Polymer Coatings Research Articles

A Review of Antimicrobial Polymer Coatings on Steel for the Food Processing Industry.

This article will focus on the issue of protection against the pathogenic biofilm development on steel surfaces within the food sectors, highlighting steel's prominence as a material choice in these areas. Pathogenic microorganism-based biofilms present significant health hazards in the food industry. Current scientific research offers a variety of solutions to the problem of protecting metal surfaces in contact with food from the growth of pathogenic microorganisms. One promising strategy to prevent bacterial growth involves applying a polymeric layer to metal surfaces, which can function as either an antiadhesive barrier or a bactericidal agent. Thus, the review aims to thoroughly examine the application of antibacterial polymer coatings on steel, a key material in contact with food, summarizing research advancements in this field. The investigation into polymer antibacterial coatings is organized into three primary categories: antimicrobial agent-releasing coatings, contact-based antimicrobial coatings, and antifouling coatings. Antibacterial properties of the studied types of coatings are determined not only by their composition, but also by the methods for applying them to metal and coating surfaces. A review of the current literature indicates that coatings based on polymers substantially enhance the antibacterial properties of metallic surfaces. Furthermore, these coatings contribute additional benefits including improved corrosion resistance, enhanced aesthetic appeal, and the provision of unique design elements.

Role of particle gradation of clay–sand mixtures on the interfacial adhesion performance of polymer coatings

Abstract The interface performance between clay–sand mixtures and concrete structures is governed by the mixture's composition and its physical properties. Moisture content and particle-size distribution play important roles in deciding the mixture's arrangement of soil particles, porosity, hydraulic conductivity and behaviour under various mechanical loadings. Application of a polymer interfacial coating can improve the bond performance between soils and concrete mainly via interfacial friction/mechanical interlocking. The present work analyses the development of interfacial strength between clay–sand mixtures and a polymer coating with changes in particle gradation. The multi-scale mechanisms at the interface are investigated, giving primary attention to soil porosity. A 50:50 clay–sand mixture exhibited a greater interfacial adhesive performance compared to other soil mixtures. In addition, the moisture-controlled pores and gradation-controlled pores demonstrated differences in macroscale interfacial strength. Both mercury intrusion porosimetry (MIP) and 129Xe nuclear magnetic resonance (NMR) were utilized to detect the pore structure of the mixtures. 129Xe-NMR revealed the pore distribution of the mixtures as ranging from macropores to nanopores, and MIP complemented the pore information by determining the critical pore entry diameter in the macropore regime. Mesopores dominated with increasing fine sand content until a threshold value was reached; thereafter, merging of pores occurred and macropores dominated.

Reproducible Synthesis of Biocompatible Albumin Nanoparticles Designed for Intra-articular Administration of Celecoxib to Treat Osteoarthritis.

Osteoarthritis (OA) is the most common form of arthritis, with intra-articular (IA) delivery of therapeutics being the current best option to treat pain and inflammation. However, IA delivery is challenging due to the rapid clearance of therapeutics from the joint and the need for repeated injections. Thus, there is a need for long-acting delivery systems that increase the drug retention time in joints with the capacity to penetrate OA cartilage. As pharmaceutical utility also demands that this is achieved using biocompatible materials that provide colloidal stability, our aim was to develop a nanoparticle (NP) delivery system loaded with the COX-2 inhibitor celecoxib that can meet these criteria. We devised a reproducible and economical method to synthesize the colloidally stable albumin NPs loaded with celecoxib without the use of any of the following conditions: high temperatures at which albumin denaturation occurs, polymer coatings, oils, Class 1/2 solvents, and chemical protein cross-linkers. The spherical NP suspensions were biocompatible, monodisperse with average diameters of 72 nm (ideal for OA cartilage penetration), and they were stable over 6 months at 4 °C. Moreover, the NPs loaded celecoxib at higher levels than those required for the therapeutic response in arthritic joints. For these reasons, they are the first of their kind. Labeled NPs were internalized by primary human articular chondrocytes cultured from the knee joints of OA patients. The NPs reduced the concentration of inflammatory mediator prostaglandin E2 released by the primaries, an indication of retained bioactivity following NP synthesis. Similar results were observed in lipopolysaccharide-stimulated human THP-1 monocytes. The IA administration of these NPs is expected to avoid side-effects associated with oral administration of celecoxib and to maintain a high local concentration in the knee joint over a sustained period. They are now ready for evaluation by IA administration in animal models of OA.

