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The multicomponent injection molding of liquid silicone rubbers (LSR) with thermoplastics, such as polybutylene terephthalate (PBT) or polyamide (PA), is a state-of-the-art technique and is used in the manufacturing process for many components in the automotive industry and in the field of sanitary engineering. Standard thermoplastics, such as acrylonitrile butadiene styrene (ABS), cannot be bonded with silicone rubbers in injection molding because of their low heat deflection temperature. In this study, we investigated ABS grades approved for medical applications to show how dynamic mold heating and various pretreatment methods for thermoplastic surfaces can be used to produce ABS-LSR test specimens. In addition, such components' sterilization effect on the adhesive bond will be shown. [ABSTRACT FROM AUTHOR]

In this work, polyhydroxybutyrate (PHB) was maleic anhydride (MA)-grafted in the molten state, using dicumyl peroxide (DCP) as a reaction initiator. Tin(II) 2-ethylhexanoate (Sn(Oct)2) and styrene monomer (St.) were used to maximize the maleic anhydride grafting degree. When PHB was modified with MA/DCP and MA/DCP/Sn(Oct)2, viscosity was reduced, suggesting chain scission in relation to pure PHB. However, when the styrene monomer was added, the viscosity increased due to multiple grafts of MA and styrene into the PHB chain. In addition, the FTIR showed the formation of a new band at 1780 cm−1 and 704 cm−1, suggesting a multiphase copolymer PHB-g-(St-co-MA). The PHB (MA/DCP) system showed a grafting degree of 0.23%; however, the value increased to 0.39% with incorporating Sn(Oct)2. The highest grafting efficiency was for the PHB (MA/DCP/St.) system with a value of 0.91%, while the PHB (MA/DCP/St./Sn(Oct)2) hybrid mixture was reduced to 0.73%. The chemical modification process of PHB with maleic anhydride increased the thermal stability by about 20 °C compared with pure PHB. The incorporation of 0.5 phr of the Sn(Oct)2 catalyst increased the efficiency of the grafting degree in the PHB. However, the St./Sn(Oct)2 hybrid mixture caused a deleterious effect on the maleic anhydride grafting degree. [ABSTRACT FROM AUTHOR]

Analysis of the chemokine analogs synthesised on a terpolymer-polystyrene, N-vinylpyrrolidone, 1,6-hexanediol diacrylate crosslinked resin (PS-NVP-HDDA) showed it can be used a good solid support for the chemical synthesis of polypeptides. The polymer with a good swelling character and chemical resistance was synthesised by the radical aqueous suspension polymerisation technique. HPLC analysis of the crude peptides synthesised on PS-NVP-HDDA resin showed that it is a better substitute for most of the currently available polymer support for peptide synthesis. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A method for obtaining bromine-containing bicyclic unsaturated polyesters by the interaction of 1,4,5,6,7,7-hexabromobicyclo-[2,2,1]-hept-5-ene-2,3-dicarboxylic acid anhydride, propanetriol and maleic anhydride was developed. It was found that unsaturated polyethers synthesized by a two-step method have a higher molecular weight (3130), density (1.461 g/cm3), viscosity (105 St) and ether number (400 ml KOH/g). It was found that the compositions of epoxy resin ED-20 with unsaturated polyether obtained by method III possess higher tensile strength (90 MPa), higher relative elongation (9%), higher Vicat resistance (2500C) than unmodified epoxy resin. It was shown that in comparison with pure epoxy resin ED-20, its composition with unsaturated polyester synthesized by method I and cured in the presence of polyethylene polyamine (ED-20: unsaturated polyester: polyethylene polyamine), has flame retardant properties, high tensile strength, higher relative elongation and thermal resistance by Vicat. The best results are achieved when the content of unsaturated polyester in the composition is 20%. [ABSTRACT FROM AUTHOR]

As the second largest synthetic rubber after styrene butadiene rubber, cis-butadiene rubber (BR) is one of the important raw materials for automobile tires and cold-resistant products. Herein, a traditional rubber preparation process was used to introduce dynamic reversible bonds into BR based on an "imitative" click reaction. Compared with traditional complex self-healing techniques, this method is undoubtedly simpler and more efficient. Dynamic reversible bonds are able to break and recombine under the stimulation of external conditions, which endow rubber with self-healing properties. We use the small biological molecule lipoic acid (LA) as a cross-linking agent and cross-link LA and BR through mechanical compounding and hot press vulcanization to obtain self-healing butadiene rubber (BLA). In addition, BLA-(Zn2+) was further prepared by introducing Zn2+ to form metal-oxygen coordination bonds with carboxyl groups. And systematically studied the effect of Zn2+ on the mechanical properties and self-healing properties of cross-linked BR. Through the combined action of disulfide bonds, hydrogen bonds and Zn2+-O coordination bonds, BLA-(Zn2+) has better properties than BLA, the tensile strength can reach 3.76 MPa, and the repair efficiency is about 82 %. This simple preparation process is certainly more cost effective. [ABSTRACT FROM AUTHOR]

