Polymers最新文献

The applications of polymeric materials are being constantly reviewed and improved. In the present world, the word hybrid, and the general idea of combining two or more inherently different approaches, designs, and materials is gaining significant attention. The area of sustainable materials with a low environmental impact is also rapidly evolving with many new discoveries, including the use of materials of a natural origin and countless combinations thereof. This review tries to summarize the current state of knowledge about hybrid polymeric materials and their applications with special attention to the materials that can be considered "environmentally friendly". As the current application field is quite broad, the review was limited to the following topics: packaging, medical applications, sensors, water purification, and electromagnetic shielding. Furthermore, this review points out the new prospects and challenges for the use of the mentioned materials in terms of creating novel solutions with different nano and micro-materials of mostly natural and renewable origin.

Surface modification of various polymer foils was achieved by UV activation and chemical grafting with cysteamine to improve surface properties and antimicrobial efficacy. UVC activation at 254 nm led to changes in surface wettability and charge density, which allowed the introduction of amino and thiol functional groups by cysteamine grafting. X-ray photoelectron spectroscopy (XPS) confirmed increased nitrogen and sulfur content on the modified surfaces. SEM analysis revealed that UV activation and cysteamine grafting resulted in distinct surface roughness and texturing, which are expected to enhance microbial interactions. Antimicrobial tests showed increased resistance to algal growth (inhibition test) and bacterial colonization (drop plate method), with significant improvement observed for polyethylene terephthalate (PET) and polyetheretherketone (PEEK) foils. The important factors influencing the efficacy included UV exposure time and cysteamine concentration, with longer exposure and higher concentrations leading to bacterial reduction of up to 45.7% for Escherichia coli and 55.6% for Staphylococcus epidermidis. These findings highlight the potential of combining UV activation and cysteamine grafting as an effective method for developing polymeric materials with enhanced antimicrobial function, offering applications in industries such as healthcare and packaging.

The Bohai oilfield is characterized by severe heterogeneity and high average permeability, leading to a low water flooding recovery efficiency. Polymer flooding only works for a certain heterogeneous reservoir. Therefore, supplementary technologies for further enlarging the swept volume are still necessary. Based on the concept of discontinuous chemical flooding with multi slugs, three chemical systems, which were polymer gel (PG), hydrophobically associating polymer (polymer A), and conventional polymer (polymer B), were selected as the profile control and displacing agents. The optimization design of the discontinuous chemical flooding was investigated by core flooding experiments and displacement equilibrium degree calculation. The gel, polymer A, and polymer B were classified into three levels based on their profile control performance. The degree of displacement equilibrium was defined by considering the sweep conditions and oil displacement efficiency of each layer. The effectiveness of displacement equilibrium degree was validated through a three-core parallel displacement experiment. Additionally, the parallel core displacement experiment optimized the slug size, combination method, and shift timing of chemicals. Finally, a five-core parallel displacement experiment verified the enhanced oil recovery (EOR) performance of discontinuous chemical flooding. The results show that the displacement equilibrium curve exhibited a stepwise change. The efficiency of discontinuous chemical flooding became more significant with the number of layers increasing and heterogeneity intensifying. Under the combination of permeability of 5000/2000/500 mD, the optimal chemical dosage for the chemical discontinuous flooding was a 0.7 pore volume (PV). The optimal combination pattern was the alternation injection in the form of "medium-strong-weak-strong-weak", achieving a displacement equilibrium degree of 82.3%. The optimal shift timing of chemicals occurred at a water cut of 70%, yielding a displacement equilibrium degree of 87.7%. The five-core parallel displacement experiment demonstrated that discontinuous chemical flooding could get a higher incremental oil recovery of 24.5% compared to continuous chemical flooding, which presented a significantly enhanced oil recovery potential.