Phase Inversion‐Induced Porous Polymer Coating for High Rate and Stable Zinc Anode

AbstractPolymer coatings are emerged as promising candidates for zinc anode artificial solid electrolyte interphase (ASEI) owing to their barrier effect and zincophilicity. However, the poor ionic conductivity of conventional polymer coatings limits their application. Herein, inspired by epidermis function, a porous poly(methylmethacrylate) (PMMA) coating is fabricated to stabilize Zn anode via a novel phase inversion method. The modified Zn anode delivers a remarkable lifespan of over 4000 h at 1 mA cm−2, 1 mAh cm−2, and 120 h at 20 mA cm−2, 20 mAh cm−2 in symmetrical cells. Moreover, porous PMMA‐Zn||NVO full cell also exhibits an excellent cycling stability over 500 cycles at 1 A g−1 as well as an ultralong lifespan exceeding 5000 cycles at 5 A g−1. The excellent cycling stability and rate performance are mainly attributed to the avoided side reactions by the coating protection, as well as the enhanced diffusion and reaction kinetics derived from the good zincophilicity and porous structure of porous PMMA. The facile and universal method for fabricating porous polymer ASEI provides a new insight for the application of conventional polymer materials in Zn anode protection.

Engineered thin coatings of cross-linked silane polymers with urea group onto polypropylene fabrics for controlled release of thymol against molds in hay

With world population on the rise, animal food source production has significantly increased. Susceptibility of hay and other sources to molds poses a serious threat to food quality and safety. This study proposes an innovative approach to address this issue – an anti-mold fungicide comprising thymol bound on silica urea thin coating of polypropylene fabrics. The coating enhances the thermal stability of thymol allowing prolonged release. Coating composition and morphology as well as thermal stability and release rates were investigated. The coating provided efficient protection against mold growth with no side effects on hay exposed to thymol fumes. The results underscore the potential of this fungicide as a safe and effective hay preservative.

Dissolution Profiles of Oral Disintegrating Tablet with Taste Masking Granule Polymer Coating in Biorelevant Bicarbonate Buffer.

The current study aimed to explore the impact of buffer species on the dissolution behavior of orally disintegrating tablets (ODT) containing a basic polymer and its influence on bioequivalence (BE) prediction. Fexofenadine hydrochloride ODT formulations were used as the model formulations, Allegra® as the reference formulation, and generic formulations A and B as the test formulations. Allegra®, generic A, and generic B are ODT formulations that contain aminoalkyl methacrylate copolymers E (Eudragit® E, EUD-E), a basic polymer commonly used to mask the bitter taste of drugs. Both generic A and generic B have been known to be bioequivalent to Allegra®. The dissolution tests were conducted using a compendial paddle, with either bicarbonate (10 mM, pH 6.8) or phosphate buffer (25 mM, pH 6.8) as the dissolution media. A floating lid was employed to cover the surface of the bicarbonate buffer to prevent volatilization. Results indicated that in phosphate buffer, the dissolution profiles of Allegra and generic B significantly varied from that of generic A, whereas in the bicarbonate buffer, the dissolution profiles of Allegra, generic A, and generic B were comparable. These findings suggest that the use of bicarbonate buffer may offer a more precise prediction of human bioequivalence compared to phosphate buffer.

Enhancing the Proton Exchange Membrane in Tubular Air-Cathode Microbial Fuel Cells through a Hydrophobic Polymer Coating on a Hydrogel.

The usage time of air-cathode microbial fuel cells (MFCs) is significantly influenced by the moisture content within the proton exchange membrane (PEM). Therefore, enhancing the water retention capability of the PEM by applying a hydrophobic polymer coating to its surface has extended the PEM's usage time by three times and increased MFCs' operational duration by 66%. Moreover, the hydrophobic nature of the polymer coating reduces contamination on the PEM and prevents anode liquid from permeating into the air cathode. Towards the end of MFC operation, the internal resistance of the MFC is reduced by 45%. The polymer coating effectively maintained the oxygen reduction reaction activity in the cathode. The polymer coating's ability to restrict oxygen transmembrane diffusion is demonstrated by experimental data showing a significant decrease in oxygen diffusion coefficient due to its presence. The degradation efficiency of the chemical oxygen demand from 16% to 35% increased by a factor of one.

