ACS Applied Polymer Materials最新文献

Recently, sustainable poly(lipoic acid) (poly(LA))-based biogels have attracted increasing interest and have been used in wearable sensing fields. However, the low stretchability and adhesion, poor self-healing, and wire transmission remain the major issues that limit the applications of poly(LA)-based gel sensors. It is urgent to develop multifunctional biogels with excellent comprehensive performance. In this work, multifunctional conductive poly(LA)-based zwitterionic biogels (denoted as PLLS gels) were fabricated by introducing hydrophilic sulfobetaine methacrylate (SBMA) through nucleophilic addition reactions with poly(LA). The addition of SBMA endowed the gels with conductivity due to the abundant anionic and cationic groups of the zwitterionic structure. The excellent biocompatibility of poly(LA) and SBMA provided the gels nontoxicity and harmlessness. As expected, the PLLS gels possessed high stretchability, adhesion, and self-healing due to the multiple dynamic bonds, including hydrogen bonds and electrostatic interactions. Besides, the gels exhibited excellent biodegradability, antioxidant, and antibacterial activities. The PLLS gels had found application as a wireless wearable sensor, which could monitor various human activities involving temperature changes, human joint movements, and voice recognition. This work not only provides a valuable strategy for constructing the sustainable gel sensors but also expands the applications of biogels to portable mobile monitoring of wireless wearable devices.

This study investigates the preparation of flexible biobased thermosets by cross-linking epoxidized linseed oil (ELO) with three different hardeners: hexamethylene diamine (HMDA), bis(hexamethylene)triamine (BHMT), and sebacic acid. In a comparative analysis of amine and carboxylic acid cross-linkers, the mechanical, thermal, and chemical properties of the resulting thermosets were evaluated using Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and tensile testing. FT-IR spectroscopy revealed the formation of an amide network in samples cured by using amine hardeners. HMDA and BHMT provided superior mechanical properties, with tensile strengths of 3.7 MPa and 2.3 MPa, respectively, compared to 2.0 MPa for sebacic acid. Glass transition temperatures were also higher for HMDA (16.0 °C) and BHMT (12.4 °C) compared with sebacic acid (-1.4 °C). Moreover, TGA showed that samples cured using sebacic acid reached the point of fastest mass loss at lower temperatures (385 °C) than thermosets cured using amine hardeners (450-470 °C), indicating their improved thermal stability. However, HMDA samples exhibited a significant mass loss of up to 40% due to evaporation during curing. This study shows the potential of amine cross-linkers for enhancing performance and underscores the need for further research into optimizing curing conditions and cross-linking chemistry.

The native oxide layer of Ca-metal electrodes impedes Ca-ion transport properties across the electrolyte–electrode interphase. Bis(trifluorosulfonyl)imide-salts (TFSI-) were reported to inhibit any ion transport due to facile degradation at the reactive interface. Poly(ethylene oxide)-based solid polymer electrolytes (SPEs) frequently use Ca(TFSI)₂ for its comparatively high ionic conductivity and hence have not achieved reversible plating/stripping from Ca-electrodes yet. To overcome this roadblock, a Ca-electrode surface treatment with Bi-salt was introduced, enabling operation of Ca/Ca symmetrical cells from a PEO-Ca(TFSI)₂ SPE for the first time. The functionalization greatly reduced interfacial resistances thus allowing reversible Ca plating and stripping from the Ca-SPE.

Quaternary ammonium iodide (QAI)-containing hydrogels with different alkyl side chain lengths were synthesized and used to develop ionic electroactive strip actuators. The strip bent at relatively low voltages, exhibiting a 5.0 mm bending displacement over the 30 mm strip length at 0.6 V, for example. The bending displacement largely depended on the applied voltages and alkyl side chain lengths. The anticipated bending mechanism is the movement of the iodide anions toward the anode, thereby driving volume contrast in the strip near the anode (volume expansion) and cathode (volume contraction). This mechanism was experimentally confirmed by monitoring the location of the iodide anions in the strip by using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) and confocal microscopy. The obtained QAI-containing actuators are operational at relatively low voltages and in water-containing environments and also have antimicrobial properties, which would be useful for biological environment applications.

