Polymer Mixtures Research Articles

Changes in Optical, Electrochemical and Electrical Conductivities in the Conductive Polymer Mixture by Adding Different Surfactants

Changes in Optical, Electrochemical and Electrical Conductivities in the Conductive Polymer Mixture by Adding Different Surfactants

Numerical Analysis of the Porous Structure of Activated Carbons Derived from Synthetic Polymers.

This paper presents original results from the unique analysis of the porous structure of activated carbons (ACs) produced through the chemical activation of polyethylene terephthalate (PET) and polyacrylonitrile (PAN), as well as from a physical mixture of both polymers. An advanced method of adsorbent surface analysis-more specifically, the new method of numerical clustering-based adsorption analysis regarding the surface heterogeneity, pore geometry and adsorption energy distribution parameters-allowed us to obtain information about the porous structure of the ACs from the synthetic polymers mentioned above. As the results showed, ACs obtained with PAN were characterised by a first adsorbed layer with the highest volume. When the surface heterogeneity, highly desirable in most advanced adsorption processes, is taken into account, the materials with the best surface properties in both potassium carbonate (K2CO3) and potassium hydroxide (KOH) activation processes were the ACs obtained with a mass proportion of PET to PAN of 1:3, which were characterised by a low degree of surface heterogeneity and a first adsorbed layer presenting a relatively large volume.

Enhancement of Solubility by Hydrotropic Techniques of Lercanidipine HCl: In-situ Nasal Gel Development

Lercanidipine HCl is a novel, third-generation, potent, vasoselective 1, 4- dihydropyridine calcium channel antagonist and a Biopharmaceutical Classification System (BCS) class II drug that aids in preventing hypertension. The final aim of the present work was to promote the solubility of lercanidipine HCl via hydrotrophy and then include it in the in-situ gel formulation. This enhancement of drug solubility was carried out by using citric acid as a hydrotropic agent. Simultaneously, using a mixture of two polymers, namely Poloxamer 407, a thermosensitive polymer with reversible thermal characteristics. Carbopol 940P is a high-viscosity builder exploited for developing in-situ gel. The optimization of preliminary batches of mixtures of both polymers was highly accepted by using 32 factorial designs. F4 was found to be highly optimized, according to all the evaluation parameters and Poloxamer 407 (18% w/v) and Carbopol 940P (0.2% w/v), with drug release of 93.23%. Goat mucosa ex-vivo investigation yielded a value of 79.14% flux at 6 hours. According to ICH guidance, the in-situ Lercanidipine HCl gel has turned up to be stable following a 6-month stability investigation. Thus, the subsequent thermoreversible in-situ gel was scouted to act as a potent nasal distributor with greater bioavailability and patient compliance for the nasal medication.

Efficient Use of Secondary Raw Material from the Production of Polyamide Construction Products

This study aimed to assess the possibility of using post-production waste and the impact of the conditioning method on the mechanical and thermomechanical properties of polyamide injection molded parts. Samples containing 5, 10, and 15 wt.% of ground post-production waste were produced using injection molding technology. The rheological properties by oscillatory rheometry, the melt mass flow rate (MFR), and the thermal stability by thermogravimetric analysis (TGA) of polymer mixtures containing recycled fraction were determined. The samples were conditioned under the following conditions: 24 h and 14 days in distilled water, in a climatic chamber, and aged in a xenon-light-accelerated aging chamber. Then, the impact and static tensile strength and heat deflection temperature (HDT) were assessed. The results show that the addition of post-production waste in the form of grinding does not significantly affect the mechanical and thermomechanical properties of the finished products. This research provides valuable information regarding the possibility of using secondary materials for manufacturing high-performance construction products. Moreover, it was proven that the process of conditioning polyamide samples in a climatic chamber was the most effective and significantly increased the impact strength of the tested material.

