Solvent Casting Research Articles

An innovative approach to develop plant-derived and CO2-based active biocomposite films towards antioxidant activity

In this study, novel biocomposites composed of CO2-derived poly(propylene) carbonate and plant-based cellulose were developed employing solvent casting technique. An innovative and rapid strategy was employed, whereby pre-dissolving cellulose improves dramatically the compatibility of poly(propylene) carbonate with cellulose whilst pristine cellulose powder displays inhomogeneous distributions of cellulose within the biocomposite. Resulting biocomposites produce flat homogeneous surfaces with low cellulose content, whilst rougher surfaces and thicker cross sections were observed in films with higher cellulose content. Developed biocomposites outperformed biocomposites produced from pristine cellulose powder in terms of homogeneity, thermal stability, antioxidant activity and biocompatibility. Higher cellulose content samples show the formation of a new hydrogen bonding network between PPC and cellulose polymer chains and this contributes to improved thermal stability. TGA results reveal improved thermal stability for high cellulose content films and show enhanced water vapor permeability. A cell viability study shows that the developed materials are biocompatible. Curcumin, a natural antioxidant, was incorporated into optimized biocomposites to produce active biocomposites with antioxidant features to accelerate wound healing. Curcumin is shown to display a sustained release profile over a time period of 3 days, and this is ideal for would healing. The curcumin-functionalized biocomposites also contributed to enhanced thermal stability and water vapor permeability. Thus, these biocomposite films show promise as active biocomposites which can be used for biomedical applications such as wound healing.

Development and characterization of groundnut shell‐derived biocarbon‐reinforced polylactic acid composite filaments for FDM

AbstractBiochar, a carbon‐rich biomass material has emerged as promising reinforcement and offers versatile applications and potential benefits in various fields, especially in fused deposition modeling (FDM). This study focuses on the development and characterization of groundnut shell‐derived biocarbon (GNSC) reinforced polylactic acid (PLA) filaments for FDM. The GNSC was synthesized through pyrolysis using a tubular furnace at temperatures 700, 800, and 900°C. Synthesized carbon was characterized using Raman spectroscopy, XRD, and SEM analysis. The results showed that the synthesized carbon particles were graphitic, spherical, and nanosized with an average diameter of 40 nm. The preferred biocarbon material, GNSC800 was selected for its high carbon content (98.25%) observed through EDX analysis. Composite filaments were produced with different GNSC800 loadings of 0.25%, 0.5%, and 0.75% using solvent casting and extrusion techniques. Thermal stability was evaluated using TGA and DSC, which showed improved properties with the addition of biocarbon. The mechanical properties and electrical conductivity were enhanced with the inclusion of biocarbon. The data were also validated using ANOVA and Tukey's test. Filament with the 0.5 wt% loading showed the most favorable thermomechanical properties exhibiting a 39.8% increase in tensile strength and a 17.5% improvement in tensile modulus.

Maleic acid crosslinked starch/polyvinyl alcohol blend films with improved barrier properties for packaging applications

Incorporating starch, which is a potential biodegradable substitute for petroleum-based polymers, into conventional polymers is challenging owing to limitations in processability and weak-performing resulting materials. Herein, corn starch/polyvinyl alcohol (PVA) blend films (starch: PVA ratio of 50:50) were prepared via the solvent casting method using glycerol as a plasticizer and with varying concentrations of maleic acid as the crosslinking agent. Fourier transform infrared spectroscopy revealed the molecular interactions of the maleic acid crosslinker with the polymeric network of starch and PVA through an ester linkage. The properties of the films were strongly dependent on the maleic acid concentration. An increasing maleic acid concentration imparted hydrophobicity to the film; therefore, water swelling was significantly reduced, and water resistance was enhanced. The film containing 20 wt% maleic acid exhibited excellent barrier properties, with the lowest oxygen and water vapor transmission rates of 0.5 ± 0.2 cc/m2⋅day and 232.3 ± 5.4 g/m2⋅day, respectively. Moreover, the mechanical properties of the film improved with increasing crosslinking. This study demonstrates that the addition of maleic acid leads to an improvement in the overall performance of starch/PVA blend films. Therefore, maleic acid-crosslinked films can be used as barrier materials in food packaging applications.

