Styrene Research Articles

The influence of myrcene on anionic copolymerization of 1,3-pentadiene and styrene

C5-dienes including 1,3-pentadiene (PD) and isoprene (IP) as by-products of naphtha cracking are important industrial raw materials for the production of thermoplastic elastomers, synthetic rubber and resins. The research on living anionic polymerization (LAP) of myrcene (MY) is also of great significance for the development of new bio-based materials and products. Focusing on the optimal utilization of C5 resources and the high-value utilization of biomass resources and the realization of green chemical production, this article reports the synthesizing of a novel terpolymer by LAP of PD, styrene (ST) and the biomass monomer MY. The discovery of the alternating sequence structure of ST and PD inspires us to further explore the development of copolymers containing this unique sequence structure. The special long branched side chain of MY and its low glass transition temperature are also conducive to the synthesis of new integrated rubbers. The 1H NMR tracking analysis indicates that the polymerization pattern changes from alternating sequence to gradient block sequence with the increase of MY content. Combined with FTIR analysis, the PD monomeric units are mainly trans-1,4 structure and MY monomeric units are predominant cis-1,4 structure. Considering the extremely high polymerization activity of MY compared to ST and PD, the copolymerization rate is significantly dependent on the concentration of the PD monomer. Despite this, due to the interactions between ST and PD ([ST¦PD] intermediate), ST still tends to form alternating segments with PD. The ternary copolymerization can be viewed as a “binary gradient copolymerization” of [ST¦PD] and MY (rMY > r[ST¦PD]).

Preparation and characterization of cardanol based vinyl ester resins as cross‐linker units

AbstractIn this study, two cardanol based epoxidized resins, NC514 with less than two epoxies per molecule and side chain epoxidized cardanol glycidyl ether (SCECGE) with approximately 2.45 epoxies (1.0 phenolic+1.45 aliphatic epoxies) per molecule were methacrylated. The methacrylated versions of cardanol based NC514 (NC514VE) and SCECGE (SCECGEVE) epoxy resins were used as cross‐linker units in vinyl ester formulations with methacrylated lauric acid (MFA) and styrene (ST) as bio‐based and synthetic based reactive diluents respectively, at various concentrations (10–40 wt%). The curing reactions of the resins were studied via FTIR and the extent of polymerization was determined for different cross‐linker units in the presence of ST and MFA. Our mechanical and thermomechanical characterizations showed that VER formulations prepared with cardanol based SCECGEVE cross‐linker unit have significantly improved properties than the samples prepared with commercially available counterpart NC514VE using either reactive diluent. These properties of SCECGEVE were also comparable with to that of methacrylated petroleum‐based diglycidyl ether of bisphenol A vinyl ester (DGEBAVE) formulations unlike NC514VE formulations due to more effective side chain functionalization and cross‐linking.

Preparation and Performance Evaluation of a Supramolecular Polymer Gel-Based Temporary Plugging Agent for Heavy Oil Reservoir.

When encountering heavy oil reservoirs during drilling, due to the change in pressure difference inside the well, heavy oil will invade the drilling fluid, and drilling fluid will spill into the reservoir along the formation fractures, affecting the drilling process. A supramolecular polymer gel-based temporary plugging agent was prepared using acrylamide (AM), butyl acrylate (BA), and styrene (ST) as reacting monomers, N, N-methylenebisacrylamide (MBA) as a crosslinking agent, ammonium persulfate (APS) as an initiator, and poly(vinyl alcohol) (PVA) as a non-covalent component. A supermolecular polymer gel with a temperature tolerance of 120 °C and acid solubility of 90% was developed. The experimental results demonstrated that a mechanically robust, thermally stable supramolecular polymer gel was successfully synthesized through the copolymerization of AM, BA, and ST, as well as the in situ formation hydrogen bonding between poly (AM-co-BA-co-ST) and PVA, leading to a three-dimensional entangled structure. The gel-forming solution possessed excellent gelling performance even in the presence of a high content of salt and heavy oil, demonstrating superior resistance to salt and heavy oil under harsh reservoir conditions. High-temperature and high-pressure plugging displacement experiments proved that the supramolecular polymer gel exhibited high pressure-bearing capacity, and the blocking strength reached 5.96 MPa in a wedge-shaped fracture with a length of 30 cm. Furthermore, the dissolution rate of the supramolecular polymer gel was as high as 96.2% at 120 °C for 48 h under a 15% HCl solution condition.