Hierarchical aerogels based on cellulose nanofibers and long-chain polymers for enhancing oil–water separation efficiency

The hydrophobic chain length of biomass-based aerogels used for oil–water separation was evaluated as a major parameter influencing the aerogels’ hydrophobicity. The properties of the porous structure were enhanced by the hierarchical assembly of the aerogels with biopolymeric structural units and polymer mineralization. The cellulose network was strengthened through silanization, and the nanocellulose network was further enhanced through coating with mineralizers containing long-chain hydrophobic molecules. Interfacial engineering was employed to establish multiscale interactions through the freeze-drying-induced modification of cellulose nanofibers and mineralized coatings of long-chain alkyl polymers. The resulting hierarchically structured aerogel exhibits low density (11.4 kg/m3), excellent mechanical compression properties across a wide temperature range (capable of enduring 100 cycles of compression), high porosity (99.2%), superhydrophobicity (152°), and recyclability. It maintains a 57.9% adsorption rate even after 40 adsorption–desorption tests, while also preserving its shape integrity. Moreover, it can be recycled and reused. At a temperature of 700 °C, the mass loss was only 44.47%, with excellent thermal stability. The aerogel can reduce oil pollutants in the ocean by adsorption, recover oil resources, and protect the natural environment. The assembly and optimization of nanofibrous matrix interfaces through the mineralization of long-chain polymers enhanced the performance of functionalized cellulose-based aerogels.

Improved electro-destruction of bacterial biofilms by coating conductive surfaces with polymers

The formation of biofilm involves cell aggregation and adherence, enveloped by a self-produced extracellular matrix. In the medical domain, biofilm-associated infections pose significant challenges, especially concerning implants. This investigation focuses on enhancing electromediated bacterial biofilm eradication through polymer coatings on the anode. These coatings catalyze reactive oxygen species (ROS) generation or convert hydrophobic coatings to bactericidal hydrophilic polycations, detaching the biofilms that are predominantly polyanionic. The first approach employs a metallized polytetrathienylporphyrin layer with ROS catalytic capability, while the second involves an insoluble hydrophobic polyamide, which, upon oxidation, transforms into a bactericidal hydrolytically degradable polycation. Both approaches show promising efficacy in augmenting electromediated Staphylococcus aureus biofilm destruction.

Clinical outcomes with biodegradable versus durable polymer drug-eluting stents in patients with ST-elevation myocardial infarction

BackgroundCoronary drug-eluting stents (DES) built with either durable (DP) or biodegradable (BP) polymeric coatings have been largely tested and are extensively available for routine use. However, their comparative performance remains an open question, particularly in more complex subsets of patients. AimsWe evaluated the outcomes of patients with ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI) using DP-DES versus BP-DES in a large multicenter real-world registry. MethodsThe population comprised patients with STEMI treated with pPCI within 12 h of symptoms onset. Those treated with more than one DES who received different polymer types were excluded. The final cohort for analysis was selected after propensity score matching (PSM), computed to generate similar groups of DP DES versus BP DES. Primary endpoint was the incidence of major adverse cardiac events (MACE), defined as the composite of total death, myocardial infarction and target lesion revascularization at 2 years. ResultsFrom January 2017 to April 2022, a total of 1527 STEMI patients underwent pPCI with a single DES type (587 DP-DES; 940 BP-DES). After PSM, 836 patients (418 patients in the DP-DES and 418 patients in the BP-DES groups), comprised the final study population. Both study groups had a similar baseline profile. Patients treated with BP-DES group had similar rates of MACE (15.3 % vs. 19.4 %, HR 0.69, 95 % CI 0.50–0.94, p = 0.022). Rates of target lesion revascularization was lower in BP DES group (0.7 % vs. 3.8 %, HR 0.17, 95 % CI 0.05–0.51, p = 0.006). ConclusionIn a cohort of STEMI patients submitted to pPCI, BP and DP DES had similar rates of the primary outcome. Patients treated with BP DES, however, had a decreased incidence of TLR at after 2-year follow-up.