In this study, iridium nanoparticles (IrNPs) on superparamagnetic iron oxide nanoparticles (SPIONs) are used to catalyze N‐heteroarene and styrene hydrogenation processes. The IrNP@SPIONs catalyst was fabricated by reducing the Ir‐salt precursors in deionized water on SPIONs (Fe3O4), and its catalytic reactivity for the hydrogenation of N‐heteroarenes and styrene under mild reaction conditions as hydrogen under pressure was evaluated. The catalyst was characterized by FTIR, Raman, XRD, SEM, XPS, ICP‐OES, and TEM. The results showed that IrNPs@SPIONs exhibited >99 % conversion with 1,2,3,4‐tetrahydroquinoline (py‐THQ) selectivity under 30 bar H2 at 100 °C temperature in 24 h using DCM as a solvent. The functional group tolerance of 6‐chloroquinoline demonstrated 99 % chemoselectivity towards the 6‐chloro‐tetrahydroquinoline (6‐Cl‐py‐THQ) formation. The reactivity trend in 2‐, 4‐, and 8‐methylquinoline was evaluated and corroborated with the DFT studies. The catalytic application was extended to the hydrogenation of styrene, which resulted in a 70 % conversion with >99 % ethylbenzene selectivity. The hydrogenation of 2‐bromostyrene produced a 75 % conversion with >99 % chemoselectivity of 2‐bromoethylbenzene. [ABSTRACT FROM AUTHOR]

Herein, ethylene-vinyl acetate copolymer/styrene ethylene butylene styrene (EVA/SEBS) blend foam with wide effective damping temperature range (ΔT) was prepared via supercritical nitrogen. The influence of the ratio of EVA and SEBS on the foaming and damping properties was studied. ΔT gradually widened into the high temperature region with the increase of SEBS content, and higher SEBS gave denser and more uniform cell structure and reduced the density of the blend foam. When the content of SEBS was 40 phr, the density of the blended foam was 0.185 g/cm³, and the ΔT was -3~54°C. These damping foams were lightweight and this work showed that damping performance could be controlled by simply adjusting blend content, which is of great significance to broaden the application environment of damping materials. [ABSTRACT FROM AUTHOR]

Sulfones are fascinating and highly used functional groups, but current syntheses still have limitations. Here, a regiodivergent transition metal-free approach towards sulfones [(E)-allylic sulfones and α-sulfonylmethyl styrenes] is reported. The method employs commercially available olefins, bases, additives, solvents, and sodium sulfinates (RSO2Na) and produces adducts in good yields. Considering that up to 4 reactions (bromination, dearomative rearrangement, E2, and SN2) are happening, this approach is very efficient. The structures of key adducts were confirmed by X-ray crystallography. [ABSTRACT FROM AUTHOR]

An efficient and practical method for the synthesis of functionalized trifluoromethyl cyclopropanes via cyclopropanation of α-trifluoromethyl styrenes with chloroacetonitrile or ethyl chloroacetate was developed. In some cases, the mixture of trans- and cis-isomers could be separated by column chromatography. The configurations of the trans-/cis-isomers were further confirmed by heteronuclear 1H–19F NOESY experiments. [ABSTRACT FROM AUTHOR]

1,2‐Cyclohexadienes generated under mild fluoride‐mediated desilylative conditions undergo efficient intramolecular [2+2] trapping, providing tricyclic alkylidene cyclobutanes with complete diastereoselectivity for the cis‐fused products. Pendent styrenes or electron‐deficient olefins can trap simple 1,2‐cyclohexadienes or their oxygenated counterparts, with 14 substrates being disclosed. Reactions proceed at ambient temperature using just cesium fluoride in up to 91 % yield, and the necessary precursors are easily accessed from substituted 2‐bromocyclohexenones. Multiple synthetic routes have been developed to install the appropriate functional groups required for [2+2] trapping. [ABSTRACT FROM AUTHOR]

Heteroarenes are common moieties in pharmaceuticals and naturally bioactive compounds. In this work, an efficient and atom‐economic rhodium and thiophenol co‐catalyzed hydroheteroarylation of styrenes with heteroarenes is reported. Alkylated unprotected heteroarenes are accessed under low catalyst loading. This protocol provides straightforward access to indoles bearing an all‐carbon quaternary center at the C3‐position. [ABSTRACT FROM AUTHOR]

Peripheral nerve injuries are challenging to repair clinically due to their limited regenerative capacity. Herein, a novel poly(3,4‐ethylenedioxythiophene):poly(4‐styrene sulfonate) (PEDOT:PSS) composited conductive silk conduit with ultrasound (US)‐triggered active release for peripheral nerve regeneration is presented. The conduit is composed of silk fibroin inverse opal tubular scaffolds and the secondary hydrogel filler that contains thermosensitive material (poly(N‐isopropylacrylamide), PNIPAM), PEDOT:PSS, and nerve growth factor (NGF). Benefiting from the integration of these functional materials and active factors, the silk fibroin conduits show excellent biocompatibility, flexibility, conductivity, and bioactivity. In particular, owing to the thermal effect of US and the temperature responsiveness of PNIPAM, the secondary filling hydrogel undergoes volume shrinkage upon US triggering, allowing the responsive NGF release. Besides, the electrical conductivity of PEDOT:PSS has been affirmed to promote neuron and axon outgrowth. Through in vivo experiments, the synergistic effect of PEDOT:PSS and US‐triggered delivery of NGF on accelerating injured nerve repair are demonstrated. These results reveal the practical value of the proposed intelligent conductive silk conduits with US responsiveness for nerve regeneration in preclinical studies. [ABSTRACT FROM AUTHOR]