Highly Efficient Separation of Ethanol Amines and Cyanides via Ionic Magnetic Mesoporous Nanomaterials.

Simple and efficient sample pretreatment methods are important for analysis and detection of chemical warfare agents (CWAs) in environmental and biological samples. Despite many commercial materials or reagents that have been already applied in sample preparation, such as SPE columns, few materials with specificity have been utilized for purification or enrichment. In this study, ionic magnetic mesoporous nanomaterials such as poly(4-VB)@M-MSNs (magnetic mesoporous silicon nanoparticles modified by 4-vinyl benzene sulfonic acid) and Co2+@M-MSNs (magnetic mesoporous silicon nanoparticles modified by cobalt ions) with high absorptivity for ethanol amines (EAs, nitrogen mustard degradation products) and cyanide were successfully synthesized. The special nanomaterials were obtained by modification of magnetic mesoporous particles prepared based on co-precipitation using -SO3H and Co2+. The materials were fully characterized in terms of their composition and structure. The results indicated that poly(4-VB)@M-MSNs or Co2+@M-MSNs had an unambiguous core-shell structure with a BET of 341.7 m2·g-1 and a saturation magnetization intensity of 60.66 emu·g-1 which indicated the good thermal stability. Poly(4-VB)@M-MSNs showed selective adsorption for EAs while the Co2+@M-MSNs were for cyanide, respectively. The adsorption capacity quickly reached the adsorption equilibrium within the 90 s. The saturated adsorption amounts were MDEA = 35.83 mg·g-1, EDEA = 35.00 mg·g-1, TEA = 17.90 mg·g-1 and CN-= 31.48 mg·g-1, respectively. Meanwhile, the adsorption capacities could be maintained at 50-70% after three adsorption-desorption cycles. The adsorption isotherms were confirmed as the Langmuir equation and the Freundlich equation, respectively, and the adsorption mechanism was determined by DFT calculation. The adsorbents were applied for enrichment of targets in actual samples, which showed great potential for the verification of chemical weapons and the destruction of toxic chemicals.

Unravelling a complex catalyst deactivation in which selectivity affects conversion: oxygen-assisted styrene synthesis at industrially-relevant conditions

The oxidative dehydrogenation of ethylbenzene (EB) into styrene (ST) has been proposed as an alternative to the conventional energy-consuming synthesis of styrene. Various types of catalysts have been reported as promising for the reaction under industrially-relevant conditions. However, they show a complex deactivation behaviour. The EB conversion and the ST selectivity decay, with an increased COx selectivity. This phenomenon was investigated by means of experimental data and reaction model analysis, using two reference inorganic catalysts. The active catalyst is the deposited coke (ODH-coke) and not directly the inorganic material. The coke is formed in the initial reaction phase and promoted by the Lewis acid sites of the inorganic material. The reaction shows an activation period in which the ODH-coke is deposited and the EB conversion reaches a maximum where O2 is fully converted. From that point onwards, the reaction model is applicable and the experimental data fit very well with low standard deviations. The model explains that the EB conversion′s decay with time on stream is associated to changes in the selectivity. Hence, EB conversion is not an independent parameter. This simplifies the understanding of this complex deactivation; the deactivating parameter is the selectivity. At this moment, we cannot discriminate between increased COx and decreased ST, or both effects, because both routes are competitive. This case represents a new type of catalyst deactivation behaviour, in which selectivity affects conversion.

