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Ultrasonic testing is widely used for defect detection in polymer composites owing to advantages such as fast processing speed, simple operation, high reliability, and real-time monitoring. However, defect information in ultrasound images is not easily detectable because of the influence of ultrasound echoes and noise. In this study, a stable three-dimensional deep convolutional autoencoder (3D-DCA) was developed to identify defects in polymer composites. Through 3D convolutional operations, it can synchronously learn the spatiotemporal properties of the data volume. Subsequently, the depth receptive field (RF) of the hidden layer in the autoencoder maps the defect information to the original depth location, thereby mitigating the effects of the defect surface and bottom echoes. In addition, a dual-layer encoder was designed to improve the hidden layer visualization results. Consequently, the size, shape, and depth of the defects can be accurately determined. The feasibility of the method was demonstrated through its application to defect detection in carbon-fiber-reinforced polymers. [ABSTRACT FROM AUTHOR]

The mechanical properties of both polymethyl methacrylate (PMMA) and polyethylene terephthate (PET) were examined in tensile and three-point bending tests, as well as their bond and interlayer shear strengths were assessed. The results obtained were employed in computer simulation of mechanical loading of temporary removable complete dentures (TRCDs). It was shown that the variations of the elastic moduli of the dental materials studied did not exceed 15.6%; the ultimate strength of PET was higher than that of PMMA by ~2.2 times in tension and by ~1.9 times in bending. Elongation at break was greater for the PET specimens than those for the PMMA ones by ~2.3 times in tension and by ~3.1 times in bending. Computer simulation has shown that when the load was applied at the angle of 90°, the tooth fractured in all cases. Stresses were much lower in the denture base concerning the critical levels. Therefore, the adhesion conditions considered did not affect the pattern of their failure, and the critical load was the same for both denture base materials. When the load was applied to canines at the angle of 45°, the critical load was below the specified level of 100 N in the PMMA denture base due to the peculiarities of TRCD design and the lower strength of PMMA. When both canines and incisors were loaded at the angle of 45°, the PET denture base could withstand the greater critical load than the PMMA one. Both mechanical tests and computer simulation results enabled to conclude that PET is the prospect denture base material for the manufacture of TRCDs and dental orthopedic treatment. [ABSTRACT FROM AUTHOR]

This letter was to present an attempt of large‐wavelength Gaussian deconvolution phase‐contrast computed tomography (LW‐GD‐PCCT) for promotion of image quality reconstructed in low‐frequency band of terahertz (THz) spectrum at 0.11 THz. The interaction between the imaging samples and the THz Gaussian beam were formulated firstly in this paper, where the unwrapped phase was extracted specifically to portray the spatial structure distribution of the samples. Additionally, a Gaussian deconvolution was employed for the further reduction of spatial distortions. Moreover, an image reconstruction was carried out with the obtained phase sinograms based on phase‐used inverse Radon transform from the different positions on the sample. For an experimental assessment of the concept of LW‐GD‐PCCT, a single ellipsoid reflector‐based THz Gaussian beam generating system was established and samples such as polystyrene (PS) foam cuboid (Sample 1), and cylinder (Sample 2) with hollow defects (air holes and triangles) were prepared carefully in this work. To experimentally evaluate the performance of the contributing to the structural imaging over soft samples. Two‐dimensional topographies of each sample were reconstructed successfully, and the obtained cross root‐mean‐square error (cross‐RMSE), cross peak signal‐to‐noise ratio (cross‐PSNR), and cross structural similarity (cross‐SSIM) were 151.6451, 26.3225, and 0.9616 for Sample 1 with a high dose of 180 projections respectively, as well as 30.3242, 33.3129, and 0.9711 for Sample 2 with a low dose of 36 projections, respectively. The obtained imaging indicators of this work showed a superiority of imaging quality over those of recent works. Furthermore, the investigation of the bearing capacity has shown promise in enhancing image quality even in low‐dose conditions. The presented results suggest that the unwrapped phase combining with Gaussian deconvolution in low‐frequency band of THz imaging would be useful to improve the reconstructed image quality, potential to highly feasible non‐destructive testing of polymer foam via large wavelength. [ABSTRACT FROM AUTHOR]

This study delves into the mechanical characteristics of polyamide PA2200 components crafted using selective laser sintering (SLS) technology. Our primary objective is to analyze the tensile behavior of the components printed at various orientations, showing its response to diverse loading conditions. Finite element method (FEM) modeling was employed to analyze the tensile behavior of these details. The time determined for breaking the detail is 9 s. In addition we forecast key properties, such as tensile behavior and strength, using machine learning (ML) techniques, and the best models are for predicting relative elongation are KNeighborsRegressor and SVR. [ABSTRACT FROM AUTHOR]

Wear is the leading cause of nozzle failure. The durability of the nozzle is affected by the material it is made from. Traditional materials are ceramics, stainless steel, brass, and polymers. One of the possible ways to improve the wear resistance of polymer nozzles is through the incorporation of dispersed fillers into them. This paper presents the results of testing polymer composites for their chemical resistance to pesticides, examining the effects of different types and amounts of fillers on the chemical and abrasion resistance. When silicon carbide was used as a filler, the strength increased by 30.2%. The experiments on chemical resistance to pesticides revealed that the nature, shape, and volume content of filler particles do not significantly affect the resistance of the compounds obtained. Tests on hydro-abrasive wear have shown that graphite and silicon carbide are effective fillers capable of reducing wear by up to 7.5 times. Based on previous research, it is recommended to use a composite compound with 15% volume of silicon carbide for nozzle manufacturing. [ABSTRACT FROM AUTHOR]

The article titled "Topical section 'Advanced Testing of Soft Polymer Materials'" discusses the importance of using advanced testing methods to characterize and analyze soft polymer materials. The increasing demand for enhanced properties and capabilities in various industries, such as e-mobility, energy generation, information technology, soft robotics, and medical engineering, has led to the need for predictive and advanced laboratory testing. The article emphasizes the importance of accuracy, relevance, productivity, and cost-effectiveness in laboratory testing, as well as the development of new concepts for soft polymeric materials, including nanotechnology, self-healing, and eco-design. The scope of the article includes the development and application of advanced testing methods for chemical, rheological, mechanical, thermal, electrical, and magnetic analysis, as well as concepts for predictive testing and realistic load simulation. The article highlights the potential of simulation tools and artificial intelligence in predicting the behavior and durability of soft polymer materials. [Extracted from the article]

