Polymer International最新文献

Amphiphilic block copolymers are characterized by the presence of distinct hydrophilic and hydrophobic regions, which are usually arranged in alternating blocks. This unique structure allows these copolymers to self-assemble into well-defined nanostructures that exhibit remarkable resistance to enzymatic hydrolysis, high biocompatibility and the ability to be customized with specific structures. These properties make them highly desirable in various applications. Self-assembled amphiphilic polypeptoids are currently under development as a promising class of pharmaceutical agents. However, the utilization of these peptides as drug carriers for efficient delivery presents a number of challenges. These challenges include less-than-optimal loading efficacy and restricted biocompatibility. Herein, a series of stable amphiphilic block copolypeptoids (PNEG-b-PNBG and PNEG-b-PNHG) were designed and synthesized by controlled ring-opening polymerization. PNEG chain segments provide hydrophilicity, while PNBG and PNHG chain segments provide hydrophobicity. The hydrophobic molecular chains aggregate in aqueous solutions, resulting in the formation of nano-assemblies. The self-assembled amphiphilic block polypeptoid copolymers were investigated. The morphologies of copolymers take the form of micelles from tens of nanometers to a few hundred nanometers. The properties of amphiphilic block copolypeptoids used as drug carriers were further investigated by conducting drug release and cytotoxicity tests. The results indicate that the cumulative release efficiency of self-assembled polypeptoid copolymers can reach up to about 91%. And they have good biocompatibility and can be expected to be safe materials for efficient drug delivery. This work could provide a facile method for the preparation of amphiphilic block peptoid copolymers for biopharmaceutical applications. © 2024 Society of Industrial Chemistry.

Due to their unique properties and use in high performance materials, the ability to obtain fluorinated polymers utilizing straightforward synthetic methods remains of interest. In this study, we report the facile synthesis of new fluoropolymers via nucleophilic addition of a di-thiol to perfluorocyclopentene. Initially, model studies were completed with perfluorocyclopentene, benzenethiol and tetramethylsilane-protected benzenethiol to identify the optimal reaction conditions for the polymerization. These reaction conditions were then utilized to prepare perfluorocyclopentene-thioether polymers from perfluorocyclopentene and 4,4′-thiobisbenzenethiol. The isolated polymers had molecular weight distributions consistent with step-growth polymers and ¹⁹F NMR spectroscopy revealed that the addition of the nucleophile to perfluorocyclopentene was controlled. Analysis by DSC showed that the polymers were amorphous with glass transition temperatures around 65 °C. TGA in both air and nitrogen showed an initial degradation temperature around 370 °C, while the air analysis produced an additional plateau with a degradation temperature near 592 °C. This is the first known report of utilizing perfluorocyclopentene for the preparation of perfluorinated-thioether polymers. © 2024 Society of Industrial Chemistry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Poly(ethylene terephthalate) (PET), both bottle grade (PET-B) and thermoform grade (PET-T), are widely used in the packaging sector. However, only PET-B is recycled and reused, while PET-T needs to be separated from recycled PET bales. This study aims to assess the impact of solid-state polymerization (SSP), chain extension and the combination of chain extension–SSP to transform PET-B and PET-T blends into PET-T-like material. The intrinsic viscosity (IV) values for PET-B blends with 10–20 wt% of PET-T are measured for the samples obtained in this study. The mechanical properties, such as tensile strength, modulus, elongation and impact strength, were also determined. The glass transition temperature, melting temperature, crystallinity and thermal degradation were also investigated. The findings suggest that the combination of SSP and chain extension leads to a significant improvement in IV and tensile strength, while SSP alone is less suitable to offer the desired IV values. © 2024 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.