Formation of polymers in the presence of dispersed mineral phase

The adsorption of oligomeric peroxide of sebacic acid on aerosols was studied. The parameters of the adsorption process were found. The effect of aerosil on the polymerization of styrene (ST), methyl acrylate (MA), butyl acrylate (BA), methyl methacrylate (MMA) and butyl methacrylate (BMA) was studied. The initiators used were oligomeric sebacic acid peroxide (OPSA), benzoyl peroxide (BP), lauryl peroxide (PL) and didecanoyl diperoxy adipinate (DP). The mineral filler increases the polymerization rate of MMA, BMA, MA, BA initiated by OPSA. Under the same conditions, the polymerization rate of ST decreases with an increase in the aerosil content in the polymerization system. BP practically does not affect the polymerization rate of vinyl monomers in the presence of aerosil. The reaction of thermal decomposition of OPSA, DP, PL and BP in styrene in the presence of aerosol was studied. An increase in the content of aerosil leads to an increase in the effective decomposition constant of OPSA, DP, PL. in the case of BP, aerosil has practically no effect on the decomposition rate.

Promotional effect and mechanism of SiO2 on Cr-Al2O3 catalysts for N2O-assisted oxidative dehydrogenation of ethylbenzene

A series of Cr-SiO2-Al2O3 (abbreviated as Cr-Si-Al) catalysts were synthesized using an evaporation induced self-assembled (EISA) method and applied to the N2O-assisted dehydrogenation of ethylbenzene (EB), offering a versatile solution for greenhouse gas recycling and a novel pathway for styrene (ST) production. Notably, the Cr-5Si-Al catalyst calcinated at 850 °C exhibited remarkable performance with a high EB conversion of 71% and a good ST selectivity of 62%, resulting in an optimal ST yield of nearly 44%. To elucidate the impact of calcination temperature and reveal the underlying promoting mechanism, numerous types of characterization particularly in-situ DRIFTS were used. Results indicated that the Cr-5Si-Al-850 catalyst possessed a distinctively ordered mesoporous structure, which improved the specific surface area and facilitated the dispersion of active species. The interaction among the multiple species in the catalyst was enhanced under the high calcination temperatures, leading to an increased ratio of Cr6+ and Oα, and thus promoting the dehydrogenation of EB. Furthermore, in situ DRIFTS revealed two favorable reaction pathways: one involving the reaction between adsorbed N2O and EB, and the other involving the reaction between adsorbed EB and N2O. These pathways led to the formation of a similar intermediate, observed at a wavenumber of 1285 cm−1. The improved adsorption of EB played a pivotal role in the excellent catalytic performance of the Cr-5Si-Al-850 catalyst.

Nitroxide-Mediated Controlled Radical Copolymerization of α-Trifluoromethylstyrenes with Styrenes.

Fluorinated polymers are important materials in everyday life; however, most monomers of widely used fluoropolymers are gaseous, and their polymerization is difficult in an ordinary laboratory. Therefore, partially fluorinated polymers have recently been reported. As an easy-to-handle fluorine-containing monomer, α-trifluoromethylstyrene (TFMST) can be used to produce partially fluorinated polymers with trifluoromethyl groups in the main chain; however, TFMST does not homopolymerize, and there are limited reports on its copolymerization with styrene (ST). In this study, we applied the controlled radical polymerization method, which is effective for the polymerization of ST, to the copolymerization of TFMST and ST. We also showed that nitroxide-mediated polymerization is effective. The content ratio of TFMST in the TFMST-ST copolymer can be controlled between 10% and 40% by changing its monomer ratio. Additionally, the polymerization of TFMST and ST with substituents was performed to increase structural variations. The thermal stability as well as water and oil repellency of the synthesized polymers with different composition ratios and substituents were also evaluated.

Indium nanocubes based recyclable fluorescent chemosensor for sustainable environmental monitoring: pH-induced fluorescence transition and selective detection of Pd(II) ions

