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 application of selenol‐X chemistry in nucleophilic substitution and Se‐Michael addition reactions for polymer chain end modification is presented. Selenol‐labeled polystyrene can easily react with alkyl halides, methyl methacrylate, methyl acrylate, pentafluorostyrene, etc. The mild conditions make it attractive for the synthesis of macromonomers. The resulting polymers are analyzed and characterized by UV, size‐exclusion chromatography (SEC), NMR, and matrix assisted laser desorption/ionization time of flight mass spectroscopy.
A novel hydrogel with super stability and toughness is obtained by polymerizing acrylamide and maleic acid in the presence of poly(vinyl alcohol) chains. Then the hydrogel is processed with dry‐anneal and loading with cation solution method in order to construct a polymer network containing covalent, crystalline, and ionic cross‐links. Various hydrogels are measured via tensile and compressive tests to determine the optimal preparation and mechanical properties of hydrogels. The hydrogels show high tensile stress of ≈ 8 MPa and toughness of ≈ 25.4 MJ m?3. The hydrogel exhibits good chemical stability that remained up to 93% of original strength after 12 h soaking in phosphate buffered saline. Finally, an energy dissipation mechanism is discussed.
In this study, the bifunctional hydroxyketone based photoinitiator (PI) 1,1′‐{[(2,3‐dihydroxybutane‐1,4‐diyl)bis(oxy)]bis(4,1‐phenylene)}bis(2‐hydroxy‐2‐methylpropan‐1‐one) (Di‐PI) is synthesized with the aim to facilitate a highly photoactive water‐soluble PI which offers high migration stability. Di‐PI provides a five times higher water‐solubility than the state of the art water soluble PI 2‐hydroxy‐1‐[3‐(hydroxymethyl)phenyl]‐2‐methyl‐1‐propanone (I2959). Photo differential scanning calorimetry (Photo‐DSC) measurements reveal that the curing speed and conversion of N‐acroylmorpholine (NAM) in aqueous solution containing 0.5 mol% of Di‐PI are only slightly lower than formulations containing the reference PI I2959 in a concentration of 1 mol%. Most importantly, Di‐PI offers almost identical activity in dipropylene glycol diacrylate (DPDA) as I2959, although its migration from cured DPDA is significantly reduced by a factor of 7.6 compared to I2959.
The shape and size distribution of polystyrene (PS) compartments formed during emulsion electrospinning in a poly(vinyl alcohol) fiber is investigated. Stimulated emission depletion microscopy is employed to image the compartments with subdiffraction (super) resolution. The size distribution of the emulsion droplets in the spinning solution emulsions is found to be the key factor for fiber and compartment morphology. By varying the emulsification method, it is demonstrated that fibers spun from miniemulsions are characterized by a homogeneous distribution of PS compartments with no indication for coalescence or breakup of PS droplets. Coarse emulsions are prone to develop fiber instabilities associated with large PS domains. The domains are irregularly distributed in the fiber. Above a critical size of domains, breakup of these domains in two daughter domains is observed. The size dependence of the emulsion droplet breakup is explained by fluid dynamics.
Reduction‐responsive biodegradable polymeric micelles based on functional 2‐methylene‐1,3‐dioxepane (MDO) copolymers are developed and investigated for triggered doxorubicin (DOX) release. The MDO‐based copolymers P(MDO‐co‐PEGMA‐co‐PDSMA) are synthesized via the simple one‐step radical ring‐opening copolymerization of MDO, poly(ethylene glycol) methyl ether methacrylate (PEGMA), and pyridyldisulfide ethylmethacrylate (PDSMA). The copolymers can self‐assemble to form micelles in aqueous solution. DOX, a model anticancer drug, is loaded into the micelles with the drug loading content (DLC) of 11.3%. The micelles can be disassembled under a reductive environment (10 × 10?3m glutathione), which results in a triggered drug release behavior. The glutathione‐mediated intracellular drug release of DOX‐loaded micelles is investigated against A549 cells. Confocal laser scanning microscopy (CLSM) results demonstrated that DOX‐loaded micelles exhibits faster drug release in glutathione monoester (GSH‐OEt)‐pretreated A549 cells, compared with untreated and buthionine sulfoximine (BSO)‐pretreated A549 cells. Based on the facile synthetic strategy, the reduction‐sensitive biodegradable micelles with triggered intracellular drug release are promising for anticancer drug delivery.
A novel poly(phenylene ethynylene) containing 2‐thiohydantoin [poly( 1 )] is synthesized. The addition of F? quenches the fluorescence, while the fluorescence of the solution only changes slightly upon addition of other anions, indicating the sensing ability of poly( 1 ) toward F?. The addition of Ag+ quenches the fluorescence of the polymer, whereas the addition of other metal ions results in only slight changes to the fluorescence. Compared with its small‐molecule counterpart, the Stern–Volmer quenching constants of poly( 1 ) toward F? and Ag+ are 165 and 105 times greater, respectively. This result indicates the amplified quenching effect of poly( 1 ).
