Journal of Polymer Science Part A: Polymer Chemistry最新文献

In this work, pyridine ring and pendent tert-butyl were introduced into the diamine NTPA in view of improving the processability and transparency of the PIs via inhibiting charge-transfer complexes (CTCs). Meanwhile, the amide linkage was simultaneously introduced in order to boost the thermal and mechanical properties of the PIs by reasonably increasing the polymer stiffness via noncovalent amide H-bonding. The dianhydride BPADA was employed in the copolymerization with the diamine comonomers of NTPA with ODA in different ratios. Due to the presence of tert-butyl and pyridine ring, the synthesized co-PIs showed good optical properties with T₅₀₀ higher than 75% for all co-PIs, reaching 83% for homopolymer BPADA-NTPA, higher solubility in organic solvents, and better hydrophobicity with maximum hydrostatic contact angle as high as 91.9°. Meanwhile, the amide H-bonding increased the mechanical properties of co-PIs with the maximum tensile strength reaching 127 MPa. Furthermore, amide H-bonding exceedingly offset the reducing effects of pendent bulky butyl groups on the thermal properties of PIs, and the T_g of the co-PIs containing NTPA moiety ranged in 244–298°C, remarkably higher than 218°C for homopolymer BPADA-ODA. This work proved cooperative synergistic effects of multiple functional groups in balancing the general properties of co-PIs.

Polyamides (PA) are a family of engineering thermoplastics used in a wide range of applications including automotive, building, construction, separation processes, textiles, and so forth. This is related to their good properties (mechanical and thermal) which can also be modified by additives, other polymers (blends and multilayers) and fillers (composites). But these complex systems (several components) make the final materials more difficult to recycle. In this review, basic statistics on the production rate of polyamides are presented and the different recycling methods are reported to compare their advantages and limitations with respect to economics and technical analyses. The discussion includes biological, chemical, mechanical, physical, and thermal treatments to reintroduce, as much as possible, the parts after their end-of-service. Finally, a general conclusion on the current state of PA recycling is presented with several openings for future developments to satisfy the concept of circular economy and general sustainability.

In celebration of his 67th birthday, this special issue of the Journal of Polymer Science honors the many accomplishments, outstanding career and impactful legacy of Professor Takuzo Aida. Professor Aida's contribution to the advancement of polymer science is wellknown, pioneering research in supramolecular polymers, bridging the gap between traditional polymer chemistry and supramolecular polymerizations. This collection of contributions from alumni, collaborators and colleagues is a testament to Professor Aida's profound impact on future generations of polymer scientists around the world. The cover of this special issue features a painting of Professor Aida by Iektje Meijer-Oosterbeek (www.iektje.nl).

Multifunctional elastomers have gained tremendous attention in the material research community. In this study, an epoxy functionalized elastomer poly(ethylene-co-vinyl acetate-co-glycidyl methacrylate) (EVA-GMA) that is commercially available was modified with dynamic covalent chemistry to make it self-healable and recyclable, as well as to investigate its adhesive properties. EVA-GMA was modified to a furfuryl-appended diene elastomer (FA-EVA-GMA) and subsequently cross-linked with bifunctional 1,2,4-triazoline-3,5-dione (bis-TAD) and bismaleimide (BMI) derivatives via electrophilic substitution (ES) and Diels-Alder (DA) chemistry, respectively. The ES modification of the elastomer was ambiently completed using bis-TAD, whereas its maleimide modification required elevated conditions (65 °C) with a longer time of 24 h. The tensile study showed a remarkable improvement in the mechanical strength upon cross-linking the elastomers. The differential scanning calorimetry (DSC) analysis elucidated the thermoreversible characteristics of both the ES and DA-derived networks, showing the cleavage of ES and DA conjugates at 135 °C (retro-ES) and 140 °C (retro-DA), respectively. The cross-linked elastomers exhibited significant self-healing characteristics (with a healing efficiency of ≈ 88%) and monitored using an optical microscope and tensile analysis. Interestingly, the bis-TAD-derived and bismaleimide functionalized EVA-elastomer showed excellent adhesive properties toward the metal surfaces, as analyzed via lap shear test.