Rapid modern industrialization and urbanization have escalated heavy metal pollution, with palladium (Pd2+) raising significant concerns due to its extensive usage in catalysis, hydrogen storage, and electronics, thereby imposing substantial risks on the environment and human health. In this study, we report a highly fluorescent indium nanocubes based chemosensor (InNCs) functionalized with perylene tetracarboxylic acid (PTCA) and 4-(pyridyl)ethenyl benzene (PEB). The InNCs exhibited emission maximum at 415 nm (λex ∼ 350 nm) with robust chemical and photo-stability, and acted as a fluorogenic probe for selective recognition of Pd2+ in aqueous medium. The fluorescence sensing properties of InNCs were thoroughly assessed via different techniques including steady-state absorption, emission and time-resolved emission spectroscopic methods. Among the various competitive analytes, only Pd2+ could induce a significant fluorescence quenching in the probe. This “turn-off” fluorescence sensing demonstrated a remarkably low LoD of ∼65 nM. Notably, with the addition of EDTA, the probe displayed good recyclability upto 4 cycles. The sensory probe was successfully employed as a reusable platform to estimate Pd(II) in different real water and soil samples with considerable accuracy (∼ 5–10 % error). Moreover, the probe exhibited a pH-induced fluorescence transition, indicating its potential to be applied as a pH sensor. The Pd(II) binding and pH-sensing mechanisms have also been elucidated through density functional theory (DFT) calculations.

Effects of Solvent and Monomer on the Kinetics of Radical Generation in Atom Transfer Radical Polymerization

AbstractUnlike classical radical polymerization, the kinetics of atom transfer radical polymerization show significant solvent dependence, possibly arising from solvent effects on the activation step. A kinetic study on the activation of the initiator ethyl α‐bromoisobutyrate by [CuITPMA]+ (TPMA=tris(2‐pyridylmethyl)amine), an initiator/catalyst combination frequently used in ATRP, was carried out in DMSO, DMF, MeCN, anisole, ethyl acetate, and their 50 vol % mixtures with styrene (STY) and methyl methacrylate (MMA). kact values varying about 3 orders of magnitude from 3.14×105 mol−1 dm3 s−1 in DMSO to 9.41×102 mol−1 dm3 s−1 in ethyl acetate were found. These values showed excellent correlation with the solvent polarity/polarizability parameter π*. The effect of MMA or STY depended on polarity compatibility between the monomer and the solvent: After monomer addition, kact decreased considerably in polar solvents, whereas it was almost unaffected in nonpolar solvents.

Carbonyl-amine condensation coupled ozonolysis of dipropylamine and styrene: Decay kinetics, reaction mechanism, secondary organic aerosol formation and cytotoxicity

Oxidation of organic amines (OAs) or aromatic hydrocarbons (AHs) produces carbonyls, which further react with OAs to form carbonyl-amine condensation products, threatening environmental quality and human health. However, there is still a lack of systematic understanding of the carbonyl-amine condensation reaction processes of OAs or between OAs and AHs, and subsequent environmental health impact. This work systematically investigated the carbonyl-amine condensation coupled ozonolysis kinetics, reaction mechanism, secondary organic aerosol (SOA) formation and cytotoxicity from the mixture of dipropylamine (DPA) and styrene (STY) by a combined method of product mass spectrometry identification, particle property analysis and cell exposure evaluation. The results from ozonolysis of DPA and STY mixture revealed that STY inhibited the ozonolysis of DPA to different degrees to accelerate its own decay rate. The barycenter of carbonyl-amine condensation reactions was shifted from inside of DPA to between DPA and STY, which accelerated STY ozonolysis, but slowed down DPA ozonolysis. For the first time, ozonolysis of DPA and STY mixture to complex carbonyl-amine condensation products through the reactions of DPA with its carbonyl products, DPA with STY's carbonyl products and DPA's bond breakage product with STY's carbonyl products was confirmed. These condensation products significantly contributed to the formation and growth of SOA. The SOA containing particulate carbonyl-amine condensation products showed definite cytotoxicity. These findings are helpful to deeply and comprehensively understand the transformation, fate and environmental health effects of mixed organics in atmospheric environment.