Formulation and Characterization of Clozapine Nanosuspension as a Sublingual Film

Background: Clozapine (CLZ) is a potent antipsychotic drug that suppresses the symptoms of schizophrenia and mania. Clozapine falls into Class II (BCS); its poor bioavailability is attributed to low water solubility and an extensive first-pass effect. Objective: To prepare CLZ as a nanosuspension (NS) to improve its low water solubility and load it into a sublingual film to enhance oral bioavailability. Methods: CLZ nanosuspensions are prepared by the “solvent anti-solvent precipitation” method using Soluplus as a stabilizing agent. We evaluated the polydispersity index (PDI) and the particle size of the CLZ nanosuspension formulations. The optimized formula of CLZ nanosuspension is loaded directly onto a sublingual thin film, eliminating the need for freeze-drying for solidification by the solvent casting approach. The sublingual films were characterized by thickness, surface pH, folding endurance, disintegration time, and in vitro dissolution rate. Results: We selected the formula F1 sublingual film as the best, as it demonstrated a uniform thickness of 0.087mm, good flexibility, and a surface pH of 6.7. It disintegrated quickly in 13 seconds and had a faster in vitro dissolution rate (3 min) compared to the CLZ ordinary films. Conclusions: The results confirmed the success of CLZ NS as a sublingual thin film for dissolution rate enhancement, which may improve oral bioavailability.

Nanocrystalline cellulose as a reinforcing agent for poly (vinyl alcohol)/ gellan-gum-based composite film for moxifloxacin ocular delivery

Nanocrystalline cellulose (NCC) is a star material in drug delivery applications due to its good biocompatibility, large specific surface area, high tensile strength (TS), and high hydrophilicity. Poly(Vinyl Alcohol)/Gellan-gum-based innovative composite film has been prepared using nanocrystalline cellulose (PVA/GG/NCC) as a strengthening agent for ocular delivery of moxifloxacin (MOX) via solvent casting method. Impedance analysis was studied using the capacitive sensing technique for examining new capacitance nature of the nanocomposite MOX film. Antimicrobial properties of films were evaluated using Pseudomonas aeruginosa and Staphylococcus aureus as gram-negative and gram-positive bacteria respectively by disc diffusion technique. XRD revealed the characteristic peak of NCC and the amorphous form of the drug. Sustained in vitro release and enhanced corneal permeation of drug were noticed in the presence of NCC. Polymer matrix enhanced the mechanical properties (tensile strength 22.05 to 28.41 MPa) and impedance behavior (resistance 59.23 to 213.23 Ω) in the film due to the presence of NCC rather than its absence (16.78 MPa and 39.03 Ω respectively). Occurrence of NCC brought about good antimicrobial behavior (both gram-positive and gram-negative) of the film. NCC incorporated poly(vinyl alcohol)/gellan-gum-based composite film exhibited increased mechanical properties and impedance behavior for improved ocular delivery of moxifloxacin.

Investigating the in-vitro bioactivity, biodegradability and drug release behavior of the newly developed PES/HA/WS biocompatible nanocomposites as bone graft substitute

The nucleation of carbonate-containing apatite on the biomaterials surface is regarded as a significant stage in bone healing process. In this regard, composites contained hydroxyapatite (Ca10(PO4)6(OH)2, HA), wollastonite (CaSiO3, WS) and polyethersulfone (PES) were synthesized via a simple solvent casting technique. The in-vitro bioactivity of the prepared composite films with different weight ratios of HA and WS was studied by placing the samples in the simulated body fluid (SBF) for 21 days. The results indicated that the the surface of composites containing 2 wt% HA and 4 wt% WS was completely covered by a thick bone-like apatite layer, which was characterized by Grazing incidence X-ray diffraction, attenuated total reflectance–Fourier transform infrared spectrometer, field emission electron microscopy and energy dispersive X-ray analyzer (EDX). The degradation study of the samples showed that the concentration of inorganic particles could not influence the degradability of the polymeric matrix, where all samples expressed similar dexamethasone (DEX) release behavior. Moreover, the in-vitro cytotoxicity results indicated the significant cyto-compatibility of all specimens. Therefore, these findings revealed that the prepared composite films composed of PES, HA, WS and DEX could be regarded as promising bioactive candidates with low degradation rate for bone tissue engineering applications.