Teflon AF–Coated Nanotextured Aluminum Surfaces for Jumping Droplet Thermal Rectification

AbstractJumping droplet thermal diodes (JDTDs) are promising candidates to achieve thermal rectification for next‐generation thermal control. However, most prior demonstrations of JDTDs have relied on monolayer‐coated copper‐based superhydrophobic (SHPB) surfaces, while lower‐cost aluminum JDTDs with more durable thin polymeric coatings have not been explored. In this work, a JDTD is constructed that employs SHPB aluminum surfaces coated with protective thin films of Teflon AF (amorphous fluoropolymer) 1601. Measurements for different heating orientations, gap heights (H), and fill ratios (ϕ) show that a maximum thermal rectification ratio of 7 can be achieved for H = 2.4 mm and ϕ = 10%. A thermal circuit is demonstrated that uses the JDTD to rectify time‐periodic temperature profiles, achieving thermal circuit effectiveness values up to 30% of the ideal‐diode limit. Coupon‐level durability tests and device‐level cycling show that dip coated Teflon AF enables stable operation of Al JDTDs over >20 cycles, improving on the performance of a monolayer‐coated surface that fails after 5 cycles. The findings of this work signify that Teflon AF coated Al SHPB surfaces can be used for thermal rectification and motivate future research into Al JDTDs for advanced thermal management applications.

PH-Responsive, Thermoset Polymer Coatings for Active Protection against Aluminum Corrosion.

This paper describes the synthesis and use of multifunctional methacrylic monomers, which contain basic (amine) functional groups, including an example in which an acid-labile tert-butylcarbamate-protected glycine is used to form a novel methacrylic monomer. The "protected" amino acid-derived functional monomer (BOC-Gly-MA) is copolymerized with an epoxide functional methacrylic monomer (GMA), to deliver novel multifunctional polymers, which are processed into powder coatings and used to study filiform corrosion at the surface of an aluminum substrate. The BOC-Gly-MA-containing copolymers were shown to improve a coating's anticorrosion performance, presenting the lowest average filiform corrosion (FFC) track length, total FFC number, and total corroded surface area (CSA) of the coatings investigated. Further to this, a mode of action for the role of BOC-Gly functional polymers in corrosion protection is proposed, supported by both solution and polymer-aluminum interface studies, delivering new insights into the mode of action of pH-responsive polymer coatings.

Hybrid Coatings Based on Polyvinylpyrrolidone/Polyethylene Glycol Enriched with Collagen and Hydroxyapatite: Incubation Studies and Evaluation of Mechanical and Physiochemical Properties.

Coating materials offers an intriguing solution for imparting inert implants with additional bioactive characteristics without changing underlying parameters such as mechanical strength. Metallic implants like endoprostheses or polymeric implants can be coated with a thin layer of bioactive film capable of stimulating bone-forming cells to proliferate or release a drug. However, irrespective of the final implantation site of such a coating biomaterial, it is necessary to conduct detailed mechanical and physicochemical in vitro analyses to determine its likely behavior under biological conditions. In this study, polymeric and composite coatings with hydroxyapatite obtained under UV light underwent incubation tests in four different artificial biological fluids: simulated body fluid (SBF), artificial saliva, Ringer's fluid, and water (as the reference fluid). The potentiometric and conductometric properties, sorption capacity, and degradation rate of the coatings were examined. Furthermore, their hardness, modulus of elasticity, and deformation were determined. It was demonstrated that the coatings remained stable in SBF liquid at a pH value of around 7.4. In artificial saliva, the greatest degradation of the polymer matrix (ranging between 36.19% and 39.79%) and chipping of hydroxyapatite in the composite coatings were observed. Additionally, the effect of ceramics on sorption capacity was determined, with lower capacity noted with higher HA additions. Moreover, the evaluation of surface morphology supported by elemental microanalysis confirmed the appearance of new apatite layers on the surface as a result of incubation in SBF. Ceramics also influenced mechanical aspects, increasing hardness and modulus of elasticity. For the polymer coatings, the value was 11.48 ± 0.61, while for the composite coating with 15% ceramics, it increased more than eightfold to a value of 93.31 ± 11.18 N/mm2. Based on the conducted studies, the effect of ceramics on the physicochemical as well as mechanical properties of the materials was determined, and their behavior in various biological fluids was evaluated. However, further studies, especially cytotoxicity analyses, are required to determine the potential use of the coatings as biomaterials.