2D/3D-printed PEDOT/PSS conductive hydrogel for biomedical sensors

The integration of conductive hydrogels and advanced three-dimensional (3D) printing is a trigger of the development of biomedical sensors for healthcare diagnostics and personalized treatment. Poly(3,4-ethylenedioxythiophene):poly(styr ene sulfonate) (PEDOT:PSS) is a versatile conductive hydrogel materials renowned for its exceptional conductivity and hydrophilicity, and 3D printing technology allows for precise and customized fabrication of electronic components and devices. In this review, we aim to explore the potential of 3D-printed PEDOT/PSS conductive hydrogel in the fabrication of biomedical sensors, with a focus on their distinct characteristics, application potential, and systematic classification. We also discuss the methods for fabricating PEDOT:PSS hydrogel electronic devices by employing 3D printing techniques, including extrusion-based 3D printing technology (fused deposition modeling, direct ink writing, and inkjet printing), powder-based 3D printing technology (selective laser sintering and selective laser melting), and photopolymerization-based 3D printing technology (stereolithography and digital light processing). The applications of 2D/3D-printed PEDOT:PSS hydrogels in biomedical sensors, such as strain sensors, pressure sensors, stretchable sensors, electrochemical sensors, temperature sensors, humidity sensors, and electrocardiogram sensor, are also summarized in this review. Finally, we provide insights into the development of 3D-printed PEDOT:PSS-based biomedical sensors and the innovative techniques for biomedical sensor integration.

Preparation and application of stimuli-responsive PET TeMs: RAFT graft block copolymerisation of styrene and acrylic acid for the separation of water-oil emulsions.

Stimuli-responsive membranes play an important role in the fields of biomedicine, food and chemical industries, and environmental applications, including separation of water-oil emulsions. In this study, we present a method to fabricate pH-sensitive membranes using UV-initiated RAFT graft copolymerization of styrene (ST) and acrylic acid (AA) on poly(ethylene terephthalate) (PET) track-etched membranes (TeMs). The optimization of polymerization conditions led to successful grafting of polystyrene (PS) and poly(acrylic acid) (PAA) onto PET TeMs, resulting in membranes with stable hydrophobicity and pH change responsiveness. The membranes show a contact angle of 65° in basic environments (pH 9) and 97° in acidic environments (pH 2). The membranes were characterized by atomic force microscopy (AFM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), thermogravimetric analyses (TGA), Fourier transform infrared spectroscopy (FTIR), contact angle (CA) methods. The PET TeMs-g-PS-g-PAA exhibited good performance in separating water-oil emulsions with a high efficiency of more than 90% and flux for direct chloroform-water 2500 L m-2 h-1 and reverse emulsions of benzene-water 1700 L m-2 h-1. This method of preparing stimuli-responsive membranes with controlled wettability and responsiveness to environmental pH provides versatility in their use in separating two types of emulsions: direct and reverse.

Pyridinium and trifluoromethanesulfonate bifunctional poly(ionic liquid)s for highly efficient and selective adsorption of anionic dyes

The efficient and selective removal of dyes from polluted water by low cost, durable, sustainable, and reusable adsorptions remain challenges. In this study, a pyridinium and trifluoromethanesulfonate bifunctional poly(ionic liquid)s, named Py-CF3SO3-PIL was prepared by co-polymerization of 4-vinyl pyridine (4VP), divinylbenzene (DVB) and styrene (ST), followed by quaternization with 1-bromobutane and anion exchange with lithium trifluoromethanesulfonate. The resulting bifunctional Py-CF3SO3-PIL exhibited remarkable adsorption capacity (2192 mg g−1) and efficiency (within 10 min) for selective removal (>99.9%) of methyl orange (MO) from (mixed) dye solutions. The superior adsorption capacity and selectivity of Py-CF3SO3-PIL towards the removal of MO was attributed to the strong electrostatic interactions and π-π stacking interaction between the adsorbent and MO dye. Detailed kinetic studies, adsorption isotherms, and thermodynamic experiments revealed an endothermic monolayer chemical adsorption mechanism of MO on Py-CF3SO3-PIL, which is perfectly matched with the Langmuir isotherm model (R2 > 0.999). Importantly, the Py-CF3SO3-PIL could be easily collected and regenerated for multiple repeated uses, highlighting its reusability. The exceptional adsorption capacity and selectivity towards anionic dyes make Py-CF3SO3-PIL a promising candidate for dye separation applications. Our findings will contribute to the rational design of functional poly(ionic liquid)s-based adsorbents for water purification.