Covalent organic frameworks (COFs) serve as suitable templates for constructing photocontrol nanozymes due to their highly tunable skeletons and controllable porous channels. Unfortunately, the development of high-performance COFs remains challenging because of their narrow absorption bandwidth, rapid electron–hole separation or recombination, and other limitations. Herein, a polyethylene glycol (PEG) engineering strategy is developed to construct high-efficiency photocontrol oxidase (OXD) mimics based on COFs. A series of COFs with PEG side chains were synthesized through the condensation of an N-containing aldehyde ligand (TPY) with PEGylated amine ligands, which were decorated with PEG chains of different lengths. By introducing PEG chains, the electron–hole recombination of COFs can be slowed down, while electron–hole separation is accelerated; meanwhile, the affinity between COFs and the substrate can be enhanced, thereby improving the photoactive OXD-like activity of COFs. The N atom in TPY induces a red shift in the band-edge absorption of COFs and reduces the band gap, further improving their light absorption performance. Notably, COF-TPY-4O exhibited greater activity than other COFs. As a proof of concept, COF-TPY-4O was used for the construction of biosensors and elimination of bacteria, demonstrating its potential as a photoactive nanozyme with good application prospects. This study highlights the construction of highly active photocontrol nanozymes through PEG engineering.

Polyester (PET) has become the focus of research in the shrink film industry due to its good heat resistance, high transparency, and excellent mechanical properties. In order to improve the shrinkage rate of the film, amorphous PET (PETG) is usually obtained by copolymerization modification using some flexible diols and so on. However, introducing flexible structures reduces the glass transition temperature (T_g) and mechanical strength, and importantly, the gas barrier properties of most PETGs are weak. Here, a series of poly(terephthalic acid-naphthalene dicarboxylic acid-ethylene glycol-neopentyl glycol) (PENTN) were prepared by melt polymerization using different contents of 1,4-naphthalene dicarboxylic acid (1,4-NDA) or 2,6-naphthalene dicarboxylic acid (2,6-NDA). The results show that the introduction of 1,4-NDA does not enhance the T_g of the copolyesters significantly, whereas the T_g of the copolyesters increases linearly with the increase in the content of 2,6-NDA. The T_g of 2,6-PENTNs ranges from 82.2 to 90.5 °C. The crystallization is inhibited effectively due to the neopentyl glycol and exhibits good transparency (>85%) and low haze value (<4%), which results in the preparation of copolyesters that are all amorphous polymers. The differences in the effects of 2,6-NDA and 1,4-NDA on the thermal properties of the copolyesters were analyzed. Meanwhile, the copolyesters were prepared into films, and the gas barrier properties were analyzed in detail. The rheological analysis reveals the free volume of the copolyester is rapidly decreasing with the introduction of the naphthalene group structure. The gas barrier property of the copolyesters can be improved to a high level. This work provides an idea for the functionalized modification of packaging materials.

Poly(N-isopropylacrylamide) (PNIPAM)-based hydrogels are widely used in the preparation of Janus actuators due to their remarkable temperature-responsive properties. However, preparing PNIPAM-based hydrogel actuators with excellent mechanical properties, mass transfer ability, and programmable deformation, as well as gaining a profound and systematic understanding of their driving mechanisms, remains a challenge to date. To address these challenges, an efficient PNIPAM-hydroxypropylmethyl cellulose/polyacrylamide-Graphene oxide (PNIPAM-HPMC/PAM-GO) Janus hydrogel actuator with strong interfacial stability was constructed based on the self-generation method; PNIPAM-HPMC was used as the active layer, and PAM-GO was used as the passive layer. The introduction of HPMC makes the active layer have excellent tensile strength (7.55–28.3 kPa) and mass transfer ability (39.07–73.03%), thereby improving the deformation ability of the actuator (239–360°). It can still achieve a 360° deformation after being actuated repeatedly 5 times. The deformation dynamics of the Janus hydrogel actuator under thermal response conditions were quantitatively analyzed by real-time tracking of the response behavior, and the important role of mechanical moduli in the deformation process of the Janus hydrogel actuator was revealed for the first time. Therein, the effect of the elastic modulus difference on the deformation of the actuator is 48 times that of the compression modulus difference. Finally, the Janus hydrogel actuator with high interface stability, mechanical robustness, time-programmable, and double-layer integration prepared in this work shows potential application in the fields of bionics, intelligent switches, and display systems.

