This study reviews light-responsive polymers in various applications, including drug delivery, information storage, sensor, self-healing material, antibacterial or anti-fouling, and environmental applications. Light-responsive polymers are a new material type being developed for various medical, electronics, engineering, and environmental applications. The working principle of light-responsive materials is based on metal-ligand interactions or non-covalent interactions between polymer functional groups, metal ions, and other filler functional groups. Light irradiation causes physical and mechanical changes in drug delivery and antibacterial systems, which results in the materials releasing more drugs or antibacterial substances. When materials in information storage devices and sensors are exposed to light, they can change color or glow. This has been applied for data storage to reveal QR codes under UV light. Additionally, this review discusses the thermodynamic aspects and computer modeling of light-responsive materials to emphasize the importance and development of these materials. Finally, light-responsive polymer development for various applications is presented.

Understanding the conformational characteristics of polymers is key to elucidating their physical properties. Cyclic polymers, defined by their closed-loop structures, inherently differ from linear polymers possessing distinct chain ends. Despite these structural differences, both types of polymers exhibit locally random-walk-like conformations, making it challenging to detect subtle spatial variations using conventional methods. In this study, we address this challenge by integrating molecular dynamics simulations with point cloud neural networks to analyze the spatial conformations of cyclic and linear polymers. By utilizing the Dynamic Graph CNN (DGCNN) model, we classify polymer conformations based on the 3D coordinates of monomers, capturing local and global topological differences without considering chain connectivity sequentiality. Our findings reveal that the optimal local structural feature unit size scales linearly with molecular weight, aligning with theoretical predictions. Additionally, interpretability techniques such as Grad-CAM and SHAP identify significant conformational differences: cyclic polymers tend to form prolate ellipsoid shapes with pronounced elongation along the major axis, while linear polymers show elongated ends with more spherical centers. These findings reveal subtle yet critical differences in local conformations between cyclic and linear polymers that were previously difficult to discern, providing deeper insights into polymer structure-property relationships and offering guidance for future polymer science advancements.

The development of narrow-bandgap polymer donors with complementary absorption and matched energy levels for perylene diimides (PDI)-based nonfullerene acceptors (NFAs) has received little attention. The high-lying highest occupied molecular orbital (HOMO) level and low degree of crystallinity of the star donor polymer PCE10 limit its application in PDI-based Organic solar cells (OSCs). In this study, two benzo[1,2-b:4,5-b′]difuran (BDF)-based narrow-bandgap polymer donors, PBDF and PBDFCl, were synthesized to improve the photovoltaic performance of PDI-based OSCs. The smaller BDF moiety with higher electronegativity endows the resulting polymers with stronger aggregation and lower HOMO energy levels. The power conversion efficiency (PCE) value of the PBDF:Ph(PDI)₃-based OSCs was 7.24%, which is much higher than that of PCE10-based OSCs (6.09%). Further chlorination of the conjugated side chain elevated the PCE to 8.84%, which is 1.4 times higher than that of PCE10-based OSCs. These results demonstrate the significant contribution of designing novel narrow-bandgap polymer donors to boost the PCE of PDI-based OSCs and highlight the importance of matching the aggregation behaviors of polymeric donor materials with that of NFAs.

The influence of the electronic and steric properties of bromoaromatic substrates on direct arylation polymerization for synthesizing high-molecular-weight conjugated polymers was investigated through a combination of experiments and calculations. Bromo-aromatic substrates with electron-withdrawing fluoro substituents exhibited higher yields and degrees of polymerization under PPh₃-assisted conditions compared to those with electron-donating or bulky methyl substituents. Additionally, excessive steric hindrance at ortho-sites or overly electron-deficient dibromoaromatic substrates leads to reaction inactivation. Calculations indicated that electron-withdrawing substituents enhanced the electrophilicity of arylpalladium-PPh₃ intermediates, facilitating the activation of electron-rich arylative substrates and promoting polymer growth. Furthermore, steric hindrance from the substituents can influence the preferred reaction pathway, thereby increasing the real reaction barriers. Both experimental and computational results suggest that bromoaromatic substrates with optimized electron-deficient characteristics significantly improve monomer conversion and polymerization efficiency with n-hexylmethylether-substituted EDOT. These findings clarify how the electronic and steric properties of bromo-aromatic substrates affect EDOT derivative activation and are expected to aid in optimizing the polymerization conditions for the preparation of high-molecular-weight conjugated polymers.