While 3‐dimensional (3D) printing technology is advancing rapidly, commonly used filament materials are struggling to meet growing expectations. Polyamide (PA) is a material with high potential to replace commonly used low‐performance filament materials, thanks to its cost‐effectiveness and optimal material properties compared to advanced engineering materials. To explore this potential, the thermal, thermomechanical, and mechanical properties (at different temperatures), as well as the wear characteristics, of PA, short carbon fiber reinforced‐PA (SCFR‐PA), and short glass fiber reinforced‐PA (SGFR‐PA) filaments were comparatively examined in this study. Differential scanning calorimeter analysis (DSC), Dynamic Mechanical Thermal Analysis (DMA), uniaxial tensile tests, and Shore D hardness tests were conducted on the 3D printed specimens. The yield strength decreased by 48% and 73%, respectively, for neat PA as compared to room temperature when tested at 40 °C and 60 °C, while for SCFR‐PA, it decreased by 40% and 60%, and for SGFR‐PA, it decreased by 33% and 48%, respectively. The findings obtained from wear tests conducted on both bottom and top surfaces have demonstrated that glass reinforcement yields better results than carbon reinforcement. The experimental findings have been compared with SEM images, revealing their consistency. Highlights: This study focuses on the performance evaluation of 3D printed PA and its composites.The mechanical properties of the materials at different temperatures were compared.Adhesive wear behavior is not directly related to fiber type, wear surface or hardness.Morphological analysis was conducted to elucidate the influence of fiber type on mechanical properties and wear behavior. [ABSTRACT FROM AUTHOR]

In this work, three cyanoalkyl silicone GC stationary-phase polymers, namely OV-105, OV-225, and OV-275, were investigated as potential extractants for dispersive liquid–liquid microextraction (DLLME). The OV-225 polymer (cyanopropylmethyl-phenylmethylsilicone) exhibited the cleanest chromatographic background and was extensively studied. The proposed polymer was tested through the DLLME of four non-steroidal anti-inflammatory drugs from aqueous samples, followed by HPLC separation with UV detection at 230 nm. To achieve the maximum enrichment, the experimental conditions that influence the DLLME process were optimized using one-factor-at-a-time and design-of-experiment (DoE) approaches. The extraction variables (polymer mass, dispersive solvent volume, buffer pH, and mixing time) were screened by implementing a two-level full factorial design (FFD). Significant variables were fine-tuned using response surface methodology based on a face-centered central composite design (CCD). The optimum conditions were 10 mg of polymer (extraction medium); 50 µL of tetrahydrofuran (dispersive solvent); 100 µL of phosphate buffer pH 2.75 ([PO43−] = 100 mM); and 3 min of vortex mixing. The addition of salt had a minimal effect on the enrichment factors. In the optimum conditions, enrichment factors up to 46 were achieved using 1.5 mL samples. Calibration curves exhibited correlation coefficients > 0.999 using 4-pentylbenzoic acid as an internal standard. The limits of quantitation were 5 ng/mL for naproxen, 10 ng/mL for diflunisal, 25 ng/mL for indomethacin, and 75 ng/mL for ibuprofen. The analysis of spiked tap water samples showed adequate relative recoveries and precision. In conclusion, the proposed polymer (OV-225) is a potential greener alternative to traditional organic extractants used in DLLME. [ABSTRACT FROM AUTHOR]

Recycling concrete with reinforcement made of basalt fibre polymers: investigations on the composite and tensile load‐bearing behaviour The use of recycling concrete is subject to restrictions in Germany, which prevent its use in environmental conditions containing de‐icing salt of exposure classes XD3 and XS3. To overcome these normative barriers, the Munich UAS is conducting research on the use of alternative reinforcement materials that completely eliminate reinforcement corrosion induced by chlorides. In this regard, non‐corrosive fibre composite bars, made of basalt, are employed, which offer ecological advantages over reinforcements made of stainless steel, glass fibre or carbon. The investigations presented here on the composite and tensile load‐bearing behaviour of basalt fibre‐reinforced polymers have arisen as part of a current research project examining the use of this type of reinforcement in bridge caps made of recycling concrete. In addition to preliminary concrete technology studies on the use of up to 100 % recycled aggregates, composite specimens made of recycled concrete and basalt fibre reinforced polymer were tested to provide insights on the load‐bearing behaviour under static and cyclic conditions. [ABSTRACT FROM AUTHOR]

The relationships between gas permeability and free volume fraction, intersegmental distance, and glass transition temperature, are investigated. They are analyzed for He, CO2, O2, CH4, and N2 gases and for five similar polyimides with a wide range of permeabilities, from very low to extremely high ones. It has been established here that there is an exponential relationship between permeability and the free volume fraction, and between permeability and the most probable intersegmental distance as measured by WAXS; in both cases, with an exponential coefficient that depends on the kinetic gas diameter as a quadratic polynomial and with a preexponential positive constant. Moreover, it has been proven that the intersegmental distance increases linearly with the free volume fraction. Finally, it has been established that the free volume fraction increases with the glass transition temperature for the polymers tested, and that they depend on each other in an approximate linear way. [ABSTRACT FROM AUTHOR]

Tuff has been used as a natural building stone in the construction industry since the earliest times. Tuff is slight, simple to manufacture, and has good isolation qualities, which is why it is used so frequently despite its low strength characteristics and high porosity. In this study, samples of white and pink tuff from the regions of Derbent and Gümele districts of Eskisehir province were treated with a water-based (water-soluble) copolymer bath to evaluate their endurance to atmospheric conditions. Spherical samples were subjected to 30-minute slake durability index testing in a water-based copolymer bath. The index values of the initial spherical samples were contrasted with the index values from the fourth cycle of the spherical samples that had received the copolymer bath treatment. Although the index values of the original spherical samples were determined to be 92.22% and 95.32%, respectively, the index values of the spherical sample sets treated with a water-based copolymer bath were determined to be 98.29% and 98.83%, respectively. The study results indicate that spherical samples with a water-based copolymer bath treatment had a greater impact on improving the slake durability index values compared to spherical samples without treatment. [ABSTRACT FROM AUTHOR]

Biodegradable polymers are an important part of the solution toolbox to achieve circularity in the plastic economy and overcome negative impacts of a linear plastic economy. Biodegradable polymers need to excel not only on a mechanical performance level in the application to fulfill their function during the use phase but also on a biodegradation performance level after use. The biodegradation performance is tailored to the application and the receiving environment of the polymer product after use, which can be both engineered systems (e.g., compost, anaerobic digestors, wastewater treatment plants) and natural systems (e.g., soils, freshwater, or marine environments). This chapter addresses key aspects of polymer biodegradability and biodegradation in both natural and engineered systems with the goal to advance a more holistic view on the topic and, thereby, provide guidance for all stakeholders working on developing, testing, and regulating biodegradable polymers. These aspects include definitions of biodegradability and biodegradation, elucidating polymer- and environmental factors that control the biodegradation process, a discussion of the analytical chemistry of polymer biodegradation, polymer biodegradability testing and certification, as well as a brief overview of research needs. In accordance with the diverse backgrounds of the authors of the chapter, this chapter targets all stakeholder groups from academics to industry and regulators. [ABSTRACT FROM AUTHOR]