Emulsion polymerization was used to create composites of polyaniline-amino-carbon nanotubes (PANI-A-CNT). Fourier transform infrared spectroscopy (FT-IR) was used to examine the chemical bonding properties of PANI and carbon nanotubes in composite materials. Transmission electron microscopy (TEM) was used to confirm that the PANI layer on the core-shell structure of PANI-A-CNT material was nanoscale in size. In order to assess the impact of various carbon nanotube contents on the electrostatic and mechanical properties of the composites, pristine carbon nanotube/ABS (p-CNT/ABS) and PANI-A-CNT/ABS composites were prepared. The mass fractions of PANI and CNT in PANI-A-CNT were 93.7 and 6.3 wt%, respectively, according to thermogravimetric analysis (TGA); hence, 4 wt% of PANI-A-CNT included 0.3 wt% CNT and 3.7 wt% PANI. The surface resistance test revealed that the PANI-A-CNT/ABS composite with 4 wt% PANI-A-CNT has a surface resistance of 10⁸ Ω, which is one time less than the surface resistance of the p-CNT/ABS composite with 4 wt% p-CNT. Moreover, PANI-A-CNT/ABS composite (0–4 wt% PANI-A-CNT) has stronger tensile and impact properties than p-CNT/ABS composite (0–4 wt% p-CNT), expanding the range of applications for ABS resin.

Responsive polymer thin films play an important role as structural components in the emerging fields of soft actuators, wearable electronics, and biomedical devices. These films are capable of changing their physical and/or chemical properties significantly in response to environmental stimuli, such as temperature, light, pH, magnetic fields, and ion strength. The integration of multifunctional designs in the polymer networks enables these films to possess advanced capabilities, including, but not limited to, structure color, self-healing, adhesion, conductivity, antimicrobial properties, and antifatigue properties. Polymer and hydrogel films are typically thinner than bulk polymer materials, ranging from nanometers to several hundred micrometers, and are usually made up of thin layers of natural or synthetic polymers. These films can be free-standing or coated on substrates. They offer faster response times, high flexibility, good adaptivity, and versatility via integrating with other functional materials. This special issue on responsive polymer and hydrogel films collects a series of review articles that detail the latest progress in this rapidly developing field, as well as original research articles that propose novel approaches to tackle practical challenges.

The review article by Dong et al. provides a comprehensive overview of recent progress in the fabrication and application of functional hydrogel films. The authors focus on two main areas: (i) the methods used to fabricate hydrogel films, and (ii) the various applications of hydrogel films in the fields of biomedicine and emerging technologies. Hydrogel films with controllable thickness, fast response times, good compliance, and tunable mechanical properties are ideal for use in artificial muscles, wound dressing, and the construction of soft actuators and flexible electronics. The review article also highlights current challenges, and provides future perspectives on the development of hydrogel films.

Yang et al. reported on the successful fabrication of self-healable, electromagnetic interference (EMI) shielding composite films that exhibit dual responsiveness to temperature and strain. To create these multifunctional films, the team incorporated carbon nanotubes into hydroxyl-terminated polybutadiene (HTPB), which was dynamically crosslinked by boric acid (BA). The HTPB-BA substrate showed excellent self-healing ability at room temperature, facilitating the autonomous recovery of electric conductivity and mechanical strength of the composite films. Dual responsiveness to temperature and strain was observed in the composite films, with electric resistance actively changing in response to variation of temperature and strain. In addition, the composite films exhibited excellent EMI shielding ability, with an effectiveness beyond 28 dB, making them ideal for commercial applications. The EMI shielding efficiency was also found to be responsive to temperatures. These respons

