Polymers最新文献

Silk fibroin (SF)-based materials attract significant interest because of their biocompability and great diversity of possible morphologies. One of the approaches to obtain SF materials is the use of an air-water or oil-water interface as a template for protein self-assembly. Surfactants can change the surface properties of adsorbed SF layers by promoting or preventing the formation of SF fiber networks. This study focuses on the influence of two typical ionic surfactants, cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium dodecyl sulfate (SDS), on the dynamic properties of SF layers adsorbed at the air-water interface. The dynamic surface elasticity, surface tension, ellipsometric angle Δ, and the film thickness were measured as a function of the surface age and surfactant concentration. The morphology of the layers was evaluated by atomic force microscopy (AFM). For the adsorption layers of globular proteins, the main effect of the surfactants consists in the protein unfolding at high concentrations and in a decrease in the electrostatic adsorption barrier. In the case of SF layers, CTAB and SDS strongly influence the protein aggregation at the air-water interface. Regardless of the sign of the surfactant charge, its addition to SF solutions results in a decrease in the surface elasticity and the destruction of the ordered structure of protein fibers at concentrations higher than 1 × 10^-4 M. With the further increase in the surfactant concentration, the thread-like aggregates disappear, the packing of thin fibers becomes less tight, a uniform layer disintegrates into separate islands, and finally, the protein is displaced from the interface.

As the trend towards the densification of integrated circuit (IC) devices continues, the complexity of interfaces involving dissimilar materials and thermo-mechanical interactions has increased. Highly integrated systems in packages now comprise numerous thin layers made from various materials. The interfaces between these different materials represent a vulnerable point in ICs due to imperfect adhesion and stress concentrations caused by mismatches in thermo-mechanical properties such as Young's modulus, coefficients of thermal expansion (CTE), and hygro-swelling-induced expansion. This study investigates the impact of thermal variations on the fracture behavior of three bi-material interfaces used in semiconductor packaging: epoxy molding compound-silicon (EMC-Si), silicon oxide-polyimide (SiO₂-PI), and PI-EMC. Using double cantilever beam (DCB) tests, we analyzed these interfaces under mode I loading at three temperatures: -20 °C, 23 °C, and 100 °C, under both quasi-static and cyclic loading conditions. This provided a comprehensive analysis of the thermal effects across all temperature ranges in microelectronics. The results show that temperature significantly alters the failure mechanism. For SiO₂-PI, the weakest point shifts from silicon at low temperatures to the interface at higher temperatures due to thermal stress redistribution. Additionally, the fracture energy of the EMC-Si interface was found to be highly temperature-dependent, with values ranging from 0.136 N/mm at low temperatures to 0.38 N/mm at high temperatures. SiO₂-PI's fracture energy at high temperature was 42% less than that of EMC-Si. The PI-EMC interface exhibited nearly double the crack growth rate compared to EMC-Si. The findings of this study provide valuable insights into the fracture behavior of bi-material interfaces, offering practical applications for improving the reliability and design of semiconductor devices, especially in chip packaging.

Hard, flexible, transparent, and hydrophobic multifunctional coatings have a wide range of applications, but they do not adequately protect against harsh conditions, especially photoaging. In this study, SiO₂ and Al₂O₃ nanoparticles were first modified by silazane and epoxy-functionalized silanes and then reacted with a polyetheramine curing agent to prepare highly crosslinked multifunctional hybrid coatings at room temperature. Due to the integration of siloxane nanoparticles and a polymer network, the multifunctional coatings presented outstanding hardness (4H), flexibility (bending diameter of 10 mm), and transmittance (>97%). The introduction of low-surface-energy PDMS and methyl-rich HMDS endowed the coatings with good hydrophobicity (water contact angle = 141.37°). The high reflectivity of SiO₂ and Al₂O₃ in the solar spectral region can help prevent photoaging of the coatings, improve their heat-shielding effect, and broaden their application scenarios. Compared with the traditional manufacturing methods, this study did not need ultraviolet irradiation, and the multifunctional transparent coatings could be prepared through a simple and efficient step-by-step strategy.