This study aimed to use the organic polymer, chitosan, as a flocculant for harvesting microalgae Chlorella. sp. Various polymer concentrations were tested. Within three min, 50 mg/L of chitosan showed the highest efficiency (98.9±0.5%), at pH 6.3, while the lowest efficiency (86.7±0.5%) was observed at pH 7.5. Harvesting efficiency in this study was chitosan concentration dependent. The present study showed that chitosan can be a promising and sustainable solution as an organic source and environmentally friendly flocculant. Additionally, it has excellent harvest productivity and requires minimum effort for quick outcomes. [ABSTRACT FROM AUTHOR]

Water filtration is an important application to ensure the accessibility of clean drinking water. As requirements and contaminants vary on a local level, adjustable filter devices and their evaluation with contaminants are required. Within this work, modular filter devices are designed featuring an adjustable surface functionalization. For this purpose, 3D‐printed structures are created consisting of bio‐based poly(lactic acid) (PLA) that are manufactured by extrusion printing. The surface of PLA is activated with amino groups that are used to install xanthates as chain transfer agents. Subsequently, photo‐iniferter (PI) polymerization is used to create cationic polymer brushes on the surface of PLA substrates. Multiple surface characterization techniques are employed to prove successful growth of polymer brushes on PLA. After initial optimization studies on flat surfaces, filter devices are printed, functionalized, and used to remove bacteria from contaminated water. Significant reduction of the number of microorganisms is detected after filtration (single filtration or cycling) and contaminating organism can also be removed from freshwater samples by simple incubation with a 3D‐printed filter. The herein developed setup for producing functional filter devices and probing their performance in affinity filtration is a useful platform technology, enabling the rapid testing of polymer brushes for such applications. [ABSTRACT FROM AUTHOR]

This work presents the proposal design for the completion of a polymer flooding injector well with waterflood flow regulator valves (FRV) in a Colombian field, based on experimental evaluations at the laboratory, intending to reduce the mechanical degradation suffered by the polymer solution at the time of injection, which allows to maintain the design parameters of the improved recovery project and reach the expected recovery factor. An analysis of the parameters and variables that influence the mechanical degradation of the polymer solution during the injection process (polymer solution concentration and the diameters of the FRV) was carried out using one laboratory methodology based on the recommended practices for the evaluation of polymers used in enhanced oil recovery operations API RP63. This work focuses on the following highlights: Evaluation of a waterflood flow regulator valve through experimental tests for polymer flooding and the designing of an initial well completion strategy to minimize mechanical degradation. The proposed valve and diameter resulted in a reduction of only 15 percentage points in the mechanical degradation of the polymeric solution when compared to a commercial water valve. [ABSTRACT FROM AUTHOR]

Amorphous solid dispersions (ASDs) enable formulations to improve the solubility of poorly soluble active pharmaceutical ingredients (APIs). The amorphous state is reached through the disruption of the crystalline lattice of an API resulting in an increased apparent solubility with faster disintegration. Nevertheless, this form is characterized by a high-energy state which is prone to re-crystallization. To ensure a stable ASD, excipients, e.g., polymers that form a matrix in which an API is dispersed, are used. The applicable polymer range is usually linked to their solubility in the respective solvent, therefore limiting the use of hydrophilic polymers. In this work, we show the applicability of the hydrophilic polymer, polyvinyl alcohol (PVA), in spray-dried solid dispersions. Using a three-fluid nozzle approach, this polymer can be used to generate ASDs with a targeted dissolution profile that is characterized by a prominent spring and desired parachute effect showing both supersaturation and crystallization inhibition. For this purpose, the polymer was tested in formulations containing the weakly basic drug, ketoconazole, and the acidic drug, indomethacin, both classified as Biopharmaceutics Classification System (BSC) class II drugs, as well as the weakly basic drug ritonavir classified as BCS IV. Furthermore, ritonavir was used to show the enhanced drug-loading capacity of PVA derived from the advantageous viscosity profile that makes the polymer an interesting candidate for spray drying applications. [ABSTRACT FROM AUTHOR]

This study discusses the feasibility of using a combined torsional-axial rheometer to indirectly measure the complex Poisson's ratio based on shear and Young's modulus. For this purpose, isothermal frequency sweeps in torsion and extension are performed sequentially on the same cylindrical specimen and under the same environmental conditions. The method is tested on two amorphous polymers, a semicrystalline polymer, a polymer blend, and a copolymer. The article includes an extensive literature review and an uncertainty assessment of the method to provide a basis for subsequent data comparison with existing research. The experimental data show a monotonic increase in the complex Poisson's ratio up to 0.5 as the temperature approaches α-relaxation for all samples, except for the amorphous polymer. The latter shows a local minimum in the complex Poisson's ratio observed near α-relaxation, which disappears after thermal annealing of the sample above the α-relaxation temperature. The real and imaginary parts of the complex Poisson's ratio are additionally determined by evaluating both phase shift angles from torsional and extensional measurements. All polymers show a certain offset between the torsional and extensional phase shift angles in the glassy state, which gradually decreases as the temperature approaches α-relaxation. The complex Poisson's ratio results are in good agreement with the literature data obtained by existing methods. This confirms that the method is applicable to polymers up to α-relaxation temperatures with significant time savings due to the nondestructive approach. This is of particular interest, given the limited availability of data in the literature. [ABSTRACT FROM AUTHOR]

In this paper, two polymers (P-AMB and P-DMAB) with aggregate induced emission (AIE) effect were synthesized successfully. Compared with the polymer monomer BNEA, P-AMB and P-DMAB not only have stronger AIE effect, but also have excellent water solubility and better light stability. In addition, the two polymers were tested for their response to different anions in aqueous solution, and both showed high selectivity and sensitivity to S2−. The sensing mechanism of S2− was studied by ultraviolet visible spectrum, infrared spectrum and 1H NMR spectrum studies. These two polymer sensors have strong anti-interference ability and wide pH response range (5.0 ~ 10.0) when detecting S2−, and could be used for qualitative and quantitative detection of S2− in 100% aqueous solution. [ABSTRACT FROM AUTHOR]

Macroscopic experimental results of the plate impact tests of polymers are generally interpreted using the free surface approximation and the acoustic approximation. However, their validity over a range of shock pressures has not been thoroughly investigated yet. We conducted molecular dynamics simulations of plate impact tests of polyethylene to obtain molecular-level insights on those two common approximations associated with the interpretation of shock pressure and spall strength. Our results revealed that the free surface approximation could slightly underpredict the shock pressure in the polymer. The spall strength computed from the free surface velocity history can be significantly smaller than the actual tensile stress in the region of spallation. [ABSTRACT FROM AUTHOR]

