UV Degradation Research Articles

UV stabilizers can foster early development of biofilms on freshwater microplastics

Interactions between microbes and microplastics are important as of emerging plastic loads in the global environment. Although diverse plastic additives are used in large amounts, there are very few studies on a quantitative comparison of plastisphere on plastics with different plastic additives. We studied the effects of two widely used UV stabilizers (benzotriazole-type UV-327 and benzophenone-type UV-531 were selected based on their persistence and toxicity) in low-density polyethylene (LDPE) on freshwater microbes. This is the first study on the sole effects of UV stabilizers used as plastic additives on freshwater in situ plastisphere biofilm development. Confocal laser scanning microscopy, assisted with proper differentiating fluorochromes and threshold-based 3D segmentation of data, was used to visualize and quantify biofilm. On the first week of biofilm growth, there was very little biovolume and a negligible amount of phototrophs on pristine LDPE contrasting other substrates. Biovolumes were significantly higher on LDPE with UV stabilizers (up to 159% higher than pristine LDPE), although the biomass was mostly dead due to toxicity (>100% higher dead biovolume than live biovolume in LDPE with UV stabilizers). After the fourth week, marginally higher biovolumes along with a revival of the biomass on LDPE with UV stabilizers were observed. The ability to induce microorganismic intracellular reactive oxygen species by UV stabilizers was detected, which may stimulate biofilm growth during the primary phase of biofilm development. Atomic force microscopy analysis denoted that LDPE with UV stabilizers exhibit considerably stronger adhesion force than pristine LDPE. These observations suggest that UV stabilizers can foster the early attachment of microbes to microplastics while killing the surface contacting layer. An alive upper layer of microbes can get developed on the dead biofilm without much disruption due to the toxicity of UV stabilizers. This occurrence can eventually boost the early development of biofilms on plastics.

Cementitious materials as promising radiative coolers for solar cells

SummaryNowadays, radiative coolers are extensively investigated for the thermal management of solar cells with the aim of improving their performance and lifetime. Current solutions rely on meta-materials with scarce elements or complex fabrication processes, or organic polymers possibly affected by UV degradation. Here, the potential of innovative cement-based solutions as a more sustainable and cost-effective alternative is reported. By combining chemical kinetics, molecular mechanics and electromagnetic simulations, it is shown that the most common cements, i.e., Portland cements, can be equipped with excellent radiative cooling properties, which might enable a reduction of the operating temperature of solar cells by up to 20 K, with outstanding efficiency and lifetime gains. This study represents a first step toward the realization of a novel class of energy-efficient, economically viable and robust radiative coolers, based on cheap and available cementitious materials.

The Effect of UV Irradiation on the Stability of Coated Fir Wood Samples

Abstract The aim of the paper consists in assessing the protection of fir wood samples against UV degradation by using polyacrylates and titanium dioxide as absorber. The irradiation was achieved for 648 hours, considered as about 2 years of weathering. Colorimetric, water absorption, and mechanical investigations were performed on samples before and after irradiation. The structural changes were evidenced by FTIR spectroscopy. Small changes in color for coated wood samples are observed after maximum 648 h of UV treatment, with the best results obtained for the specimen covered with Paraloid B72-TiO2. Higher compressive strengths were observed for the polymer-TiO2 coatings, in correlation with a smaller water absorption capacity of the studied samples. FTIR revealed shifted peaks with increased intensities as proof of structural changes produced by irradiation of lignin and polyacrylates. The results highlight that Paraloid B72 and Paraloid B67 mixed with TiO2 can be used as efficient UV protective coatings for fir wood.