This study aims to develop a green composite based on two biomass-based components via the curing of an oligomeric furfuryl resin coupled with 18–31 wt% cellulose powder. The curing was performed in an atmospheric pressure open air oven. The chemical composition of the used pre-polymer was characterized with Fourier transform infrared and NMR spectroscopy and its curing reaction was followed by differential scanning calorimetry. The final cured composites were characterized to investigate the effect of cellulose addition on their morphology, dimensional stability, and thermo-mechanical performances. The manufactured composite showed good thermal stability up to 200°C with a storage modulus higher than 2 GPa, and a mass loss under 3%. Moreover, the filler improved the composite dimensional stability upon crosslinking by 38% and the mechanical performances with respectively 15% and 40% increase in the Young's and flexural moduli. By the same token, cellulose prevented the typical foaming of poly(furfuryl alcohol) resins crosslinked at high temperature and low pressure. Preliminary tests highlighted the excellent processability of the developed composite, which was used to manufacture a static demonstrator coupling different fabrication techniques, that is, 3D printing (direct ink writing), high temperature compression molding and CNC machining.

Due to low losses, optical fibers are excellent optical waveguides, but manipulating the wavefront below the diffraction limit while keeping fabrication costs down is a significant challenge. Top-down lithographic methods can create arbitrary nanostructures on the fiber end face to manipulate the wavefront. Still, this method requires a flat fiber end face, which can only be made using elaborate preparation processes. We present a facile coating method in which we transfer a hexagonally packed monolayer of gold nanoparticles onto an untreated fiber end face. Using a poly(N-isopropylacrylamide) particle coating, we could transfer the free-floating monolayer from a water-air interface to the fiber end face. Our self-assembly method enables plasmonic gratings on rough surfaces and objects with large aspect ratios, which have been challenging for existing nanofabrication methods. Using electromagnetic simulation, we demonstrate the performance and utility of the concept as a refractive index sensor in which we consider different lattice constants. Our simulations cover possible analyses by calculating the structure under air, water, and polymer environments. Thus, we study the potential applications of low-cost fiber-based sensors with low optical losses.

Poly(3,4-ethylenedioxythiophene) (PEDOT) has been widely used in electrode materials, electrochromic materials, biosensors, supercapacitor, and solar cells, etc. In these applications, high requirement for the stability of PEDOT is indispensable. This study focused on enhancing the stability of electro-polymerized PEDOT electrodes by in-situ doping and solvent treatment in order to reduce the dissolution products of PEDOT under photoelectric conditions. The post-treatment was a combination of soaking and/or rising with deionized water, anhydrous ethanol and sulfuric acid solution (pH = 2) for different times. Among them, the sample rinsed successively with anhydrous ethanol and deionized water was the most effective post-treatment method, which can reduce the dissolution amount by 35%. Through doping para-toluenesulfonic acid (TsOH), the dissolution amount was further decreased by 58%. The surface hydrophobicity of PEDOT was increased from 23° to 38° after doping with TsOH, which was beneficial to the stability of PEDOT. Except for sodium polystyrene sulfonate (PSS) doping, the photocurrent response of PEDOT can be increased by doping other selected substances. Specially, the photocurrent response of TsOH-PEDOT was increased by 59%. There is a certain negative correlation between dissolution amount and the photocurrent response, suggesting less dissolution is conductive to maintaining high photoelectric performance.

Radical ring-opening polymerization (RROP) of cyclic ketene acetals allows for the synthesis of functional and biodegradable polyesters. To gain a better understanding of RROP, kinetic studies of this reaction method are thus essential but still rare. In here we conducted kinetic experiments on RROP of 2-methylene-1,3,6-trioxocan (MTC) for the first time. In line with earlier findings, the kinetic behavior could be distributed into a chain growth, stationary and step growth behavior probably caused by dominating branching and recombination reactions impacting the polymerization with increasing conversion. The impact of reaction conditions, such as monomer concentration, reaction temperature and source of energy input (Oil bath, microwave, UV light) were varied systematically. All of these factors were studied towards their influence on polymerization rate constant, density of branches (DB), polymer dispersity and molar mass. While each of these factors were impacted by the reaction conditions, the DB was only depending on monomer conversion. Elution fractionation of PMTC samples with high conversion proved decreasing DB with increasing molar mass. Altogether, this study gives a holistic insight into the kinetics of MTC under various means of free RROP, paving the way for developing a more hydrophilic polyester with adjustable DB and molecular weight.