This article reports on the synthesis of materials containing both a fluoroalkyl group and a diazonaphthoquinone (DNQ) moiety as well as the fabrication of negative- and positive-tone stencil patterns. Additionally, the photoreaction mechanism that contributes to the pattern formation process is discussed, and the application of these materials is explored in the pixel-formation process in organic light-emitting diode (OLED) displays. Fluoroalkylated diazonaphthoquinone (RF2D1) was synthesized using chemically binding a DNQ unit, which can be converted into carboxylic acid derivatives having stronger polarity, with two fluorinated alkyl chains. The purified compound is found to be soluble in a nonpolar fluorous solvent and can be uniformly coated as a thin film. When the thin film of RF2D1 is exposed to 365 nm UV light, its solubility in a fluorous solvent decreases due to the Wolff rearrangement and subsequent hydrolysis of a ketene moiety. In contrast, when a mixture of RF2D1 and a hydrophobic, fluorinated copolymer is tested for the patterning process, the copolymer delays the conversion of the ketene intermediate to carboxylic acid, resulting in the dissolution of the exposed areas in the fluorous solvent. Finally, the applicability of these materials in micropatterning is demonstrated by adopting them in the orthogonal photolithography process to create pixels of OLEDs. [ABSTRACT FROM AUTHOR]

In recent years, there has been a growing interest in the field of 3D printing technology. Among the various technologies available, fused deposition modeling (FDM) has emerged as the most popular and widely used method. However, achieving optimal results with FDM presents a significant challenge due to the selection of appropriate process parameters. Therefore, the objective of this research was to investigate the impact of process parameters on the tribological and frictional behavior of acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) 3D-printed parts. The design of experiments (DOE) technique was used considering the input design parameters (infill percentage and layer thickness) as variables. The friction coefficient values and the wear were determined by experimental testing of the polymers on a universal tribometer employing plane friction coupling. Multi-response optimization methodology and analysis of variance (ANOVA) were used to highlight the dependency between the coefficient of friction, surface roughness parameters, and wear on the process parameters. The optimization analysis revealed that the optimal 3D printing input parameters for achieving the minimum coefficient of friction and linear wear were found to be an infill percentage of 50% and layer thickness of 0.1 mm (for ABS material), and an infill percentage of 50%, layer thickness of 0.15 mm (for PLA material). The suggested optimization methodology (which involves minimizing the coefficient of friction and cumulative linear wear) through the optimized parameter obtained provides the opportunity to select the most favorable design conditions contributing to a more sustainable approach to manufacturing by reducing overall material consumption. [ABSTRACT FROM AUTHOR]

Type IV hydrogen storage cylinders comprise a polymer liner and offer advantages such as lightweight construction, high hydrogen storage density, and good fatigue performance. However, they are also characterized by higher hydrogen permeability. Consequently, it is crucial for the polymer liner material to exhibit excellent resistance to hydrogen permeation. International organizations have established relevant standards mandating hydrogen permeation tests for the liner material of type IV on-board hydrogen storage cylinders. This paper provides a comprehensive review of existing research on hydrogen permeability and the hydrogen permeation test methods for the polymer liner material of type IV on-board hydrogen storage cylinders. By delving into the hydrogen permeation mechanism, a better understanding can be gained, offering valuable references for subsequent researchers in this field. This paper starts by thoroughly discussing the hydrogen permeation mechanism of the liner material. It then proceeds to compare and analyze the hydrogen permeation test methods specified by various standards. These comparisons encompass sample preparation, sample pretreatment, test device, test temperature and pressure, and qualification indicators. Then, this study offers recommendations aimed at enhancing the hydrogen permeation test method for the liner material. Additionally, the influence of test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material is discussed. Finally, the influences of the test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material are discussed. Future research direction on the hydrogen permeability and hydrogen permeation test method of the liner material of the type IV hydrogen storage cylinder has been prospected. [ABSTRACT FROM AUTHOR]

Reference point indentation (RPI) is a novel experimental technique designed to evaluate bone quality. This study utilizes two RPI instruments, BioDent and Osteoprobe, to investigate the mechanical responses of several 3D-printed polymers. We correlated the mechanical properties from a tensile test with the RPI parameters obtained from the BioDent and OsteoProbe. In addition, we tested the same polymers five years later (Age 5). The results show that for Age 0 polymers, the elastic modulus is highly correlated with average unloading slope (r = 0.87), first unloading slope (r = 0.85), bone material strength index (BMSi) (r = 0.85), average loading slope (r = 0.82), first indentation distance (r = 0.79), and total indentation distance (r = 0.76). The ultimate stress correlates significantly with first unloading slope (r = 0.85), average unloading slope (r = 0.83), BMSi (r = 0.81), first indentation distance (r = 0.73), average loading slope (r = 0.71), and total indentation distance (r = 0.70). The elongation has no significant correlation with the RPI parameters except with the average creep indentation distance (r = 0.60). For Age 5 polymers, correlations between mechanical properties and RPI parameters are low. This study illustrates the potential of RPI to assess the mechanical properties of polymers nondestructively with simple sample requirements. Furthermore, for the first time, 3D-printed polymers and aged polymers are investigated with RPI. [ABSTRACT FROM AUTHOR]

Due to the temperature dependence of stress–strain response in polymers, it is essential to characterize these materials at cryogenic temperatures for use as dielectrics in superconducting electronics. To date, limited efforts have been carried out to explore the experimental devices and procedures required for mechanical testing of polymer thin films in a cryogenic environment. In this work, we develop a novel tensile testing apparatus for thin film samples in cryogenic temperature conditions. The system's highly cost-effective design, simple manufacturing process, and ease of integration into conventional mechanical test equipment are discussed. Finite element (FE) analyses are utilized to show the effective operating range of the apparatus in terms of environmental chamber temperature and sample stiffness. Digital image correlation (DIC) is also used to show that frame deformation is minimal during testing, validating the finite element analyses. Polyimide tape samples are tested in tension at room temperature and in a liquid nitrogen (LN2) cooled environment. Room temperature test results are compared to published data for verification. Results obtained herein demonstrate the accuracy and usability of this apparatus for mechanical characterization of thin films in cryogenic conditions. The experimental methodology presented in this work also has the potential to be extended to the characterization of thin films from other material classes for cryogenic applications. [ABSTRACT FROM AUTHOR]