A high loading of high‐density and high‐atomic‐number fillers are necessary to obtain desirable X‐ray attenuation characteristics from radiation shields. However, at high filler loadings, the mechanical and viscoelastic properties of polymers are severely impaired, posing a long‐term threat to the mechanical integrity and radiation protection, and the radiation shield temperature may increase after prolonged exposure to ionizing radiation, accelerating the aging of the polymer matrix. In addition, inadequate thermal conduction can make the user uncomfortable while using radiation shields for personal protection. Unfortunately, little attention has been paid to the viscoelastic, stress relaxation, and thermal conductivity‐related features of these densely loaded systems, despite the significant effect of these parameters on long‐term applications and user compliance. In the present work, two different styrene butadiene styrene (SBS) copolymers were used to develop SBS‐tungsten (W) composites. At 500 phr W loading, significant attenuation of X‐rays was achieved along with good tensile strength and elongation at break. The results indicate that the concentration of styrene in the SBS and W loading substantially affected the attenuation, mechanical and rheological properties, and tensile stress relaxation rates. The thermal conductivity increased by >100%, and after gamma irradiation, faster cooling was observed in the W‐loaded composites beyond 300 phr of W loading. The 40% styrene composite demonstrated superior heat transfer at high W loadings owing to the better dispersion and distribution of the W filler in the SBS matrix. Rheological results showed that SBS‐W composites with 30% styrene had a more pronounced Payne effect than those with 40% styrene. Stress relaxation and morphological analyses also revealed changes in the W dispersion in the SBS matrix depending on the styrene content. [ABSTRACT FROM AUTHOR]

This study increases the mass transfer of hydrophobic contaminants in a microbial fuel cell-based trickling filter (MFC/TF) by adding non-aqueous phase liquid. The removal efficiency, mineralization efficiency and elimination capacity of styrene are respectively increased by 1.56 times, 1.86 times and 1.52 times, the power density is increased by 2.6 times and the internal resistance is reduced by approximately 22% after adding 10% silicone oil to the MFC/TF. This is mainly attributed to a decrease in the internal resistance after adding silicone oil, which increases electron transfer on the surface of the auxiliary anode packing and increases the number of electricity-producing bacteria. Adding 10% silicone oil to the MFC/TF increases the number of degrading bacteria and electricity-generating bacteria in the MFC/TF by 2.3–2.5 times. The performance of the MFC/TF using 10% silicone oil is significantly increased because there is increased mass transfer of styrene in the MFC/TF and increased power generation. [Display omitted] [ABSTRACT FROM AUTHOR]

Aim: Styrene monomer (SM) is a basic chemical used as a raw material for polystyrene and unsaturated polyester resins and in the production of synthetic resins, synthetic rubbers, paints, and adhesives. To date, it is unclear whether SM is associated with the aggravation of atopic dermatitis. The aim was to investigate the effects of SM on atopic dermatitis-like skin lesions induced by mite allergen in NC/Nga mice. Methods: Male mice were injected intradermally with mite allergen on their right ears. In the presence of an allergen, SM (3.5 or 350 μg/animal/week) was administered by intraperitoneal injection. We evaluated clinical scores, ear thickening, histologic findings, and the protein expressions of cytokines and chemokines. Results: Macroscopic and microscopic examinations demonstrated that exposure to SM at a dose of 3.5 μg caused an exacerbation of atopic dermatitis-like skin lesions related to mite allergen. These changes were consistent with the level of histamine in the ear tissue as an overall trend. In contrast, 350-μg SM did not show significant enhancement effects. Conclusion: These results indicate that SM exacerbated atopic dermatitis-like skin lesions at hundred-fold lower levels than the level that causes no observed adverse effects as determined by histologic changes in rodent livers. SM could be at least partly responsible for the recent increase in atopic dermatitis. Styrene monomer (SM) is classified as an International Agency for Research on Cancer group 2B carcinogen and includes neurotoxicity and respiratory disorders. However, the effects of SM as a chemical substance on existing allergic pathophysiology have not been elucidated yet. This study demonstrated that SM exacerbated murine atopic dermatitis-like skin lesions at hundred-fold lower levels than the level that causes no observed adverse effects as determined by histologic changes in rodent livers, which was concomitant with the local level of histamine. These data hasten a need for comprehensive research to clarify the chemical pollutants' effects of doses much lower than NOAEL on vulnerable pathophysiologies such as allergy/atopy. [ABSTRACT FROM AUTHOR]

The graphene-modified styrene-acrylic-epoxy emulsion protective coating was prepared by physical blending method with waterborne epoxy emulsion, Kaolin, self-made rust transfer agent and graphene oxide dispersion as the modified materials of styrene-acrylic emulsion. The effects of styrene-acrylic-epoxy emulsion ratio and content of Kaolin, rust transfer agent and graphene oxide dispersion on the bonding strength of the coating were discussed, and the tensile properties and basic properties of the coating were investigated. The results show that the bond strength of the coating increases with the increase of the mass ratio of waterborne epoxy emulsion and increases first and then decreases with the increase of the content of Kaolin,rust transfer agent and graphene dispersion. When mphenyl acrylic: Qepoly =1:2 and content of Kaolin,rust transfer,graphene oxide dispersion is 10,3,0. 2,respectively,coating basic performance is good,and the coating resistivity is much larger than ordinary metal materials,exceUent protective effect. [ABSTRACT FROM AUTHOR]