Optimizing rheological performance of unsaturated polyester resin with bio-based reactive diluents: A comprehensive analysis of viscosity and thermomechanical properties

Bio-based reactive diluents (RD) have been explored as alternative to styrene (STY) in unsaturated polyester resin (UPR). Among the different candidates, acrylated epoxidized soybean oil (AESO) and epoxidized linseed oil (ELO) stand out as triglyceride derivatives. Aditionally, methyl methacrylate (MMA), trimethylolpropane triacrylate (TMPTA) with acrylic functionality, limonene (LIM), and cinnamates (CINN), has been tested in different percentages. Firstly, their efficiency in viscosity reduction has been studied. Best results were obtained after the addition of MMA, LIM, and CINN at 5 wt%. These RD achieve a viscosity reduction of 48.9 %, 76.7 %, and 22.9 %, respectively, compared to the reference sample. The industrial utilization of CINN as RD is impeded by its reactivity, as has been evidenced by its prolonged reaction time (24 min) and low reaction enthalpy. The thermo-mechanical properties studied through flexural tests, Shore D hardness, Charpy's Impact test, and heat deflection temperature (HDT), show that the developed UPRs exhibit a decrease in resistant mechanical properties while doubling their ductility by using LIM and MMA as bio-based RD (1.88 and 2.15 kJ m−2, respectively). The HDT study results demonstrate a certain level of thermal stability when MMA is employed (56 °C), which is 15 % lower in the case of LIM. Therefore, it is observed that UPRs with bio-based RD exhibit balanced and improved thermo-mechanical properties in terms of ductility and strength, especially with the use of a 5 wt % of LIM and MMA.

High-Density Coordinatively Unsaturated Zn Catalyst for Efficient Alkane Dehydrogenation.

The exploration of non-noble metal catalysts for alkane dehydrogenation and their catalytic mechanisms is the priority in catalysis research. Here, we report a high-density coordinatively unsaturated Zn cation (Zncus) catalyst for the direct dehydrogenation (DDH) of ethylbenzene (EB) to styrene (ST). The catalyst demonstrated good catalytic performance (∼40% initial EB conversion rate and >98% ST selectivity) and excellent regeneration ability in the reaction, which is attributed to the high-density (HD) distribution and high-stability structure of Zncus active sites on the surface of zinc silicate (HD-Zncus@ZS). Density functional theory (DFT) calculations further illustrated the reaction pathway and intermediates, supporting that the Zncus sites can efficiently activate the C-H bond of ethyl on ethylbenzene. Developing the high-density Zncus catalyst and exploring the catalytic mechanism laid a good foundation for designing practical non-noble metal catalysts.

Synthesis of styrene–acrylate emulsion by glow discharge electrolysis plasma and its application for the conservation of simulated disrupting murals in Dunhuang Mogao grottoes

AbstractIn this work, a styrene (ST)–acrylate emulsion was synthesized via glow discharge electrolysis (GDE) plasma technique. A possible forming mechanism was proposed. Moreover, the adhesion property of the emulsion was evaluated for the conservation of simulated disrupting murals. The results showed that under optimum conditions, the solid content, emulsion conversion, and gel rate are 29.0%, 85.6%, and 1.04%, respectively. The obtained ST–acrylate emulsion is spherical in shape, with a particle size of about 100 nm. The property of ST–acrylate emulsion prepared by GDE is superior to that of the commercial ST–acrylate emulsion for the conservation of simulated disrupting murals. Compared with other methods, GDE has the advantages of simple steps, controllable reaction, environmental friendliness, no chemical initiator, and no N2 atmosphere.