Development and characterization of a non-enzymatic electrochemical biosensor for rapid determination of sorbent-based extracted trazodone and doxepin in complicated samples

BackgroundGiven the importance of achieving optimal therapeutical concentration in patients treated with antidepressants, this study investigates a novel technique for the simultaneous determination of trazodone (TRZ) and doxepin (DOX) in human plasma and serum samples for the first time. ResultsTo achieve simultaneous determination of two antidepressants, TRZ and DOX, a novel detection system was designed: a non-enzymatic voltammetric biosensor based on boron-reduced graphene oxide/manganese oxide nanoparticles (GCE/B-rGO/MnO NPs). The detection was accomplished after pre-concentration and extraction trace amounts of the analytes using the thin film-solid phase microextraction (TF-SPME) technique, which employed polyvinyl alcohol/polyvinyl acetate/copper oxide nanoparticles (PVA/PVAc/CuO NPs) electrospun nanofibers.The successful preparation of composite nanofibers and modified electrodes was confirmed using the evaluation of field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX). Also, the composite nanofibers were characterized with attenuated total reflectance-Fourier transform-infrared (ATR-FT-IR) and X-ray diffraction (XRD). In the solution of TRZ and DOX, under optimum experimental conditions, the linear dynamic ranges (LDRs) were 0.1–20.0 μmol L−1 and 0.5–27.0 μmol L−1, respectively. Also, the limit of detection (LOD) values of TRZ and DOX were 0.032 and 0.150 μmol L−1. SignificancePVAc acts as a cross-linking agent for PVA, and their mixture is effective for sample preparation and pre-concentration of analytes in complex matrices. Also, adding CuO NPs to this polymeric mixture enhanced the adsorption efficiency.Taking advantage of the high surface area of MnO NPs and the high electrical conductivity of B-rGO, and considering the superiority of their simultaneous utilization, the constructed electrochemical biosensor is both cost-effective and rapid. It demonstrates excellent stability, repeatability, and sensitivity for the simultaneous determination of TRZ and DOX under optimal conditions.This biosensor, the first of its kind, is specifically designed for the simultaneous determination of TRZ and DOX in human plasma and serum samples, representing a significant advancement in biosensing technology.

Efficient high-throughput method utilizing neural network potentials to calculate interaction energies, validated by clean transfer experiment of CVD graphene with polymer mixtures

In this study, we designed a computational model involving energy decomposition using ground state energy minimized geometries resulting from a general-purpose neural network potential (ANI-1ccx). The numerical simulations show a distribution of energies, which indicate a two-fold reduction in interaction energy and polarity shift in electrostatic interaction, highlighting the computational novelty in exploring over a million metastable configurations. Experimentally, we validate our model by observing that using a mixture of two distinct polymers in the wet transfer process reduces transfer-induced doping and strain on transferred CVD graphene compared to the conventional single polymer wet transfer method, primarily due to decreased polymer contamination from the transfer process. This reduction is linked to the decreased interaction energy in the mixture of polymethyl methacrylate and angelica lactone polymer on graphene.

Predicting compatibilized polymer blend toughness.

Polymer blends can yield superior materials by merging the unique properties of their components. However, these mixtures often phase separate, leading to brittleness. While compatibilizers can toughen these blends, their vast design space makes optimization difficult. Here, we develop a model to predict the toughness of compatibilized glassy polymer mixtures. This theory reveals that compatibilizers increase blend toughness by creating molecular bridges that stitch the interface together. We validate this theory by directly comparing its predictions to extensive molecular dynamics simulations in which we vary polymer incompatibility, chain stiffness, compatibilizer areal density, and blockiness of copolymer compatibilizers. We then parameterize the model using self-consistent field theory and confirm its ability to make predictions for practical applications through comparison with simulations and experiments. These results suggest that the theory can optimize compatibilizer design for industrial glassy polymer blends in silico while providing microscopic insight, allowing for the development of next-generation mixtures.

Drag reduction and degradation of binary polymer solutions

Polymer-induced drag reduction has yielded great potential benefits for industrial processes after more than 70 years of research. However, the limitation of low shear stability has hindered further applications. This study investigates the rheology, drag reduction rate (DR), and degradation of binary polymer mixtures comprising a rigid polymer (diutan gum, DG) and a flexible polymer (polyethylene oxide, PEO). The solutions all exhibited shear-thinning behavior, and the mixed solution was less viscous than the pure PEO or DG solutions at the total concentration of 100 ppm. When fixing the PEO concentration at 50 ppm, the mixed solution viscosity significantly increased with the DG concentration. The drag reduction performance of the pure PEO solution, pure DG solution, and various proportions of binary polymer mixtures was analyzed using an in-house rotor device. The DRs of the solutions increased with the Reynolds number (Re), and decreased with shearing time. The binary solution significantly improved the shear stability of the solution without loss of DR compared to the pure PEO solution. The theoretical model for molecular degradation in turbulent flow excellently fitted the experimental data of relative drag reduction with time. Furthermore, the synergistic interaction parameter was calculated, and it was positive for most cases in the mixtures. Additionally, when Re was fixed, the synergistic interaction parameter, related to the composition of binary polymer mixtures, initially decreased and then increased with time.

