA) are obtained by the thiol‐ene click reaction. The Fourier transform infrared, X‐ray photoelectron spectroscopy, and transmission electron microscopy results exhibit the successful graft of P((R)‐OMA) polymer to the silica surface, and the P((R)‐OMA) polymer in the hybrid particles is about 10 wt% from the TGA curves. These as‐prepared hybrid particles combine excellent mechanical stability of silica and good chirality of polymer, making them promising for chromatographic resolution, catalytic synthesis, and (stereo‐) selectivity applications.
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.
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.
Stationary and time‐resolved electron spin resonance spectroscopy measurements are employed to investigate the kinetics of the surface‐initiated reversible addition fragmentation chain transfer (RAFT) polymerization of n‐butyl acrylate from silica nanoparticles using both R‐ and Z‐group‐attached trithiocarbonates as RAFT agents. The obtained kinetic parameters reveal that the addition rate coefficient in the main equilibrium of RAFT graft polymerizations is significantly smaller than the one for comparable RAFT polymerizations in solution phase, as translational diffusion of surface‐attached molecules is limited. In comparison to the R‐group approach, the equilibrium constants of the Z‐group approach are about one to two orders of magnitude smaller due to a stronger shielding of the RAFT moieties.
Iron‐mediated atom‐transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in N‐methylpyrrolidin‐2‐one (NMP) solution is investigated via online VIS/NIR spectroscopy up to 2500 bar. The activation–deactivation equilibrium constant, KATRP, decreases towards higher NMP content due to the formation of catalytically less active FeII/NMP species. The reaction volume increases from 1 to 15 cm3 mol?1 in passing from 16 to 92 mol% NMP. The same effects are observed for monomer‐free model systems with poly(MMA)–Br as the initiator. Investigations into iron‐catalyzed ATRP of MMA in less polar solvents or even without an additional solvent (i.e., for bulk ATRP) yield KATRP values, which are by two to three orders of magnitude higher than in the presence of NMP.
A novel pyrene‐functionalized thiophene compound ( Thi‐Pyr ) and pyrene‐functionalized styrene polymers ( P7–9 ) are synthesized via 1,3‐dipolar cycloaddition reaction between the azide functional groups of the precursors and 1‐ethynylpyrene. Glass transition temperature of the styrene polymers increases remarkably upon the covalent attachment of the pyrene unit through triazole linkers, whereas the thermal stabilities of the styrene polymers are not affected by the incorporation of pyrene moieties. Thi‐Pyr exhibits the characteristic pyrene monomer emission bands; on the other hand, P7–9 show the excimer emission bands of pyrene due to the excitation of ground state dimeric species. The monomer emissions of Thi‐Pyr and the excimer emissions of P7–9 are distinguishably increased by the addition of HP2O73?, Cl?, and Br? anions. The responses of Thi‐Pyr and P7–9 to the addition of HP2O73? are stronger than any other anions, indicating their selectivity to HP2O73? anion to some extent.
A series of conjugated microporous polymers (CMPs) from 1,3,6,8‐tetrabromocarbazole and its alkylated derivative is synthesized via Suzuki cross‐coupling polycondensation. These polymer networks are stable in common organic solvents and thermally stable. The pore properties (pore size and surface area) of this kind of CMPs can be tuned by using either a linker with different geometries or carbazole substituted with alkyl groups. All of the polymers show high isosteric heats of CO2 adsorption (27.1–30.8 kJ mol?1) because the incorporation of nitrogen atoms into the skeleton of the CMP enhances the interaction between the pore wall and CO2 molecules. The polymer PPTBC shows a high Brunauer–Emmett–Teller specific surface area up to 917 m2 g?1 with a high CO2 uptake ability of 2.93 mmol g?1 at 1.13 bar/273 K. These data show that these materials are potential candidates for applications in post‐combustion CO2 capture and sequestration technology.
Spontaneous catalyst‐free polymerizations of 4‐ethynylpyridine (4EPy) and 2‐ethynylpyridine with bifunctional quaternizing agents (QAs) of bis(bromomethyl)arenes provide highly crosslinked polymer networks in high yields. 13C cross‐polarization magic‐angle spinning (CP/MAS) NMR, Fourier transform IR (FTIR) and diffuse reflectance vis spectroscopy confirm that these networks consist of polyacetylene main chains substituted with pyridyl and pyridiniumyl groups, the latter interconnected with –CH2(arylene)CH2– linkers. Variation of the 4EPy/QA ratio in the polymerization feed results in networks with different extents of crosslinking and pyridyl/pyridiniumyl ratio (N/N+ from 0 to 1.32). Networks exhibit photoluminescence and are also moderately active in CO2 capture (the highest uptake is 16.4 cm3 (STP) g?1 at 293 K and an equilibrium CO2 pressure of 750 Torr).
A novel type of single white‐light‐emitting copolymers, PF‐DTFOx, derived from poly(9,9‐dioctylfluorene) (PF) in which 2,7‐di‐(2‐thienyl)‐9‐fluorenone (DTFO) is introduced as an orange‐emitting unit, is reported, and their application in white‐light polymer light‐emitting devices (PLEDs) is explored. Because of the very simple structure of DTFO, the synthetic routes to PF‐DTFOx are not complicated, and the raw materials are cheap; these are advantageous in reducing the fabrication cost of white‐light PLEDs. In the fluorescence spectra, PF‐DTFOx in solid powder shows dual peaks at around 460 and 560 nm. In white‐light PLEDs, the color of the white‐light emission is tunable; this can be achieved by changing the content of DTFO in PF‐DTFOx. The light‐emission color varies from blue‐white to pure white and orange‐white when the composition of DTFO increases. All the PLEDs based on PF‐DTFOx exhibit maximum luminance above 1800 cd m?2 and a color rendering index above 80.