Synthesis, Characterisation, and In Vitro Evaluation of Biocompatibility, Antibacterial and Antitumor Activity of Imidazolium Ionic Liquids.

In recent decades, ionic liquids (ILs) have garnered research interest for their noteworthy properties, such as thermal stability, low or no flammability, and negligible vapour pressure. Moreover, their tunability offers limitless opportunities to design ILs with properties suitable for applications in many industrial fields. This study aims to synthetise two series of methylimidazolium ILs bearing long alkyl chain in their cations (C9, C10, C12, C14, C16, C18, C20) and with tetrafluoroborate (BF4) and the 1,3-dimethyl-5-sulfoisophthalate (DMSIP) as counter ions. The ILs were characterised using 1H-NMR and MALDI-TOF, and their thermal behaviour was investigated through DSC and TGA. Additionally, the antimicrobial, anticancer, and cytotoxic activities of the ILs were analysed. Moreover, the most promising ILs were incorporated at different concentrations (0.5, 1, 5 wt%) into polyvinyl chloride (PVC) by solvent casting to obtain antimicrobial blend films. The thermal properties and stability of the resulting PVC/IL films, along with their hydrophobicity/hydrophilicity, IL surface distribution, and release, were studied using DSC and TGA, contact angle (CA), SEM, and UV-vis spectrometry, respectively. Furthermore, the antimicrobial and cytotoxic properties of blends were analysed. The in vitro results demonstrated that the antimicrobial and antitumor activities of pure ILs against t Listeria monocytogenes, Escherichia coli, Pseudomonas fluorescens strains, and the breast cancer cell line (MCF7), respectively, were mainly dependent on their structure. These activities were higher in the series containing the BF4 anion and increased with the increase in the methylimidazolium cation alkyl chain length. However, the elongation of the alkyl chain beyond C16 induced a decrease in antimicrobial activity, indicating a cut-off effect. A similar trend was also observed in terms of in vitro biocompatibility. The loading of both the series of ILs into the PVC matrix did not affect the thermal stability of PVC blend films. However, their Tonset decreased with increased IL concentration and alkyl chain length. Similarly, both the series of PVC/IL films became more hydrophilic with increasing IL concentration and alkyl chain. The loading of ILs at 5% concentration led to considerable IL accumulation on the blend film surfaces (as observed in SEM images) and, subsequently, their higher release. The biocompatibility assessment with healthy human dermal fibroblast (HDF) cells and the investigation of antitumoral properties unveiled promising pharmacological characteristics. These findings provide strong support for the potential utilisation of ILs in biomedical applications, especially in the context of cancer therapy and as antibacterial agents to address the challenge of antibiotic resistance. Furthermore, the unique properties of the PVC/IL films make them versatile materials for advancing healthcare technologies, from drug delivery to tissue engineering and antimicrobial coatings to diagnostic devices.

Transdermal Delivery of Niacin Through Polysaccharide Films Ameliorates Cutaneous Flushing in Experimental Wistar Rats.

