Search Results (1,005)

Polyethylene terephthalate (PET) is a widely used polymer whose accumulation in the environment poses a significant pollution challenge. This study explores the degradation of bis(2-hydroxyethyl) terephthalate (BHET) and terephthalic acid (TPA)—two monomers commonly produced during PET hydrolysis and widely used as intermediates in PET recycling—through Advanced Oxidation Processes (AOPs) employing KrCl (222 nm) and XeBr (283 nm) excimer lamps in the presence of hydrogen peroxide (H₂O₂). The effects of the H₂O₂/monomer mass ratio, initial monomer concentrations, and reaction volume on degradation efficiency were systematically evaluated. The results demonstrate that excimer lamp technology, particularly KrCl, holds promising potential for the effective degradation of both BHET and TPA, and thus represents a viable strategy for PET waste treatment. Full article

This study investigates the influence of cellulose nanofibrils (CNFs) on the polymerization kinetics of methyl methacrylate (MMA) during in situ suspension polymerization at 70 °C (343.15 K). Four CNF concentrations were evaluated and compared to a reference system without CNFs. Polymerizations were carried out in a thermostatted flask immersed in an ethylene glycol bath and covered to ensure thermal stability. The temperature profiles of both the reaction medium and the surrounding bath were continuously recorded, allowing for the calculation of heat flow, polymerization rate (R_p), and monomer conversion. The incorporation of CNFs led to a significant increase in R_p and faster MMA conversion. This effect was attributed to the presence of nanocellulose within the polymerizing medium, which restricted diffusion and contributed to the onset of the phenomenon of autoacceleration. Additionally, CNFs promoted a higher total heat release, underscoring the need for thermal control during scale-up. The resulting material qualifies as a biocomposite, as biobased nanofibrils became integrated into the polymer matrix. These findings demonstrate that CNFs act as effective kinetic promoters in MMA polymerizations and may serve as functional additives to enhance both reaction performance and sustainability. However, safety considerations remain critical when transferring this approach to industrial processes. Full article

Morphine is an opioid extracted from the poppy plant and highly effective for moderate to severe pain management. Development of techniques to measure the concentration of this highly addictive drug in various matrices is very important. This work was aimed at the development of a sensitive electrochemical method for detection of morphine in wastewater. Molecularly imprinted (MIP) electrodes were made by the electro-polymerization process using pyrrole as a monomer. Electro-polymerization was performed on glassy carbon electrodes in the presence of morphine before the extraction of the entrapped morphine molecules. Various techniques were employed to monitor the polymerization and response of the fabricated electrodes toward morphine. These techniques included Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). The morphine concentration was determined using SWV and CV by measuring the change in the redox peak current of [Fe(CN)₆]^−3/−4. These MIP electrode sensors were used to analyze morphine concentrations between 0 and 80.0 nM solution. The SWV showed a wider linear response region than CV. The detection limit using SWV was found to be 1.9 nM, while using CV, the detection limit was 2.75 nM. This MIP electrode sensor exhibited specificity when other closely related molecules were included and hence has potential as a cheap alternative technique for analysis of morphine. Full article

Divinylisoprene rubber, a copolymer of butadiene and isoprene, is used as raw material for rubber technical products, combining isoprene rubber’s elasticity and butadiene rubber’s wear resistance. These properties depend quantitatively on the copolymer composition, which depends on the kinetics of its synthesis. This work aims to theoretically describe how the monomer mixture composition in the butadiene–isoprene copolymerization affects the activity of the TiCl₄-Al(i-C₄H₉)₃ catalytic system (expressed by active sites concentration) via kinetic modeling. This enables development of a reliable kinetic model for divinylisoprene rubber synthesis, predicting reaction rate, molecular weight, and composition, applicable to reactor design and process intensification. Active sites concentrations were calculated from experimental copolymerization rates and known chain propagation constants for various monomer compositions. Kinetic equations for active sites formation were based on mass-action law and Langmuir monomolecular adsorption theory. An analytical equation relating active sites concentration to monomer composition was derived, analyzed, and optimized with experimental data. The results show that monomer composition’s influence on active sites concentration is well described by a two-step kinetic model (physical adsorption followed by Ti–C bond formation), accounting for competitive adsorption: isoprene adsorbs more readily, while butadiene forms more stable active sites. Full article