The main objective of this research is to evaluate the influence of coating based on cellulose micro/nanofibrils (CMF) and carboxylated styrene butadiene rubber (XSBR) on sack kraft paper, for possible use in packaging. Filmogenic solutions were applied manually as a coating on sack kraft paper. These solutions were prepared by suspensions of CMF 1.5 % w/v with the addition of different content of XSBR (0, 2, 10, and 20 % about the total mass of CMF). Uncoated sack kraft paper was used as control. Films were obtained by casting and characterized physically, morphologically, and mechanically. The results demonstrated that XSBR and CMF composite suspension showed good performance as a coating on sack kraft paper. The formation of homogeneous structures well distributed on paper can be observed on scanning electron microscope images. Coatings containing XSBR presented a smoother surface, less porosity and hydrophilicity, and a greater coalescence, with good properties of air resistance and water vapor permeability. However, regarding mechanical properties, there were no improvements in coated papers. Therefore, the present study contributed information on the development of more flexible and hydrophobic cellulosic papers for possible applications in the industrial packaging sector. [ABSTRACT FROM AUTHOR]

There is a growing interest in developing more efficient synthetic alternatives for the synthesis of nitrogen-containing allylic compounds. This article presents a straightforward two-step protocol to produce 5-(3-azidoprop-1-en-2-yl)benzo[d][1,3]dioxole 4 from the natural product safrole. The method yielded the expected α-azidomethyl styrene 4, in good yield, via a dearomative rearrangement. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ensuring wellbore stability is of utmost importance for safety when drilling in deep formations. However, high temperatures severely disrupt the drilling fluid gel system, leading to severe stability issues within ultra-deep formations containing micropores. This study focused on the development of a polymer-based plugging material capable of withstanding high temperatures up to 200 °C. A kind of microsphere, referred to as SST (styrene–sodium styrene sulfonate copolymer), was synthesized with a particle size of 322 nm. Compared to polystyrene, the thermal stability of SST is greatly improved, with a thermal decomposition temperature of 362 °C. Even after subjecting SST to hot rolling at 200 °C for 16 h, the particle size, elemental composition, and zeta potential remained stable within an aqueous dispersion system. The results of core displacement and NMR tests demonstrate that SST considerably reduces the pore diameter with a remarkable plugging efficiency of 78.9%. Additionally, when drilling fluids reach 200 °C, SST still enhances drilling fluid suspension and dispersion, and reduces fluid loss by over 36% by facilitating the dispersion of clay particles, improving the gel structure of the drilling fluid, resisting clay dehydration, and promoting plugging. The development of SST provides valuable insights into the preparation of high-temperature-resistant microspheres and the formulation of effective plugging agents for deep-well drilling fluids. [ABSTRACT FROM AUTHOR]

Since alkyd resins include hazardous solvents, converting alkyds into waterborne hybrid polymers is an essential research topic. Here, alkyd/styrene acrylic waterborne hybrid polymers were synthesized in the presence of monomers, water, emulsifiers, and an initiator by using synthesized alkyd resins at 0%, 5%, 10%, and 15% ratios based on the total monomer ratio. A mini-emulsion technique and a semi-batch polymerization method were used to synthesize the latexes. Two different biosources, tall oil fatty acids (TOFA) and hemp seed oils (HSO), were used to synthesize the alkyd resins. Synthesized waterborne hybrid latexes and their films were analyzed by using FTIR, NMR, particle size, MFFT, TGA, DSC, CA, AFM, and mechanical tests. It was determined that the type and concentration of the alkyds affected the viscosity, particle size, Tg and MFFT values, and appearance. It was also identified that alkyd incorporation took place with grafting and that the alkyd concentration was particularly effective in increasing the particle size. In addition, experiments were carried out on waterborne paint systems for exterior paint by using synthesized hybrid polymer emulsions. It was observed that the alkyd content was not effective in changing the paint color in hybrid latexes. As a result, it is suggested that hybrid waterborne latexes could be used for exterior paints. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The emulsion polymerization of styrene was investigated using polystyrene‐b‐[polystyrene‐r‐poly(methacrylic acid)] amphiphilic block‐random copolymers (BRCs) of different compositions as stabilizers. These stabilizers with molar masses <20,000 g/mol, which possess unique dispersion behaviour (i.e., self‐assembly with low aggregation numbers) when dissolved in aqueous medium at alkaline pH, were prepared by the nitroxide‐mediated bulk polymerization of styrene to achieve a desired molar mass followed by chain extension by batchwise addition of styrene and methacrylic acid monomers to obtain the stabilizing group. Emulsion polymerizations of styrene stabilized by these BRCs yielded stable latexes with particle diameters that range between 30 and 150 nm. When different concentrations of the stabilizer (2–3.5 mM) were utilized for emulsion polymerization of styrene, a similar novel emulsion polymerization mechanism observed previously by our group for the acrylic‐acid based amphiphilic BRCs was also seen, further validating the difference between this class of polymeric surfactants and conventional small molecule surfactants, block copolymers, or alkali soluble resins. The performance of methacrylic‐acid based BRCs was more efficient and yielded higher surface coverage of the polystyrene latexes when compared to the acrylic‐acid based BRCs as a result of the more hydrophobic nature of the former. [ABSTRACT FROM AUTHOR]

A mathematical model for polymerization kinetics and molar mass development in the nitroxide‐mediated polymerization (NMP) of vinyl monomers in supercritical carbon dioxide (scCO2) has been developed. The method of moments is used for molar mass development. The perturbed‐chain statistical associating fluid theory (PC‐SAFT) equation of state is used to estimate the number of stable phases present at equilibrium in the reaction mixture, critical number average chain length at which polymer particles are formed, and monomer concentration in each phase. Pure and binary PC‐SAFT interaction parameters are estimated from liquid–liquid equilibrium (LLE) and liquid–vapour equilibrium (LVE) experimental data at 60 to 129°C. The effect of pressure on monomer conversion and molar mass development in the polymerization of styrene (Sty) using benzoyl peroxide (BPO) and 2,2,6,6‐Tetramethylpiperidinyl‐1‐oxyl (TEMPO) at 120°C and 300–500 bar is studied. It was observed that increasing pressure increases polymerization rate without significantly affecting molar mass development. [ABSTRACT FROM AUTHOR]