Hofmann-MOF-derived CoFeNi nanoalloy@CNT as a magnetic activator for peroxymonosulfate to degrade benzophenone-1 in water

As the extensively-employed UV stabilizer, 2,4-dihydroxybenzophenone (benzophenone-1 (BP1)) has been proven an endocrine disruptor, developing of useful technologies for eliminating BP1 is highly desired. Because SO4•−-based oxidation technologies are promising for eliminating emerging pollutants, cobalt (Co) is an extremely useful catalyst for peroxymonosulfate (PMS) activation, and it is critical to developing an advantageous cobaltic catalyst for PMS activation. Herein, an exceptional catalyst is developed for the first time from a Hofmann-type MOF ([CoFe]pyrazine[Ni(CN)4]), which is then pyrolyzed to afford CoFeNi alloy nanoparticles (NPs) confined in carbon nanotubes (CNTs), resulting in CoFeNi@CNT (CFNC). This CFNC would exhibit numerous promising features: (1) as Co represents the most efficient metal for activating PMS, CoFeNi alloy would offer superior activities for PMS activation; (2) the strong magnetism of CoFeNi alloy enables CFNC to be magnetically controllable; (3) CoFeNi alloy NPs confined within CNT would be guarded to increase its durability; (4) the interlaced structures of CFNC make it exhibit much more reactive surface areas for activating PMS. Thus, CFNC exhibits a significantly stronger activating capability than Co3O4, which is the benchmark heterogeneous catalyst for PMS. Furthermore, CFNC could also be reusable and remain highly effective, stable, and robust for multiple cycles of BP1 degradation with minimal leaching of CoFeNi alloy. Mechanisms of PMS activation and elimination path of BP1 by CFNC are also elucidated via the theoretical DFT calculation and experimental data to supply valuable information about behaviors of BP1 degraded by Hofmann MOF-derived magnetic catalysts.

Reactive chlorine species in the enhanced degradation of UV stabilizers during the sunlight/free chlorine process

Benzotriazole (BT) and 5-methyl-1H-benzotriazole (5-MeBT) are the most commonly used UV stabilizers and recalcitrant contaminants that are widely distributed in aquatic environments. The novelty of this study was to investigate the role of RCSs in the enhanced degradation of BT and 5-MeBT during the sunlight/free chlorine process. The results showed that sunlight/free chlorine could enhance the degradation of BT and 5-MeBT compared with that obtained with sunlight irradiation and chlorination alone, and this process was well described by pseudo-first-order kinetics. The degradation rate constants of BT and 5-MeBT during sunlight/free chlorine treatment at pH 7 were 0.094 ± 0.001 min−1 and 0.134 ± 0.002 min−1, respectively. The degradation rates further increased with increases in the chlorine dosage and under alkaline conditions (3.818 ± 0.243 min−1 for BT and 7.754 ± 0.716 min−1 for 5-MeBT at pH 9). The enhanced removal obtained during the sunlight/free chlorine process could be attributed to the generation of HO• and reactive chlorine species (RCSs), such as Cl• and ClO•. Under alkaline conditions, RCSs were the dominant reactive species, and their contribution increased from 21.2% to 98.7% with increases in the pH from 7 to 9; this phenomenon was due to changes in free chlorine and BT speciation. Radical scavenging tests further verified that BT was mainly decomposed by ClO•, and ClO• showed high reactivity toward deprotonated BT through second-order rate constant estimation. A byproduct analysis demonstrated that BT underwent hydroxylation and chlorine substitution, and a high yield of 1-chlorobenzotriazole (1-ClBT) formation was observed. Even though the sunlight/free chlorine process resulted in a low level of mineralization, no Microtox® toxicity was detected in the treated solutions. Briefly, the significant contribution of ClO• to BT removal under alkaline conditions implies that sunlight/free chlorine could be utilized in a broader range of treatment conditions.

Polar Wax as Adhesion Promoter in Polymeric Blend Films for Durable Photovoltaic Encapsulants.

