Macromolecular Rapid Communications最新文献

Poly(2-isopropyl-2-oxazoline) (PiPrOx) is a biocompatible polymer with a temperature-sensitive behavior that exhibits hydrophilic-hydrophobic phase transition in response to temperature changes via lower critical solution temperature (LCST). Typically, the LCST of PiPrOxs changes significantly depending on their molecular weight or concentration. In this study, bottlebrush polymers (PiPrOx-BPs) are created using cascade enyne metathesis polymerization of PiPrOx-based macromonomer. The unique bottlebrush shape of PiPrOx-BPs, with densely packed side chains, makes them more stable and less sensitive to changes in their size or concentration. Unlike traditional linear PiPrOx, the PiPrOx-BPs showed minimal changes in thermal transition temperatures, even with large changes in their molecular weight or concentration. The measurements showed that PiPrOx-BPs undergo sharp and consistent changes in behavior, making them more reliable for applications like sensors, drug delivery, and other systems that need precise temperature control. This research offers valuable insights into how the design of polymers can improve their performance in various practical uses.

Surface fouling is a major concern in health care, marine industry, and water purification plants. Polymeric coatings are traditionally utilized to reduce the attachment of foulants on a surface, however low density and thickness of polymer brushes formed by surface initiated polymerization methods, surface exhaustion by continuous exposure to the foulants, and mechanical vulnerability in harsh environments, limit the antifouling performance of these traditional coatings. Recent trends in bioinspired polymeric coatings combine antifouling properties of super-hydrophobic, and highly hydrated lubricating polymers with mechanical properties of micro- and nano-particles to yield contact active, foulant releasable and stimuli responsive materials with superior antifouling performance. This review specifically highlights the development of next generation bioactive antifouling coatings using nature as an inspiration and a discussion of their benefits, over traditional polymeric coatings. The bioinspired coatings obtained are further evaluated for their potential applications in the marine environment, as delivery carriers, in implants, biosensors, and in urinary catheters.

Currently, the high light transmittance and high haze thermally conductive polyimide film with excellent comprehensive performance exhibits great application prospects, while there are still challenges for achieving. Here, boehmite nanowires (BhNs) with an aspect ratio up to 60 for the modification of transparent polyimide (CPI) derived from the polymerization of fluorodiamine and fluorodianhydride, are prepared. Due to the unique size and orientation distribution of BhNs in CPI films, the as prepared CPI-BhN composite films show in-plane thermal conductivity up to 5.89 W m^-1 K^-1, which is almost an order of magnitude higher than that of pure CPI (0.626 W m^-1 K^-1). Meantime, optimal CPI-BhN composite films show a light transmittance of 52.9% at 550 nm and a haze of 35.3%. In addition, the BhNs form a strong hydrogen bond with the CPI polymer chains, enhancing the mechanical properties of the composite films. Studies on thermal stability, fatigue resistance, and flame retardancy indicate that the CPI-BhN composite films have excellent performances. These findings provide a new idea for the design and fabrication of high-performance composite films for new-generation optoelectronic devices.

The influence of solvent mixtures on electrospinning polymer solutions plays a crucial role in both the electrospinning process and the characteristics of the resulting fibers. Solvents with varying properties can be used to optimize thermodynamic stability, viscosity, evaporation rate, and dielectric constant of a solution simultaneously. This study investigates the fabrication of highly porous poly-2,6-diphenyl-p-phenylene oxide (PPPO) fibers via electrospinning from binary and ternary solvent mixtures. The resulting fibers exhibit significant porosity both at the surface and in the core, as evidenced by their high surface area and textured morphology. These features render the fibers highly effective for sampling volatile organic compounds (VOCs). Adsorption performance is evaluated under passive and dynamic conditions using Musk Xylene as a simulant. Compared to granular PPPO, the fibrous membranes achieved nearly a fourfold increase in passive adsorption and an sevenfold increase in dynamic adsorption. These findings highlight the potential of PPPO electrospun fibers as superior materials for VOC sampling applications.

In order to improve the disadvantages of traditional hydrogels such as low mechanical strength and lack of responsiveness, different types of nanoparticles or nanostructures are added into the hydrogel network through in situ polymerization, self-assembly techniques, and other strategies, giving hydrogels a variety of special properties, such as stimulation sensitivity, optical or electrical properties, and reversibility. With the development of nano materials and synthesis technology, nanocomposite hydrogels have shown great potential in drug delivery, tissue engineering, motion detection, and wastewater treatment, and have been extensively studied in recent years. This review comprehensively elucidates the state-of-the-art preparation strategies and underlying response mechanisms of diverse stimulus-responsive nanocomposite hydrogels, spanning temperature, pH, humidity, electrical, and light responses. It systematically dissects their applications in biomedicine, environmental remediation, flexible sensing, and composite phase change materials. Moreover, it delves into future prospects and challenges, emphasizing the need for continuous innovation to unlock their full potential in emerging fields and address existing limitations.