It is usually desired but often challenging to improve the wet traction, and reduce the abrasion and rolling resistance simultaneously in tread rubber, which is referred to as "magic triangle" in tire industry. To fulfill this goal, the filler dispersion and interfacial interaction required to be improved, as they are two essential factors to concurrently govern the ultimate properties of rubber composites. Herein, we synthesized the epoxidized solution polymerized styrene butadiene rubber (ESSBR) with different epoxy level, and used them as interfacial compatibilizer to promote the silica dispersion and silica/rubber interfacial interaction. The epoxy of ESSBR would react with silanol on silica surface and co‐crosslink with SSBR simultaneously, therefore build a strong bridge between rubber matrix and filler. By incorporation of 20 phr of ESSBR‐15% (15% of double bonds on main chain was epoxidized), the wet grip was improved by 40%, and DIN abrasion and rolling resistance were reduced by 38% and 21%, respectively with hardly sacrifice the mechanical properties. We envisage that this study provides an approach for the fabrication of rubber composites with improved silica dispersion and strengthened interfacial interaction. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Crystopal is a mechanically strong yet highly decorative plastic with a translucent and crackled appearance that was produced in the 1960s by the artist and plastics engineer Armand G. Winfield (1919–2009) and his company, Crystopal, Ltd. Many of Winfield’s collected plastic objects are housed within the Syracuse University Libraries, but some lack complete archival descriptions, including plastic compositions. To address this, the non-invasive and non-destructive determination of the polymer identities in Winfield’s artifacts was performed by Raman spectroscopy. Our studies generally begin with the database matching of an artifact spectrum to that of a polymer standard, but when objects known to be fabricated from Crystopal were analyzed, a database of over 100 representative polymers failed to yield the chemical identity of the plastic. However, the Raman spectrum of Crystopal displayed a unique chemical fingerprint that revealed it to be composed of an unsaturated polyester crosslinked with styrene. This Raman spectrum was added to the database and used as reference for the unambiguous identification of Crystopal artifacts, distinguishing them from decorative plastics with similar appearances. The addition of Crystopal to the polymer database provides a pathway toward establishing artifact provenance and preserving objects crafted from this unique and decorative plastic.

Abstract Background Styrene (CAS 100-42-5) is widely used as polystyrene and acrylonitrile–butadiene–styrene resin such as plastic, rubber, and paint. One of the primary uses of styrene is food utensils and containers, but a small amount of styrene transferred into food can be ingested by eating. Styrene is metabolized into styrene 7,8-oxide (SO). SO is mutagenic in bacteria and mouse lymphoma assays. It is clastogenic in cultured mammalian cells. However, styrene and SO are not clastogenic/aneugenic in rodents, and no rodent in vivo gene mutation studies were identified. Methods To investigate the mutagenicity of orally administered styrene, we used the transgenic rodent gene mutation assay to perform an in vivo mutagenicity test (OECD TG488). The transgenic MutaMouse was given styrene orally at doses of 0 (corn oil; negative control), 75, 150, and 300 mg/kg/day for 28 days, and mutant frequencies (MFs) were determined using the lacZ assay in the liver and lung (five male mice/group). Results There were no significant differences in the MFs of the liver and lung up to 300 mg/kg/day (close to maximum tolerable dose (MTD)), when one animal with extremely high MFs that were attributed to an incidental clonal mutation was omitted. Positive and negative controls produced the expected results. Conclusions These findings show that styrene is not mutagenic in the liver and lung of MutaMouse under this experimental condition.

Hydroformylation of olefins is widely used in the chemical industry due to its versatility and the ability to produce valuable aldehydes with 100% atom economy. Herein, a hybrid phosphate promoter was found to efficiently promote rhodium-catalyzed hydroformylation of styrenes under remarkably mild conditions with high regioselectivities. Preliminary mechanistic studies revealed that the weak coordination between the Rhodium and the P=O double bond of this pentavalent phosphate likely induced exceptional reactivity and high ratios of branched aldehydes to linear products.

Abstract The EFSA Panel on Food Additives and Flavourings (FAF) was requested to evaluate the safety of the smoke flavouring Primary Product Scansmoke SEF7525 (SF‐004), for which a renewal application was submitted in accordance with Article 12(1) of Regulation (EC) No 2065/2003. This opinion refers to the assessment of data submitted on chemical characterisation, dietary exposure and genotoxicity of the Primary Product. Scansmoke SEF7525 is obtained from a tar produced from a mixture of red oak, white oak, maple, beech and hickory. Based on the compositional data, the Panel noted that the identified and quantified proportion of the solvent‐free fraction amounts to 32.6 weight (wt)%, thus the applied method does not meet the legal quality criterion that at least 50% of the solvent‐free fraction shall be identified and quantified. At the maximum proposed use levels, dietary exposure estimates calculated with Food Additive Intake Model (FAIM) ranged from 0.6 to 3.8 mg/kg body weight (bw) per day at the mean and from 1.1 to 10.1 mg/kg bw per day at the 95th percentile. Based on the available information on genotoxicity on 44 identified components, the Panel concluded that two substances in the Primary Product, styrene and benzofuran, raise a potential concern for genotoxicity. In addition, a potential concern for genotoxicity was identified for the unidentified part of the mixture. Considering that the exposure estimates for styrene and benzofuran are above the threshold of toxicological concern (TTC) value of 0.0025 kg/kg bw per day for DNA‐reactive mutagens and/or carcinogens and since further data are needed to clarify their potential genotoxicity, the Panel concluded that the potential safety concern for genotoxicity of the Primary Product cannot be ruled out.