Niacin, an established therapeutic for dyslipidemia, is hindered by its propensity to induce significant cutaneous flushing when administered orally in its unmodified state, thereby constraining its clinical utility. This study aimed to fabricate, characterize, and assess the in-vitro and in-vivo effectiveness of niacin-loaded polymeric films (NLPFs) comprised of carboxymethyl tamarind seed polysaccharide. The primary objective was to mitigate the flushing-related side effects associated with oral niacin administration. NLPFs were synthesized using the solvent casting method and subsequently subjected to characterization, including assessments of tensile strength, moisture uptake, thickness, and folding endurance. Surface characteristics were analyzed using a surface profiler and scanning electron microscopy (SEM). Potential interactions between niacin and the polysaccharide core were investigated through X-ray diffraction experiments (XRD) and Fourier transform infrared spectroscopy (FTIR). The viscoelastic properties of the films were explored using a Rheometer. In-vitro assessments included drug release studies, swelling behavior assays, and antioxidant assays. In-vivo efficacy was evaluated through skin permeation assays, skin irritation assays, and histopathological analyses. NLPFs exhibited a smooth texture with favorable tensile strength and moisture absorption capabilities. Niacin demonstrated interaction with the polysaccharide core, rendering the films amorphous. The films displayed slow and sustained drug release, exceptional antioxidant properties, optimal swelling behavior, and viscoelastic characteristics. Furthermore, the films exhibited biocompatibility and non-toxicity towards skin cells. NLPFs emerged as promising carrier systems for the therapeutic transdermal delivery of niacin, effectively mitigating its flushing-associated adverse effects.

Physicochemical and thermal characterization of the edible shellac films incorporated with oleic acid to enhance flexibility, water barrier and retard aging

In this work, shellac plasticized with oleic acid was solvent cast to prepare the flexible and water-resistant film for packaging applications. The films were prepared with varying amounts of oleic acid and studied in detail for appearance, surface morphology, thermal, chemical, barrier, mechanical, and robustness. The surface morphology confirmed the smooth surface of films up to SH-OA20 (100:20 w/w; shellac: oleic acid). Fourier-transform infrared spectroscopy confirmed that oleic acid reduced the hydrogen bonding of the shellac matrix to provide a plasticization effect. Also, the thermal analysis showed a reduction in the melting enthalpy. Moreover, the plasticized films had a better barrier to water vapor due to increased smoothness and reduction in brittleness. Adding oleic acid also increased the elongation at break up to 40 % without any changes in tensile strength. The flexibility of the films increased with the oleic acid content, making them resistant to burst, crumbling, bending, rolling, and stretching. Oleic acid also showed the retardation of aging and thermal aging of shellac. In the future, the long-term stability and migration of the films can be investigated.

DESIGN AND OPTIMIZATION OF ESCITALOPRAM OXALATE ORAL DISSOLVING FILMS BY RESPONSE SURFACE METHODOLOGY

Objective: To develop and optimise the oral dissolving films of escitalopram oxalate by response surface methodology. Methods: Oral dissolving film compositions were optimized by central composite design. The films are prepared by solvent casting method. Initially, different polymers were screened and based on the results polyvinyl alcohol was selected as polymer, propylene glycol was selected as plasticizer. Concentration of polymer and concentration of plasticizer were fixed as independent variables; tensile strength, percent elongation, elastic modulus and amount dissolved up to 5 min (%D5 min) were taken as responses. Results: The prepared films exhibited good surface characteristics. The thickness, uniformity of weight, surface pH and drug content are within acceptable range. The mechanical properties like tensile strength, folding endurance, percent elongation and elastic modulus were determined. The statistical analysis showed that polymer concentration has a positive effect on disintegration time and the plasticizer concentration has a significant effect on folding endurance. The prepared film relesases nearly 95% at the end of 5 min. The design space was used to optimize the quantities of polymer and plasticizer. The comparison of checkpoint experiment batch responses are corelating with the predicted responses. Conclusion: Escitalopram oxalate oral dissolving films was successfully designed and optimized by response surface method. It was concluded that the prepared films exhibit good mechanical properties and maximum release within 10 min.