Scintillation and structural properties of copolymers and mixtures of styrene, 9-vinylcarbazole and 4-vinylbenzyl chloride based plastic scintillators

The research team has developed new plastic scintillators in the form of microspheres, called PSm, by combining styrene, 9-vinylcarbazole (VK), and 4-vinylbenzyl chloride (VBC). The primary objective of this study was to explore the feasibility of incorporating the fluorescent solute (VK) into the polymer structure to prevent its leaching out when PSm are utilized in liquid flow through detection systems or organic solvents. The secondary aim was to examine the impact of adding the chlorine functional group to the scintillation polymer, with the intention of replacing it with an extractant in the future to create covalently linked PSresins.The findings of the study reveal that the homopolymer of polyvinylcarbazole (PVK) performs poorly while used as a unitary scintillator system for plastic scintillation measurements. However, the incorporation of monomers in the form of copolymers with styrene has a more significant impact on scintillation properties compared to the mixture of homopolymers. In the case of 9-vinylcarbazole (VK), its presence at a weight proportion of 10% leads to an increase in scintillation efficiencies, although it is still inferior to the classical PS. Conversely, the situation is different for 4-vinylbenzyl chloride (VBC), where the chlorine in the copolymer results in higher quenching, and the polymer is also less resistant to organic solvents due to the formation of short polymer chains. For VBC, the mixture of polymers yields better results and enables the production of covalently linked PSresins.

Naringenin-loaded poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-based devices have an anti-inflammatory activity on microglia

Retinal degenerative diseases, such as retinitis pigmentosa, represent a significant fraction of the burden of blindness. This kind of diseases involves the activation of microglial cells which causes neuroinflammation. Flavonoids, such as naringenin (Nar), are able to modulate the pro-inflammatory behavior of the microglia cells but their low bioavailability often hinders this activity. In this context, the aim of this research activity was the development of implantable drug delivery systems through Nar encapsulation into a polymeric matrix, as a valuable way to increase its bioavailability. For this purpose, a blend between microbial poly(3-hydroxybutyrate-co-3-hydroxyvaerate) (PHBV) and poly(d,l-lactide-co-glycolide (PLGA) was processed by means of two different fabrication techniques, i.e., melt-spinning and wet-spinning, to fabricate rods designed for ocular implantation. The two developed kinds of rod had different morphology and thermal properties, as demonstrated by scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. In addition, an increase in Nar concentration in the starting polymeric mixture (1–5 wt% respect to device weight) determined a higher drug encapsulation efficiency, with a resulting drug loading increasing from 0.5 to 3.5 % and from 0.4 to 4.4 % for melt- and wet-spun rods, respectively. A significant effect of processing technique and drug loading on the resulting release kinetics was also observed, with the devices loaded with a higher percentage of Nar reaching a 100 % cumulative drug release after 38 and 73 days in the case of wet- and melt-spun rods, respectively. In addition, the wet-spun rods showed a first order drug release kinetics while the melt-spun rods a zero order one. The bioactivity of the wet-spun rods was tested on lipopolysaccharide-activated BV2 as well as primary murine microglia cells, thus demonstrating the ability of the released flavonoid to favor cell maturation from a pro-inflammatory to an anti-inflammatory phenotype.

