Methacrylic Acid-ethyl Acrylate Research Articles

PH-responsive CuS/DSF/EL/PVP nanoplatform alleviates inflammatory bowel disease in mice via regulating gut immunity and microbiota

The clinical treatment of inflammatory bowel disease (IBD) is challenging. We developed copper sulfate (CuS)/disulfiram (DSF)/methacrylic acid-ethyl acrylate copolymer (EL)/polyvinylpyrrolidone (PVP) nanoplatform (CuS/DSF/EL/PVP) and evaluated its efficiency for treating IBD. After oral administration, the pH-sensitive EL protected the CuS/DSF/EL/PVP against degradation by acidic gastric juices. Once the colon was reached, EL was dissolved, releasing DSF and Cu2+. Further, the main in vivo metabolite of DSF can bind to Cu2+ and form copper (II) N, N-diethyldithiocarbamate (CuET), which significantly alleviated acute colitis in mice. Notably, CuS/DSF/EL/PVP outperformed CuS/EL/PVP and DSF/EL/PVP nanoplatforms in reducing colonic pathology and improving the secretion of inflammation-related cytokines (such as IL-4 and IL-10) in the colonic mucosa. RNA-seq analysis revealed that the nanoplatform reduced colonic inflammation and promoted intestinal mucosal repair by upregulating C-type lectin receptor (CLR)-related genes and signaling pathways. Furthermore, CuS/DSF/EL/PVP showed potential for improving colitis Th1/Th17 cells through innate immunity stimulation, down-regulation of inflammatory cytokines, and upregulation of anti-inflammatory cytokines. Additionally, the intervention with CuS/DSF/EL/PVP led to increased intestinal flora diversity, decreased Escherichia–Shigella abundance, and elevated levels of short-chain fatty acid (SCFA)-producing bacteria Prevotella, Lactobacillus, and Bifidobacterium, indicating their potential to modulate the dysregulated intestinal flora and suppress inflammation. Statement of SignificanceOur study introduces the CuS/DSF/EL/PVP nanoplatform as a therapeutic strategy for treating inflammatory bowel disease (IBD). This approach demonstrates significant efficacy in targeting the colon and alleviating acute colitis in mice. It uniquely modulates gut immunity and microbiota, exhibiting a notable impact on inflammation-related cytokines and promoting intestinal mucosal repair. The nanoplatform's ability to regulate gut flora diversity, combined with its cost-effective and scalable production, positions it as a potentially transformative treatment for IBD, offering new avenues for personalized medical interventions.

Doping Na+ into Polyvinyl Alcohol: Methacrylic Acid-Ethyl Acrylate (PVA/MAA:EA) Polymer Blend Electrolytes; A Way to Improve the Blend’s Thermal, Structural, Optical and Electrical Properties

Pristine and doped films of polyvinyl alcohol (PVA): poly (methacrylic acid-ethyl acrylate)(MAA-EA) (50:50) blend with various weight percentages (5, 10 and 15 wt%) of sodium chloride (NaCl) (Na+ ions) were prepared by a simple solution casting method. Exhibiting a decrease in diffraction peak intensities with increasing weight percentage of NaCl salt content, X-ray diffraction (XRD) indicated a decrease in crystallinity or less polymer blend. Thermogravimetric analysis (TGA) showed a decreasing trend in melting temperature of the doped films compared with the pure films. From the optical absorption and conductivity studies, among the prepared samples, the film with 15 wt% NaCl showed minimum absorption edge, direct band gap and indirect band gap values of 4.02, 4.52, 3.54 eV, respectively, and the maximum ionic conductivity of 9.85 × 10−8 S/cm.