The diversity, complexity, heterogeneity, and drug resistance of tumors make it challenging to meet the clinical needs of a single apoptosis-inducing chemotherapy. The combination of apoptosis and ferroptosis is expected to address the side effects of chemotherapy and enhance therapeutic efficacy. Here, an amphiphilic pH-responsive doxorubicin (DOX) and ferrocene (Fc)-containing copolyprodrug (P(ADH-DOX-Fc)-PEG) was designed with high DOX and Fc content of 66.5% and 0.58 mmol/g by a facile polycondensation for combining chemotherapy with ferroptosis in cancer treatment. A drug self-delivery system (DSDS) with an average hydrodynamic diameter (D_h) of 135 nm can be easily obtained via self-assembly with the polyprodrug blocks as the hydrophobic core and PEG as the hydrophilic brush. The cumulative DOX release reached 72.7% in the simulated tumor intracellular acidic microenvironment within 56 h, whereas the premature drug leakage was only 6.2% in the simulated normal physiological medium. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay results indicated an IC₅₀ of 8.2 μg/mL, exhibiting enhanced anti-tumor efficacy and a successful combination of apoptosis and ferroptosis, with a combination index (CI) of 0.88.

Copolymers of fluoroethylene and vinyl ethers (FEVE) are soluble and curable at relatively low temperature, and are used as high-performance coatings and paints. Currently, most market-available FEVE products obtained through solution polymerization contain a large fraction of organic solvent, and hence, volatile organic compound (VOC) emissions cause environmental issues. In this study, the emulsion copolymerization of chlorotrifluoroethylene (CTFE) and vinyl ethers using an environmentally friendly emulsification system to produce waterborne FEVE was investigated. In addition to mixed nonionic and ionic surfactants, macromolecular monomer with double bond and polyoxyethylene segments were used in the emulsification system. The effect of adding macromolecular monomer and polyoxyethylene segment length of the nonionic surfactant on emulsion copolymerization were analyzed. An optimized emulsifier system for FEVE is proposed, and the prepared FEVE latexes exhibit excellent storage stability and film formation ability.

In this study, a pair of dicarboxylic acids as cis-trans isomerism—citraconic acid (CA) and mesaconic acid (MA), was incorporated into polymeric networks of poly(N-isopropylacrylamide) (PNIPAM)-based core-shell microgels via semi-batch precipitation polymerization. We demonstrated that the pH-temperature dual responsiveness of the core-shell microgels is highly correlated with the structure and position of the acid isomers. Both the cis-trans molecular structure and the crosslinking position of the dicarboxylic acids significantly influenced the hydration capacity and surface charge density of the core-shell microgels. These diverse properties first influenced the swelling behavior, further affecting the interfacial behavior of the microgels, including the oil-water dynamic interfacial tension and air-water compression isotherms. Furthermore, the rheological behavior of the microgel suspensions also displayed distinct dependences on the frequency and temperature, illustrating that the cis-trans molecular structure and crosslinked position of the dicarboxylic acids also significantly influenced the interparticle clustering in the bulk solution. Our results suggest that the pH sensitivity of the cis-trans dicarboxylic acid isomer affects the ionization and surface charge distribution of the core or shell layers of individual microgels, which further determines the interparticle interaction and cooperative rearrangement at interfaces and in the bulk.