In organic solar cells, the aggregation and crystallization of polymers are significant for bulk heterojunction. Blending with acceptor materials, polymer donor materials can adjust their aggregation by the movement of the chain segments. In this paper, the unfused structures based on thiophene and carbazole are respectively designed and introduced into the donor-acceptor copolymer donor materials to investigate the influence of flexible and rigid structures on polymer-aggregation leading photoelectric performance. The material and quantum chemical property investigations show that the selection and design of the blocks are important for the properties of the terpolymers, and the resulting polymer:Y6 devices achieve improvements in performance from 13.85% to 15.66% (especially for fill factors from 63.37% up to 69.81%). This result contributes to designing and optimizing efficient polymers.

Antimicrobial polymeric coatings rely not only on their surface functionalities but also on nanoparticles (NPs). Antimicrobial coatings gain their properties from the addition of NPs into a polymeric matrix. NPs that have been used include metal-based NPs, metal oxide NPs, carbon-based nanomaterials, and organic NPs. Copper NPs and silver NPs exhibit antibacterial and antifungal properties. So, when present in coatings, they will release metal ions with the combined effect of having bacteriostatic/bactericidal properties, preventing the growth of pathogens on surfaces covered by these nano-enhanced films. In addition, metal oxide NPs such as titanium dioxide NPs (TiO₂ NPs) and zinc oxide NPs (ZnONPs) are used as NPs in antimicrobial polymeric coatings. Under UV irradiation, these NPs show photocatalytic properties that lead to the production of reactive oxygen species (ROS) when exposed to UV radiation. After various forms of nano-carbon materials were successfully developed over the past decade, they and their derivatives from graphite/nanotubes, and composite sheets have been receiving more attention because they share an extremely large surface area, excellent mechanical strength, etc. These NPs not only show the ability to cause oxidative stress but also have the ability to release antimicrobial chemicals under control, resulting in long-lasting antibacterial action. The effectiveness and life spans of the antifouling performance of a variety of polymeric materials have been improved by adding nano-sized particles to those coatings.

Pumice aggregates with low density and high porosity are widely used in lightweight concrete. The high water retention ability of pumice aggregates adversely affects the properties of fresh concrete. Additionally, pumice aggregates' inadequate mechanical strength and durability hinder concrete performance. In recent years, research on coated aggregates has gained traction to improve the physical properties, mechanical strength, and durability characteristics of concrete. In this study, coarse pumice aggregates were coated with polyester and partially substituted with uncoated aggregates at ratios of 0%, 25%, 50%, 75%, and 100% in lightweight concrete formulations. Specific weight and water absorption tests were performed on the aggregates, while slump and unit weight tests were performed on fresh concrete mixtures. SEM-EDX analyses, unit weight, water absorbing capacity, sorptivity, compressive strength, freeze-thaw resistance, and sulfate resistance tests were performed on concrete specimens. The results indicated that the polyester coating significantly increased the specific weight of the aggregates and decreased the water absorption rates by up to 85%. Despite the coated aggregates resulting in decreased compressive strength of concrete specimens, they demonstrated reduced water absorbing capacity and sorptivity characteristics relative to reference concrete. Moreover, concrete made with coated aggregates exhibited better results in freeze-thaw and sulphate resistance tests.

The effectiveness of ultraviolet-C light-emitting diodes (UVC LEDs) is currently limited by the lack of suitable encapsulation materials, restricting their use in sterilization, communication, and in vivo cancer tumor inhibition. This study evaluates various silicone oils for UVC LED encapsulation. A material aging experiment was conducted on CF1040 (octamethylcyclotetrasiloxane), HF2020 (methyl hydro polysiloxanes), and MF2020-1000 (polydimethylsiloxane) under UVC radiation for 1000 h. The analysis assessed transmittance changes and chemical composition alterations throughout the aging process. Notably, HF2020 showed an increase in transmittance before 500 h, indicating a curing process attributed to the photolysis of Si-H, leading to the formation of Si-O-Si. Further testing on 265 nm UVC LEDs, both with and without HF2020 encapsulation, showed that the encapsulated LEDs exhibited a remarkable maximum increase of 27% in radiant power compared to their unencapsulated counterparts. Additionally, these encapsulated LEDs sustained higher radiant power levels during the first 200 h of operation. Notably, its potential application in photodynamic therapy is significant; by activating photosensitizers with higher UVC exposure, it facilitates the rapid production of reactive oxygen species, leading to effective cancer cell destruction within a short timeframe.