Processability evaluation of multiparticulate units prepared by selective laser sintering using the SeDeM Expert System approach

3D printing in dosage forms fabrication is in the focus of researchers, however, the attempts in multiparticulate units (MPUs) preparation are scarce. The aim of this study was to fabricate different size MPUs by selective laser sintering (SLS), using different polymers, and investigate their processability based on the SeDeM Expert System approach.MPUs (1- or 2-mm size) were prepared with model drug (ibuprofen or caffeine), polymer (poly(ethylene)oxide (PEO), ethyl cellulose (EC) or methacrylic acid-ethyl acrylate copolymer (MA-EA)) and printing aid. Comprehensive sample characterization was performed and experimentally obtained parameters were mathematically transformed and evaluated using the SeDeM Expert System framework. The obtained samples exhibited irregular shape, despite the spherical printing object design. Polymer incorporated notably affected MPUs properties.The obtained samples exhibited low bulk density, good flowability-, as well as stability-related parameters, which indicated their suitability for filling into capsules or sachets. Low density values implied that compressibility enhancing excipients may be required for MPUs incorporation in tablets. Samples containing EC and MA-EA were found suitable for compression, due to high compacts tensile strength. The obtained results indicate that SeDeM Expert System may extended from powder compressibility evaluation tool to framework facilitating powders/multiparticulate units processing.

ASD Formation Prior to Material Characterization as Key Parameter for Accurate Measurements and Subsequent Process Simulation for Hot-Melt Extrusion

Process simulation facilitates scale-up of hot-melt extrusion (HME) and enhances proper understanding of the underlying critical process parameters. However, performing numeric simulations requires profound knowledge of the employed materials’ properties. For example, an accurate description of the compounds’ melt rheology is paramount for proper simulations. Hence, sample preparation needs to be optimized to yield results as predictive as possible. To identify the optimal preparation method for small amplitude oscillatory shear (SAOS) rheological measurements, binary mixtures of hydroxypropylmethylcellulose acetate succinate or methacrylic acid ethyl acrylate copolymer (Eudragit L100-55) together with the model drugs celecoxib and ketoconazole were prepared. The physical powder mixtures were introduced into the SAOS as a compressed tablet or a disk prepared via vacuum compression molding (VCM). Simulations with the derived parameters were conducted and compared to lab-scale extrusion trials. VCM was identified as the ideal preparation method resulting in the highest similarity between simulated and experimental values, while simulation based on conventional powder-based methods insufficiently described the HME process.

Trojan pH-Sensitive Polymer Particles Produced in a Continuous-Flow Capillary Microfluidic Device Using Water-in-Oil-in-Water Double-Emulsion Droplets.

A facile and robust microfluidic method to produce nanoparticle-in-microparticle systems (Trojan systems) is reported as a delivery vector for the oral administration of active pharmaceutical ingredients. The microfluidic system is based on two coaxial capillaries that produce monodisperse water-in-oil-in-water (W/O/W) double emulsions in a highly controlled fashion with precise control over the resulting particle structure, including the core and shell dimensions. The influence of the three phase flow rates, pH and drying process on the formation and overall size is evaluated. These droplets are then used as templates for the production of pH-sensitive Trojan microparticles after solvent evaporation. The shell of Trojan microparticles is made of Eudragit®, a methacrylic acid-ethyl acrylate copolymer that would enable the Trojan microparticle payload to first pass through the stomach without being degraded and then dissolve in the intestinal fluid, releasing the inner payload. The synthesis of the pH-sensitive Trojan microparticles was also compared with a conventional batch production method. The payloads considered in this work were different in nature: (1) fluorescein, to validate the feasibility of the polymeric shell to protect the payload under gastric pH; (2) poly(D,L-lactic acid/glycolic acid)-PLGA nanoparticles loaded with the antibiotic rifampicin. These PLGA nanoparticles were produced also using a microfluidic continuous process and (3) PLGA nanoparticles loaded with Au nanoparticles to trace the PLGA formulation under different environments (gastric and intestinal), and to assess whether active pharmaceutical ingredient (API) encapsulation in PLGA is due efficiently. We further showed that Trojan microparticles released the embedded PLGA nanoparticles in contact with suitable media, as confirmed by electron microscopy. Finally, the results show the possibility of developing Trojan microparticles in a continuous manner with the ability to deliver therapeutic nanoparticles in the gastrointestinal tract.