The time-dependencies of polymer mean-square displacements g(t) provide significant tests of some modern theories of polymer dynamics. Familiar models propose that g(t) is described by a series of power-law regimes g(t)∼tα, the models predicting values of α and time regimes within which those values will be found. g(t) has been obtained quantitatively over a wide range of times by means of computer simulations, permitting comparison of simulation measurements with these models. Here, we demonstrate a path for quantitatively analyzing g(t). We show that we can readily distinguish between regimes in which g(t) actually follows a power law in time, does not follow a power law in time, or has an inflection point. The method accurately determines local values of the exponent, without imposing any a priori assumption as to the exponent's value.

Two significant clinical issues associated with the use of urinary catheters are catheter-associated urinary tract infection and encrustation. This study describes the design of novel hydrogels based on fatty acid-containing p(hydroxyethylmethacrylate, HEMA) and their resistance to both microbial adherence and encrustation. Incorporation of fatty acids increased the contact angle (surface hydrophobicity), decreased the ultimate tensile strength only after storage at pH 9 in artificial urine (AU) but not at lower pH values, decreased the Young's modulus and % elongation at break (both stored in deionised water, AU pH 6 and AU pH 9) and decreased equilibrium swelling (only when stored in deionised water or AU pH 6 but not AU pH 9). Moderate reductions in adherence of Escherichia coli, Proteus mirabilis and Staphylococcus epidermidis to certain fatty acid containing (primarily decanoic acid and myristic acid) hydrogels were observed. No relationship was observed between hydrogel contact angle and resistance to microbial attachment. Most fatty acid-containing hydrogels exhibited significant, concentration-dependent resistance to encrustation, postulated to be due both to a greasy film resultant from the formation of the calcium/magnesium fatty acid salts at the surface and the role of Tween^® 80 in facilitating the removal of the fatty acid salts from the surface of the hydrogel. The observed enhanced resistance of the hydrogels to encrustation offers opportunities for the use of such systems as platforms for coatings of urinary catheters.

Breast ultrasound elastography phantoms are valued for their ability to mimic human tissue, enabling calibration for quality assurance and testing of imaging systems. Phantoms may facilitate the development and evaluation of ultrasound techniques by accurately simulating the properties of breasts. However, selecting appropriate tissue-mimicking materials for realistic and accurate ultrasound exams is crucial to ensure the ultrasound system responds similarly to real breast tissue. We conducted a systematic review of the PubMed, Scopes, Embase, and Web of Sciences databases, identifying 928 articles in the initial search, of which 19 were selected for further evaluation based on our inclusion criteria. The chosen article focused on tissue-mimicking materials in breast ultrasound elastography phantom fabrication, providing detailed information on the fabrication process, the materials used, and ultrasound and elastography validation of phantoms. The phantoms fabricated from Polyvinyl Chloride Plastisol, silicon, and paraffin were best suited for mimicking breast, fatty, glandular, and parenchyma tissues. Adding scatterers to these materials facilitates accurate fatty and glandular breast tissue simulations, making them ideal for ultrasound quality assurance and elastography training. Future research should focus on developing more realistic phantoms for advanced medical training, improving the practice of difficult procedures, enhancing breast cancer detection research, and providing tailored tissue characteristics.

Porous polymer membranes with highly interconnected open-cellular structure and high toughness are crucial for various application fields. Polymerized high internal phase emulsions (polyHIPEs), which usually exist as monoliths, possess the advantages of high porosity and good connectivity. However, it is difficult to prepare membranes due to brittleness and easy pulverization. Copolymerizing acrylate soft monomers can effectively improve the toughness of polyHIPEs, but it is easy to cause emulsion instability and pore collapse. In this paper, stable HIPEs with a high content of butyl acrylate (41.7 mol% to 75 mol% based on monomers) can be obtained by using a composite emulsifier (30 wt.% based on monomers) consisting of Span80/DDBSS (9/2 in molar ratio) and adding 0.12 mol·L^-1 CaCl₂ according to aqueous phase concentration. On this basis, polyHIPE membranes with high open-cellular extent and high toughness are firstly prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. The addition of the RAFT agent significantly improves the mechanical properties of polyHIPE membranes without affecting open-cellular structure. The toughness of polyHIPE membranes prepared by RAFT polymerization is significantly enhanced compared with conventional free radical polymerization. When the molar ratio of butyl acrylate/styrene/divinylbenzene is 7/4/1, the polyHIPE membrane prepared by RAFT polymerization presents plastic deformation during the tensile test. The toughness modulus reaches 93.04 ± 12.28 kJ·m^-3 while the open-cellular extent reaches 92.35%, and it also has excellent thermal stability.

