A simple and straightforward addition or defluorination of α-(trifluoromethyl)styrenes with 2-nitroimino-imidazolidine (2a), 2-(nitromethylene)imidazolidine (2b), 2-cyanoimino-thiazolidine (2c), and ...(E)-1-methyl-2-nitroguanidine (2d), in a controlled manner, was developed. The hydroamination of α-(trifluoromethyl)styrenes with 2a, 2b, 2c, and 2d was completed in the presence of DBN at room temperature within 0.5-6 h, affording structurally diverse β-trifluoromethyl-β-arylethyl analogues of neonicotinoids in moderate to good yields. The γ,γ-difluoro-β-arylallyl analogues of neonicotinoids were also successfully synthesized via defluorination of α-(trifluoromethyl)styrenes, with 2a and 2c using NaH as base at an elevated temperature together with a prolonged reaction time of 12 h. The method features simple reaction setup, mild reaction conditions, broad substrate scope, high functional group compatibility, and easy scalability.
The control of the nanostructure and the addition of nanoparticles to polymers have led to structural and functional property enhancements in a number of polymeric systems as a material answer to ...continuous requirements from advanced industrial sectors. The availability of new nanoparticles with extraordinary properties (i.e. carbon nanotubes, graphenes, but also nanoclays, nanocellulose, metals and ceramics) have determined new and exciting possibilities for a continuous enlargement of polymer markets. However, the potentialities of these new materials are still strongly dependent on the development and scaling-up of reliable processing routes. Therefore, the purpose of this report is to review the main processing approaches for nanostructured polymers and nanocomposites starting with a brief review of available nanoparticles and on their functionalization to promote a better polymer–particle interaction. Regarding processing, the review firstly addresses the bottom-up approaches typically adopted for nanostructured polymers, blends and copolymers. Then, the different technologies required by the top-down processing of thermoplastic and thermosetting polymer matrix systems are reviewed. Finally, the report addresses the recent applications of nanostructured polymers and nanocomposites as matrices of advanced composite materials. In all cases, the main processing approaches and the main structural and functional properties characterizing these materials and their potential and current industrial applications are specifically addressed.
meso-Tetraphenyl-21,23-dithiaporphyrin was selectively monobrominated at one beta-pyrrolic position in good yields. This dithiaporphyrin was then functionalized by Heck reaction with styrene ...derivatives containing different electronic features. The reaction profile was found to depend on the electronic characteristics of the styrene derivatives; the new compounds were fully characterized.
Inspired by the structural white of natural fibers, this work here demonstrated a novel passive radiative cooling design that builds random, three-dimensional pores in polymer matrix via the phase ...separation-based method. The pore size and structure are controlled by the compatibility between the shape-supporting matrix and other soluble polymers, where the semi-crystalline polypropylene (PP) was used as the shape-supporting matrix that is insoluble in any organic solvent at room temperature, and the soluble polymers were styrene-butadiene-styrene block copolymer (SBS) and styrene-ethylene-propylene-styrene block copolymer (SEPS). The experimental results revealed that those macroporous PP sheets have high solar reflectance (~97%) and tunable thermal emissivity (0.81-0.67). The outdoor thermal measurement also shows that those macroporous PP film-covered devices displayed a temperature (44.0 °C), much lower than those of air (50.0 °C) and neat-PP-covered device (60.4 °C). The complete simulation of a building thermal behavior evaluation shows that the macroporous PP roof-covered buildings exhibit a higher cooling effect than the neat PP roof-covered building in summer. Therefore, the required cooling power of the macroporous PP roof-covered buildings saved about 200 W compared with the neat PP roof-covered building on a typical summer day.
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•The bio-inspired design of the random pore structure for radiative cooling.•Investigate the effect of the pores' size and shape on the optical properties.•Estimate the heat insulation effect of building covered by the structured material.