Synthesis of silver nanoclusters in colloidal scaffold for biolabeling and antimicrobial applications

A robust method to prepare silver nanoclusters (AgNCs) inside a methacrylic acid-ethyl acrylate (MAA-EA) nanogel is proposed, where AgNCs were produced within the nanogel scaffold via UV-photoreduction. The impact of UV irradiation time on the formation of AgNCs and their application in biolabeling and antimicrobial properties were examined. The AgNCs formation is described by two stages; (1) Agn (n = 2–8) nanoclusters formation between 0 and 25 min, and (2) larger silver nanoparticles (AgNPs) formed via aggregation inside the nanogel. The antimicrobial performance depended on the size and concentration of silver ions (Ag+). A maximum inhibitory concentration (MIC) of 1.1 ppm was observed for antimicrobial test with yeast, and a MIC of 11 and 22 ppm was recorded for Escherichia. coli and Staphylococcus aureus respectively. Combining with the green illumination property of AgNCs (emitted at 525 nm) with dead yeast, it could be used for biolabeling. By tuning the size through photoirradiation, the nanogel templated AgNCs is a promising candidate for antimicrobial and biolabeling applications.

Boost of solubility and supersaturation of celecoxib via synergistic interactions of methacrylic acid-ethyl acrylate copolymer (1:1) and hydroxypropyl cellulose in ternary amorphous solid dispersions

A current trend in the development of amorphous solid dispersions (ASDs) is the combination of two polymers for synergistic enhancement in supersaturation of poorly soluble drugs. We investigated the supersaturation potential of celecoxib (CXB) using combinations of methacrylic acid-ethyl acrylate copolymer (1:1) (EL 100–55) and hydroxypropyl cellulose (HPC) SSL. Initially, the supersaturation potential of single polymers and combinations in various ratios was assessed. While EL 100–55 and HPC SSL alone showed limited potential in solubility enhancement of CXB the combination of both polymers led to a boost of CXB solubility, whereby most promising results were obtained using a 50:50 polymer ratio. Binary and ternary CXB ASDs (10% drug load) were prepared via vacuum compressing molding (VCM) and hot melt extrusion (HME). ASDs were studied by exploring the miscibility and intermolecular interactions and tested for their dissolution performance. HPC SSL was identified to be a suitable precipitation inhibitor when added to a fast dissolving CXB: EL 100–55 ASD. Ternary ASDs showed even further dissolution improvement, when processed by HME. The combination of heat and shear stress led to a homogeneous and intimate mixture of EL 100–55 and HPC SSL, resulting in formation of synergistic interactions with pronounced impact on CXB supersaturation.

Development, Characterization, Optimization, and In Vivo Evaluation of Methacrylic Acid-Ethyl Acrylate Copolymer Nanoparticles Loaded with Glibenclamide in Diabetic Rats for Oral Administration.

The methacrylic acid–ethyl acrylate copolymer nanoparticles were prepared using the solvent displacement method. The independent variables were the drug/polymer ratio, surfactant concentration, Polioxyl 40 hydrogenated castor oil, the added water volume, time, and stirring speed, while size, PDI, zeta potential, and encapsulation efficiency were the response variables analyzed. A design of screening experiments was carried out to subsequently perform the optimization of the nanoparticle preparation process. The optimal formulation was characterized through the dependent variables size, PDI, zeta potential, encapsulation efficiency and drug release profiles. In vivo tests were performed in Wistar rats previously induced with diabetes by administration of streptozotocin. Once hyperglycemia was determined in rats, a suspension of nanoparticles loaded with glibenclamide was administered to them while the other group was administered with tablets of glibenclamide. The optimal nanoparticle formulation obtained a size of 18.98 +/− 9.14 nm with a PDI of 0.37085 +/− 0.014 and a zeta potential of −13.7125 +/− 1.82 mV; the encapsulation efficiency was of 44.5%. The in vivo model demonstrated a significant effect (p < 0.05) between the group administered with nanoparticles loaded with glibenclamide and the group administered with tablets compared to the group of untreated individuals.