In this work, for the first time, naphthalene (NA)-based polymers were synthesized by one-stage Friedel–Crafts crosslinking. The influence of NA functionalization by -OH, -SO3H, and -NO2 groups on the polymers' porosity and distribution of the catalytically active phase (Pd) was studied. Synthesized catalytic systems containing 1 wt.% of Pd either in the form of Pd(II) species or Pd(0) nanoparticles supported on NA-based polymers were tested in a model reaction of Suzuki cross-coupling between 4-bromoanisole and phenylboronic acid under mild reaction conditions (60 °C, ethanol-water mixture as a solvent). These novel catalysts demonstrated high efficiency with more than 95% of 4-bromoanisole conversion and high selectivity (>97%) for the target 4-methoxybiphenyl. [ABSTRACT FROM AUTHOR]

Atomic force microscopy (AFM) has been adopted in both industry and academia for high‐fidelity, full‐profile topographic characterization. Typically, the tiny tip of the cantilever and the limited traveling range of the scanner restrict AFM measurement to relatively flat samples (recommend 1 µm). The primary objective of this work is to address these limitations using a large‐range AFM (measuring height >10 µm) system consisting of a novel repairable high aspect ratio probe (HARP) with a nested‐proportional‐integral‐derivative (nested‐PID) AFM system. The HARP is fabricated using a reliable, cost‐efficient bench‐top process. The tip is then fused by pulling the end of the micropipette cantilever with a length up to hundreds of micrometers and a tip diameter of 30 nm. The design, simulation, fabrication, and performance of the HARP are described herein. This instrument is then tested using polymer trenches which reveals superior image fidelity compared to standard silicon tips. Finally, a nested‐PID system is developed and employed to facilitate 3D characterization of 50‐µm‐step samples. The results demonstrate the efficacy of the proposed bench‐top technique for the fabrication of low‐cost, simple HAR AFM probes that facilitate the imaging of samples with deep trenches. [ABSTRACT FROM AUTHOR]

The possibilities of fabrication and properties of new furan-containing polymers based on 5-hydroxymethylfurfural (5-HMF) and nitrogen-containing co-monomers (urea and melamine) have been studied. Two series of polymers, namely, 5-HMF-melamine and 5-HMF-urea at different ratios of the furan component: melamine (urea) were obtained. The effect of temperature in the range of 80–180 °C on the degree of cross-linking of polymers was studied. The thermostability of polymers was investigated by the TGA method. The polymers were tested for fire resistance according to GOST 28157-89 standard. It is demonstrated that obtained materials show increased heat and fire resistance in comparison to similar urea- and melamine-formaldehyde resins. It is recommended to use the developed polymers as non-combustible heat-insulating materials. [ABSTRACT FROM AUTHOR]

This paper is oriented toward the specific testing of polymer composites and textile PA66 cords used as reinforcement for composites. The aim of the research is to validate the proposed new testing methods for low-cyclic testing of polymer composites and PA66 cords for the characterization of material parameters useful as input data for computational tire simulations. Part of the research is the design of experimental methods for polymer composites and test parameters such as load rate, preload, and other parameters such as strain for the start and stop of cycle steps. The DIN 53835-13 standard is used for the conditions of textile cord during the first five cycles. A cyclic load is carried out at two temperatures of 20 °C and 120 °C. The testing method includes a hold step for 60 s between each loop. The video-extensometer technique is used for testing. The paper evaluated the effect of temperatures on the material properties of PA66 cords. The true stress-strain (elongation) dependences between points for the video-extensometer of the fifth cycle of every cycle loop are the data results from composite tests. The forcestrain dependences between points for the video-extensometer are the data results from tests of the PA66 cord. These dependencies can be used as input material data of textile cords in the computational simulation of tire casings using a custom material model definition. The fourth cycle in every cycle loop of polymer composites can be considered a stable cycle because the change in the maximum true stress between the fourth and fifth cycles is 1.6%. Other results of this research include a relationship between stress and the number of cycle loops as the second-degree polynomial curve for polymer composites and a simple relationship to describe the value of the force at each end of the cycles for a textile cord. [ABSTRACT FROM AUTHOR]

This work is focused on the separation of a daughter radionuclide 221Fr from medicinal 225Ac to provide a source of pure 221Fr fraction for other studies. To achieve such a goal, diglycolamide extraction agents were immobilized on polymer matrix and tested in extraction chromatography experiments. Particularly experiments with N,N,N´,N´tetrakis2-ethylhexyldiglycolamide in nitric acid medium provided promising results and the material was further studied in column experiments. The chosen conditions of separation provided 221Fr in yields over 65% with 225Ac contamination under 1% in less than 5 min, which is a sufficient proof of concept suitable for further studies. [ABSTRACT FROM AUTHOR]

This work is focused on the age-old challenge of developing optical sensors for acidity measurements in low-pH aqueous solutions (pH < 5). We prepared halochromic (3-aminopropyl)amino-substituted quinoxalines QC1 and QC8 possessing different hydrophilic–lipophilic balance (HLB) and investigated them as molecular components of pH sensors. Embedding the hydrophilic quinoxaline QC1 into the agarose matrix by sol-gel process allows for fabrication of pH responsive polymers and paper test strips. The emissive films thus obtained can be used for a semi-quantitative dual-color visualization of pH in aqueous solution. Being exposed to acidic solutions with pH in the range of 1–5, they rapidly give different color changes when the analysis is performed in daylight or under irradiation at 365 nm. Compared with classical non-emissive pH indicators, these dual-responsive pH sensors allow for an increase in the accuracy of pH measurements, particularly in complex environmental samples. pH indicators for quantitative analysis can be prepared by the immobilization of amphiphilic quinoxaline QC8 using Langmuir–Blodgett (LB) and Langmuir–Schäfer (LS) techniques. Compound QC8 possessing two long alkyl chains (n-C8H17) forms stable Langmuir monolayers at the air–water interface, and these monolayers can be successfully transferred onto hydrophilic quartz and hydrophobic polyvinylchlorid (PVC) substrates using LB and LS techniques, respectively. The 30-layer films thus obtained are emissive, reveal excellent stability, and can be used as dual-responsive pH indicators for quantitative measurements in real-world samples with pH in the range of 1–3. The films can be regenerated by immersing them in basic aqueous solution (pH = 11) and can be reused at least five times. [ABSTRACT FROM AUTHOR]

Recent studies suggest that the incorporation of graphene in resin-based dental materials might enhance their mechanical properties and even decrease their degree of contraction during polymerization. The present study aimed at comparing the three-point flexural strength (FS), the compressive strength (CS), and the Vickers hardness (VH) of a CAD/CAM poly-methylmethacrylate (PMMA)-based resin, a recently introduced graphene-reinforced CAD/CAM PMMA-based resin (G-PMMA), and a conventional dental bis-acryl composite resin (BACR). No significant differences (p > 0.05) were detected among the materials in terms of flexural strength. On the other hand, a mean flexural modulus value of 9920.1 MPa was recorded in BACR group, significantly higher compared to the flexural modulus detected for G-PMMA (2670.2 MPa) and for conventional PMMA (2505.3) (p < 0.05). In terms of compressive modulus (MPa) and compressive strength (MPa), BACR was significantly stiffer than PMMA and G-PMMA. Concerning VH measurements, a significantly increased hardness emerged comparing the BACR group (VH 98.19) to both PMMA and G-PMMA groups (VH 34.16 and 34.26, respectively). Based on the finding of the present study, the graphene-reinforced (PMMA)-based polymer herein tested was not superior to the conventional PMMA and seemed not able to be considered as an alternative material for permanent restorations, at least in terms of hardness and mechanical response to compressive stress. More research on the mechanical/biological properties of G-PMMAs (and on graphene as a filler) seems still necessary to better clarify their potential as dental restorative materials. [ABSTRACT FROM AUTHOR]