Poly(N-vinyl-2-pyrrolidone), or PVP, nanogels loaded with gadolinium nitrate (Gd(NO₃)₃·6H₂O) were synthesized by ionizing irradiation, aiming for potential applications in magnetic resonance imaging (MRI). A comprehensive characterization of PVP and Gd aqueous solutions with different VP-monomer-to-Gd ratios was conducted before and after irradiation. The results indicate a complexation between PVP and Gd ions before irradiation. The size of the nanogels exhibited a strong dependence on several factors, including PVP molecular weight, concentration, temperature, and the precise timing of Gd introduction relative to the irradiation process. A quantification study was conducted to investigate the impact of molecular weight, the VP/Gd ratio, and Gd addition before or after the irradiation process on the concentration of free Gd ions. These findings offer valuable insights into optimizing the synthesis of Gd-loaded PVP nanogels for potential applications, highlighting the critical factors that influence their size and stability. Full article

To rationally utilize and develop agricultural waste products, this research involved the synthesis of degradable high water-absorbing resin through the graft copolymerization of cotton straw (CS) with monomers. Among them, acrylic acid (AA) and acrylamide (Am) are used as grafting copolymer monomers, cellulose in the straw serves as the network framework, and MBA acts as the crosslinking agent. ⁶⁰Co gamma rays as initiators. Different concentrations of alkaline solution were used to dissolve the cellulose in the straw. Single-factor and orthogonal experiments were conducted to optimize the experimental conditions. various analytical methods such as thermogravimetric analysis (TG), X-ray crystallography (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM) were employed to characterize the structure and properties of the product. ⁶⁰Co gamma rays as initiators, can reduce the pollution caused by chemical initiators and lower energy consumption. Through this research, agricultural waste can be effectively utilized, reducing environmental pollution, lowering industrial energy consumption, and synthesizing degradable and environmentally friendly high-absorbent resins. The product can be applied to agricultural water retention agent, fertilizer controlled release agent and other aspects. Full article

Series of pyrene-labeled diols (Py₂-DOs) and polyols (Py-POs) were synthesized by coupling a number (n_PyBA) of 1-pyrenebutyric acids to diols and polyols to yield series of end-labeled linear (n_PyBA = 2) and branched (n_PyBA > 2) oligomers, respectively. Pyrene excimer formation (PEF) between an excited and a ground-state pyrene was studied for the Py₂-DO and Py-PO samples by analyzing their fluorescence spectra and decays in tetrahydrofuran, dioxane, N,N-dimethylformamide, and dimethyl sulfoxide. Global model-free analysis (MFA) of the pyrene monomer and excimer fluorescence decays yielded the average rate constant (<k>) for PEF. After the calculation of the local pyrene concentration ([Py]_loc) for the Py₂-DO and Py-PO samples, the <k>-vs.-[Py]_loc plots were linear in each solvent, with larger and smaller slopes for the Py₂-DO and Py-PO samples, respectively, resulting in a clear kink in the middle of the plot. The difference in slope was attributed to a bias for PEF between pyrenes close to one another on the densely branched Py-PO constructs resulting in lower apparent [Py]_loc and <k> values. This study illustrated the ability of PEF to probe how steric hindrance along a main chain affects the dynamic encounters between substituents in multifunctional oligomers such as diols and polyols. Full article

To examine how reaction media influence the copolymerization processes of acrylamide-based copolymers, [BMIM]Oac and water were utilized as the reaction media. Four copolymers P(AM-SSS) (H₂O), P(AM-UA) (H₂O), P(AM-SSS) (ILs), and P(AM-UA) (ILs) were synthesized using the soluble monomer sodium p-styrene sulfonate (SSS), the insoluble monomer 10-undecylenoic acid (UA), and acrylamide (AM). The properties of the copolymers were characterized using infrared spectroscopy and ¹H NMR, and the copolymerization rates of the monomers and the segment sequences of the copolymers were calculated. The results indicated that copolymerization of SSS in ionic liquids could reduce the length of the continuous units of AM in the copolymer’s molecular chain from 231.2866 to 91.1179, with a more uniform distribution within the molecular chain. The thermal stability and micro-morphology of the copolymers were tested using a synchronous thermal analyzer and scanning electron microscopy, and the resistance of the copolymer solutions to temperature, salt, and shear were evaluated. Comparisons revealed that the three-dimensional spatial structure formed by the copolymers in ionic liquids is robust and loose. When AM and SSS polymerize in [BMIM]Oac, the resulting copolymer exhibits a higher viscosity retention rate in temperature and shear resistance tests, with a thermal decomposition temperature reaching 260 °C. Conversely, when AM and UA polymerize in [BMIM]Oac, the copolymer demonstrates good salt resistance, maintaining a viscosity retention rate of 259.04% at a Na⁺ concentration of 200,000 mg/L. Therefore, the ionic liquid [BMIM]Oac can enhance the various application performances of copolymers formed by monomers with different solubilities and AM. Full article