UTILIZATION RED DRAGON FRUIT PEEL (HYLOCEREUS POLYRHIZUS) ETHANOL EXTRACT IN ORAL THIN FILM STRIP AS A MOUTH FRESHENER

Objective: The aim of this study was to formulate an oral thin film strip (OTFS) contained the red dragon fruit peel (RDFP) ethanol extract (Hylocereus polyrhizus) and evaluate the characteristic, stability and antibacterial activity against Streptococcus mutans (S. mutans). Methods: The film was made using the solvent casting method by adding a variety of concentration ethanol extract of red dragon fruit peel (5%, 10%, and 15%). The films were evaluated in organoleptic test, weight, thickness, pH, disintegration time, folding endurance, stability test and antibacterial activity. Results: The results showed that the film provided a distinctive color, aroma, and taste of the extract. The result of film evaluation had weight between 0.07-0.21 g, thickness between 0.10-0.20 mm, pH between 5.70-5.99, disintegration time between 34.99-49.13 s, and folding endurance between 321.00-812.83 times. The films were stable for 2 mo at a variety storage temperature (4±2 ℃, 28±2 ℃, and 40±2 ℃). The films showed antibacterial activity for 5%, 10% and 15% with the diameter of inhibition 8.5 mm, 10.8 mm, and 12.9 mm, respectively. Conclusion: Ethanol extract of RDFP can be utilized as a mouth freshener film that is stable for 2 mo and has antibacterial activity against S. mutans.

Nanocomposite films of polycaprolactone and amorphous/sintered wollastonite nanoparticles for potential biomedical applications

Precipitation of an apatite layer on the surface of bioactive materials is considered an important step in the bone healing procedure. Wollastonite (CaSiO3) bioglass has been recently employed as a bone replacement material and also, a carrier for targeted drug delivery. Regarding the impact of a material structure on its biological activity, to achieve the 100 % clinical success, realizing the material crystallinity and bone bonding potential can be important. Therefore, this study tried to prepare pure wollastonite (WS) nano-powders (<20 nm) via an easy and fast hydrothermal process. Different quantities (5, 10 and 15 wt%) of the amorphous and crystalline particles have been added to polycaprolactone (PCL) to obtain composite films via a simple solvent casting technique. The in-vitro bioactivity of the prepared particles as well as composite films was studied by placing the samples in the simulated body fluid (SBF) for 21 days. The physicochemical and microstructural properties of the products were then characterized by XRD, FTIR, FESEM, EDS and TEM. Moreover, the influence of the crystallinity on the bioactivity of the synthesized nanoparticles and also the obtained composite films was investigated for the first time. The results indicated that the amorphous bioglass and the surface of composite containing 15 wt% WS were completely covered by a thick bone-like apatite layer Therefore, these findings revealed that the prepared composite films composed of amorphous WS could be regarded as promising bioactive candidates for bone filling applications.

Effect of Keratin Waste on Poly(ε-Caprolactone) Films: Structural Characterization, Thermal Properties, and Keratinocytes Viability and Proliferation Studies

Keratin extracted (KE) from chicken feathers was used for the production of composite films comprising poly(ε-caprolactone) (PCL) and keratin (PCL/KE films). The process involved the extraction of keratin from chicken feathers using a 0.1 M NaOH solution, followed by characterization via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The PCL was synthesized through the ring-opening polymerization (ROP) of ε-caprolactone (ԑ-CL) with Sn(Oct)2 as a catalyst. Films were prepared via solvent casting, including pure PCL films and those enriched with different weight percentages of KE (10%, 15%, 25%, and 30%). The films were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and scanning electron microscopy (SEM). SEM analysis revealed a more uniform incorporation of KE within the PCL matrix in the case of the 15% keratin-enriched film (PCL/KE15) as compared to other keratin percentages. The thermal analysis showed a positive influence of keratin on the thermal stability of the films. Keratinocytes viability and proliferation tests on the PCL/KE15 film demonstrated compatibility with cells. Collectively, these results hold relevance for potential biomedical applications of PCL/KE films.