Polymer materials are increasingly used in all spheres of human activity. Today, it is difficult to imagine our life without the use of polymer products. Polymers have played a crucial role in the development of many industries and, of course, can be considered as one of the main drivers of technological progress. The research on the creation of new polymer materials that are obtained by modifying known polymers with various fillers, including nanomaterials, is widespread nowadays. In the foreseeable future, the time will come for modified polymer composites, when up to 75% of all things and materials that surround us will contain nano-additives. Due to their unique properties, these polymer compounds are in demand not only in industry and in everyday life, but also in medicine. One well-known nanomaterial is carbon nanotubes. The existing applications of nanotubes are almost limitless. Using them as modifying additives, it is possible to improve the properties of almost all known materials: polymers, alloys, plastics, rubbers, concretes, etc. In this review paper, the well-known polymer polypropylene and carbon nanotubes are selected as the main subjects of this study. This choice is due to their high demand in medicine, electronics, construction, etc.

By the late 1970s, plastics had emerged as the most widely used materials globally. The discovery, development, and processing of diverse polymeric materials have profoundly shaped modern life and driven the expansion of numerous industries. Given the widespread interest in the utilization of these materials, it has become increasingly imperative to design their life cycles from the outset. This approach aims to maximize their utility while minimizing their environmental footprint. This review aims to identify and analyze the key challenges in polymer processing applicable to both additive and formative manufacturing methods, emphasizing the relationship between processing and recycling within the framework of sustainability. Modern polymer processing techniques play a crucial role in enhancing the sustainability of polymer products by improving recycling potential (with consideration of polymer type, source, and additives), cost-effectiveness, carbon footprint, and key properties such as durability, lifespan, performance, and environmental impact. It will also explore the concept of the circular economy and its integration into modern processing methods, including extrusion, injection molding, and 3D printing. Additionally, current polymer recycling methods are analyzed with respect to their effectiveness, sustainability, and compatibility with the original materials. Moreover, the discussion emphasizes the benefits of a circular economy compared to a linear one by exploring the concepts of closed-loop and open-loop systems, along with their diverse applications depending on the material and the initial processing method employed. To ensure that humanity continues to benefit from polymer materials while striving for a waste-free environment, it is essential to integrate the principles of sustainable development from the very beginning.

Many antifungal agents, including isoconazole nitrate (ISN), suffer from low aqueous solubility and inconsistent dissolution kinetics, which limit their therapeutic potential. To address these challenges, this study aimed to enhance the solubility and stability of ISN through the development of inclusion complexes with hydroxypropyl-β-cyclodextrin (HP-β-CD). HP-β-CD inclusion complexes were prepared using a spray-drying technique and characterized through phase-solubility studies, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (¹H-NMR), and differential scanning calorimetry (DSC). The inclusion complex significantly improved ISN solubility, increasing from 0.5088 mg/mL to 3.6550 mg/mL. These complexes were incorporated into a thermosensitive, mucoadhesive in situ gel system using Pluronic^® F127 and hydroxypropyl methylcellulose (HPMC) to optimize vaginal drug delivery. The formulations were evaluated for gelation temperature, viscosity, swelling behavior, and pH, confirming their suitability for vaginal application. Antimicrobial studies demonstrated that the ISN/HP-β-CD gels exhibited superior activity against Candida albicans, C. glabrata, and C. krusei compared to ISN alone. In vitro release studies further revealed sustained drug release following Peppas-Sahlin kinetics, supporting enhanced bioavailability and prolonged therapeutic action. This study demonstrates that the ISN/HP-β-CD-loaded in situ gel system offers a promising and effective approach for improving the solubility, stability, and antifungal efficacy of ISN for the treatment of vaginal infections.