A series of styrene-butadiene di-block copolymers with high cis-1,4 unit content (greater than 92%) polybutadiene (PB) and isotactic-rich polystyrene (PS) (mmmm > 65%) was synthesized using α-diimine nickel catalysts (Ni-diimine). Four different Ni-diimine catalysts were synthesized via a complexing reaction between nickel (II) naphthenate and laboratory-made α-diimine ligands L1, L2, L3 and L4, which have different steric volume structures. The results indicate that the Ni-diimine catalyst prepared using the L4 ligand with a higher steric volume can effectively initiate the block polymerization of butadiene and styrene, and the resulting polymer has distinguished cis-1,4 structure unit PB and high isotactic-selective PS block. Differential scanning calorimetry and electrochemical performance tests show that these block copolymers with cis-1,4-regulated and isotactic-selective polymerization have advantages in terms of high-temperature and low-temperature resistance as well as corrosion resistance. Therefore, these copolymers are expected to be widely used in some harsh industrial environments.

Natural organic matter plays an important role in oceanic hydrothermal systems through a combination of geological and chemical processes. However, identifying the hydrothermal pathways of organic compounds is still quite limited, preventing us from understanding how organic matter is transformed in hydrothermal systems. In this study, we focus on the reaction pathways of alkenes, which represent a key functional group intermediate linking the most abundant hydrocarbons in seafloor hydrothermal environments. Three major pathways are observed for alkenes under mild hydrothermal conditions, including hydration, oxidation, and dimerization. The pathway distributions of alkenes can be affected by the presence of dissolved metal salts; hydration of alkenes is driven by metal ions via the change of solution pH, while alkene dimerization is controlled by pH and the type of metal cations and complexes. Overall, this study identifies alkene hydrothermal pathways and highlights the important roles of metal salts in controlling hydrothermal transformations. Plain Language Summary: In oceanic hydrothermal systems, organic matter transformations are important for producing and accumulating oil and natural gas, as well as serving as a source of energy and food for the subsurface life. Alkenes are a key intermediate linking the most abundant hydrocarbons such as alkanes and carboxylic acids in seafloor hydrothermal environments. Identifying the reaction pathways and mechanisms of alkenes is essential to understand how organic matter is produced and transformed in hydrothermal fluids. In this study, we conducted both laboratory experiments and geochemical modeling of alkenes under simulated oceanic hydrothermal conditions. The results show that hydration and dimerization of alkenes are favored in acidic hydrothermal solutions, whereas alkene oxidation is affected much less. Additionally, dissolved metal salts could selectively control the hydrothermal pathway of alkenes. The findings provide insights toward understanding the fate and reaction of organic matter in complex natural hydrothermal systems. Key Points: Three alkene pathways including hydration, oxidation, and dimerization are observed under mild hydrothermal conditionsDistribution of alkene hydrothermal pathways is affected by solution pH and dissolved metal saltsGeochemical modeling is consistent with experimental observations [ABSTRACT FROM AUTHOR]

Organocatalysis with chiral iodoarenes has emerged as a powerful approach for performing enantioselective transformations. However, it suffers from the need to utilize stoichiometric amounts of peroxy acids or similar high energy oxidants. Electrosynthesis enables eliminating stoichiometric redox reagents by replacing them with electric stimuli. In this context, an electrochemically‐promoted variant of the chiral iodoarene‐catalyzed asymmetric diacetoxylation of styrenes was evaluated. The screening of reaction parameters established a set of conditions under which, for the first time, an enantioselective electrochemical oxidation mediated by a chiral iodoarene achieving a catalytic turnover has been accomplished. The reaction was applied for the synthesis of an array of products in 15–60 % yields and 0–84 % ee. The modest efficiency of the electrocatalysis was traced to a partial direct oxidation of styrene substrates leading to racemic products and undesired dimeric side‐products. Cyclic voltammetry measurements demonstrated that such outcome originates from a somewhat difficult electrochemical oxidation of the applied iodoarene catalyst. Present work provides important insights and implications for the design of more efficient electrocatalytic systems employing chiral iodoarenes as mediators. [ABSTRACT FROM AUTHOR]

A photoredox‐mediated radical amidation ring‐expansion sequence that enables the generation of all‐carbon quaternary centers bearing a protected aminomethyl substituent is described. The methodology can be applied to both styrene and unactivated alkene substrates generating structurally diverse sp3‐rich amine derivatives in a concise manner. [ABSTRACT FROM AUTHOR]