Hybridization of natural fibers with ceramic materials for reinforcing composites allows the optimization of the properties of these materials. For this reason, the present study aims to investigate physical, mechanical, water absorption, swelling and thermal properties as well as morphological characteristics of a hybrid Paederia foetida fibers–alumina powder (PFs–Al₂O₃)-reinforced epoxy composite. Epoxy resin served as the matrix, while PFs and Al₂O₃ were employed as reinforcement. Five types of composites were fabricated using the hot-pressing technique. The corresponding ratios of PFs:Al₂O₃ volume fractions (%) considered here were 0:40 (SFA), 10:30 (SFB), 20:20 (SFC), 30:10 (SFD) and 40:0 (SFE). The results reveal that the density of the hybrid PFs–Al₂O₃ composites decreased for increasing volume fractions of PFs: from 2.173 g cm⁻³ of SFA to 1.042 g cm⁻³ of SFE. The highest values of tensile strength (i.e. 49.085 MPa), tensile elastic modulus (i.e. 1.431 GPa) and impact strength (24 kJ m⁻²) were obtained for the SFD composite material with 30% volume fraction of PFs and 10% volume fraction of Al₂O₃: this happened because interface bonds between PFs, Al₂O₃ and epoxy phases achieved their optimal configuration. Overall, mechanical properties of the hybrid PFs–Al₂O₃-reinforced epoxy composites were superior to those of composites reinforced only by PF fibers or only by Al₂O₃. Water absorption and swellability reached their maximum values at the steady state occurring after tested samples remained immersed in water for 820 h. The SFE composite reinforced only by PFs presented the highest water absorption and swelling (i.e. 6.034% and 5.81%, respectively) while for all other hybrid composites (SFD, SFC and SFB) these two quantities remained below 5%. Density and volume fraction of voids of hybrid PFs–Al₂O₃-reinforced composites were consistent with the corresponding properties of the composites reinforced only by Al₂O₃ or PFs. SFD was also the most thermally stable material. Scanning electron microscopy observations of fractured surfaces indicated that the microstructure of the PFs–Al₂O₃-reinforced epoxy composites presents several voids, fiber pullouts and transverse fibers, which together optimize the mechanical response of the composite material. Remarkably, the SFD composite material was highly competitive with the most recently developed hybrid composites employing natural reinforcements. © 2024 Society of Industrial Chemistry.

Graphene and its derivatives are promising energy storage devices due to their high specific surface area, chemical and thermal durability and high charge transfer power. Still, their stacking and aggregate behavior can limit their practical application. To address this issue, reversible addition–fragmentation chain-transfer (RAFT) polymerization as controlled radical polymerization was applied to functionalize the surface of graphene oxide with poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) via the ‘grafting from’ method. This strategy enhances the distance between graphene sheets by occupying physical volume while improving effective charge transfer through tertiary amine groups participating in the doping process. X-ray diffraction was used to determine interlayer spacing after polymer grafting, which increased from 0.28 to 1.71 nm after polymer grafting. The hybridization of materials with diverse properties was used to enhance charge transfer capability for supercapacitor applications. PDMAEMA-functionalized graphene oxide, nano-manganese dioxide and polyaniline were combined to create a successful nanocomposite as electrode active material. The morphological structure and chemical composition of the synthesized nanocomposite were analyzed, and its electrochemical performance was evaluated using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The nanocomposite exhibited a maximum specific capacitance, energy density and power density of 364.72 F g⁻¹ (at a scan rate of 50 mV s⁻¹), 239.08 Wh kg⁻¹ and 678.34 W kg⁻¹, respectively. The final nanocomposite's energy storage capacity significantly increased compared to the individual components due to hybridization's synergistic impact, reducing charge transfer resistance. © 2024 Society of Industrial Chemistry.

Nowadays, there is a rising interest in the packaging industry regarding more environment-friendly (i.e. biodegradable and/or compostable) polymer-based solutions, especially for film blowing applications. However, replacing traditional, fossil resource-based polymers typically used for such applications is not an easy task, since the more environment-friendly solutions must have adequate features in terms of processability and final properties. In this work, three commercial biodegradable (and, at least partially, biobased) polymers were investigated by a preliminary rheological and mechanical analysis, in order to perform film manufacturing experiments in laboratory equipment. Furthermore, oxygen and water vapour barrier properties were studied by permeability measurements. The investigation was ultimately performed on films produced in industrial equipment, and the results were compared to those for a typical, standard polypropylene (PP) film used in flexible packaging applications. It was found that the mechanical properties were adequate (in some cases, even up to 25–30% higher than for the PP counterpart), as well as oxygen permeability. On the other hand, water permeability was significantly higher than that of PP films, and this should be taken into account in cases where high water vapour barrier properties are required. © 2024 Society of Industrial Chemistry.