Experimental Investigation of the Effect of Surfactant–Polymer Flooding on Enhanced Oil Recovery for Medium Crude Oil

High technical and financial risks are involved in exploring and exploiting new fields; hence, greater focus has placed on the development of environmentally friendly, cost-effective, and enhanced oil recovery (EOR) options for existing fields. For reservoirs producing high-density crudes and those with high interfacial tensions, water flooding is usually less effective due to density differences—hence the advent of polymer and surfactant flooding. For cost-effective and eco-friendly EOR solutions, a biopolymer and a surfactant synthesized from Jatropha seeds are used in this study to determine their effectiveness in increasing the oil recovery during core flooding analysis. The experiment involved an initial water flooding that served as the base cases of three weight percentages of polymers and polymeric surfactant solutions. The results for the polymer flooding of 1 wt%, 1.5 wt%, and 2 wt% showed an incremental oil recovery in comparison to water flooding of 16.8%, 17%, and 26%, while the polymeric surfactant mixtures of 5 wt% of surfactant and 1 wt%, 1.5 wt%, and 2 wt% of a polymer recorded 16.5%, 22.3%, and 28.8%, and 10 wt% of surfactant and 1 wt%, 1.5 wt%, and 2 wt% of a polymer recorded incremental oil recoveries of 20%, 32.9%, and 38.8%, respectively.

Elucidation of Dithiol-yne Comb Polymer Architectures by Tandem Mass Spectrometry and Ion Mobility Techniques.

Polymers have a wide range of applications depending on their composition, size, and architecture. Varying any of these three characteristics can greatly impact the resulting chemical, physical, and mechanical properties. While many techniques are available to determine polymer composition and size, determining the exact polymer architecture is more challenging. Herein, tandem mass spectrometry (MS/MS) and ion mobility mass spectrometry (IM-MS) methods are utilized to derive crucial architectural information about dithiol-yne comb polymers. Based on their unique fragmentation products and IM drift times, dithiol-yne oligomers with distinct architectures were successfully differentiated and characterized. Additionally, experimental collision cross-sections (Ω) derived via IM-MS were compared to theoretically extracted Ω values from molecular dynamics simulated structures to deduce the architectural motif of these comb oligomers. Overall, this work demonstrates the benefits of combining various mass spectrometry techniques in order to gain a complete understanding of a complex polymer mixture.

Preparation of h‐BN/PMMA composites by in situ polymerization and research on their structure and properties

AbstractInorganic fillers like hexagonal boron nitride (h‐BN) have the potential to enhance the thermal conductivity of polymer mixtures. However, it has been restricted due to poor dispersion of particles in polymer matrices by melt mixing process. The addition of inorganic powders into sticky prepolymer is expected to alleviate the aggregation of powders. In this paper, h‐BN/polymethyl methacrylate (PMMA) composites were prepared by in situ polymerization of methyl methacrylate (MMA) with 5 and 20 μm of h‐BN particle as fillers respectively, for even distribution of fillers with in composites. The structures and properties of composites were characterized by FT‐IR, DSC, TGA, SEM, laser thermal conductivity meter and universal electronic tester. By SEM, it can be seen that a highly uniform dispersion of h‐BN in PMMA. When the mass fraction of h‐BN is 20 wt%, the thermal conductivity of the composites is increased by 107% for 5 μm h‐BN and 189% for 20 μm h‐BN, respectively. With the mass constituting of 5 wt% h‐BN, majority of mechanical characteristics of the composite, such as tensile strength, tensile modulus, along with impact strength, are enhanced, alongside a decrease in bending strength. This work would provide a filling strategy of h‐BN into the polymer matrices to achieve uniform dispersion, and enhance both the thermoconductivity and mechanical strength of thermoplastic composites.Highlights A technique for creating h‐BN/PMMA composites using in suit redox polymerization. Ehancing the thermal conductivity of these composites is achievable through the even distribution of h‐BN flakes within the PMMA matrix. It provides a reference for the design of future h‐BN/PMMA composites with favorable the thermal conductivity which achieves a good balance between performance and cost.

Towards natural care products: Structural and deposition studies of bio-based polymer and surfactant mixtures