Binuclear complexes have attracted extensive attention in fields such as catalysis because of their likely bimetallic synergistic effect; however, the mechanism and factors influencing this synergism remain unclear. In this work, six bis-β-ketoimine binuclear titanium complexes 4a–4f containing different alkylthio sidearms and configurations were synthesized and characterized by nuclear magnetic resonance hydrogen spectrum (¹H-NMR), nuclear magnetic resonance carbon spectrum (¹³C-NMR), Fourier transform infrared spectrum (FTIR), and elemental analysis. The intermetallic distances of isomeric complexes 4a, 4d, 4e and 4f determined through density functional theory (DFT) optimization were in the order 4a<4d<4e<4f and were found to significantly influence the catalytic performance for ethylene (co)polymerization. These complexes could efficiently catalyze ethylene polymerization and ethylene/1-hexene or ethylene/1-octene copolymerization with high activity to produce high-molecular-weight ethylene homo- and co-polymers. Among the three binuclear titanium complexes 4a–4c with similar structures but different lengths of alkylthio sidearms, complex 4a, which contained the shortest methylthio sidearm, exhibited the highest activity for ethylene polymerization and copolymerization with 1-hexene or 1-octene. Additionally, for ethylene/1-hexene or ethylene/1-octene copolymerization, it showed the highest comonomer incorporation compared with propylthio (4b) and octylthio (4c) derivatives because of the smaller steric hindrance of the methyl group in 4a and the more open coordination space for vinyl monomers. Furthermore, among the isomeric complexes 4a, 4d, 4e and 4f, complex 4a with the shortest bimetallic distance also exhibited the highest activity towards ethylene (co)polymerization, and the highest 1-hexene or 1-octene incorporation in comparison with its regioisomeric counterparts 4d, 4e and p-phenyl-bridged analog 4f, owing to a more appropriate bimetallic distance that is conducive to a synergistic effect.

Herein, a simple method for preparing poly(vinylidene fluoride) (PVDF) films with controlled β/γ ratios by spin-coating assisted by potassium bromide (KBr) is proposed. The results show that the relative fraction of the β phase (denoted as F_β) for the films prepared on the KBr surface first decreased until a critical temperature (denoted as T_c) was reached, and then increased with increasing spin-coating temperature. This was related to the dissolved K and Br ions in the films. Further experiments showed that below T_c, high humidity can enhance F_β but exhibit an adverse effect at and above T_c. The high content of K and Br ions in the PVDF/KBr blend film and larger shear stress can facilitate the formation of the β phase, leading exclusively to the formation of β- and γ-phases. The mechanism responsible for the change in F_β with temperature was proposed: below T_c, the decrease in water intake with increasing temperature results in the decline of F_β, whereas above T_c, the increase in F_β with temperature is attributed to the synergistic effect of ions and shear stress. Ultimately, this paves the way for fabricating PVDF films with tailored β/γ ratios for electroactive and energy-harvesting applications.

Ultra-high molecular weight polyethylene (UHMWPE) is widely utilized in low-dimensional materials due to its ultra-long chain imparted excellent strength and modulus. By employing gel-molding technology with a gradient temperature control, this study successfully produced gel films with varying shish crystal contents of the UHMWPE with a molecular weight of 8.0 million. The structural evolution during film hot-stretching was investigated by in-situ wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), ultra-small-angle X-ray scattering (USAXS), and ex-situ methods of scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The ultra-long molecular chains delay stress transfer during stretching but provide more nucleation sites for shish-kebab crystallization to form well-ordered shish-kebab crystals under high strain. The reserved high-content shish facilitates structural evolution, inducing the formation of highly-ordered shish-kebab crystals that eventually transfer into shish crystals in the later stage of stretching. The samples with low shish content, although the structural evolution is facilitated during stretching, predominantly result in newly formed shish-kebab crystals through melt recrystallization. However, some unoriented lamellae persists in unreserved samples stretching progress, leading to less ordered shish-kebab structures. By comparing with previous work of UHMWPE with low molecular weights, we demonstrate that the ultra-long molecular chains also play a key role on enabling the construction of highly-ordered shish-kebab crystals with high shish content during hot-stretching of UHMWPE gel films, providing new insights into processing control and optimization for engineering applications.