Design of advanced buccal films with kiwiberry extract to prevent oral mucositis: From in vitro buccal models to ex vivo studies

Oral mucositis (OM) is a common side effect of cancer treatments characterized by disruption of the oral mucosa integrity, inflammation, and pain. The treatment strategies to prevent and treat OM are still unsatisfactory, leading to the search of new active compounds, particularly from natural sources, such as Actinidia arguta fruits. A. arguta is a perennial vine and its fruit, commonly known as kiwiberry, has been associated with different therapeutic properties and pro-healthy benefits, particularly antioxidant, anti-inflammatory and anticancer effects. These bioactive properties are due to the fruit outstanding content in phenolic compounds, vitamins, and organic acids, which attracted the researcher's attention for potential application in pharmaceutical industry. The aim of this study is to develop buccal films with A. arguta fruit extract as active ingredient to prevent OM symptoms. The films were prepared by solvent casting after placing 50 g of a buccal film mixture prepared with 1% of HPMC K100 LV EP, 2.5% glycerin, and 100 mL of A. arguta extract as solvent. Different films parameters were assessed, namely physical features (weight: 194.8 mg; thickness: 0.37 mm; disintegration time: 15.05 min; moisture content: 10.53%; swelling capacity: 55.95%), mechanical properties (resistance to extension: 10.11 N; percent of elongation: 36.10%; Young's modulus: 0.0034 MPa) and antioxidant/antiradical activities (TPC = 6.46 mg GAE/g film; FRAP = 49.45 μmol FSE/g film; ABTS = 3.74 mg AAE/g film; DPPH = 4.90 mg TE/g film). In vitro cell assays attested the absence of negative effects on HSC-3 and TR146 oral cell lines. Most important, the compounds release profile were assessed through in vitro and ex vivo models coupled to LC/DAD-ESI-MS quantification and the results revealed high permeation of rutin, quercetin-3-O-glucoside and catechin. Overall, these results highlight the significant potential of buccal films with A. arguta fruit extract to prevent OM condition.

Bioceramic filled PLA based nanocomposites for biomedical application: An experimental investigation

Orthopedic implants require innovative biodegradable materials to eliminate the need for a second surgery post-healing and to counteract the stress shielding issues associated with conventional metallic implants. Polylactic acid (PLA) was chosen for its biocompatibility and biodegradability within the human body. Hydroxyapatite (HAP) and eggshell nanoparticles (ESNPs) were selected as bioceramics due to their similarity to the major constituents of human bone. In the present study, ESNPs were prepared through a ball mill. HAP and Mg particles coated with TiO2 (TiO2@Mg) were synthesized through chemical precipitation and the sol-gel technique, respectively. Subsequently, four samples were prepared: PLA/ESNP/Mg (PEM), PLA/HAP/Mg (PHM), PLA/ESNP/TiO2@Mg (PEMT), and PLA/HAP/TiO2@Mg (PHMT) using the solvent casting process. The addition of Mg demonstrated an enhancement of degradation rates, and TiO2@Mg served to eliminate hydrogen release from Mg. The confirmation of synthesized NPs and PLA nanocomposites was validated through Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and Field-Emission Scanning Electron Microscopy (FE-SEM) analysis. The prepared PEMT and PHMT showed tensile strength (42.70 ± 7.55 MPa and 31.57 ± 3.84 MPa), tensile modulus (1624.49 ± 155.05 MPa and 1674.25 ± 87.04 MPa), and shore D hardness (79.41 ± 2.40 SHN and 77.81 ± 3.18 SHN), respectively. The findings showed that PEMT and PHMT composites exhibited enhanced surface roughness, hydrophilicity, degradation rate, and swelling behavior compared to PEM and PHM samples. Moreover, the viability of MG63 cells cultured in different diluted extracts of both samples reached approximately 80 %, indicating no observable cytotoxicity and a hemolysis rate of less than 1.4 %, indicating the potential for use in maxillofacial region implants.