Mechanical strength and gastric residence time of expandable fibrous dosage forms

Expandable, gastroretentive dosage forms are promising for precise control of drug concentration in blood. So far, however, short gastric residence times and safety considerations have limited their use. To mitigate such limitations, in this work expandable fibrous dosage forms were investigated for mechanical strength and gastric residence time in dogs. The fiber formulation comprised ibuprofen drug; water-absorbing, high-molecular-weight hydroxypropyl methylcellulose (HPMC) excipient; fiber-strengthening, enteric methacrylic acid-ethyl acrylate excipient; and barium sulfate, a gastrointestinal contrast agent. The fibers were coated either with a hydrophilic sugar, or with a strengthening enteric excipient. Upon administration to a dog, in the stomach the dosage form with sugar-coated fibers expanded to 1.7 times its initial radius in 50–100 minutes, and disintegrated after 4.8 hours. The dosage form with the enteric-excipient-coated fibers, by contrast, expanded to 1.6 times the initial radius in 5 hours, and fractured after 31 hours due to cyclic loads applied by the contracting stomach walls. The fragments passed into the small intestine where they dissolved in less than 2–3 hours. Diametral compression tests and dynamic fatigue failure models show that the substantial increase in gastric residence time is due to strengthening of the fibers by the enteric-excipient coating. Because the enteric excipient is a rubbery semi-solid in the acidic gastric fluid and dissolves in the pH-neutral intestinal fluids, safety concerns should be minimal. Thus, expandable fibrous dosage forms can be readily designed for prolonged, safe gastric retention.

Polymerization Mechanism and Kinetics of Preparation of Methacrylic Acid-Ethyl Acrylate Copolymer Emulsion Reverse Demulsifier

It was shown that methacrylic acid-ethyl acrylate copolymer (P(EA-MAA)) emulsion has a good reverse demulsification performance for treatment of water produced in oilfields. Its polymerization mechanism, kinetics and demulsification mechanism are important for its application and scale-up production. Therefore, they were studied in the research described in this paper. It was found that the demulsification mechanism of P(EA-MAA) was related to the ion compositions of the produced water and the conformation change of P(EA-MAA) when it was dissolved in the produced water. The distributions of monomer and surfactant before the polymerization were investigated and we found that there were both homogeneous nucleation and micellar nucleation during the first stage of emulsion polymerization. The relationships among the polymerization rate (Rp), monomer concentration ([M]), initiator concentration ([I]) and surfactant concentration ([S]) were studied. The emulsion copolymerization kinetic equation was Rp∝[M]0.64 [I]0.68 [S]0.41, which is related with the nucleation mechanism of the polymerization mechanism. In addition, the activation energy was 34.50 kJ/mol.

Expandable, dual-excipient fibrous dosage forms for prolonged delivery of sparingly-soluble drugs

In this work, expandable fibrous dosage forms containing water-absorbing and fiber-strengthening excipients are investigated for prolonged delivery of sparingly-soluble drugs. The formulation comprised: sparingly-soluble ibuprofen drug; water-absorbing, high-molecular-weight hydroxypropyl methylcellulose (HPMC) excipient; and strengthening methacrylic acid-ethyl acrylate excipient. Upon immersion in a dissolution fluid, the single fibers and all the dosage forms (fiber volume fractions, φ = 0.16, 0.39, and 0.56) expanded roughly at the same rate. The size of the dosage forms doubled in fifteen minutes, and they were converted into a highly viscous gel. The gel was stabilized by the strengthening excipient for over two days. Eighty percent of the drug was released from single fibers in less than an hour, and in thirty-eight hours from the dosage form with φ = 0.56. Theoretical models suggest that if φ is small, drug release is limited by the diffusion of drug molecules through the thin fibers, which is fast. If φ is large, however, drug release is limited by the diffusion of drug molecules through the thick, monolithic dosage form gel, which is slow. Between these extremes, the drug release time increases exponentially with φ.