Technological developments in the solar photovoltaic field must guarantee the high performance and low deterioration of solar cells in order for solar power plants to be more efficient and competitive. The solar cell needs comprehensive protection offered by a polymeric encapsulant, which improves UV stability, reduces water and moisture absorption, reduces oxygen and vapor permeability and enhances mechanical resistance. Moreover, high transparency and adhesion yields improved the solar panel performance. The current work analyzes polymeric films based on poly(ethylene-co-vinyl acetate) (EVA) and polyolefin (PO) for photovoltaic encapsulant use (the high temperature resistance is improved by adding PO to EVA, as investigated and documented before). To enhance the mechanical resistance and optical properties of the investigated matrices, a crosslinking agent, an adhesion promoter and stabilizing agents have been incorporated in both EVA and EVA/PO systems. The adhesion promoter is a polar wax–silane-free agent; the absence of the silane function allows the integrity of the module to be maintained over time. All samples were characterized through mechanical and rheological analysis, and their long-term UV stability was investigated by accelerated ageing and by FTIR and UV–vis spectroscopy. The obtained results suggest that the presence of a crosslinking agent, an adhesion promoter and stabilizers in EVA/PO-based films allows for the achievement of the required features for the encapsulants, showing mechanical and rheological behavior similar to those of EVA containing the same additives.

Long-lasting renewable antibacterial graphene/N-halamine-coated cotton fabrics benefitting from enhanced UV stability and quantitative tracking of bactericidal factors

In this study, anionic GO aqueous dispersion and cationic QAS aqueous solution with specific concentrations were applied for the fabrication of modified cotton fabrics (MCFs) through the layer-by-layer self-assembly method. The chlorinated cotton fabrics with optimized protocol possessed excellent ultraviolet-blocking properties, with a UPF value of 323.08. Moreover, graphene greatly improved the UV stability of N-halamine, which could also be proved in the UV aging test of MCFs. In addition, the modification procedure also endowed cotton fabrics with superhydrophobic properties, thus broadening the application range of cotton fabric. The obtained GQC10 possessed excellent antibacterial activity, with all inoculated S. aureus and E. coli O157:H7 being completely killed within 5 min and 1 min of contact time, respectively. Indicated by the quantitative function relation between the active chlorine content (ACC) and the surface sheet resistance (SSR) of the MCFs, a novel and simple method for the determination of ACC was established. This method could be used to monitor the antimicrobial efficacy to ensure its sustainability. Furthermore, according to the variation frequency of SSR, the risk level of bacterial hazards in different places could be evaluated, thus broadening the application range of N-halamine-based antibacterial cotton fabrics.

The Effect of Ultraviolet Light Stabilizers on Color Stability, Melt Properties and Tensile Properties of Mixed Waste Plastics Blends

Plastic waste disposal is among the most challenging problems of the current era. Therefore, new methods and applications for the utilization of waste plastics are increasingly needed. To find them, it is essential to research and develop the material properties of recycled plastics. The effect of different ultraviolet light (UV) stabilizers on the color stability, melt properties and tensile properties of mixed waste plastics blends was studied in this paper. The mixed waste plastics collected from two different waste sources were prepared as specimens by injection molding, and studied with two different types and loading amounts of UV stabilizers. UV absorbers (UVAs) and hindered amine light stabilizers (HALS) were used as UV stabilizers. A specimen produced without the addition of a UV stabilizer was used as a reference specimen of both the blends. After the accelerated weathering, the addition of a UVA provided an improved, smaller change in color than the addition of HALS. Among the tensile properties, the addition of UV stabilizers clearly improved the tensile strength and tensile modulus for almost all the studied specimens. Additionally, the melt properties of both the studied plastic blends were found to be increased by the addition of UV stabilizers.

Recycling of spent mushroom substrate biowaste as an Anti-UV agent for Bacillus thuringiensis

It is highly desirable to develop a Bacillus thuringiensis (Bt) formulation with high UV resistibility to increase its application duration in the field. In this work, we studied spent mushroom substrate extract (SMSE) for its anti-UV activity on Bt. The results demonstrated that SMSE could efficiently protect the active components of Bt from UV irradiation. After 96 h of UV exposure, the residual toxicity of Bt fermentation of the SMSE (0.6%, w/v) treatment was 17 times higher than that of the control treatment. SMSE was mainly composed of lignin (77.69%), carbohydrate (7.58%) and protein (4.18%). The anti-UV activity was shown by the lignin and carbohydrate fractions, but not the protein fractions. In addition, it was found that lignin and lignin-carbohydrate complex (LCC) in the SMSE were a type of lignin with low sugar content, low thermal stability, narrow molecular weight distribution and were typical gramineous plant lignin. Lignin and LCC possessed highly UV-screening effects and reactive oxygen species scavenging ability that could improve the UV stability of Bt formulation. Our study provides a green method for the utilization of SMS biowaste and increased the UV stability of Bt formulation.