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.
Polynorbornenes with allylic acetoxy terminus are obtained by ring‐opening metathesis polymerization of the norbornene derivatives followed by quenching with 1,4‐diacetoxy‐2Z‐butene. Treatment of these polymers with a range of nucleophiles in the presence of a Pd‐catalyst gives the corresponding polynorbornenes bearing different end groups. The same protocol is used to modify the end groups of polymeric ladderphanes. Incorporation of an end‐group‐modified polynorbornene on indium tin oxide (ITO) surface perturbs the electrochemical properties of the ITO electrode.
The cationic polymerization of 1,3‐pentadiene using a tert‐butyl chloride (tBuCl)/TiCl4 initiating system in CH2Cl2 at different reaction conditions is reported. It is shown that the reaction rate increases with the increase of the tBuCl/TiCl4 molar ratio, while the molecular weight distribution becomes narrower. Well‐defined oligo(1,3‐pentadiene)s ( ≤ 3500 g mol?1; / ≤ 3.0) are obtained at high tBuCl/TiCl4 molar ratio (340) and low temperature (–78 °C). 1H and 13C NMR spectroscopy studies reveal the presence of tert‐butyl head and –CH2–Cl end groups. The number‐average functionalities (Fns) at the α‐ and ω‐ends are calculated to be Fn(tBu) > 1 and Fn(Cl) < 1, respectively. The general mechanism of 1,3‐pentadiene polymerization is proposed.
In this paper, the acid–base bifunctional microporous organic nanotube networks (MONNs–SO3H–NH2) are successfully prepared by combination of hyper‐crosslinking core–shell bottlebrush copolymers and a postfunctionalization strategy. Based on the large surface area, good multiporosity interconnectivity, and robust organic frameworks, the acid–base bifunctional MONNs catalyst shows a high catalytic activity and excellent reusability for one‐pot cascade reactions.
A facile and novel method for the synthesis of monodisperse hyper‐crosslinking polymer nanoparticles (HPNs) is reported in the combination of vesicle bilayer templating and hyper‐crosslinking technology. Monodisperse polymer nanoparticles (PNs) around 61 nm are first obtained through the confined reaction of vinylbenzyl chloride and divinylbenzene in the bilayers of the vesicles, and then the PNs are turned into HPNs through the Friedel–Crafts‐type hyper‐crosslinking reaction. The finally obtained HPNs demonstrate small and uniform size, high Brunauere–Emmette–Teller surface area up to ≈1300 m2 g−1, a very high micropore area above 1000 m2 g−1 and a micropore volume of 0.55 cm3 g−1. In addition, they also show the carbon dioxide adsorption capacity of 2.87 mmol g−1 (273 K, 1 bar), which is among the best CO2 adsorption property for “Davankov Resins.”
Nanostructured aniline formaldehyde resin/polysilazane hybrid materials are produced by twin polymerization of 2,2′‐spirobi[3,4‐dihydro‐1H‐1,3,2‐benzodiazasiline] ( 1 ). An alternative synthetic concept for similar hybrid materials, the apparent twin polymerization, is employed by using the combination of the deficient twin monomer tetrakis(phenylamino)silane ( 2 ) with hexamethylenetetramine (HMTA). Both processes for the synthesis of polysilazane hybrid materials occur under volatilization of byproducts such as ammonia or aromatic nitrogen compounds. The thermal properties of the twin monomer 1 and the combination of 2 /HMTA, respectively, are investigated by differential scanning calorimetry and thermogravimetric analysis. Aniline‐formaldehyde resin/polysilazane hybrid materials are characterized by solid state 13C‐ and 29Si‐NMR spectroscopy and transmission electron microscopy. The inorganic network remains hydrolyzable and can be functionalized after polymerization at temperatures below 500 °C due to residuary reactive Si?N bonds. Thermal treatment at 1100 °C leads to the formation of amorphous Si/C/N hybrid materials.
Well‐defined magnetic polyelectrolytes with tetrachlorideferrate (FeCl4?) as counter ion are prepared. In this approach, norbornene‐based monomer containing ammonium chloride group (TAENDI‐Cl) is designed and synthesized. Well‐defined magnetic polymers (Poly(TAENDI‐FeCl4)) are obtained by ring‐opening metathesis polymerization of TAENDI‐Cl in the presence of Grubbs third generation catalyst followed by complexing with FeCl3. Magnetic block copolymers are thus prepared. Both the monomer and polymers are paramagnetic as measured by superconducting quantum interference device method. Studies show that the magnetic susceptibility increases with increasing degree of polymerization (DP) and reaches maximum at DP of 100, and then decreases with increasing DP. Block copolymer with lower FeCl4? content shows higher magnetic susceptibility. And, by introducing FeCl4?, the polymers show obviously magnetic responsive in solution, powder, and film which have potential applications in magnetic switching, transport, and separation.
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