Herein, we report a comprehensive computational study to understand the stereoinduction of (R)-SEGPHOS chiral diphosphine ligand in copper(I) hydride (CuH)-catalyzed enantioselective incorporation of CO2 with styrene. Mechanistic studies disclose that the stereoselectivity of the final reductive hydroxymethylation product is collectively controlled by the steps of 1,2-hydrocupration of styrene and CO2 insertion into the Cu–C bond. The multimodal stereochemical analyses, including the topographic steric mapping of the chiral (R)-SEGPHOS-ligated CuH catalyst, distortion/interaction, and intermolecular non-covalent interaction analysis on the 1,2-hydrocupration transition states, consistently point to the steric shielding from the P-substituents of the (R)-SEGPHOS ligand to the substrate as the origin of π-facial selectivity in the 1,2-hydrocupration step. Both (R)-SEGPHOS ligands bearing the P-DMTB and P-phenyl substituents can provide sufficient steric repulsion for shielding the re-face approach of the substrate to the Cu–H bond, and thus the (S)-alkylcopper(I) intermediates could be yielded with high enantioselectivity. By contrast, the stereoselectivity of CO2 insertion into (S)-alkylcopper(I) intermediate is primarily determined by the ligand-CO2 dispersion stabilizing interaction. Relative to the (R)-SEGPHOS ligand with the P-phenyl substituents, the substantially enhanced dispersion stabilizing interactions from the P-DMTB substituents of (R)-SEGPHOS ligand to CO2 could help raise the favorability of the inner-sphere CO2 insertion into the Cu–C bond, and thus allow the construction of C–CO2 bond with outstanding stereoselectivity. [ABSTRACT FROM AUTHOR]

The precise and efficient construction of axially chiral scaffolds, particularly toward the aryl-alkene atropoisomers with impeccably full enantiocontrol and highly structural diversity, remains greatly challenging. Herein, we disclose an organocatalytic asymmetric nucleophilic aromatic substitution (SNAr) reaction of aldehyde-substituted styrenes involving a dynamic kinetic resolution process via a hemiacetal intermediate, offering a novel and facile way to significant axial styrene scaffolds. Upon treatment of the aldehyde-containing styrenes bearing (o-hydroxyl)aryl unit with commonly available fluoroarenes in the presence of chiral peptide-phosphonium salts, the SNAr reaction via an exquisite bridged biaryl lactol intermediate undergoes smoothly to furnish a series of axially chiral aldehyde-containing styrenes decorated with various functionalities and bioactive fragments in high stereoselectivities (up to >99% ee) and complete E/Z selectivities. These resulting structural motifs are important building blocks for the preparation of diverse functionalized axial styrenes, which have great potential as efficient and privileged chiral ligands/catalysts in asymmetric synthesis. The precise and efficient construction of axially chiral scaffolds, particularly toward the aryl-alkene atropoisomers remains challenging. Here, the authors discuss an organocatalytic asymmetric nucleophilic aromatic substitution reaction of aldehyde-substituted styrenes involving a dynamic kinetic resolution process via a hemiacetal intermediate, offering a pathway to axial styrene scaffolds. [ABSTRACT FROM AUTHOR]

In this study, the water swellable rubber DPNR‐g‐PAM‐g‐PSt (DPP) was prepared by emulsion polymerization in a tert‐butyl hydroperoxide/tetraethylenepentamine initiation system using deproteinized natural rubber (DPNR) as the substrate, acrylamide (AM) and styrene (St) as the monomers, and Brij‐35 as the emulsifier. On this basis, the bentonite (BT) was added for coblending. The successful grafting of AM and St was verified by particle size, contact angle, Fourier transform infrared, 1H‐NMR, scanning electron microscope, and differential scanning calorimetry. The effects of blending with different amounts of bentonite on the mechanical properties and water absorption properties were discussed. The water swellable rubber DPP and DPP/BT prepared in this study have good prospects for applications in industry, construction, medical care, environmental protection, soil improvement, and nuclear waste treatment. [ABSTRACT FROM AUTHOR]

Tailor‐made poly(vinyl alcohol)‐b‐poly(styrene) copolymers (PVA‐b‐PS) for separation membranes are synthesized by the combination of reversible‐deactivation radical polymerization techniques. The special features of these di‐block copolymers are the high molecular weight (>70 kDa), the high PVA content (>80 wt%), and the good film‐forming property. They are soluble only in hot dimethyl sulfoxide, but by the "solvent‐switch" technique, they self‐assemble in aqueous media to form micelles. When the self‐assembled micelles are cast on a porous substrate, thin‐film membranes with higher water permeance than that of PVA homopolymer are obtained. Thus, by using these tailor‐made PVA‐b‐PS copolymers, it is demonstrated that chemical cross‐linkers and acid catalysts can no longer be needed to produce PVA membranes, since the PS nanodomains within the PVA matrix act as cross‐linking points. Lastly, subsequent thermal annealing of the thin film enhances the membrane selectivity due to the improved microphase separation. [ABSTRACT FROM AUTHOR]

A quadruple N‐heterocyclic carbene/cobalt/photoredox/Brønsted base catalysis to realize branch‐selective hydroacylation of styrenes with aromatic and aliphatic aldehydes is demonstrated. This protocol allows access to branched ketones from readily available materials in an atom‐economical manner. The quadruple catalysis can transfer a formyl hydrogen of aldehydes as a hydrogen radical equivalent onto the terminal carbon of an alkene by controlled electron and proton transfers. [ABSTRACT FROM AUTHOR]