The industrial interest in the patterning of polymeric surfaces at the micro/nanoscale to include new functionalities has considerably increased during the last years. Hierarchical organization of micro/nanometric surface textures yields enhanced functional properties such as hydrophobicity, hydrophilicity, antibacterial activity, and optical or chromatic effects to cite some. While high accuracy methods to pattern hierarchical surfaces at the nanoscale have been developed, only some of them have been applied for high volume manufacturing with limited success, mainly because they rely on the use of expensive machinery and moulds or complicated inserts. Therefore, a method using low cost recyclable tooling and process conditions applicable to high-volume manufacturing is currently missing. In this work, a scalable and low-cost method to replicate hierarchical micro/nanostructured surfaces on plastic films is presented, which can be latter used as inlays for injection moulded parts with standard processing conditions. This method is used to demonstrate the feasibility of replicating three level hierarchical micro/nano textured surfaces using recyclable bio-based polymers (of high relevancy in the current plastic pollution context) achieving replication ratios above 90%, comparing the replication results with those obtained in polypropylene. The presence of the micro/nanotextures substantially increases the contact angle of all the polymers tested, yielding values higher than 90° in all the cases. Also, various mechanical properties of the replicated parts for all the polymers injected are characterized one and thirty days after the samples were manufactured, showing fairly constant values. This highlights the validity of the replicated surfaces, regardless of the biopolymers special crystallization characteristics. [ABSTRACT FROM AUTHOR]

Porous organic polymers incorporating nitrogen-rich functionalities have recently emerged as promising materials for efficient and highly selective CO2 capture and separation. Herein, we report synthesis and characterization of new two-dimensional (2D) benzene- and triazine-based azo-bridged porous organic polymers. Different synthetic approaches towards the porous azo-bridged polymers were tested, including reductive homocoupling of aromatic nitro monomers, oxidative homocoupling of aromatic amino monomers and heterocoupling of aromatic nitro monomers and a series of aromatic diamines of different lengths and rigidity. IR spectroscopy, 13C CP/MAS NMR spectroscopy, powder X-ray diffraction, elemental analysis, thermogravimetric analysis, nitrogen adsorption–desorption experiments and computational study were used to characterize structures and properties of the resulting polymers. The synthesized azo-bridged polymers are all amorphous solids of good thermal stability, exhibiting various surface areas (up to 351 m2 g−1). The obtained results indicated that the synthetic methods and building units have a pronounced effect on the porosity of the final materials. Reductive and oxidative homocoupling of aromatic nitro and amino building units, respectively, lead to 2D azo-bridged polymers of substantially higher porosity when compared to those produced by heterocoupling reactions. Periodic DFT calculations and Grand-canonical Monte Carlo (GCMC) simulations suggested that, within the used approximations, linear linkers of different lengths do not significantly affect CO2 adsorption properties of model azo-bridged polymers. [ABSTRACT FROM AUTHOR]

The Johann Gregor Mendel Czech Antarctic Station (JGM), located in the northern part of James Ross Island in Antarctica, provides a facility for research in many scientific disciplines, such as geography, geology, climatology and biology. In 2015 its activities were extended by the testing of plastics. When synthetic polymers, often referred to as plastics, are exposed to outdoor conditions they undergo irreversible changes due to the absorption of incident solar UV radiation and the consequent reactions with oxygen. Their stability and reliability for outdoor applications are tested through weathering at various locations around the world. Until 2015, when systematic research into plastics started at the JGM, no information on the resistance of plastics to the Antarctic climate was available. [ABSTRACT FROM AUTHOR]

In tissue engineering bioresorbable polymers are commonly used to mimetize a damaged tissue characteristics. In spite of that, we did not find a comparative study of the response of the same cell to dense, porous, and fibrous biomaterials. The present work aimed to study the in vitro of pure polymers [poly (ε-caprolactone) (PCL) and poly (hydroxybutyrate-co-hydroxyvalerate) (PHBV)] and their 75:25 blend in dense, porous, and fibrous forms in Vero cells, a fibroblast cell line. The biomaterials were characterized morphologically by scanning electron microscopy (SEM). The MTT assay was used for analysis of possible cytotoxicity. Vero cells were cultured on biomaterials for 120 h and submitted to SEM, morphological and cytochemical analyses. The dyes used were crystal violet (morphology), toluidine blue at pH 4.0 (for nucleic acids and glycosaminoglycans) and 2.5 (for glycosaminoglycans only), periodic acid-Schiff reactive (for neutral sugars), xylidine ponceau at pH 2.5 (for total proteins), and picrosirius/hematoxylin (for selective collagen analysis). The biomaterials studied were not considered citocytotoxic. The cells were able to adhere to and proliferate on the substrates. The cytochemical data indicate that the cells have high functional activity, with high protein synthesis on the scaffolds but do not accumulate acid or neutral sugars. The cells on the fibrous polymers appear to be more elongated, following the shape of the fibers. Regarding the scaffold form (porous or fibrous), the in vitro data do not show great superiority of one type to the other. Then, all the polymers tested are suitable for tissue engineering. [ABSTRACT FROM AUTHOR]

The improvement of adsorbent materials with specific characteristics is very important in different environmental applications such as the removal of undesirable elements (wastewater treatment) or separation of elements or radionuclides and remediation of organic pollutants from their solutions. Herein, a cross-linked poly(acrylic acid-dimethyl aminoethyl methacrylate) was prepared by a copolymerization technique in the existence of N, Ǹ-methylene bis-acrylamide as a cross-linked agent using gamma irradiation (γ-rays) to induce the polymeric reaction at a minimum radiation dose of 30kGy. The optimization of polymer preparation was done using different parameters such as radiation dose, cross-linker amount, and monomer ratios. The batch mode was applied for the investigation of copper removal from their aqueous solutions using the synthesized polymer. Besides, the theoretical models were checked for experimental data to describe the nature of the adsorption process. Also, the confirmation of adsorption was evaluated using SEM, EDX, XRD, and FTIR to explain the adsorption processes. Furthermore, desorption prepared polymer was tested and the results exhibited that the HNO3 is the best desorption agent. The reusability of the synthesized polymer also was examined for six cycles and the results confirmed that there is no remarkable change in the uptake of polymer. [ABSTRACT FROM AUTHOR]

