Aqueous Dispersions of Nanostructured Particles Hybridized with Mono- and Multifunctional POSS Methacrylates: Heterophase Polymerization and Material Properties of the Resulting Latex Films

The synthesis of aqueous dispersions of hybrid acrylic copolymer particles containing either a monofunctional or a multifunctional oligomeric silsesquioxane as a comonomer has been performed by heterophase free radical polymerization. The miniemulsion process allowed to produce stable latexes, as opposed to the less controlled emulsion route. The thermal, mechanical and surface properties of the nanocomposite latex films have been investigated

New Polymer-Supported Mono- and Bis-Cinchona Alkaloid Derivatives: Synthesis and Use in Asymmetric Organocatalyzed Reactions

The straightforward synthesis of polystyrene-supported Chinchona alkaloids and their application in the asymmetric dimerization of ketenes is reported. Six different immobilized derivatives, consisting of three dimeric and two monomeric 9-O ethers, were prepared by “click” anchoring of soluble alkaloid precursors on to azidomethyl resins. The resulting insoluble polymer-bound (IPB) organocatalysts were employed for promoting the dimerization of in-situ generated ketenes. After opening of the ketene dimer intermediates with N,O-dimethylhydroxylamine, valuable Weinreb amides were eventually obtained in good yield (up to 81 %) and excellent enantiomeric purity (up to 96 % ee). All of the IPB catalysts could be recycled effectively without significant loss of activity and enantioselectivity. The extension to other asymmetric transformations (meso-anhydride desymmetrization and α-amination of 2-oxindoles) is also briefly discussed

Microplastic pollution in the sediments of interconnected lakebed, seabed, and seashore aquatic environments: polymer-specific total mass through the multianalytical “PISA” procedure

The total mass of individual synthetic polymers present as microplastic (MP < 2 mm) pollutants in the sediments of interconnected aquatic environments was determined adopting the Polymer Identification and Specific Analysis (PISA) procedure. The investigated area includes a coastal lakebed (Massaciuccoli), a coastal seabed (Serchio River estuarine), and a sandy beach (Lecciona), all within a natural park area in Tuscany (Italy). Polyolefins, poly(styrene) (PS), poly(vinyl chloride) (PVC), polycarbonate (PC), poly(ethylene terephthalate) (PET), and the polyamides poly(caprolactame) (Nylon 6) and poly(hexamethylene adipamide) (Nylon 6,6) were fractionated and quantified through a sequence of selective solvent extractions followed by either analytical pyrolysis or reversed-phase HPLC analysis of the products of hydrolytic depolymerizations under acidic and alkaline conditions. The highest concentrations of polyolefins (highly degraded, up to 864 μg/kg of dry sediment) and PS (up to 1138 μg/kg) MPs were found in the beach dune sector, where larger plastic debris are not removed by the cyclic swash action and are thus prone to further aging and fragmentation. Surprisingly, low concentrations of less degraded polyolefins (around 30 μg/kg) were found throughout the transect zones of the beach. Positive correlation was found between polar polymers (PVC, PC) and phthalates, most likely absorbed from polluted environments. PET and nylons above their respective LOQ values were found in the lakebed and estuarine seabed hot spots. The pollution levels suggest a significant contribution from riverine and canalized surface waters collecting urban (treated) wastewaters and waters from Serchio River and the much larger Arno River aquifers, characterized by a high anthropogenic pressur

Singling Out the Role of Molecular Weight in the Crystallization Kinetics of Polyester/Clay Bionanocomposites Obtained by In Situ Step Growth Polycondensation

The isothermal crystallization kinetics of a set of bio-nanocomposites produced by in situ catalytic step growth polycondensation of adipic acid and 1,4-butanediol in the presence of Moroccan clay beidellite (BDT) organo-modified with hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, CTA) was investigated and compared with that of the parent poly(butylene adipate) (PBA) matrices from which the clay had been extracted. In situ bio-nanocomposites had different contents (0−5 wt %) of CTA/BDT nanofillers characterized by different extents of organo-modification (CTA/BDT equivalent ratios from 0 to 5). Theb isothermal crystallization rates of the ionanocomposites and of the parent PBA matrices were investigated by differential scanning calorimetry (DSC) at 45, 40, and 37 °C and analyzed according to the Avrami model. The bionanocomposites with an intermediate (2 wt %) concentration of organoclays with a higher CTA/BDT ratio (3 and 5) showed the highest exfoliation degree, along with an increase in the crystallization rates, compared to those of the parent PBA matrices, which was larger than that in the other nanocomposites. The lack of a simple correlation between the nanoclay content/composition and crystallization kinetics was ascribed to the molecular mass, an additional variable for in situ bio-nanocomposites as compared to nanocomposites prepared by simple physical blending of nanoclays with a single polymer matrix. The specific contribution of the molecular mass to the crystallization kinetics was untangled from those of the organoclay content and CTA/BDT ratio by comparing each bio-nanocomposite with its parent polymer matrix. The crystallization rate of the nanocomposites was always found to reach a maximum within an intermediate range of molecular weights of the polymer matrix, a behavior previously reported only for pure polymers. Such differences in the crystallization rate of in situ bio-nanocomposites may affect the crystalline phase morphology and, in polymorphs such as in PBA, phase composition, with consequent effects on properties that may be of interest for specific applications