Tamarind seed polysaccharide-metformin insert: Higher ocular retention, slow-release, and efficacy against corneal burn

Metformin (MET) can be an alternative therapeutic strategy for managing ocular burn primarily because of its pleiotropic mechanism. Longer retention on the ocular surface and sustained release are necessary to ensure the efficacy of MET for ocular application. Although the high aqueous solubility of MET is good for formulation and biocompatibility, it makes MET prone to high nasolacrimal drainage. This limits ocular residence and may be a challenge in its application. To address this, polymers approved for ophthalmic application with natural origin were analyzed through in silico methods to determine their ability to bind to mucin and interact with MET. An ocular insert of MET (3 mg/6 mm) was developed using a scalable solvent casting method without using preservatives. The relative composition of the insert was 58 ± 2.06 %w/w MET with approximately 14 %w/w tamarind seed polysaccharide (TSP), and 28 %w/w propylene glycol (PG). Its stability was demonstrated as per the ICH Q1A (R2) guidelines. Compatibility, ocular retention, drug release, and other functional parameters were evaluated. In rabbits, efficacy was demonstrated in the 'corneal alkali burn preclinical model'. TSP showed potential for mucoadhesion and interaction with MET. With adequate stability and sterility, the insert contributed to adequate retention of MET (10–12 h) in vivo and slow release (30 h) in vitro. This resulted in significant efficacy in vivo.

Preparation, characterization and decomposition test on Tapanuli organoclay reinforced cellulose acetate/cellulose acetate butyrate blend composites

The need for biodegradable composites has increased for many applications in recent years. Cellulose acetate (CA) and cellulose acetate butyrate (CAB) are relatively easy and cheap to fabricate, as well as relatively easy to decompose compared to other polymers. These materials are transparent and lightweight with low tensile properties. In this current study, the effect of Tapanuli clay addition on tensile and decomposition properties of CA and CA–CAB systems were investigated. Tapanuli organoclay was prepared by a cation exchange treatment using hexadecyltrimethylammonium bromide (HDTMA-Br) surfactant to Na-bentonite. Prior to the treatment, the Tapanuli clay was subjected to purification from organic and carbonate compounds and to balance the cations by homogenizing them into Na+. The basal spacing of Tapanuli clay increased from 1.52 nm up to 1.98 nm. CA and CA −5 wt% CAB composites were then synthesized using a solvent casting method. It was found that the addition of both 5 wt% CAB and 7 wt% organoclay in CA decreased the tensile strength and reduced the mass loss by 70%. After 45 days of the decomposition test, it was indicated that the presence of 5 wt% CAB in CA reduced the mass loss of the system by about 50%. These findings were con-firmed by the Scanning Electron Microscope (SEM) images which showed different patterns of as-synthesized and decomposed materials. In conclusion, the presence of 1 wt% Tapanuli organoclay slightly increased the decomposed mass of CA film and enhanced the tensile strength of CA-co-CAB.

Fabrication of Antimicrobial Hydrogel Using Biodegradable Blended Materials for Skin Applications

Biodegradable polymers are very useful polymers in biomedical applications. In this research, several hydrogels were fabricated by using two polymers, Polyvinyl alcohol (PVA) and Chitosan (Chs) by the solvent casting method in order to use them for skin applications. Several tests were carried out on these membranes such as Agar diffusion method to examine their antimicrobial activities, Fourier transform infrared microscopy (FTIR) test to study the differences in their chemical structures. Uniaxial tensile test was performed to examine the mechanical characteristics of these membranes. In addition, the wettability test was used to investigate the hydrophobicity or hydrophilicity of the surfaces. The results showed that all membranes are hydrophilic, of which the contact angles are less than 90°. The membrane manufactured from 75:25 Chs-PVA is more hydrophobic (contact angle is 74°) than other membranes made of 50:50 Chs-PVA and 25:75 Chs-PVA as the contact angles were 59° and 61°, respectively. The tensile test results indicate that the membrane fabricated of the PVA and the membrane that was fabricated by 75% Chs and 25% PVA has the highest tensile strength of 17.9 MPa, 16.2 MPa and Young^’ s Modulus of 181.2 MPa and 7.18 MPa, respectively. The highest strain at break was observed by the membrane of 25:75 Chs-PVA which equals to 24.67%. Chitosan membranes showed inhibition zones of about 2.99 cm and 2.75 cm in length, and 75:25 Chs-PVA membranes showed 5.1 and 5.91 cm in length for E.coli. To sum up, this copolymer is considered as promising hydrogel for skin applications such as wound dressing.