Sulfamethymidine, a commonly employed sulfonamide, is introduced into the human body through the food chain, posing a threat to human health. Consequently, the development of a rapid and efficient detection technique is imperative. In this investigation, a photoresponsive sulfamethyridiazine-imprinted polymer was synthesized to etch a silicon core, thereby effectively addressing the limitations encountered with conventional molecularly imprinted polymers including diminished binding capacity, restricted site accessibility and sluggish binding kinetics. The photosensitive monomer utilized in the molecularly imprinted polymers is 5[(4 (methylacryloxy) phenyl) diazene] isophthalic acid, which exhibits a stimulating reaction mechanism. The N=N bond undergoes photoisomerization, transitioning between trans and cis configurations. The adsorption experiment provides additional evidence that the hollow molecularly imprinted polymers exhibit a higher adsorption capacity, achieving a value of 0.192 mmol L⁻¹. The experiments conducted to assess selectivity and repeatability confirm that the photoresponsive molecularly imprinted polymers exhibit a high level of selectivity and favorable repeatability. Following four cycles, the adsorption rate remains consistently at 64.3%. Additionally, the recoveries of the actual samples ranged from 95.6% to 99.7%. This finding presents a novel approach to detecting the concentration of trace pollutants in intricate substrates. © 2024 Society of Industrial Chemistry.

The development of self-healing materials is an effective strategy to improve the service life of polymer materials. In this study, self-healing waterborne fluorinated polyurethane-acrylate (WFPUA) containing UV-responsive coumarin groups was prepared by Pickering emulsion polymerization using modified cellulose nanocrystal as a stabilizer. The effect of double bond-terminated waterborne polyurethane content on emulsion polymerization and latex film properties was mainly studied. Due to the dynamic reversibility of the coumarin groups and the synergistic effect of hydrogen bonds, the optimized sample (WFPUA-30) had excellent mechanical properties and self-healing properties. The tensile strength was 5.24 MPa and the elongation at break was 267%. The self-healing efficiency of tensile strength and elongation at break after 6 h of repair was 86.52% and 93.20%, respectively. In addition, due to the presence of fluorine-containing groups, the water and oil contact angles of the latex film could reach 101.7° and 82.1°, respectively. This work broadens the way for the manufacture of self-healing and multifunctional waterborne polyurethane-acrylates. © 2024 Society of Industrial Chemistry.

The block structure of olefin block copolymer (OBC) elastomer gives it good elasticity and heat resistance relative to other polyolefin elastomers. However, the non-polar nature of OBC chains limits its comprehensive properties like dyeing and toughening for polar engineering plastics. In this work, maleic anhydride (MA) and dicumyl peroxide (DCP) were selected as a typical polar monomer and a radical initiator to modify the polarity of OBC elastomer. During the melt-grafting process, the DCP content was tuned to optimize the grafting efficiency while the MA-to-OBC ratio was fixed at 5 wt%. It was found that all the melt-grafting reactions show high efficiency and can be finished in 3 min at 170 °C. With the increase of DCP content, the estimated grafting degree of OBC-g-MA elastomer increases from 0.40% to 1.16% along with increased gel content from 4.27% to 22.44%. A suitable grafting process was obtained with a DCP content of 3.0 wt% by balancing grafting efficiency and final mechanical properties. The optimized OBC-g-MA elastomer with a grafting degree of 0.92% has a mechanical strength of 17.15 MPa, a Young's modulus of 26.35 MPa, elongation of 1564% and strain recovery of 59.73%. Additionally, the contact angle test shows that polar grafting can increase surface hydrophilicity while excessive crosslinking promotes hydrophobicity. Therefore, our work has demonstrated the feasibility of the reactive melt-grafting method to prepare OBC-g-MA elastomer and can also provide a processing reference for other chemical functionalization of polyolefin thermoplastic elastomers. © 2024 Society of Industrial Chemistry.

Mankind has erected monoliths and stone structures for millennia to ensure stories and culture are passed on to future generations. In the modern era, monuments and architecture are designed with the intention of lasting several decades to hundreds of years and may utilize an arrangement of natural and synthetic materials. Choice of substrate helps ensure the longevity of these structures, but coatings are utilized to provide additional characteristics and subsequent protection to the finished product. Protective coatings come in a variety of base materials and are utilized to address specific degradation concerns. Advances in this field focus on protection of the surface while preventing any unintended damage to the substrate. This mini review summarizes the advances in protective coatings useful for historical monuments and architecture up to January 2024. © 2024 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.