In this work, a novel synthesis approach of gold nanohybrid materials (Au/SH‐OPPs) is demonstrated using the thiol‐functionalized organic porous polymers (SH‐OPPs) as a support by a combination of hyper‐cross‐linking and molecular templating of functionalized bottlebrush copolymers. HAuCl4 as the gold source is in situ reduced to produce Au nanoparticles based on the strong action of gold with the thiol groups. The monodispersed Au nanoparticles are anchored on the SH‐OPPs with the small average particle size (3.0 ± 1.0 nm) and the high loading about 18%. Moreover, the resultant Au/SH‐OPPs exhibit excellent catalytic performance for the selective oxidation of benzyl alcohol.
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.
Polyacrylonitrile (PAN) with high molecular weight and low dispersity is successfully synthesized by visible‐light‐induced metal‐free radical polymerization at room temperature. This polymerization technique uses organic dye Eosin Y as photocatalyst and benzenediazonium tetrafluoroborates as initiator. Gel permeation chromatography‐multiangle laser light scattering shows the absolute molar weight of the PAN more than 1.50 × 105 g mol−1 with a polydispersity index < 1.3 while MALDI‐TOF MS and 19F NMR spectroscopy indicate the F‐chain‐end process. The first‐order kinetic behavior, molecular weight distributions shifting, and “ON/OFF” experiment results suggest this reaction may follow the atom‐transfer‐like radical polymerization mechanism. In addition, this new approach allows for the efficient synthesis of well‐defined random copolymers.
Amphiphilic block copolymers based on sucrose methacrylate (SMA) and alkyl methacrylates (alkyl = ethyl, butyl, and hexyl) are synthesized by atom transfer radical polymerization, employing CuBr/CuBr2/2,2,2‐tribromoethanol/1,1,4,7,10,10‐hexamethyltriethylenetetramine as a catalyst/deactivator/initiator/ligand system. Poly(alkyl methacrylate)s with similar polymerization degrees are used as macroinitiators for SMA polymerization. The introduction of PSMA blocks with molar mass varying from 2000 to 12 000 g mol−1 results in changes in the solubility, thermal stability, and water swelling capacity. The copolymers are able to stabilize water/oil emulsion and also to self‐assemble in solution, as verified by gel permeation chromatography and dynamic light scattering, as well as in solid state, as verified by atomic force microscopy.
The synthesis of telechelic poly(ether sulfone)s with methoxy end groups is reported. Molecular weights ranging from 1600 to 2800 g mol?1 and polydispersities of 1.1–1.2 are synthesized by chain‐growth condensation polymerization. The initiator is chosen by using semiempirical calculations and 19F NMR spectroscopy measurements. The polymers are characterized by NMR spectroscopy and matrix‐assisted laser desorption/ionization time of flight (MALDI‐TOF) mass spectrometry (MS), and are terminated by a methoxy group at one end and a fluorine at the other, and up to approximately 20% polymer of similar mass but slightly higher polydispersity, methoxy terminated at both ends, is present, along with less than 5% of polymer terminated at both ends by fluorine atoms. These do not need to be separated, and can be converted to methoxy‐ending telechelic blocks, yielding polyvalent, reactive rigid building blocks for copolymer synthesis.
Poly(spirobifluorene)s and their derivatives with three primary colors are promising for application in efficient and stable polymer light‐emitting diodes (PLEDs). Here, a novel approach is reported to tune the emission colors of blue‐light‐emitting poly(spirobifluorene)s through a charge‐transfer mechanism from the side chain to the main chain. By using the electron‐rich 2,3,6,7‐tetra‐octyloxyfluorene unit as the side chain and incorporating the electron‐deficient dibenzothiophene‐S,S‐dioxide ( SO ) unit into the main chain, a series of polyspirobifluorene derivatives are successfully developed. They all display efficient green photoluminescence and electroluminescence. The observed green emission can be ascribed to both intramolecular and intermolecular charge transfer from the pendant 2,3,6,7‐tetra‐octyloxyfluorene unit to the SO unit in the main chain. Single‐layer PLEDs of these polymers reveal a maximum luminance efficiency of 1.99 cd A?1 and a maximum power efficiency of 1.30 lm W?1 with Commission Internationale de L'Eclairage coordinates of (0.37, 0.54).