Oppositely charged polymer-surfactant systems are expected to interact with formation of coacervate complexes near composition of charge-neutrality. Such behaviour is widely used in formulated products (e.g. household and personal care), where the co-deposition of coacervates and active ingredients on various surfaces is triggered by dilution. A transition towards the use of more sustainable ingredients is currently ongoing as a response to the need of more environmentally conscious choices in production, albeit slowed down by the often more complex and not fully understood bulk and interfacial behaviour of new ingredients. In this work, mixtures of a medium-chain fatty acid (sodium decanoate) and two grades of bio-based cationic modified inulin were studied. The phase behaviour was determined in a wide composition matrix. The formation of coacervate complexes was observed for the mixture with the higher charge density polymer at a surfactant concentration of 1–3 wt%, close to the surfactant critical micellar concentration in pure water. Such behaviour was confirmed by DLS and SAXS data, suggesting surfactant-polymer complexation in a concentrated phase of packed micelles with a micelle-to-micelle distance of ∼4.5 nm. In situ ellipsometry and neutron reflectometry experiments were conducted to study the effect on surface deposition when diluting. The ellipsometry showed an adsorbed mass of ∼1.3–1.9 mg/m2, consistent with the deposition of a coacervate layer, and considerably higher than the neat, adsorbed polymer layer of ∼0.3 mg/m2. In the case of the neutron reflectometry experiments, dilution was performed before contact with the surface (pre-mixing), and no adsorption of coacervates was observed, but rather the adsorption of a polymer layer (0.49–0.85 mg/m2). The different results obtained with the different techniques highlight the kinetic nature of bulk coacervate formation and deposition, and the competition between these two phenomena. Maximal deposition can be achieved if one can control this time window either by tuning the composition of the system or the experimental set-up, to mimic the conditions of a specific application.

Comparative investigation of activation energy and biot number on quadratic convective flow of a radiating micropolar fluid

In this study, we evaluate the significance of activation energy for initiating a chemical reaction in a two-dimensional laminar flow of a micropolar fluid over a semi-infinite inclined plate. The internal heat transfer mechanism of fluid is modeled with considerations of radiation and convective thermal boundary conditions. The momentum equation uses quadratic density relations in the concentration and temperature differences in buoyancy. In addition, flow through a porous medium surrounded by an inclined plate is modeled by the Darcy-Forchheimer model. Using a spectral successive linearization approach achieves the numerical results for the dimensionless equations. Basic characteristics of flow are examined for a range of dimensionless physical parameters. Quadratic convection is observed to have a stronger impact on the physical components of the flow than linear convection. In addition, compared to the linear illustration, the quadratic convection scenario results in a 14 % − 19 % increase in surface drag and heat transmission rate and a 5 % − 9 % decrease in mass transfer rate. Further, a higher activation energy corresponds with a higher concentration of micropolar fluid. Furthermore, as the radiation and Biot number rise, the velocity and rate of heat transfer correspondingly increase. We believe that the obtained results apply to aerosol technologies and polymeric mixtures used under extreme temperatures and concentrations.

Electrospun Membranes Based on Quaternized Polysulfones: Rheological Properties-Electrospinning Mechanisms Relationship.

Composite membranes based on a polymer mixture solution of quaternized polysulfone (PSFQ), cellulose acetate phthalate (CAP), and polyvinylidene fluoride (PVDF) for biomedical applications were successfully obtained through the electrospinning technique. To ensure the polysulfone membranes' functionality in targeted applications, the selection of electrospinning conditions was essential. Moreover, understanding the geometric characteristics and morphology of fibrous membranes is crucial in designing them to meet the performance standards necessary for future biomedical applications. Thus, the viscosity of the solutions used in the electrospinning process was determined, and the morphology of the electrospun membranes was examined using scanning electron microscopy (SEM). Investigations on the surfaces of electrospun membranes based on water vapor sorption data have demonstrated that their surface properties dictate their biological ability more than their specific surfaces. Furthermore, in order to understand the different macromolecular rearrangements of membrane structures caused by physical interactions between the polymeric chains as well as by the orientation of functional groups during the electrospinning process, Fourier transform infrared (FTIR) spectroscopy was used. The applicability of composite membranes in the biomedical field was established by bacterial adhesion testing on the surface of electrospun membranes using Escherichia coli and Staphylococcus aureus microorganisms. The biological experiments conducted establish a foundation for future applications of these membranes and validate their effectiveness in specific fields.