Polylactide (PLA) becomes brittle shortly after physical aging, posing significant challenges for practical applications. This issue can be effectively overcome through a pre-melt-stretching process, known as mechanical rejuvenation. However, the underlying mechanisms remain poorly understood due to the intricate multilevel structures in pre-stretched PLA and their evolution during physical aging. Herein, PLA containing 12% D-isomer units is utilized as a model system to eliminate the influence of structures such as mesophase and crystals. The samples remain fully amorphous throughout the pre-stretching and subsequent aging processes. Notably, during physical aging, the pre-stretched samples retain their ductility, while the isotropic samples exhibit increased embrittlement. Thermal analysis is employed to elucidate the changes in the amorphous phase during aging. The results reveal the impact of the amorphous segmental mobility on the ductility change during aging, which is primarily governed by the fraction of mobile amorphous phase (X_MAF), with a critical threshold determining the ductile-to-brittle transition. This work would shed light on the toughening of physically aged glassy polymers.

4D printing, which combines the design freedom of 3D printing with the responsiveness of smart materials, is revolutionizing the creation of active structures. These structures can change shape in response to external stimuli, paving the way for advancements in robotics, biomedicine, and beyond. However, a comprehensive review article highlighting recent advancements in 4D printed shape memory actuators (SMAAs) is lacking. This review explores the exciting potential of 4D printing for intelligent SMAAs. It examines the concept of shape memory and the materials used, like shape-memory polymers (SMPs), shape-memory alloys (SMAs), and shape-memory polymer composites (SMPCs). It then dives into compatible 3D printing techniques and design principles for achieving programmed shape changes. Different categories of 4D printed SMAAs are explored, showcasing their potential applications in diverse fields. The review concludes by discussing challenges and future directions, emphasizing the massive potential of 4D printing for creating the next generation of actuators, making it a valuable resource for researchers in the field.

The charge carrier density and chain aggregation state of the conjugated polymer film are regarded unanimously as two factors affecting its electric transport properties. While chemical doping enhances the carrier concentration in polymer semiconductors, the dopant molecules also function as extraneous impurities, which hinder the aggregation ordering and crystallization of the polymer chains. Thus, the dopant level and the aggregation ordering should be compromised especially for organic field effect transistors (OFET) application. In this work, the processing-structure-performance relationships in poly(3-hexylthiophene) (P3HT) doped with low levels of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) is investigated. A microfluidic and ultrasonic field-assisted solution processing strategy (FU) is employed to enhance the chain conformation order in the solution. By virtue of the UV-vis absorption, X-ray scattering, and X-ray absorption spectroscopy, the FU-processed P3HT solution with 1 wt.% doping level demonstrated the highest conformation order in terms of large chain conjugation length and optimal aggregate packing, which further dictating the highest mobility of the corresponding F4TCNQ-doped P3HT film. The chain conjugation length is found to correlate more directly with OFET performance than the macroscopic crystallinity of the film and thus is proposed to be more intrinsic for understanding the electronic transport physics of conjugated polymers.

For nanomedical targeting and drug delivery purposes, the noncovalent assembly of polymer building blocks into defined nanostructures is an intense area of research. One of the key assets desirable to know for the potential nanocarrier is the stability under conditions close to those in application scenarios. Here, a series of polymer building blocks based on poly(ethylene glycol) (PEG), which comprise a functional end group facilitating self-assembly into supramolecular polymer bottlebrushes (SPBs), is hydrodynamically studied. The building blocks, and consequently the assemblies, are labeled with a cyanine5 (Cy5) dye enabling selective tracing of the materials in human serum (HS) in analytical ultracentrifugation (AUC) experiments. Our experiments reveal a long-term stability of the noncovalent assemblies over one month of storage of the materials in HS at body temperature. At the same time, the interaction of some of the Cy5 moieties with the transport protein human serum albumin (HSA) is evidenced.

Positive temperature coefficient (PTC) materials exhibit significant potential in thermal management due to their adaptive temperature regulation. However, current PTC materials are often constrained in the thermal regulation within the low-temperature range due to the high Curie temperatures. Achieving low Curie temperatures often requires small-molecule polymer matrices, which can compromise mechanical properties and lead to phase change material leakage. To overcome this challenge, this study innovatively proposes a generalized design strategy for bi-continuous phase thermally controlled PTC composite materials (PTCCM) based on polyimide aerogel (PIA) encapsulation. PIA forms a continuous backbone structure, while 1-Tetradecanol serves as a fibrous phase change matrix. Additionally, multi-doped conductive fillers construct an efficient fiber bundle-like network. In the temperature range of 10-50 °C, the PTC strength achieves 3.55, with a low resistivity of 1.5 Ω m. Thanks to its stable PIA skeleton and perfect conductive network, PTCCM can accurately stabilize the device temperature at 29.5 ± 1.5 °C under different low-temperature environments and voltages. The temperature control accuracy is as high as 0.03 °C, presenting excellent cycling stability. These characteristics make it promising in meeting stringent thermal management demands.