A new D–A copolymer ( PBDT‐DTQx) based on the 2,3‐di(5‐hexylthiophen‐2‐yl)quinoxaline acceptor unit and a bithienyl‐substituted benzodithiophene (BDT) donor unit is designed and synthesized for application as the donor material in polymer solar cells (PSCs). The polymer film shows a broad absorption band covering the wavelength range from 300 to 720 nm and a low highest occupied molecular orbital (HOMO) energy level at ?5.35 eV. A device based on PBDT‐DTQx :PC70BM ([6,6]‐phenyl‐C71‐butyric acid methyl ester) (1:2.5, w/w) with chloronaphthalene as a solvent additive displays a power conversion efficiency (PCE) of 3.15%. With methanol treatment, the PCE of the PSCs is further improved to 3.90% with a significant increase of the short‐circuit current density, Jsc, from 10.10 mA cm?2 for the device without the methanol treatment to 11.71 mA cm?2 for the device with the methanol treatment.
Flame‐retardant polypropylene (PP)/carbon nanotubes (CNTs) nanocomposites influenced by surface functionalization and surfactant molecular weights are studied. 3‐Aminopropyl‐triethoxysilane (APTES) is utilized to modify the CNTs (f‐CNTs), and maleic‐anhydride‐grafted PP (MAPP) with two molecular weights ( of 800 and 8000 g mol?1) is used to further improve the dispersion of f‐CNTs in the PP matrix. Thermal gravimetric analysis (TGA) and microscale combustion calorimetry (MCC) reveal that the molecular weight of MAPP directly affects the thermal stability and flammability of PP/f‐CNTs PNCs: both MAPP polymers ( of 800 and 8000 g mol?1) increase the thermal stability of PP; however, the heat release rate of PP/f‐CNTs is reduced in the presence of MAPP ( of 800 g mol?1) and increased in the presence of MAPP ( of 8000 g mol?1). MAPP ( of 800 g mol?1) also results in a lower viscosity of the PP/f‐CNTs PNCs compared with pure PP.
Copolymerization of ethylene with 4‐penten‐1‐ol (4P1O) is conducted by using a half‐titanocene catalyst. The incorporation of 4P1O is high as approximately 10 mol%. The assignments of the 13C NMR spectrum and the analysis of the sequence distribution show the existence of not only the alternative structure but also the repeated 4P1O units. The product of the reactive ratios is calculated as ca. 2.
A two‐step synthesis of high‐molecular‐weight and bio‐based poly(butylene succinate) (PBS) from succinic anhydride and butane‐1,4‐diol is established, in which the first step is a 12 h atmospheric polycondensation at 95 °C in the presence of succinic acid. The subsequent polymerization, catalyzed by Novozym 435 suspended in toluene, yields PBS with a molecular weight above 73 000 g mol?1. The recovered lipase catalyst appears to give similar performance after six cycles. The versatility of this atmospheric synthetic route to PBS copolymers is validated through the syntheses of poly(butylene succinate‐co‐butylene malate) (PBSM), poly(butylene succinate‐co‐butylene fumarate) (PBSF), and poly(butylene succinate‐co‐butylene terephthalate) (PBST), in which succinic acid is replaced by corresponding di‐acids as monomers.
The doping of a liquid crystalline (LC) photoemissive compound into a LC polymethacrylate with photoemissive side groups induces repeatable changes in the photoemission wavelength upon mechanical grinding and thermal annealing. The color changes observed in a handwritten pattern demonstrate the successful induction of anisotropic photoemission behavior in a LC composite polymeric film parallel to the grinding direction. The LC characteristics of the composite films play an important role in the directional selectivity of the polarized mechanoinduced color change.
In this study, the self‐assembly of ionic porphyrins and polyelectrolytes in dependence on the polyelectrolyte architecture and molecular mass is investigated systematically. The systems consist of tetravalent anionic meso‐tetrakis(4‐sulfonatophenyl)‐porphyrin (TPPS), which is combined with different positively charged macroions: poly(amidoamine) dendrimer of generation 4, linear polylysine of different molecular masses, poly(diallyldimethylammonium chloride), and a cylindrical poly‐l ‐lysine brush. Light scattering reveals defined supramolecular assemblies with hydrodynamic radii between R H = 30 nm and R H = 180 nm. Further, size and shape of TPPS–polyelectrolyte assemblies are substantially affected by the polyelectrolyte architecture but less by the molecular mass of the polyelectrolyte. ζ‐potential measurements detect an assembly charge corresponding to the excess component that is responsible for the aggregate being stable in solution.
Novel self‐healing silicone rubbers are prepared by a two‐step procedure: aminopropyl methyl phenyl polysiloxanes is first reacted with salicylaldehyde and then with copper acetate. The reversible nature of the metal–ligand coordination interaction between polysiloxanes with pendent Schiff‐base groups and Cu2+ has endowed silicone rubbers with superior self‐healing properties. As compared with other self‐healing silicone rubbers based on hydrogen bonds or Diels–Alder reaction, this cross‐linked system shows high healing power. The materials are cut into two parts and put together in a mold for 1 h at 30 °C, observing a macroscopic healing and a strength recovery up to 87.0%.