Using vegetable oils as a plasticizer or processing aid in green rubber products is becoming popular due to environmental concerns. However, differences in vegetable oil processing result in varying amounts of low-molecular-weight (low-MW) free fatty acids (FFAs) in their composition, which range from 2% to 30%. This research investigated how the properties of silica-filled styrene butadiene rubber (SBR) and butadiene rubber (BR) blends were affected by the presence of FFAs in palm oil (PO). The rubber compounds containing a 70/30 SBR/BR blend, 30 phr of silica, and 2 phr of bis-(3-triethoxysilylpropyl) tetrasulfide (TESPT), and the vulcanizing agents were prepared and tested. The PO content was kept constant at 20 phr, while the number of FFAs, i.e., lauric acid (LA), palmitic acid (PA), and oleic acid (OA), in PO varied from 10–30%. The viscosity, dynamic mechanical properties, morphology, cure characteristics, and mechanical properties of the rubber blend were then measured. Regardless of the FFA types, increasing FFA content in PO decreased scorch time, cure time, minimum torque, and viscosity. As the FFA content increased, the torque difference and crosslink density also increased, which led to higher hardness, modulus, tensile strength, and abrasion resistance. The FFA types had a slight effect on the vulcanizate properties, even though LA showed slightly better mechanical properties than PA and OA. The results reveal that FFAs in PO not only improve processability but also function as a co-activator in silica-filled sulfur-vulcanized SBR/BR blend compounds. [ABSTRACT FROM AUTHOR]

Understanding the fatigue behaviors of weld joints is significant in engineering practice. Rotary friction welding (RFW) can join the additively manufactured polymer components. Until now, no research has focused on the fatigue behavior of polymer components jointed via RFW. This study investigates the fatigue life of ABS/PC dissimilar components fabricated via RFW and proposes the fatigue mechanism based on the failure structure. This work uses five different cyclic loads and rotational speeds to investigate the fatigue life. The fatigue life of the RFW of ABS/PC dissimilar rods is better compared with the pure ABS and pure PC specimens due to weld and integrity microstructural changes resulting from the combination of ABS and PC materials. The number of cycles until the rupture of RFW of ABS/PC dissimilar components (y) can be determined by the cyclic load (x) according to the prediction equation of y = −838.25x2 − 2035.8x + 67,262. The fatigue life of the RFW of ABS/PC dissimilar components increase with the increased rotational speed. The number of cycles until rupture (y) can be determined by the different rotational speeds (x) according to the prediction equation of y = 315.21x2 + 2710.4x + 32,124. [ABSTRACT FROM AUTHOR]

This study evaluated the wound-healing activity of a polymer, Poly(3,4-ethylenedioxythiophene):poly-(styrene sulfonate) (PEDOT: PSS), and determined its mechanism based on angiogenic activity in a full-thickness excision wound model in Spraque Dawley (SD) rats. Administering PEDOT: PSS (1.6) 1.5 ppm at a dose of 50 mg/kg/day significantly improved wound healing in the SD rats on the eleventh day after the incision was created. PEDOT: PSS-treated animals presented no anti-inflammatory skin effects; however, there was an increase in angiogenic behavior. VEGF was found to be significantly elevated in the PEDOT: PSS-treated groups seven days post-incision. However, only a higher concentration of PEDOT: PSS increased TGF-β1 expression within the same time frame. Our results showed that PEDOT: PSS enhances wound healing activity, mainly in terms of its angiogenic effects. In this paper, we describe the highly conductive macromolecular material PEDOT: PSS, which demonstrated accelerated wound-healing activity in the animal incision model. The results will further provide information regarding the application of PEDOT: PSS as a dressing for medical use. [ABSTRACT FROM AUTHOR]

The present study describes the facile synthesis and comprehensive characterization of new oxido and peroxidoniobium(V) complexes with biogenic ligands, maltol (malt) and deferiprone (def) in their co-ordination sphere, viz., [NbO(malt)3]2·9H2O (1), Na2[Nb(O2)3(malt)]·H2O (2) and Na2[Nb(O2)3(def)]·2H2O (3). The complexes were characterized using various analytical and spectroscopic techniques (FTIR, Raman, NMR, UV-visible, TGA, ICP-OES and elemental analysis). The charge neutral complex 1 was further characterized by single crystal XRD analysis, and the proposed structures of the peroxidoniobium (pNb) complexes 2 and 3 were validated by density functional theory (DFT) studies. A comparative investigation on the in vitro effect of the title compounds and a set of previously reported polymer-anchored peroxidoniobium complexes, [Nb(O2)3(sulfonate)2]3−-PSS [PSS = poly(sodium 4-styrene sulfonate)] (5), [Nb2(O2)6(carboxylate)2]4−-PA [PA = poly(sodium acrylate)] (6) and [Nb(O2)3(carboxylate)]2−-PMA [PMA = poly(sodium methacrylate)] (7), on the activity of the model enzyme wheat thylakoid acid phosphatase has revealed that each of the compounds is an effective inhibitor of the enzyme (IC50 values varying within the range 1–64 μM). The results of the detailed enzyme kinetic study demonstrated that the compounds induce their inhibitory effect via distinct pathways. The oxidoniobium complex 1 as well as polymer-anchored pNb complexes acted as classical non-competitive inhibitors of ACP, whereas the monomeric pNb complexes emerged as mixed inhibitors of the enzyme (Kii > Ki). Notably, the complexes serve as excellent recyclable catalysts for selective styrene epoxidation with H2O2, affording 99% styrene conversion, ≥98% epoxide selectivity and a high turnover number of 1740 under eco-friendly solventless conditions. [ABSTRACT FROM AUTHOR]

The palladium-catalyzed aminofluorination of styrenes using novel N-fluorobenzenesulfonimide (NFSI) derivatives with deprotectable substituents, and the selective deprotection and transformation of the resulting products into amines under mild reaction conditions are herein disclosed. [ABSTRACT FROM AUTHOR]