Because of their potential “smart” applications, multifunctional stimuli-responsive polymers are gaining increasing scientific interest. The present work explores the possibility of developing such materials based on the hydrolytically stable N-3-dimethylamino propyl methacrylamide), DMAPMA. To this end, the properties in aqueous solution of the homopolymer PDMAPMA and copolymers P(DMAPMA-co-MMA_x) of DMAPMA with the hydrophobic monomer methyl methacrylate, MMA, were explored. Two copolymers were prepared with a molar content x = 20% and 35%, as determined by Proton Nuclear Magnetic Resonance (¹H NMR). Turbidimetry studies revealed that, in contrast to the homopolymer exhibiting a lower critical solution temperature (LCST) behavior only at pH 14 in the absence of salt, the LCST of the copolymers covers a wider pH range (pH > 8.5) and can be tuned within the whole temperature range studied (from room temperature up to ~70 °C) through the use of salt. The copolymers self-assemble in water above a critical aggregation Concentration (CAC), as determined by Nile Red probing, and form nanostructures with a size of ~15 nm (for P(DMAPMA-co-MMA₃₅)), as revealed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The combination of turbidimetry with ¹H NMR and automatic total organic carbon/total nitrogen (TOC/TN) results revealed the potential of the copolymers as visual CO₂ sensors. Finally, the alkylation of the copolymers with dodecyl groups lead to cationic amphiphilic materials with an order of magnitude lower CAC (as compared to the unmodified precursor), effectively stabilized in water as larger aggregates (~200 nm) over a wide temperature range, due to their increased ζ potential (+15 mV). Such alkylated products show promising biocidal properties against microorganisms such as Escherichia coli and Staphylococcus aureus. Full article

Background: Pregnancies in patients with systemic lupus erythematosus (SLE) have always been considered high-risk. D-dimer is known for its role in excluding the diagnosis of thrombosis and has been associated with lupus reactivation; however, its physiological elevation during pregnancy limits its utility in this population. Fibrin monomer (FM) has been shown in multiple studies to remain stable in pregnant women. The objectives of this study were to evaluate D-dimer and FM levels, as well as to assess the role of FM in SLE activity during pregnancy. Methods: The subjects included 76 pregnant women with SLE diagnosed according to the Systemic Lupus International Collaborating Clinics (SLICC) 2012 criteria. The assessment of disease activity was in accordance with the Systemic Lupus Erythematosus Pregnancy Disease Activity Index (SLEPDAI). Results: The log₁₀-transformed D-dimer (LtDD) and FM (LtFM) concentrations in the pregnant women with lupus were 1.229 (0.722–1.953) and 4.17 (3.01–5.34) µg/mL, respectively. A multivariate regression indicated that 59.1% of the variation in LtDD was influenced by the gestational age and SLEPDAI, while only 18.3% of the fluctuation in LtFM was affected by these factors. The concentration of LtFM was an independent factor in predicting SLE flare and disease activity level according to the SLEPDAI in pregnant women. Conclusions: In conclusion, this study’s findings suggest that elevated levels of both D-dimer and FM were observed in pregnant patients with SLE. However, only FM levels can be used as a prognostic factor in assessing the risk of SLE reactivation during pregnancy. Full article

This study developed cholesteric liquid crystal broadband reflective films using zinc oxide nanoparticles (ZnO NPs) and homotriazine UV-absorbing dye (UV-1577) to enhance infrared shielding. Unlike benzotriazole-based UV absorber UV-327, which suffers from volatility and contamination, UV-1577 exhibits superior compatibility with liquid crystals, higher UV absorption efficiency, and enhanced processing stability due to its larger molecular structure. By synergizing UV-1577 with ZnO NPs, we achieved a gradient UV intensity distribution across the film thickness, inducing a pitch gradient that broadened the reflection bandwidth to 915 nm and surpassing the performance of previous systems using UV-327/ZnO NPs (<900 nm). We conducted a detailed examination of the factors influencing the reflective bandwidth. These included the UV-1577/ZnO NP ratio, the concentrations of the polymerizable monomer (RM257) and chiral dopant (R5011), along with polymerization temperature, UV irradiation intensity, and irradiation time. The resultant films demonstrated efficient ultraviolet shielding via the UV-1577/ZnO NPs collaboration and infrared shielding through the induced pitch gradient. This work presents a scalable strategy for energy-saving smart windows. Full article