Timing of Complete Multivessel Revascularization in Patients Presenting With Non-ST-Segment Elevation Acute Coronary Syndrome

BackgroundComplete revascularization of the culprit and all significant nonculprit lesions in patients with non–ST-segment elevation acute coronary syndrome (NSTE-ACS) and multivessel disease (MVD) reduces major adverse cardiac events, but optimal timing of revascularization remains unclear. ObjectivesThis study aims to compare immediate complete revascularization (ICR) and staged complete revascularization (SCR) in patients presenting with NSTE-ACS and MVD. MethodsThis prespecified substudy of the BIOVASC (Percutaneous Complete Revascularization Strategies Using Sirolimus Eluting Biodegradable Polymer Coated Stents in Patients Presenting With Acute Coronary Syndrome and Multivessel Disease) trial included patients with NSTE-ACS and MVD. Risk differences of the primary composite outcome of all-cause mortality, myocardial infarction (MI), unplanned ischemia-driven revascularization (UIDR), or cerebrovascular events and its individual components were compared between ICR and SCR at 1 year. ResultsThe BIOVASC trial enrolled 1,525 patients; 917 patients presented with NSTE-ACS, of whom 459 were allocated to ICR and 458 to SCR. Incidences of the primary composite outcome were similar in the 2 groups (7.9% vs 10.1%; risk difference 2.2%; 95% CI: −1.5 to 6.0; P = 0.15). ICR was associated with a significant reduction of MIs (2.0% vs 5.3%; risk difference 3.3%; 95% CI: 0.9 to 5.7; P = 0.006), which was maintained after exclusion of procedure-related MIs occurring during the index or staged procedure (2.0% vs 4.4%; risk difference 2.4%; 95% CI: 0.1 to 4.7; P = 0.032). UIDRs were also reduced in the ICR group (4.2% vs 7.8%; risk difference 3.5%; 95% CI: 0.4 to 6.6; P = 0.018). ConclusionsICR is safe in patients with NSTE-ACS and MVD and was associated with a reduction in MIs and UIDRs at 1 year.

On the quantification of biocidal activity of protective coatings

The conventional deposition/drying procedure results in the formation of cationic polymer coatings on glass slides that are capable of binding bacterial and yeast cells. A three-minute water treatment removes up to 80% of cells from the surface, and both the removed and remaining cells are dead. The results obtained clarify the mechanism of the biocidal action of adsorbed layers of poly(diallyldimethylammonium chloride) and the protocol for quantifying their biocidal activity.

Recent advances in anticorrosive coatings based on sustainable polymers: Challenges and perspectives

The present paper provides a comprehensive review of sustainable polymer-based anticorrosive polymeric coatings. We have presented the economical and environmental impact of corrosion in terms of Gross National Product (GDP) in a pie chart to highlight the motive behind using sustainable polymer-based anticorrosive coatings as an effective and most convenient method for protecting the underlying metal surface. Also, consumer awareness for eco-friendly considerations, followed by health protection, has driven a significant change in the aforementioned sector. Accordingly, about 16.8 % increase has been found in the use of sustainable resource-based coatings during the last two decades. Besides presenting literature on different sustainable polymers, the review also highlights the corrosion protection mechanism of barrier, sacrificial, and inhibitive coatings. A comparative study of different coating systems, along with their corrosion protection summaries and relevant industrial applications, has been given in a separate table.