Styrene is a nonpolar organic compound used in very high volume for the industrial scale production of commercially important polymers such as polystyrene resins as well as copolymers like ...acrylonitrile butadiene styrene, latex, and rubber. These resins are widely used in the manufacturing of various products including single‐use plastics such as disposable cups and containers, protective packaging, heat insulation, and so forth. The large‐scale utilization leads to the over‐accumulation of styrene waste in the environment causing deleterious health risks including cancer, neurological impairment, dysbiosis of central nervous system, and respiratory problems. To eliminate the accumulating waste. Microbial enzyme‐based system represents the most environmental friendly and sustainable approach for elimination of styrene waste. However, comprehensive understanding of the enzyme–substrate interaction and associated pathways would be crucial for developing large‐scale disposal systems. This study aims to understand the molecular interaction between the protein‐ligand complexes of the styrene catabolic reactions by bacterial enzymes of sty operon. Molecular docking analysis for catalytic enzymes namely, styrene monooxygenase (SMO), styrene oxide isomerase (SOI), and phenylacetaldehyde dehydrogenase (PAD) of the bacterial sty operon was carried out with their individual substrates, that is, styrene, styrene oxide, and phenylacetic acid, respectively. The binding energy, amino acids forming binding cavity, and binding interactions between the protein‐ligand binding sites were calculated for each case. The obtained binding energies showed a stable association of these complexes indicating the future scope of their utilization for large‐scale bioremediation of styrene, and its commercially used polymers and copolymers.
This series of publications describes research rendering soft polyisobutylene (PIB)‐based thermoplastic elastomers 3D printable by blending with rigid chemically compatible thermoplastics. The ...molecular structure, morphology, physical properties, and 3D printability of such blends have been systematically investigated. The authors' first report was concerned with the rendering of soft poly(styrene‐b‐isobutylene‐b‐styrene) (SIBS) 3D printable by blending with rigid polystyrene (PS). Here they report the macromolecular engineering of SIBS/polyphenylene oxide (PPO) blends for 3D printing. PPO, a rigid high‐performance thermoplastic, is compatible with the hard PS block in SIBS; however, neither PPO nor SIBS can be directly 3D printed. The microphase‐separated structures and physical properties of SIBS/PPO blends are systematically tuned by controlling blending ratios and molecular weights. Suitable composition ranges and desirable properties of SIBS/PPO blends for 3D printing are optimized. The morphology and properties of SIBS/PPO blends are characterized by an ensemble of techniques, including atomic force microscopy, small‐angle X‐ray scattering, and thermal and mechanical properties testing. The elucidation of processing‐structure‐property relationship of SIBS/PPO blends is essential for 3D printing and advanced manufacturing of high‐performance polymer systems.
Additive manufacturing of thermoplastic elastomer poly(styrene‐b‐isobutylene‐b‐styrene) (SIBS) is achieved by blending with polyphenylene oxide (PPO). The morphology and physical properties of SIBS/PPO blends as well as their effects on 3D printability are systematically investigated.
Styrene-acrylonitrile-copolymer (SAN) and acrylonitrile-butadiene-styrene-copolymer (ABS) are gaining in importance as food contact materials. Oligomers and other non-intentionally added substances ...can migrate into foodstuffs. Five SAN and four ABS samples from the German market and manufacturers were extracted and the extractable oligomers were characterised by high performance liquid chromatography-mass spectrometry/ultraviolet detection/chemiluminescence nitrogen detection/fluorescence detection and gas chromatography-mass spectrometry. Trimers, formed from acrylonitrile and styrene units, were determined to be the dominating group of extractable oligomers in SAN and ABS in concentrations of about 4900-15800 mg/kg material. Furthermore, styrene-acrylonitrile dimers, styrene oligomers, styrene monomer and ethylbenzene were identified in the sample extracts. Migration testing with three consecutive migrations for multiple use articles was performed for two SAN articles. Migration of trimers into water, 3% acetic acid, 10% and 20% ethanol under hot-fill conditions (70°C, 2 h) was not detectable above 9 µg/dm
2
, while 50% ethanol acting as a food simulant for milk (124 µg/dm
2
trimers during the third migration) was shown to overestimate the actual migration into milk (< 11 µg/dm
2
trimers at 70°C, 2 h). 2-Amino-3-methyl-1-naphthalenecarbonitrile (AMNC), an oligomer degradation product and a primary aromatic amine, was detected in all material sample extracts (0.3-17.1 mg/kg material) and was released into food simulants in low amounts (< 0.014 µg/dm
2
during the third migration into 50% ethanol at 70°C, 2 h).