Influence of Particle Size and Drug Load on Amorphous Solid Dispersions Containing pH-Dependent Soluble Polymers and the Weak Base Ketoconazole

Among the great number of poorly soluble drugs in pharmaceutical development, most of them are weak bases. Typically, they readily dissolve in an acidic environment but are prone to precipitation at elevated pH. This was aimed to be counteracted by the preparation of amorphous solid dispersions (ASDs) using the pH-dependent soluble polymers methacrylic acid ethylacrylate copolymer (Eudragit L100–55) and hydroxypropylmethylcellulose acetate succinate (HPMCAS) via hot-melt extrusion. The hot-melt extruded ASDs were of amorphous nature and single phased with the presence of specific interactions between drug and polymer as revealed by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy (FT-IR). The ASDs were milled and classified into six particle size fractions. We investigated the influence of particle size, drug load, and polymer type on the dissolution performance. The best dissolution performance was achieved for the ASD made from Eudragit L100–55 at a drug load of 10%, whereby the dissolution rate was inversely proportional to the particle size. Within a pH-shift dissolution experiment (from pH 1 to pH 6.8), amorphous-amorphous phase separation occurred as a result of exposure to acidic medium which caused markedly reduced dissolution rates at subsequent higher pH values. Phase separation could be prevented by using enteric capsules (Vcaps Enteric®), which provided optimal dissolution profiles for the Eudragit L100–55 ASD at a drug load of 10%.

Physical Stability and Dissolution of Lumefantrine Amorphous Solid Dispersions Produced by Spray Anti-Solvent Precipitation.

This study aims to develop amorphous solid dispersion (ASD) of lumefantrine with a cost-effective approach of spray anti-solvent precipitation. Four acidic polymers, hydroxypropylmethylcellulose phthalate (HPMCP), hydroxypropylmethylcellulose acetate succinate (HPMCAS), poly(methacrylic acid–ethyl acrylate) (EL100) and cellulose acetate phthalate (CAP) were studied as excipients at various drug-polymer ratios. Of the studied polymers, satisfactory physical stability was demonstrated for HPMCP- and HPMCAS-based ASDs with no observed powder X-ray diffraction peaks for up to 3 months of storage at 40 °C/75% RH. HPMCP and HPMCAS ASDs also achieved greater drug release levels in the dissolution study than other polymers. The HPMCP-based ASDs with a drug:polymer ratio of 2:8 exhibited a maximum drug release of 140 μg/mL for up to 2 h, which is significantly higher than the currently marketed formulation of Coartem® (<80 ng/mL). Relatively, the CAP and EL100 ASDs indicated a higher water content and crystallized within a day when stored at 40 °C/75% RH. The choice of polymer, and the drug-polymer ratio played a crucial role in the solubility enhancement of lumefantrine. Our study indicates that the developed spray anti-solvent precipitation method could be an affordable approach for producing ASDs.

Effect of K+ ion doping on structural and physical properties of PVA/MAA:EA polymer blend electrolytes

ABSTRACT A solid polymer blend electrolyte was prepared by using Polyvinyl alcohol (PVA) and Methacrylic Acid Ethyl acrylate (MAA: EA) polymers with different weight percentages (Wt%) of Potassium Chloride (KCl) by using solution casting technique, with water as a solvent. The structural, thermal, optical, and electrical properties of the prepared samples were studied. The X-ray diffraction pattern shows the decreasing trend in the degree of crystallinity due to the incorporation of KCl into the polymeric matrix. From the FTIR analysis, some peak intensities were decreasing and shifted in the case of KCl complexed films, which results in the complexation between the polymer blend and dopant ions. The TGA analysis reveals that the thermal stability of the KCl complexed films increases as dopant concentration increases. The SEM images reveal the structural reorganisation of polymer chains in the KCl complexed polymer blend electrolytes. UV-VIS spectra show that the optical constants such as absorption edge and band gap (both direct and indirect) values are decreased with an increase in KCl concentration. From conductivity data, it was noticed that the conductivity increased with the increase in the K+ ion concentration. The maximum ionic conductivity of 1.85 × 10−7 S/cm was obtained for the sample having 15 wt% of KCl salt.