Unidirectional composites exhibit the highest strength when stretched along the fibers. However, the proper determination of the strength faces great methodological difficulties. The main problems of tensile testing of polymer composites consisted in development of the specimen shape and the method of specimen fixation which ensure the minimum impact of the stress concentration near the grips on the strength measurements. A conventional shape of the specimen with fillets is unsuitable for unidirectional polymers owing to the splitting occurring in the fillet zones upon loading. Therefore, the specimens are usually standardized in the form of rectangular strips fixed using tabs or special grips which provide constant transverse forces. However, with such a specimen shape, a significant stress concentration inevitably occurs at the edge of grips, and the lower the ratio of the interlayer shear modulus to the longitudinal Young's modulus, the greater the stress concentration impact. For the purpose of the most correct determination of the strength, we propose to use specimens with smoothly varying dimensions at the same cross-sectional area which ensures keeping the total number of unbroken fibers in each section. The specimen thickness decreases when moving from the working part of the specimen to the gripping part, whereas the width (while maintaining the section area) grows to prevent the collapse of the specimen resulting from transverse forces in standard self-tightening grips. Analytical and FEM modeling is performed to select a rational contour shape. Technological equipment has been developed, and a procedure of manufacturing testing specimens has been worked out. The tensile test of specially manufactured curvilinear reinforced specimens showed higher strength values compared to standard rectangular strips or specimens with semicircular fillets. [ABSTRACT FROM AUTHOR]

In this paper, a self-repairing polyurethane without external stimulation was synthesized. First, a reversible acyl hydrazone bond was introduced into the polyurethane molecular chain. The bond could be dynamically reversible under acidic stimulation to repair the material damage. After that, different contents of bis(2-ethylhexyl) phosphate components were added to modify the material in the synthesis, and its performance was compared to pure polyurethane (PU-0). The polymer was tested using digital viscometer, differential scanning calorimeter (DSC), thermogravimetric analysis (TG), tensile test, etc. The results showed that the addition of bis(2-ethylhexyl) phosphate can promote the healing of the material, so that the synthetic polyurethane material can be repaired to a certain extent without external stimulation. [ABSTRACT FROM AUTHOR]

Context: Global studies on Argemone mexicana L. (Papaveraceae) traditionally used against malaria in Mali are limited to its low-mass compounds activities, and little information on its bioactive polysaccharides is available. Objective: This study determines the structure and the immunomodulatory activity of polysaccharides from aerial parts of A. mexicana. Materials and methods: Acidic polysaccharides from this plant material named HMAmA1 and HMAmA2 were isolated from water extracts. Their monosaccharide composition was determined by gas chromatography. Glycosidic linkages were determined using GC-MS. NMR was also applied. The polymers were tested for effects on the human complement system in vitro at different doses. Results: The monosaccharide composition showed that the two polysaccharides contained in different amounts the following monomers: arabinose, rhamnose, galactose, and galacturonic acid. Overall structural analysis showed the presence of a low ratio of 1,2-linked rhamnose compared to 1,4-linked galacturonic acid with arabinogalactans substituted on position 4 of rhamnose. NMR data showed the presence of galacturonans alternated by rhamnogalacturonans bearing arabinose and galactose units. a-Linkages were found for L-arabinose, L-rhamnose and D-galacturonic acid, while b-linkages were found for D-galactose. The two polysaccharides exhibited strong complement fixation activities, with HMAmA1 being the highest potent fraction. ICH50 value of HMAmA1 was 5 µg/mL, compared to the control BPII being 15.9 µg/mL. Discussion and conclusions: Polysaccharides form A. mexicana presented a complement fixation effect. The complement system is an important part of the immune defense, and compounds acting on the cascade are of interest. Therefore, these polymers may be useful as immunodulatory agents. [ABSTRACT FROM AUTHOR]

The aim was to prepare copolyimide (BPDA/PMDA-PDA) films of low thermal expansion coefficient by incorporating 1,2,4,5-benzenetetracarboxylic anhydride (PMDA) into polymer backbones 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA)/p-phenylenediamine (PDA). FTIR and WAXD were used to explore the chemical and physical microstructure of the PIs films. DMA, TMA and TGA were used to characterize the mechanical and thermal performance of the PIs film respectively. The results show that the smectic structure of the film was destroyed by introducing rigid PMDA groups. The free volume fraction of polymers reached its maximum value when 40 wt % PMDA was added. The glass transition temperature of the polymers increased from 330 to 430°C and the thermal decomposition temperature declined slightly with the addition of PMDA. The inflection point in thermal expansion coefficient (CTE) of the BPDA-PDA polymers in TMA test reached as high as 470°C. The glass transition temperature of the polymers increased but the service temperature range narrowed with the addition of PMDA. The optimized PMDA concentration to obtain a best CTE was 5% as was revealed by the experimental results. The insights obtained from the experiments indicated that excessive introduction of PMDA into the polymers could increase the glass transition temperature significantly. However, the operating temperature range may be reduced. This research could offer practical and valuable references to the application for co-PI films. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) sewer pipes have operated for decades in a hostile environment, raising concern among sewer managers over the longevity of their drainage systems. Inspection data (CCTV and Panoramo®) reveals that severe defects have already surfaced, yet it is unknown if the material properties of PVC sewers have been affected. In order to address this issue, extensive testing (among others flexural and tensile tests, FT-IR, X-ray, viscosity measurements) was conducted on eight exhumed PVC sewer pipes (16–43 years old) with known defects and one brand-new for reference purposes. Visual examination during excavation revealed various failure causes, including uncontrolled handling of the pipes during construction or due to digging activities in the direct vicinity of the pipes. The test results indicate that physical ageing is extensively detected while other degradation mechanisms had minimal or no effect on the investigated pipes. However, mechanical testing on exhumed 3-layer pipes show that the incorporation of layered wall constructions is potentially a critical factor for the structural status of the pipe. [ABSTRACT FROM AUTHOR]