Современные стратегии формирования полимерных покрытий. Часть 1

Современные стратегии формирования полимерных покрытий. Часть 1

Formulation and evaluation of mucoadhesive microspheres of metronidazole

Objective: Develop and evaluate mucoadhesive microspheres using Chitosan, Sodium alginate, and Sodium carboxymethyl cellulose (NaCMC) for sustained oral delivery of Metronidazole, aiming to improve bioavailability. Methods: Metronidazole-loaded microspheres were prepared via ionotropic gelation method with varying polymer ratios. Particle size, entrapment efficiency, swelling index, mucoadhesion (sheep mucosae), morphology (SEM), in-vitro wash-off test, drug release profile, and stability (6 months) were evaluated. Results: Chitosan content positively correlated with microsphere size. Entrapment efficiency ranged from 51.43% to 94.15%. Chitosan-based formulations, especially MTZ-7 (Chitosan:NaCMC, 3:1), displayed the highest mucoadhesion. SEM analysis revealed rough, spherical microspheres with a continuous polymeric coat. In-vitro wash-off test demonstrated prolonged residence time for Chitosan formulations. Sustained drug release was observed throughout the study, with MTZ-7 exhibiting the most desirable release profile. Stability studies showed no significant changes in drug release for selected formulations after 6 months. Conclusions: Chitosan-based microspheres, particularly MTZ-7, demonstrated superior mucoadhesive properties, sustained and controlled drug release, and desirable stability. These findings suggest the potential of Chitosan-based microspheres as a promising oral drug delivery system for Metronidazole, potentially addressing bioavailability concerns and improving therapeutic efficacy.

Chitosan-Caffeic Acid Antibacterial Coating for PDMS Surfaces: A Sustained Moxifloxacin Release and Prolonged Coating Adhesion

Central venous catheters (CVCs) are largely used to administer chemotherapy, hemodialysis, and other treatments. Mostly made of polydimethylsiloxane (PDMS), these medical devices present an intrinsic risk of infection due to the possible formation of biofilm, thus increasing the risk of complications. Drug-releasing polymer coatings are a well-recognized strategy for combating biofilm formation. However, adhesion of the coating to the substrate over time is a major challenge. Therefore, this work aimed to design a chitosan-based coating designed to have maximum adhesion and stability to guarantee sustained drug release and antibacterial properties for at least 14 days. A coating composed of chitosan (CS) as a drug carrier, caffeic acid (CA) and copper sulphate (Cu) as crosslinkers, and moxifloxacin (Mox) as an antibiotic, was deposited through a controlled casting process onto functionalized PDMS surface. PDMS surface modification was investigated by X-ray photoelectron spectroscopy (XPS), and Fourier-transfer infrared (FTIR). Antibiotic release over time was measured in pseudo-physiological conditions (pH 7.4 and at 37 °C). Indirect cytotoxicity assays were performed on human dermal fibroblasts (HDF). The adhesion of the as-designed coating was evaluated by a specially designed pull-off test, before and after aging for 14 days in PBS. XPS and FTIR analyses confirmed the successful PDMS surface modification. The CS-CA-Cu-Mox coating resulted in being non-cytotoxic towards HDF and exhibited sustained moxifloxacin release for up to 49 days. Furthermore, the CS-CA and CS-CA-Cu coatings presented antibacterial activity for 21 days against E. coli, and for 14 days against S. aureus. Importantly, the coating maintained stable adhesion after 14 days in pseudo-physiological conditions. This study provides new insights into the adhesion behavior of polymeric coatings for medical devices, which is rarely reported in the literature.

Dielectric characterization of fiber‐ and nanofiller‐reinforced polymeric materials

AbstractThis review provides an in‐depth analysis of the electrical responses and relaxation behaviors of various polymeric materials including fiber‐reinforced polymer composites, polymer nanocomposites (PNC), and nanofiller‐reinforced polymeric films and coatings using dielectric spectroscopy (DS). The underlying theory of DS, corresponding instrumentation, various dielectric parameters, relevant equations, interpretations, and polarization mechanisms are thoroughly explored. The impact of synthetic and natural fibers and a diverse range of nanofillers on the dielectric responses and relaxation mechanisms of fiber‐reinforced composites, and PNC and films, respectively, are also examined. For each summarized article, we provide an overview of the composite or film preparation, followed by concise explanations of the dielectric behaviors under diverse conditions, including variations in temperature, frequency, moisture levels, fiber/filler ratios, and chemical treatment. In essence, this review contributes to a nuanced understanding of the intricate relationship between material structure, properties, and performance via DS data interpretation across a spectrum of scenarios.