Lignin as a bioactive polymer and heavy metal absorber- an overview

As a pulping and bio-refinery by-product with phenolic chemical structure, lignin indicated high potential as natural antioxidant activity, UV blocker, antibacterial and toxic material absorbent properties. Presence of phenolic hydroxyl groups in lignin structure plays the main role of its antioxidant activity. However, lignin antioxidant power can change depending on its other structural features and functional groups like ortho-methoxy groups, –OCH3 groups, the α-CH2 groups, the aliphatic carbonyl groups, and the size of π-conjugated systems. Lignin in mixture with synthetic polymers, improved their thermal stability. Lignin has high UV light absorbing potential in broad-spectrum (UVA, UVB). Adding 1–5% of lignin into hand cream indicated excellent range of sun protection factor (SPF) with more than 95% UV light absorption. Lignin also indicated strong UV light protection when applied in different transparent film and protect paint, oil, and varnish from UV degradation. Lignosulfonate and other modified lignin including chemically modification, nano-particles and lignin hydrogel indicated high potential as heavy metal absorber.

Screening of antimicrobials, fragrances, UV stabilizers, plasticizers and preservatives in sewage treatment plants (STPs) and their risk assessment in India

Community/industrial wastewater is the prime source of anthropogenic chemicals, its treatment is often a daunting task and unaffordable for many countries. Emerging Contaminants (ECs) have been drained into wastewater after continuous use/misuse and Conventional treatments in STPs do not remove them completely. ECs including antimicrobial agents, synthetic musks, Benzotriazole UV stabilizers (BUVSs), plasticizers, and preservatives are frequently reported in environment, and cause health effects to non-target organisms. Monitoring of ECs is important to understand their status in aquatic environment. Hence, it was aimed to monitor ECs (n = 21) from 11 STPs in Tamil Nadu, India. The detection frequency of most of these analytes was >90%. Antimicrobials ranged from 247 to 22,714 ng/L and 11–14,369 ng/L in influents and effluents, respectively. The synthetic musks were in the order of Tonalide > Galaxolide > Musk Ketone. BUVSs ranged from 4 to 1632 ng/L (influents) and < LOD to 29,853 ng/L (effluents). Concentration of phthalates in influents and effluents were < LOD - 11,311 ng/L and < LOD - 17,618 ng/L, respectively. Parabens were found in the order of Prophyl > Methyl > Ethyl > Butyl in influents and Methyl > Prophyl > Butyl > Ethyl in effluents. Mass loads of ECs through STPs were found as antimicrobials > plasticizers > fragrances > BUVSs > Preservatives. This study reveals increasing usage of ECs and inadequate treatment processes at STPs in India. Also helps to adopt suitable treatment processes to remove ECs from wastewater and to reuse the wastewater.

In situ synthesis of MAPbX3 perovskite quantum dot-polycaprolactone composites for fluorescent 3D printing filament