Cellular lattices with architectural intricacy or metamaterials have gained a substantial amount of attention in the past decade due to the recent advances in additive manufacturing methods. The lattice topology controls its physical and mechanical properties; therefore, the main challenge is selecting the appropriate lattice topology for a desired function and application. In this work, we comprehensively study the topology–property relationship of three classes of polymer metamaterials based on triply periodic minimal surfaces (TPMS) of sheet/shell and ligament types, and other types of well-known strut-based lattices. The study uses a holistic approach of designing, additive manufacturing, microstructural characterization, and compressive uniaxial mechanical testing of these polymer lattices that are 3D-printed using the laser powder bed fusion technique known as selective laser sintering (SLS). In total, 55 lattices with different topologies and relative densities were 3D-printed and tested. Printing quality was assessed using scanning electron microscopy and micro-computed tomography. The extracted mechanical properties of elastic modulus, yield strength, plateau strength, and energy absorption are thoroughly compared between the different lattice architectures. The results show that all the investigated ligament-based TPMS polymer lattices exhibit bending-dominated elastic and plastic behavior, indicating that they are suitable candidates for energy absorbing applications. The sheet-based TPMS polymer lattices, similarly to the well-known Octet-Truss lattice, exhibited an elastic stretching-dominated mode of deformation and proved to have exceptional stiffness as compared to all other topologies, especially at low relative densities. However, the sheet-based TPMS polymer lattices exhibited a bending-dominated plastic behavior which is mainly driven by manufacturing defects. Overall, however, sheet-based TPMS polymer lattices exhibited the best mechanical properties, followed by strut-based lattices and finally by ligament-based TPMS lattices. Finally, it is depicted that at high relative densities, the mechanical properties of lattices of various architectures tend to converge, which implies that the topological effect is more significant at low relative densities. Generally, this study provides important insights about the selection of polymer mechanical metamaterials for various applications, and shows the superiority of TPMS-based polymer metamaterials as compared to several other classes of polymer mechanical metamaterials. [ABSTRACT FROM AUTHOR]

Polymer flooding is drawing lots of attention because of the technical maturity in some reservoirs. The first commercial polymer flooding in China was performed in the Daqing oilfield and is one of the largest applications in the world. Some laboratory tests from Daqing researchers in China showed that the viscoelasticity of high molecular weight polymers plays a significant role in increasing displacement efficiency. Hence, encouraged by the conventional field applications and new findings on the viscoelasticity effect of polymers on residual oil saturation (ROS), some high-concentration high-molecular-weight (HCHMW) polymer-flooding field tests have been conducted. Although some field tests were well-documented, subsequent progress was seldom reported. It was recently reported that HCHMW has a limited application in Daqing, which does not agree with observations from laboratory core flooding and early field tests. However, the cause of this discrepancy is unclear. Thus, a systematic summary of polymer-flooding mechanisms and field tests in China is necessary. This paper explained why HCHMW is not widely used when considering new understandings of polymer-flooding mechanisms. Different opinions on the viscoelasticity effect of polymers on ROS reduction were critically reviewed. Other mechanisms of polymer flooding, such as wettability change and gravity stability effect, were discussed with regard to widely reported laboratory tests, which were explained in terms of the viscoelasticity effects of polymers on ROS. Recent findings from Chinese field tests were also summarized. Salt-resistance polymers (SRPs) with good economic performance using produced water to prepare polymer solutions were very economically and environmentally promising. Notable progress in SRP flooding and new amphiphilic polymer field tests in China were summarized, and lessons learned were given. Formation blockage, represented by high injection pressure and produced productivity ability, was reported in several oil fields due to misunderstanding of polymers' injectivity. Although the influence of viscoelastic polymers on reservoir conditions is unknown, the injection of very viscous polymers to displace medium-to-high viscosity oils is not recommended. This is especially important for old wells that could cause damage. This paper clarified misleading notions on polymer-flooding implementations based on theory and practices in China. [ABSTRACT FROM AUTHOR]

This manuscript presents the preparation of polymer layers based on polythiophene (PTh) and its 3-substituted derivatives (substituents 4-(CH3O)C6H4 and 4-(CF3)C6H4 marked as PThOCH3 and PThCF3, respectively) on platinum electrodes by cyclic voltammetry (CV). The polymerization process and the morphology of resulting layers were discussed analysing of CV-voltammograms and scanning electron microscopy (SEM), respectively. Subsequently, the prepared polymers were tested as active/sensitive media of two types of sensors: (i) electrochemical sensor detecting ammonia in aqueous environment, whose response was evaluated by electrochemical impedance spectroscopy (EIS); (ii) chemiresistor detecting NH3 in atmosphere, whose response was evaluated by measurement of resistance. It was found that both the physical (morphology, homogeneity, relative thickness) and receptor properties of the polymer layer deposited on electrode surface are significantly affected by the nature of substituent attached to the thiophene ring. The mutual context of ammonia detection in both environments is discussed. [ABSTRACT FROM AUTHOR]

Heterogeneous membranes made of a polymer matrix and containing nano-metric fillers in their structure may present improved physicochemical and process properties compared to homogeneous membranes made only of polymer materials. Membranes made of a PEBAX®2533 block copolymer were tested with fillers such as ZIF-8, SiO2 and POSS-Ph being dosed to them. The material analysis and process tests indicate that these nanomaterials can be used as fillers for heterogeneous membranes. Chemometric analyses determined the influence of individual fillers on selected physicochemical properties of the materials which were used to produce the membranes. For specific concentrations of these fillers, improvement in the permeability and selectivity of the membranes, or at least in one of these parameters, was achieved. The greatest increase in permeability against the homogeneous membrane was obtained for membranes containing 10 wt% ZIF-8 (for CO2, an increase of 2.07 times; for CH4, 2.36 times; for N2, 3.08 times). In turn, the greatest increase in selectivity was obtained for the CO2/CH4 mixture for the membrane containing 5 wt% SiO2 (1.15 times), and for the CO2/N2 mixture for the membrane containing 2 wt% POSS-Ph (1.21 times). [ABSTRACT FROM AUTHOR]

Polymeric micelle forming from self-assembly of amphiphilic macromolecules is one of the most potent drug delivery systems. Fatty acids, naturally occurring hydrophobic lipid components, can be considered as potential candidates for the fabrication of block copolymer micelles. However, examples of synthesis of responsive block copolymers using renewable fatty acids are scarce. Herein, we report the synthesis, characterization and testing of block copolymer micelles composed of a renewable fatty-acid-based hydrophobic block and thermoresponsive hydrophilic block for controlled drug delivery. The block copolymers of functionalized fatty acid and poly(N-isopropylacrylamide) (PNIPAM) were prepared via consecutive microwave-assisted reversible addition fragmentation chain transfer (RAFT) polymerization. The block copolymers with variable hydrophobic block length self-assembled in aqueous media and formed spherical nanoparticles of ~30 nm with low critical micelle concentration (CMC). To demonstrate the proof-of-concept, carbamazepine (CBZ) was used as a hydrophobic model drug to evaluate the performance of these micelles as nanocarriers. The in vitro drug release tests were carried out below (25 °C) and above (37 °C) the lower critical solution temperature (LCST) of the block copolymer. The drug release showed obvious temperature-triggered response and an accelerated drug release at 37 °C. [ABSTRACT FROM AUTHOR]