This work aims to determine the mechanism of the photomechanical response of poly(Methyl methacrylate) polymer doped with the photo-isomerizable dye Disperse Red 1 using the non-isomerizable dye Disperse Orange 11 as a control to isolate photoisomerization. Samples are free-standing thin films with thickness that is small compared with the optical skin depth to assure uniform illumination and photomechanical response throughout their volume, which differentiates these studies from most others. Polarization-dependent measurements of the photomechanical stress response are used to deconvolute the contributions of angular hole burning, molecular reorientation and photothermal heating. While photo-isomerization of dopant molecules is commonly observed in dye-doped polymers, the shape changes of a molecule might not couple strongly to the host polymer through steric mechanical interactions, thus not contributing substantially to a macroscopic shape change. To gain insights into the effectiveness of such mechanical coupling, we directly probe the dopant molecules using dichroism measurements simultaneously while measuring the photomechanical response and find mechanical coupling to be small enough to make photothermal heating-mediated by the transfer of optical energy as heat to the polymer-the dominant mechanism. We also predict the fraction of light energy converted to mechanical energy using a model whose parameters are thermodynamic material properties that are measured with independent experiments. We find that in the thin-film geometry, these dye-doped glassy polymers are as efficient as any other material but their large Young's modulus relative to other organic materials, such as liquid crystal elastomers, makes them suitable in applications that require mechanically strong materials. The mechanical properties and the photomechanical response of thin films are observed to be significantly different than in fibers, suggesting that the geometry of the material and surface effects might play an important role.

Industrial wastewater containing heavy metal ions presents serious economic risk to the environment. In this study, a novel compound of aminated cellulose with jeffamine EDR148 was prepared to improve cellulose's adsorptive behavior towards metal ions. This study undertook a straightforward and efficient cellulose modification through homogeneous chlorination in N,N'-butylmethylimidazolium chloride to produce 6-deoxychlorocellulose (Cell-Cl), followed by a reaction with jeffamine EDR148 and ultimately resulting in the formation of aminated cellulose (Cell-Jef148). Structural and chemical characteristics of Cell-Cl and Cell-Jef148 were determined using different techniques. Various adsorption conditions were applied to evaluate the optimal adsorption conditions for the removal of Cu(II), Ni(II), and Pb(II) ions. Cell-Jef48 revealed a greater affinity and higher adsorption efficiency of 480.3, 420.5, and 463.2 mg/g for Cu(II), Ni(II), and Pb(II) ions, respectively. Different kinetics and adsorption isothermal models were studied to investigate the adsorption mechanism and interactions between Cell-Jef148 and metal ions. The results fitted the Langmuir and pseudo-second-order models. Corresponding to the Langmuir model, Cell-Jef148's maximum adsorption capacities were 952.38, 609.76, and 769.23 mg/g for Cu(II), Ni(II), and Pb(II) ions, respectively, with a high correlation coefficient, R², in the range of 0.99575-0.99855. The research results of this study support Cell-Jef148's adsorption of heavy metal ions, and the regeneration of adsorbent highlights the potential applications of cellulose-based materials in wastewater treatment.

Metallic injection molding combines aluminum flake metallic pigments with polymers to directly produce components with metallic luster, improving production efficiency and reducing environmental impact. However, flake line defects that occur in regions where ribs or flow paths intersect remain a significant challenge. This study proposes a velocity model that considers the flow characteristics between the surface and core layers and an alignment model that incorporates the orientation of aluminum flakes to predict appearance defects. Through this approach, the mechanisms of appearance defect formation were systematized, and the appearance defects caused by flow velocity differences between the surface and core layers, flake alignment uniformity, and reflection angles were visualized. Both prediction models demonstrated a 50% prediction accuracy, successfully identifying two out of four observed defects. This research addresses the limitations of previous prediction methods, which only considered the surface layer, by introducing a novel approach that accounts for the core layer. It is expected to contribute to reducing defects and improving quality in industries requiring high-quality metallic appearances.