Thermodiffusion, diffusion and Soret coefficients of binary polymeric mixtures in toluene and cyclohexane

Abstract We present the results of experimental study on measuring the thermodiffusion, molecular diffusion and Soret coefficients of polystyrene (4,880 g/mol) in the pure solvents toluene and cyclohexane at 298 K and atmospheric pressure. The experiments have been carried out for a wide range of concentrations, starting from the diluted state with 2 % polystyrene mass fraction (proposed in the DCMIX4 project) up to the semidilute regime of 20 % polystyrene mass fraction. In addition, we present a complete characterisation of the thermophysical properties of the analysed mixtures. Thermodiffusion, molecular diffusion and Soret coefficients of binary polymeric samples have been measured by combining the traditional thermogravitational column technique, the thermogravitational microcolumn and the optical beam deflection method. In toluene, the obtained experimental results are consistent with literature, showing that the magnitude of the mass transport thermoproperties decrease significantly with increasing polystyrene concentration, which is a first indication of an approaching glass transition in the concentrated regime. The results for thermodiffusion and molecular diffusion coefficients in cyclohexane as a function of concentration exhibit a similar trend. Nevertheless, the Soret coefficient seems to show an opposite tendency for the two solvents, increasing in magnitude for cyclohexane, at least up to the analysed polystyrene concentration.

Максвеллівська релаксація і внутрішнє тертя в системі полівінілбутираль-полівінілхлорид

The Maxwellian relaxation and internal friction of a mixture of amorphous polymers: polyvinyl butyral (PVB) - polyvinyl chloride (PVC) are studied. It has been found that by changing the temperature (T) and content (j ) of the ingredients, it is possible to control the value of viscoelastic moduli, viscosity, damping force, and energy dissipation due to Maxwellian relaxation caused by the action of ultrasonic vibrations with a frequency (w ) of 0.4 MHz on the composite. The use of computational methods, models, and a phenomenological approach made it possible to differentiate the effects of relaxation and indicate the ways to optimally combine the desired properties of the components in the system.

Multistimuli responsive microcapsules produced by the prilling/vibration technique for targeted colonic delivery of probiotics

This study aimed to microencapsulate the probiotic strain Lactiplantibacillus plantarum 4S6R (basonym Lactobacillus plantarum) in both microcapsules and microspheres by prilling/vibration technique. A specific polymeric mixture, selected for its responsiveness to parallel colonic stimuli, was individuated as a carrier of microparticles. Although the microspheres were consistent with some critical quality parameters, they showed a low encapsulation efficiency and were discarded. The microcapsules produced demonstrated high yields (97.52%) and encapsulation efficiencies (90.06%), with dimensional analysis and SEM studies confirming the desired size morphology and structure. The results of thermal stress tests indicate the ability of the microcapsules to protect the probiotic. Stability studies showed a significant advantage of the microcapsules over non-encapsulated probiotics, with greater stability over time. The release study under simulated gastrointestinal conditions demonstrated the ability of the microcapsules to protect the probiotics from gastric acid and bile salts, ensuring their viability. Examination in a simulated faecal medium revealed the ability of the microcapsules to release the bacteria into the colon, enhancing their beneficial impact on gut health. This research suggests that the selected mixture of reactive polymers holds promise for improving the survival and efficacy of probiotics in the gastrointestinal tract, paving the way for the development of advanced probiotic products.

Stretchable hydrogels of chitosan/hyaluronic acid induced by polyelectrolyte complexation around neutral pH

In this work, we propose the formation of stretchable hydrogels at neutral pH from the physical crosslinking of chitosan (CS) and hyaluronic acid (HA) by polyelectrolyte complexation. A mixture of CS (Mw ≈ 600 kg/mol, degree of acetylation ≈ 50 %) solution and HA (Mw ≈ 77 kg/mol) solution was prepared with an excess of salts screening the electrostatic interactions CS/HA. In a controlled manner, the polyelectrolyte complexation was induced through the progressive dialysis of the salted polymer mixture against a sodium acetate solution (AcONa, 0.01 M) for 7 days. Depending on [HA], various materials were obtained: viscous solutions at [HA] = 0.75 % (w/v); hydrogels at [HA] = 1.50–2.24 % (w/v) with Young modulus of 14 kPa and stretchable to 200 %. The small angle X-ray scattering characterization of the hydrogels revealed a multiscale organization related to the conformation of the polymers induced by the physical interactions. The dialysis process with AcONa was optimized by adding a dialysis step against a zinc acetate solution containing Zn2+. The combination of polyelectrolyte complexation between CS/HA and metal complexation between Zn2+ and the polymers led to an enhancement of the hydrogel stretchability up to 400 %.