Impact of Hot-Melt Extrusion Processing Conditions on Physicochemical Properties of Amorphous Solid Dispersions Containing Thermally Labile Acrylic Copolymer

For successful formulation of amorphous solid dispersions (ASDs) using hot-melt extrusion, it is imperative to understand the effect that heat and shear rate has on the physicochemical properties of the excipient. In this study, we investigated the influence of hot-melt extrusion parameters on solvent-free binary ASDs of ibuprofen (IBU), a model active pharmaceutical ingredient, in methacrylic acid-ethyl acrylate copolymer type A, 1:1, EUDRAGIT® L100-55 (EUD). To evaluate the impact of barrel temperature, screw speed, and residence time on EUD mass average molar mass and IBU release profile, size-exclusion chromatography and dissolution testing were used, respectively. The optimal conditions were established for IBU loadings less than 40 wt. %. For ASD formulations prepared using the ideal variables, spectral and thermal analyses confirmed that, under dry conditions at a temperature of 25°C, IBU remained amorphous during an 18-month storage period. After 28 months, formulations with active pharmaceutical ingredient content above 30 wt. % started to recrystallize. A temperature–composition phase diagram, constructed using melting point depression and glass-transition temperature measurements of IBU–EUD mixtures, correlated well with the long-term physical stability. The effect that minor-to-moderate polymer degradation within the extrudates has on their long-term physical stability and dissolution characteristics is analyzed and discussed.

Amorphous solid dispersions of weak bases with pH-dependent soluble polymers to overcome limited bioavailability due to gastric pH variability – An in-vitro approach

Several drugs are pH-dependent soluble weak bases with a poor solubility in the intestinal pH range. Additionally a variable gastric pH, which is a common issue in the population, potentially reduces the in-vivo performance due to reduced solubility at elevated pH. Aiming to avoid the influence of variable gastric pH on the dissolution performance, enteric polymers – hydroxypropylmethylcellulose acetate succinate (HPMCAS), hydroxypropylmethylcellulose phthalate (HP-55, HP-50) and methacrylic acid ethylacrylate copolymer (Eudragit L100-55) together with nevirapine as model drug were used for the preparation of solid dispersions by hot-melt extrusion. We were able to generate solid dispersions without crystalline residuals. The resulting solid dispersions were further tested for stability and dissolution performance applying two different pH-shift experiments (non-sink conditions), to simulate standard and altered gastric conditions. Solid dispersions made of enteric polymers were independent to gastric pH variability and exhibited superior dissolution performances compared to their respective physical mixtures and neat nevirapine.

The influence of polymer excipients on the dissolution and recrystallization behavior of ketoconazole: Application, variation and practical aspects of a pH shift method

The formulation of amorphous solid dispersions (ASDs) is an effective way to improve the bioavailability of poorly water-soluble active pharmaceutical ingredients (APIs). The combination of an amorphous state of the drug and the presence of crystallization-inhibiting polymers retains a high amount of dissolved API over time. ASDs with ketoconazole and different polymers were manufactured by spray drying and their characteristics as well as performance were analyzed. Dissolution tests with a change of the dissolution medium from 0.1 M HCl to phosphate buffer at pH 6.8 to simulate pH conditions for instant release formulations, and a direct dissolution of the ASDs in phosphate buffer pH 6.8 to simulate conditions for an enteric formulation, were performed. All ASDs with API contents between 25 and 50% by weight were completely X-ray amorphous. Varying dissolution behaviors between medium change and direct dissolution occurred. It was possible to identify the superior ASD-compositions for both types of tests. The acidic polymers methacrylic acid-ethyl acrylate copolymer, hypromellose acetate succinate and the solubilizer macrogolglycerol hydroxystearate showed the best performances. The combination of the acidic polymers with macrogolglycerol hydroxystearate showed an improved dissolution behavior at higher API contents. The optimization of such formulations with different release-patterns plays an important role for the enhancement of the oral bioavailability of poorly water-soluble drugs.