Early bird gets the network: The relative importance of reactivity ratios, Ψ parameter, and crosslinker level on gel formation in FRP

AbstractNetwork topology is manipulated in free‐radical copolymerization via proper selection of crosslinker type and its respective properties when paired with specific monomers. Our prior work has focused on the impact of the reduced reactivity parameter Ψ applied to a pendent vinyl, characteristic for each monomer/crosslinker pair, yet here we assess the relative importance of the comonomer reactivity ratios to see whether one factor can counterbalance the other. The traditional reactivity ratio determines when the crosslinker molecule is incorporated into the polymer backbone, while the reduced reactivity Ψ parameter relates to the efficiency of the resulting pendent side chain vinyl being utilized to form a crosslink node at some later point during the polymerization. Both factors are then contrasted with simply the overall loading of crosslinker. Either n‐butyl methacrylate (n‐BMA) or styrene (STY) was chosen as a primary backbone monomer to copolymerize with one of three crosslinkers: 1,4‐butanediol dimethacylate (BDDMA), 1,4‐butanediol diacrylate (BDDA), or divinylbenzene (DVB). Both kinetics and gel can be most dramatically boosted when a crosslinker is applied having a reactivity ratio favouring early insertion. This in turn leads to an earlier onset of gel formation, which ultimately results in greater final gel content. This amplification of both kinetics and gel can overcome an otherwise small Ψ due to crosslinker or main monomer choice. This reactivity ratio effect was further confirmed by Monte Carlo simulations. By whatever mechanism (higher Ψ, lower rA, or higher crosslinker level), earlier onset of gelation produces more gel overall and a tighter network topology.

Ir0/graphdiyne atomic interface for selective epoxidation.

The development of catalysts that can selectively and efficiently promote the alkene epoxidation at ambient temperatures and pressures is an important promising path to renewable synthesis of various chemical products. Here we report a new type of zerovalent atom catalysts comprised of zerovalent Ir atoms highly dispersed and anchored on graphdiyne (Ir0/GDY) wherein the Ir0 is stabilized by the incomplete charge transfer effect and the confined effect of GDY natural cavity. The Ir0/GDY can selectively and efficiently produce styrene oxides (SO) by electro-oxidizing styrene (ST) in aqueous solutions at ambient temperatures and pressures with high conversion efficiency of ∼100%, high SO selectivity of 85.5%, and high Faradaic efficiency (FE) of 55%. Experimental and density functional theory (DFT) calculation results show that the intrinsic activity and stability due to the incomplete charge transfer between Ir0 and GDY effectively promoted the electron exchange between the catalyst and reactant molecule, and realized the selective epoxidation of ST to SO. Studies of the reaction mechanism demonstrate that Ir0/GDY proceeds a distinctive pathway for highly selective and active alkene-to-epoxide conversion from the traditional processes. This work presents a new example of constructing zerovalent metal atoms within the GDY matrix toward selective electrocatalytic epoxidation.

Toward Biosourced Elastomer from β-Farnesene and Styrene: Synthesis, Properties, and Mechanical Performance

Encouraged by the growing need for sustainability in the rubber industry, attempts have been made to fabricate biobased elastomers to replace existing petro-derived polymers for useful applications. Here, we demonstrate a simple and sustainable route to synthesize biobased elastomers based on β-farnesene (FA) and styrene (STY) under a high-temperature persulfate emulsion process for tire applications. The synthesized copolymer, poly(farnesene-co-styrene) (PFS), showed molecular weight (Mw) of 108 500 g/mol and 162 100 g/mol for 30 and 50 wt % styrene contents. The commoner reactivity ratios showed nonideal copolymerization behavior, as evaluated using Fineman–Ross and Kelen-Tüdös methods. The macromolecular chemical structure of PFS elastomers was confirmed by FT-IR and NMR analyses. The copolymer showed complete 1,4-cis and trans-microstructure formation. The glass-transition temperature (Tg) values of PFS elastomers were obtained in the range of −58 and −38 °C, depending on the styrene content. The PFS gum elastomers displayed improved thermal stability and single degradation pattern compared to the pristine polyfarnesene. Besides, carbon black was incorporated into the PFS elastomer matrix to prepare rubber vulcanizates for desired mechanical properties. The 50/50 FA/STY rubber vulcanizates displayed good tensile strength (4.43 MPa), elongation at break (183%). The 80/20 and 70/30 FA/STY rubber vulcanizates exhibited good wet skid resistance compared to its pristine polyfarnesene vulcanizate. This work provides an efficient approach to using emulsion polymerization for developing sustainable rubbers on an industrial scale for multifaceted applications.