Castor‐oil derived polyurethane/barium titanate piezoelectric smart composite coatings for energy harvesting applications: Prediction and experimental characterization of electro‐elastic properties

AbstractSustainable and environment‐friendly polymer composite smart paints/coatings with polyurethane (PU) derived from castor‐oil (CO) as the matrix and barium titanate (BTO) microparticles as piezo‐active inclusions (2, 4, 6, 8, and 10 vol.%) have been prepared employing ultrasonication and solvent casting, followed by contact DC poling method. Relative dielectric constants varied from 5.26 ± 0.37 for pristine COPU to 8.9 ± 0.36 for COPU/10 vol.% BTO composite, at a frequency of 1 kHz. Piezoelectric strain constant d33 of the poled films varied from 0.0 pC/N for pristine castor‐oil based polyurethane (COPU) to 1.2 pC/N for COPU/10 vol.% BTO (CPBT‐5) composite. Tensile tests showed that the elastic modulus varied from 1.98 ± 0.003 MPa for pristine COPU to 5.13 ± 0.02 MPa for COPU/10 vol.% BTO composite. Dynamic mechanical analysis confirmed the viscoelastic nature of the smart paints. Measurement of current–voltage response under different compressive loads indicates that COPU/10 vol.% BTO composite can generate a current of ~28 nA and voltage of ~8 V under a dynamic compressive load of 40 N, applied at a frequency of 1 Hz. These experiments were complemented by Fourier transform infra‐red spectroscopy and scanning electron microscopy. In addition, finite element analyses based on periodic boundary conditions have been performed to predict the effective electro‐elastic properties of these piezoelectric smart composite coatings.Highlights Castor‐oil‐based PU piezoelectric composites with BTO inclusions were developed. Increase in BTO content up to 10 vol.% increases dielectric constant by ~1.7 times. COPU/BTO composites exhibit significantly increased piezoelectric response. Elastic and viscoelastic properties are also enhanced with increasing BTO content. Finite element models show a good match with experimental results.

A comparison between solvent casting and electrospinning methods for the fabrication of HPMC fast-dissolving films: investigation of the physicochemical, mechanical and drug release characteristics

The fast-dissolving film is an innovative dosage form that rapidly delivers the loaded drug upon contact with saliva. Many studies have been conducted on the fabrication of fast-dissolving films using hydroxy propyl methyl cellulose (HPMC) as a common film-forming agent with solvent-casting method or sometimes with electrospinning. However, there is no comparison of these two methods on the physicochemical, mechanical, and drug-release behavior of HPMC films. This paper aims to compare bisoprolol-containing fast-dissolving films composed of HPMC and polyethylene glycol (PEG) as plasticizer constructed by solvent-casting and electrospinning methods. Given the formulation parameters (e.g., plasticizer and polymer concentrations) and process parameters (e.g., tip-to-needle distance, voltage, and feed rate), various solvent-casting films and nanofiber mats were prepared. Films were characterized in terms of disintegration time, folding endurance, thermal behavior (using DSC), crystallin structure (using XRD), drug content, and drug release. The size and morphology of nanofibers were also evaluated by SEM. Solvent-casting film composed of 6% w/v HPMC and 6% v/v PEG400, as well as nanofiber mat composed of 13% w/v HPMC and 3% w/v PEG2000 were successfully constructed. DSC and XRD analysis revealed that the crystalline structure of bisoprolol converted into the amorphous structure in the polymeric films. Nanofibers were smooth and free of beads with a mean size of 0.66 ± 0.19 μm. In terms of flexibility, the nanofiber mats outperformed the solvent-casting films. The disintegration time of the nanofiber mat was less than that of the solvent-casting film (3 s versus 30 s). Besides, nanofibers indicated faster release. The superior performance of nanofiber mats can be attributed to their nanostructure. The results showed that the characteristics of the fast-dissolving films fabricated of HPMC, including disintegration time, release rate, and flexibility could be improved through the electrospinning process.