Thermosensitive Poly(N-isopropylacrylamide) (PNIPAm) films were synthesized via atmospheric pressure dielectric barrier discharge (APDBD) plasma polymerization. In order to control the thickness of the films, a spin coating technique was used during the deposition of N-isopropylacrylamide (NIPAM) monomer solution onto several glass substrates. We used the coefficient of determination (R-square value) in linear regression to investigate the significance and optimize spin coating parameters during the fabrication of NIPAM coatings before exposure to APDBD plasma to ensure reproducible and uniform film properties. The spin coating parameters investigated in this study include spin speed, spin time, and NIPAM solution concentration with R-square values of 0.978, 0.946, and 0.944, respectively. Also, as a result of the thermosensitive nature of NIPAM, the spin coating operating conditions of temperature and humidity were maintained at 39.0 °C and 15%, respectively. During the APDBD plasma polymerization, argon was used as the discharge gas, and the distance between the two parallel electrodes and plasma frequency were maintained at 5.0 mm and 17 kHz, respectively. The plasma exposure time required for polymerization of PNIPAm coatings was optimized to 60 s. Also, the results showed that a coating with minimal defects had an optimal thickness of 5.18 μm, fabricated under conditions of 90 wt.% NIPAM concentration, spin speed of 4000 rpm, and total spin time of 7 s. Full article

Neurotransmitters such as serotonin regulate key physiological and cognitive functions, yet real-time detection remains challenging due to the limitations of conventional techniques like amperometry and microdialysis. Fluorescent molecularly imprinted polymer nanoparticles (fMIP-NPs) offer a promising alternative and are typically synthesized via solid-phase synthesis, in which template molecules are covalently immobilized on a solid support to enable site-specific imprinting. However, strong template–template interactions during this process can compromise selectivity. To overcome this, we incorporated a poly(methacrolein-co-methacrylamide)-based template anchoring strategy to minimize undesired template interactions and enhance imprinting efficiency. We optimized the synthesis of poly(methacrolein-co-methacrylamide) under three different conditions by varying the monomer compositions and reaction parameters. The poly(methacrolein-co-methacrylamide) synthesized under Condition 3 (5:1 methacrolein-to-methacrylamide molar ratio, 1:150 initiator-to-total monomer ratio, and 4.59 M total monomer concentration) yielded the most selective fMIP-NPs, whose fluorescence intensity increased with an increase in serotonin concentration, rising by up to 37% upon serotonin binding. This improvement is attributed to higher aldehyde functionality in the poly(methacrolein-co-methacrylamide) which enhances template immobilization and generates a rigid imprinted cavity to interact with serotonin. These findings suggest that the developed fMIP-NPs hold significant potential as imaging probes for neurotransmitter detection, contributing to advanced studies in neural network analysis. Full article

In this study, poly-DL-lactic acid (PDLLA) was synthesized via ring-opening polymerization (ROP) to develop a biomedical scaffold for tissue engineering. A rotary evaporator with a two-stage vacuum pump under an inert atmosphere and constant stirring was used. A factorial design with three factors (oligomerization time, ROP time, and catalyst concentration) at two levels was applied. Polymers were characterized by FTIR, capillary viscometry, ¹H-NMR, DSC, and TGA. The kinetic study revealed a first-order model, indicating that the polymerization rate depends linearly on monomer concentration. The activation energy (70.5 kJ/mol) suggests a moderate energy requirement, consistent with ring-opening polymerization, while the high pre-exponential factor (6.93 × 10⁶ min⁻¹) reflects a significant frequency of molecular collisions. The scaffold was fabricated via extrusion and 3D printing, and its morphology, porosity, mechanical properties, and contact angle were studied. The highest molecular weight PDLLA was obtained with 6 h of oligomerization, 4 h of ROP, and 1% catalyst concentration. The samples exhibited thermal stability below 40 °C, while the scaffold reached 71.6% porosity, an 85.97° contact angle, and a compressive strength of 4.24 MPa with an elastic modulus of 51.7 MPa. These findings demonstrate the scaffold’s potential for biomedical applications. Full article

The removal of per- and polyfluoroalkyl substances (PFAS) from global aquatic environments is an emerging issue. However, little attention has been paid to addressing accumulated PFAS through their removal. This study demonstrates the encapsulation of perfluoroalkyl carboxylic acids (PFCAs) within polymer microspheres that dissolve in supercritical carbon dioxide (scCO₂). PFCAs were effectively captured by a hindered amine-supported monomer, 2,2,6,6-tetramethyl-4-piperidyl methacrylate (TPMA), in methanol (MeOH) through a simple acid-base reaction. The PFCA-loaded TPMA underwent dispersion polymerization in MeOH in the presence of poly(N-vinylpyrrolidone) (PVP) as a surfactant, producing microspheres with high monomer conversions. The microsphere size depended on the molecular weight and concentration of PVP, as well as the perfluoroalkyl chain length of the PFCAs. X-ray photoelectron spectroscopy (XPS) revealed that the perfluoroalkyl chains migrated from the interior to the surface of the microspheres when exposed to air. These surface perfluoroalkyl chains facilitated dissolution of the microspheres in scCO₂, with cloud points observed under relatively mild conditions. These findings suggest the potential for managing PFCA-encapsulated microspheres in the scCO₂ phase deep underground via CO₂ sequestration. Full article