New methodologies for the detection, identification, and quantification of microplastics and their environmental degradation by-products

Sampling, separation, detection, and characterization of microplastics (MPs) dispersed in natural water bodies and ecosystems is a challenging and critical issue for a better understanding of the hazards for the environment posed by such nearly ubiquitous and still largely unknown form of pollution. There is still the need for exhaustive, reliable, accurate, reasonably fast and cost efficient analytical protocols allowing the quantification not only of MPs, but also of nanoplastics (NPs) and of the harmful molecular pollutants that may result from degrading plastics. Here a set of newly developed analytical protocols, integrated with specialized techniques such as pyrolysis-gaschromatography-mass spectrometry (Py-GC/MS), for the accurate and selective determination of the polymers most commonly found as MPs polluting marine and freshwater sediments are presented. In addition, the results of an investigation on the low molecular weight volatile organic compounds (VOCs) released upon photo-oxidative degradation of microplastics highlight the important role of photoinduced fragmentation at a molecular level both as a potential source of hazardous chemicals and as accelerators of the overall degradation of floating or stranded plastic debris

Use of statistical design of experiments for surface modification of Kapton films by CF4 O2 microwave plasma treatment

A statistical design of experiments (DoE) was used to evaluate the effects of CF4 O2 plasma on Kapton films in which the duration of treatment, volume ratio of plasma gases, and microwave power were selected as effective experimental factors for systematic investigation of surface modification. Static water contact angle (W), polar component of surface free energy (S p) and surface O/C atomic ratio were analyzed as response variables. A significant enhancement in wettability and polarity of the treated films compared to untreated Kapton films was observed; depending on the experimental conditions, W very significantly decreased, showing full wettability, and S p rose dramatically, up to ten times. Within the DoE the conditions of plasma treatment were identified that resulted in selected optimal values of W, Sp and O/C responses. Surface chemical changes were detected by XPS and ATR-IR investigations that evidenced both the introduction of fluorinated groups and the opening of the imide ring in the plasma-treated films

Use of statistical design of experiments for surface modification of Kapton films by CF4-O2 microwave plasma treatment

A statistical design of experiments (DoE) was used to evaluate the effects of CF4-O2 plasma on Kapton films in which the duration of treatment, volume ratio of plasma gases, and microwave power were selected as effective experimental factors for systematic investigation of surface modification. Static water contact angle (θW), polar component of surface free energy (γSp) and surface O/C atomic ratio were analyzed as response variables. A significant enhancement in wettability and polarity of the treated films compared to untreated Kapton films was observed; depending on the experimental conditions, θW very significantly decreased, showing full wettability, and γSp rose dramatically, up to ten times. Within the DoE the conditions of plasma treatment were identified that resulted in selected optimal values of θW, γSp and O/C responses. Surface chemical changes were detected by XPS and ATR-IR investigations that evidenced both the introduction of fluorinated groups and the opening of the imide ring in the plasma-treated films

Additive Manufacturing of Wet-Spun Polysulfone Medical Implants

Research on additive manufacturing (AM) of high-performancepolymersprovides novel materials and technologies for advanced applicationsin different sectors, such as aerospace and biomedical engineering.The present article is contextualized in this research trend by describinga novel AM protocol for processing a polysulfone (PSU)/N-methyl-2-pyrrolidone (NMP) solution into medical implant prototypes.In particular, an AM technique involving the patterned depositionof the PSU/NMP mixture in a coagulation bath was employed to fabricatePSU implants with different predefined shape, fiber diameter, andmacropore size. Scanning electron microscopy (SEM) analysis highlighteda fiber transversal cross-section morphology characterized by a denseexternal skin layer and an inner macroporous/microporous structure,as a consequence of the nonsolvent-induced polymer solidificationprocess. Physical-chemical and thermal characterization of the fabricatedsamples demonstrated that PSU processing did not affect its macromolecularstructure and glass-transition temperature, as well as that afterpost-processing PSU implants did not contain residual solvent or nonsolvent.Mechanical characterization showed that the developed PSU scaffoldtensile and compressive modulus could be changed by varying the macroporousarchitecture. In addition, PSU scaffolds supported the in vitro adhesionand proliferation of the BALB/3T3 clone A31 mouse embryo cell line.These findings encourage further research on the suitability of thedeveloped processing method for the fabrication of customized PSUimplants