Polymers that exhibit both a high refractive index and superior transmittance are critically sought for optoelectronic device applications. Polyarylates are considered one of the most promising classes of optical materials for such purposes. Nevertheless, the demand for polyarylates with enhanced refractive indices and elevated light transmission levels is growing. This study introduced a series of innovative polyarylates synthesized via nucleophilic reactions involving bisphenol with a pendant cardo structure and acid chloride derived from a biobased diacid (2,5-thiophenedicarboxylic acid). These polyarylates demonstrated a relatively high refractive index (n_d = 1.695), excellent light transmission (T_400 nm > 86% and T_avg > 92%), and ideal low dispersion (Abbe number = 23). The elevated refractive index can be attributed to the high molar polarizability of thiophene, whereas the exceptional transmittance is credited to the bulky cardo-ring structure that minimizes interactions between polymer chains. Furthermore, these polyarylates displayed excellent thermal properties and solubility, enhancing their processability. This research offers a viable strategy for developing high-refractive-index polymers with excellent transmittance for optical applications.

Porous structures are a common design in the preparation of compressive, flexible strain sensors. It can endow the flexibility and permeability of flexible sensors while effectively increasing the specific surface area and reducing its mass. However, efficient preparation of porous strain sensors with accurate measurement results, high stability, wide operating range, and excellent durability remains challenging. Herein, the salt template method combined with vacuum casting and freeze-drying processes were used to prepare a pristine three-dimensional porous foam model, and a porous lightweight thermoplastic polyurethane (TPU)/carbon nanotube (CNT)@silver nanoparticles (AgNPs) (Vc-TPU/CNT@AgNPs) strain sensor with high compressibility was prepared by impregnating CNTs and growing AgNPs in situ. Thanks to the reduction of AgNPs inside the foam as an interlayer contact point, the resulting microstructure effectively changes the force on the sensor during compression. Meanwhile, the lap of AgNPs as a conductive filler between the layers effectively reduces the overall resistance during foam compression, resulting in a significant increase in sensor sensitivity (gauge factor = 1.40) and giving the sensor a superior linear fit (R² = 0.99875), a wide sensing range (5–70% strain, 88 pa ∼35 kPa pressure), and a rapid response and recovery time (20 ms). The in situ growth of AgNPs and π–π bonding interaction between TPU and CNT then provide excellent durability (500 cycles, 50% strain) for the Vc-TPU/CNT@AgNPs strain sensor. Furthermore, the strain sensors can be successfully used to monitor human motion, ranging from small vibrations in tendons and ears to large strain movements, such as finger flexion and foot stamping. This work provides a proven method for the preparation of porous flexible strain sensors with excellent linearity, good sensitivity, lightness and breathability, and durability, which have promising applications in the field of wearable electronics.

Although the proportion of binder in batteries is tiny, it plays a significant role in maintaining the integrity of the electrode structure and ensuring the cycling stability of batteries. This study, based on the concept of “redox mediators (RMs),” involved the design and synthesis of a series of Se–Se bonds containing polyurethanes, which have been used as binders for lithium iron phosphate cathodes in lithium-ion batteries (LIBs). Se–Se contained binders as RMs not only accelerate the redox kinetics of the battery but also improve the discharge specific capacity and lithium-ion (Li⁺) transport rate of the battery. The synergistic movement of the hard and soft segments in the polyurethane endowed the binders with high elasticity, and the hydrogen bonding within the binders further enhanced the mechanical properties and reduced the volume change of the electrode during charging and discharging, thus improving the electrochemical cycling performance of the battery. After 500 cycles at 1 C, LIBs with PUPEG-400 as the binders boasted the highest initial discharge specific capacity of 139.77 mA h g^–1, while those with PUPEG-2000 as the binders exhibited the highest capacity retention of 72.37%.