The development of functionalized polymer-based filament enables the fused deposition modeling (FDM) 3D-printed materials or structures with a wide range of unique functions. This work explores the use of MAPbX3 (MA = CH3NH3, X = Cl, Br, I or mixture of them) perovskite quantum dots (PQDs) by harnessing their unique optical properties for the development of fluorescent 3D printing filaments. Firstly, a one-pot strategy for scalable synthesis of MAPbX3 PQDs-polycaprolactone (PCL) composite was proposed by in situ formation of PQDs in PCL matrix. To demonstrate the ability for the obtained PQDs-PCL composites to fabricate fluorescent filaments, the effects of filament functionalization on optical properties of PQDs, as well as thermal and mechanical properties of polymer matrix were then comprehensively studied. Owing to the good protective capability of PCL, the synthesized PQDs-PCL composites exhibit comparable PLQY and enhanced UV, water and thermal stability compared to that of pure PQDs. Moreover, high concentration of embedded PQDs in PQDs-PCL composites was obtained with decreasing amount of PCL. The aggregation of PQDs at high temperature combined with the poor interaction between PQDs and surrounding PCL matrix led to the decreased thermal transition temperature and reduced mechanical properties in PQDs-PCL composites relative to pure PCL. The glass transition temperature was found to decrease by 5.5 °C, while the mode of failure changed from plastic fracture for pure PCL to brittle fracture for the highest concentration of PQDs in PCL tested. Consequently, PQD-PCL composites were further processed into fluorescent filaments and further fluorescent objects or structures via 3D printing. Green LED and white LED devices were realized by the combination of UV LED chip with 3D printed MAPbBr3 PQD-PCL thin-film, and blue LED chip with MAPbBr3 PQD-PCL thin-film and K2SiF6:Mn4+ phosphor, respectively, demonstrating that the PQDs-functionalized 3D printing filaments have great potential in fields of optoelectronic application.

Investigating the Physicochemical Property Changes of Plastic Packaging Exposed to UV Irradiation and Different Aqueous Environments

A wide range of weathering processes contributes to the degradation of plastic litter items which leads to the formation of microplastics that may be detrimental to marine ecosystems and the organisms inhabiting them. In this study, the impact of UV exposure on the degradation of clear polypropylene (CPP), black polypropylene (BPP), and polyethylene terephthalate (PET) packaging materials was investigated over a period of 6 weeks under dry air conditions representing the terrestrial environment. The exposure was conducted using differently sized and shaped samples at irradiation intensities of 65 W/m2 and 130 W/m2. Results indicated that UV irradiation led to changes in the properties of PET, BPP, and CPP that were proportional to the intensity delivered, leading to a higher level of mass loss, carbonyl indices, crystallinities, and microhardness in all polymer types at 130 W/m2 relative to 65 W/m2. However, material shape and size did not have a significant influence on any property for any of the test materials. Increased mass loss over time was accompanied by considerable increases in carbonyl index (CI) for both PPs. Clear PP (CPP) underwent the most severe degradation, resulting in the highest mass loss, increase in crystallinity, and CI. BPP was less degraded and modified by the UV irradiation than the CPP, indicating that the colorant, carbon black, provided some degree of protection to the bulk polymer material. PET was the least degraded of the three materials, suggesting this polymer type is more resistant to UV degradation. The differences in the degradation behaviours of the three test materials under dry environmental conditions indicate that the UV exposure history of plastic litter might play an important role in its potential for further degradation once it reaches the marine environment. Furthermore, analysis of samples exposed to UV in aqueous media reveals a more irregular set of trends for most material properties measured. Overall, the degree of degradation resulting from UV irradiation in dry environments was more pronounced than in aqueous environments, although the most significant property changes were observed for materials without previous UV exposure histories. Samples with previous UV histories showed higher resistance to further crystallinity changes, which appeared to be due to crosslinking in the pretreatment exposures inhibiting chain alignment into crystalline structures. The effect of solution medium was insignificant, although the presence of water allowed hydrolytic degradation to proceed simultaneously with UV degradation for PET. The reduction of CI in pretreated materials in the aqueous exposures, combined with the mass loss, suggest that the degraded surface layer erodes or products dissolve into surrounding solution medium, leaving a fresh surface of plastic exposed.