Structural and optical properties of VO2+doped methacrylic acid ethylacrylate (MAA:EA) copolymer films

AbstractPure and VO2+doped methacrylic acid ethylacrylate (MAA:EA) copolymer films were prepared by using a solution casting method. Various techniques including X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, scanning electron microscopy and electron paramagnetic resonance were employed for characterization of the samples. XRD patterns showed some degree of crystallinity of the doped polymer films due to interaction of the MAA:EA copolymer with VO2+. FT-IR spectral studies of pure and VO2+doped MAA:EA copolymer films displayed significant structural changes within the doped copolymer film indicating the complexation. The optical absorbance of the pure and VO2+doped films were measured in the 200 nm to 800 nm wavelength range. The values of the absorption edge and indirect band gaps were calculated. The optical band gap decreased with the increase of mol% of VO2+. From the EPR spectra, the spin- Hamiltonian parameters (g and A) were evaluated. The values of the spin-Hamiltonian parameters confirmed that the vanadyl ions were present in MAA:EA copolymer films as VO2+molecular ions in an octahedral site with a tetragonal compression (C4v). The morphology of the copolymer samples was examined by scanning electron microscopy. The enhanced crystalline nature of the doped copolymer was identified from SEM analysis.

Structural, thermal and optical properties of $${\hbox {Cu}}^{2+}$$ Cu 2 + doped methacrylic acid–ethyl acrylate (MAA:EA) copolymer films

Pure and \({\hbox {Cu}}^{2+}\) doped methacrylic acid–ethyl acrylate (MAA:EA) copolymer films were prepared using the solution cast technique. The amorphous feature of the copolymer was depicted using X-ray diffraction scans and degree of crystallinity was found to vary with increasing doping content. UV–Vis absorption spectra in the wavelength region 200–900 nm were used to evaluate the optical properties like direct band gap, indirect band gap and absorption edge. The optical band gap decreased with the increase of mol% of \(\hbox {Cu}^{2+}\) ions. Fourier transform infrared spectral studies on pure MAA:EA and \(\hbox {Cu}^{2+}\) ions-doped films revealed the vibrational changes that occurred due to the effect of dopant salt in the copolymer. Thermal properties of these films were investigated by employing differential scanning calorimetry and thermogravimetric analysis. The variation in film morphology was examined by scanning electron microscopy. Electron paramagnetic resonance (EPR) spectra of all the doped samples exhibited signals due to \(\hbox {Cu}^{2+}\) ions with the effective g-values \(g_{\Vert } = 2.177\) and \(g_{\bot }= 2.058\). The observed variation in the EPR signal intensity is due to the isolated and aggregated copper ions. The photoluminescence spectra of \(\hbox {Cu}^{2+}\) ions-doped MAA:EA copolymer exhibited four emission peaks at 480 (blue), 579 (yellow), 604 (red) and 671 nm (red).

Structural, Thermal and Optical Properties of Mn2+ Doped Methacrylic Acid – Ethyl Acrylate (MAA:EA) Copolymer Films

Abstract Pure and Mn2+ doped Methacrylic Acid Ethylacrylate (MAA:EA) copolymer films were prepared by using the solution cast technique. Investigations were conducted using DSC, TGA, XRD, FTIR, UV–Vis, SEM and EPR. Thermal properties of these films were investigated with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Using the DSC thermograms, glass transition temperature (Tg ) and melting temperature (Tm ) of copolymer films were measured. Thermogravimetric curves of the pure and Mn2+ doped MAA:EA copolymer showed two distinct steps of weight loss. The optical absorbance of the pure and Mn2+ doped films were measured in the 200–800 nm wavelength range. The values of absorption edge, direct and indirect band gaps were calculated. The optical band gap decreased with the increase of mol% of Mn2+ ions. The enhanced amorphous nature of the doped copolymer has been identified from X-ray diffraction analysis. FTIR spectral studies of pure and Mn2+ doped MAA:EA copolymer films display significant structural changes within the copolymer film indicating the complexation. The morphology of the copolymer samples was examined by scanning electron microscopy (SEM). EPR spectra of all the doped samples exhibit a single absorption line centered at g=2.005. The observed variation in the EPR signal intensity is due to the existence of interacting paramagnetic centers.