Summary
In this study, styrene‐butadiene‐styrene (SBS) was used to develop a novel functionalized electrospun membrane for the effective treatment of heavy metals in direct contact membrane ...distillation (DCMD) applications. Functionalization was achieved by the addition (doping) of the super hydrophobic Al2O3 nanoparticles (Al NPs) within the matrix of the membrane during electrospinning. Neat (pristine nondoped) and doped SBS membranes were tested. The performance of the SBS membranes were also compared with fabricated polyvinylidene fluoride membranes with and without doping with Al NPs. The membrane characteristics were tested via Fourier transform infrared, scanning electron microscopy, pore size, and porosity investigations. The wettability of the membranes was investigated with respect to the liquid entry pressure (LEP) and contact angle. The performance of the membranes was tested in a DCMD setting for its ability to treat water containing salt (NaCl) and heavy metals (Cr (VI), Cd, Pb) in various concentration in a single and multicomponent systems. The SBS member exhibited excellent hydrophobicity characteristics such as a high LEP (16.87 psi) and contact angle (141° ± 2°). It also had superior permeate flux rate compared to the other prepared membranes (54.4 LMH). The addition of the Al2O3 nanoparticles enhance the performance of the membranes substantially. Slight decline in the flux was observed after 14 hours of continuous operating time that could be attributed to agglomeration, adsorption, or temperature polarization effects. The SBS AL NPs membranes also demonstrated excellent flux for saline solutions of varied concentrations with 99% salt rejection.
Styrene‐butadiene‐styrene electrospun membrane for direct contact distillation applications. Membrane surface enhanced with Al2O3 functionalized nano particles with super hydrophobic structure. High permeate flux rate and retention of heavy metals and salt.
Using photocatalytic oxidation to convert basic chemicals into high value compounds in environmentally benign reaction media is a current focus in catalytic research. The challenge lies in gaining ...controllability over product formation selectivity. We design covalent triazine frameworks as heterogeneous, metal‐free, and recyclable photocatalysts for visible‐light‐driven switchable selective oxidation of styrene in pure water. Selectivity in product formation was achieved by activation or deactivation of the specific photogenerated oxygen species. Using the same photocatalyst, by deactivation of photogenerated H2O2, benzaldehyde was obtained with over 99 % conversion and over 99 % selectivity as a single product. The highly challenging and sensitive epoxidation of styrene was carried out by creating peroxymonocarbonate as an initial epoxidation agent in the presence of bicarbonate, which led to formation of styrene oxide with a selectivity up to 76 % with near quantitative conversion. This study demonstrates a preliminary yet interesting example for simple control over switchable product formation selectivity for challenging oxidation reactions of organic compounds in pure water.
Metal‐free covalent triazine frameworks were designed for visible‐light‐driven switchable selective oxidation of styrene in pure water. By deactivation of photogenerated H2O2, benzaldehyde was obtained with over 99 % conversion and selectivity. Epoxidation of styrene with peroxymonocarbonate as an initial epoxidation agent in the presence of bicarbonate produced styrene oxide with a selectivity up to 76 % and near quantitative conversion.
The content of styrene units in nonhydrogenated and hydrogenated styrene‐butadiene‐styrene and styrene‐isoprene‐styrene triblock copolymers significantly influences product performance. A size ...exclusion chromatography method was developed to determine the average styrene content of triblock copolymers blended with tackifier in adhesives. A complete separation of the triblock copolymer from the other additives was realized with size exclusion chromatography. The peak area ratio of the UV and refraction index signals of the copolymers at the same effective elution volume was correlated to the average styrene unit content using nuclear magnetic resonance spectroscopy with commercial copolymers as standards. The obtained calibration curves showed good linearity for both the hydrogenated and nonhydrogenated styrene‐butadiene‐styrene and styrene‐isoprene‐styrene triblock copolymers (r = 0.974 for styrene contents of 19.3–46.3% for nonhydrogenated ones and r = 0.970 for the styrene contents of 23–58.2% for hydrogenated ones). For copolymer blends, the developed method provided more accurate average styrene unit contents than nuclear magnetic resonance spectroscopy provided. These results were validated using two known copolymer blends consisting of either styrene‐isoprene‐styrene or hydrogenated styrene‐butadiene‐styrene and a hydrocarbon tackifying resin as well as an unknown adhesive with styrene‐butadiene‐styrene and an aromatic tackifying resin. The methodology can be readily applied to styrene‐containing polymers in blends such as poly(acrylonitrile‐butadiene styrene).
![Synthesis of [beta]-Substit...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1434-193X/small "Synthesis of [beta]-Substituted meso-Tetraaryl-21,23-dithiaporphyrins by Heck Reaction")
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