Lignin-based non-crosslinked nanocarriers: A promising delivery system of pesticide for development of sustainable agriculture

Lignin sulfonate (LS), a waste material from the paper pulping, was modified with benzoic anhydride to obtain benzoylated lignin sulfonates of adjustable hydrophilicity (BLS). When BLS was combined with difenoconazole (Di), a broad-spectrum fungicide, lignin-based, non-crosslinked nanoparticles were obtained either by solvent exchange or solvent evaporation. When a mass ratio of 1:5 LS: benzoic anhydride was used, the Di release from Di@BLS5 after 1248 h was ca. 74 %, while a commercial difenoconazole microemulsion (Di ME) reached 100 % already after 96 h, proving the sustained release from the lignin nanocarriers. The formulation of Di in lignin-based nanocarriers also improved the UV stability and the foliar retention of Di compared to the commercial formulation of the fungicide. Bioactivity assay showed that Di@BLS5 exhibited high activities and duration against strawberry anthracnose (Colletotrichum gloeosporioides). Overall, the construction of fungicide delivery nano-platform using BLS via a simple non-crosslinked approach is a novel and promising way to develop new formulations for nanopesticide and the development of sustainable agriculture.

Effects of m-Aramid/p-Aramid Blend Ratio on Tensile Strength due to UV Degradation for Firefighter Clothing Fabrics and Development of Predictive Equation for Tensile Strength.

This study focused on the m-Aramid/p-Aramid blend ratio of the fabrics, clarified the quantitative relationship between UV exposure and strength retention, and developed a mathematical model to calculate tensile strength from an arbitrary amount of UV exposure energy. The results of tensile strength tests before and after UV exposure showed that the decrease in tensile strength due to UV degradation depended on the combination of p-Aramid and m-Aramid blend percentages. Tensile strength for all blend ratios decreased exponentially with UV exposure energy and was within the range of results for fabrics with p-Aramid 100% and m-Aramid 100%. The retention fraction of tensile strength, which represents the tensile strength after UV exposure relative to the initial tensile strength, decreased exponentially with increasing the fraction of UV exposure energy for all fabrics used in this study. Fitting the retention fraction of tensile strength to the fraction of UV exposure energy, two groups of fabrics were classified based on m-Aramid blends of 40% or more and 60% or less. This model can predict the tensile strength of firefighter clothing fabrics that retain high mechanical strength when exposed to UV light and design the strength of firefighter clothing with consideration of degradation over time.

2,2'-Dihydroxy-4,4'-dimethoxy-benzophenon as Bifunctional Additives for Passivated Defects and Improved Photostability of Efficient Perovskite Photovoltaics.

Organic-inorganic hybrid perovskite solar cells (PSCs) have developed rapidly in the past decade, but their commercial applications are restricted by further improvement in their photovoltaic performance and stability. Herein, we propose a facile and effective method employing 2,2'-dihydroxy-4,4'-dimethoxy-benzophenon (BP6) as bifunctional additive to construct efficient and photostable PSCs. BP6, as an additive, improves the crystallization quality of perovskite absorbers and further inhibits defect-mediated non-radiative recombination through interaction between the C═O group and defects; as a UV absorber, BP6 protects the PSCs from UV degradation by effectively absorbing UV light through molecular tautomerism under continuous strong UV irradiation. Eventually, the champion PSC demonstrates an efficiency of 22.85% with enhanced UV stability after addition of 0.024 wt % BP6. These results reveal that addition of UV absorbers (such as BP6 in this study) is a simple and effective strategy to fabricate efficient and photostable PSCs.

Experimental and COSMO-RS theoretical exploration of rutin formulations in natural deep eutectic solvents: Solubility, stability, antioxidant activity, and bioaccessibility

The present study aimed to estimate the solubility of rutin in twelve natural deep eutectic solvents (NADES) and to compare experimental results with the theoretical prediction by the COSMO-RS program. The mandatory component in all investigated systems was choline chloride (ChCl), and the variable component was hydrogen bond donor (HBD), including organic acids, sugars, alcohols, and urea. The FRAP method tested the antioxidant activity of rutin formulations in NADES systems. It was found that theoretical prediction and experimentally determined solubilities of rutin were in excellent agreement. The highest solubility of rutin was observed in 1,2-propanediol (ChCl:1,2PD), 59.30 mg/mL and urea-based systems (ChCl:Ur), 57.99 mg/mL. These systems were further investigated, including dissolution efficiency study, stability to UV and hydrogen-peroxide degradation, and bioaccessibility of rutin by in vitro digestion model. It was found that ChCl:Ur protected rutin against UV-induced oxidation. It was also found that rutin solubilization in ChCl:Ur and ChCl:1,2PD retained rutin for 78.64% and 76.57% in digestive fluids after in vitro digestion and enhanced bioaccessibility compared to the control for more than 60%.

Upscale recycling of nonwoven polypropylene waste using a novel blending method

AbstractWaste management of the nonwoven polypropylene (PP) fabric has become an emerging issue due to its increased usage. This study presents the upscale recycling of PP nonwoven fabric scrap generated during medical‐grade disposable gown manufacturing. To prepare PP and carbon black (CB) nanocomposite, a two‐step novel melt blending process is used. A maximum density of 937 kg/m3, shore D hardness of 74.45, and highest improvement in UV degradation resistance with a carbonyl index of 0.40 is recorded at 2 wt% of the CB while melt flow index is the lowest at 0.5 wt% of the CB. The results of this study revealed the peak melting point (161.81°C), thermal degradation temperature (421°C), highest flexural strength (49.16 MPa), and Izod impact strength (6.76 kJ/m2) are at 0.50 wt% of CB loading. A morphological study indicated that the highest agglomeration of CB particles was found at 2 wt% CB. The results showed that the optimum value of CB in PP nanocomposite is 0.5 wt%, at which the majority of the properties are maximized. This research might pave the way for the recycling of nonwoven PP waste fabric and provide an alternative to the exciting virgin raw materials.

Alcohol-Stable Perovskite Nanocrystals and Their In Situ Capsulation with Polystyrene.

In recent years, lead halide perovskite nanocrystals (PNCs) have presented potential scalable applications in all fields due to their outstanding properties. However, most commonly used PNCs capped with oleic acid (OA) and oleylamine (OAm) suffer from bad stability in polar solutions and thus require various surface protections with organic or inorganic materials. Encapsulation with highly hydrophobic polystyrene (PS) is one of the most efficient ways to protect PNCs; however, the presently used swelling-shrinking strategy faces several challenges, such as weak interaction between PS chains and the surface ligands in nonpolar media causing a low encapsulation efficiency, and serious aggregation of PS particles during the shrinkage process leading to very different particle sizes. Herein, alcohol-stable polyacrylic acid-capped CsPbBr3 PNCs (i.e., PAA-PNCs) are first synthesized and then in situ encapsulated with PS shells by polymerizing styrene monomer on the PNC surfaces in a polar organic solvent (e.g., ethanol). The in situ PS-encapsulated PAA-PNCs (i.e., PAA-PNCs@iPS) exhibit outstanding monodispersity, remarkable water, heat, and UV stability, high fluorescence activity, and color purity. The unique synthesis strategy and good performances of PAA-PNCs@iPS will boost the applications of PNCs in LEDs, biological imaging, and chemosensing.

Analysis of Thermoplastic Copolymers by Mild Thermal Degradation Coupled to Ion Mobility Mass Spectrometry.

Thermal desorption/degradation with an atmospheric solids analysis probe (ASAP) and ion mobility (IM) separation are coupled with mass spectrometry (MS) analysis and tandem mass spectrometry (MS/MS) fragmentation to characterize thermoplastic elastomers. The compounds investigated, which are used in the manufacture of a wide variety of packaging materials, are mainly composed of thermoplastic copolymers, but also contain additional chemicals ("additives"), like antioxidants and UV stabilizers, for enhancement of their properties or protection from degradation. The traditional method for analyzing such complex mixtures is vacuum pyrolysis followed by electron or chemical ionization mass spectrometry, often after gas chromatography separation. Here, an alternative, faster approach, involving mild degradation at atmospheric pressure (ASAP) and subsequent characterization of the desorbates and pyrolyzates by IM-MS, and if needed, MS/MS is presented. Such multidimensional dispersion considerably simplifies the resulting spectra, permitting the conclusive separation, characterization, and classification of the multicomponent materials examined.