Poly(L-lactic acid) (PLLA) has been widely concerned because of its excellent biodegradability and biocompatibility. However, the poor crystallization ability of PLLA during the molding process not only leads to weak mechanical properties but also reduces the processing efficiency, which limits the application of PLLA greatly. Enhancing crystallization ability of PLLA via introducing inorganic nanoparticles usually sacrifices biodegradability or transparency. Here, the microfine fibers with stereocomplex (SC) crystallites were incorporated into PLLA film to tailor the crystallization ability of PLLA as well as the mechanical properties. The results confirmed that the crystallization ability of PLLA matrix under different circumstances could be greatly enhanced by a few amounts of SC crystalline fibers, and synchronously enhanced tensile strength and ductility were also achieved, especially at relatively high temperature. Due to the relatively homogeneous dispersion of SC crystalline fibers and the similar refractive index between components, the PLLA-based film also exhibited high transparency, up to 85%-90% depending on the content of SC crystalline fibers. This work provides guidance for manufacturing transparent PLLA-based packaging materials with good crystallization capability and mechanical properties.

As the application scenarios of aerogels expand, higher requirements are put forward for the materials used to prepare aerogels. Due to the unique chemical structure, polytetrafluoroethylene (PTFE) has excellent properties such as high-temperature resistance, hydrophobicity, and chemical stability. However, the PTFE aerogels are difficult to be molded due to the weak interaction between resin particles. In this work, poly(ethylene oxide) (PEO) was selected as the carrier to assist the PTFE aerogels molding. The pure PTFE aerogels were prepared by homogeneously mixing PTFE aqueous dispersion and PEO, freeze-drying, and high-temperature sintering. When the mass fraction of PTFE and PEO were appropriate, the porosity of PTFE aerogels exceeded 90% and had a hierarchical honeycomb structure. Results showed that the PTFE aerogels not only had excellent hydrophobicity but also possessed superior acoustic insulation, mechanical strength, thermal insulation, and heat resistance properties. Specifically, the water contact angle is about 140°. The noise reduction coefficient is 0.34 and the average sound absorption coefficient is greater than 88% in the frequency range of 2000–6400 Hz. Meanwhile, the thermal conductivity in the air is about 0.045 W/(m·K), and the initial thermal decomposition temperature is 450 °C. More importantly, the PTFE aerogels had excellent temperature and corrosion resistance. Even after extremely thermal and chemical treatment, they remained unchanged porous structure as well as acoustic and thermal insulation properties, which exhibits great potential for application in many harsh environments.

The recovery of ionic liquids (ILs) has attracted growing attention as an indispensable process in “green” industrial applications. Forward osmosis (FO) has proven to be a sustainable method for concentrating the very dilute aqueous solutions of ILs at ambient temperature, in which semi-permeable membranes play a vital role in determining the recovery efficiency. Herein, we use interfacial polymerization method to prepare thin-film composite membranes consisting of polyamide skin layer and electrospun nanofibrous substrate with tunable water permeability and IL selectivity for osmotic enrichment of imidazolium ILs from their dilute aqueous solutions through FO process. The resulting FO membrane shows a compact polyamide layer with a thickness of 30–200 nm, guranteeing a high selectivity to ILs and water. Meanwhile, the nanofibrous substrate with large and interconnect pores as well as low tortuosity, providing mechanical and permeable support for the composite membranes. IL structure influences the osmotic pressure difference as well as the interactions with polyamide layer of the membrane and thus determines the whole concentration process. First, the alkyl chain growth augments the osmosis pressure difference between the ILs solution and draw solution, resulting in an enhancement in driving force of water osmosis and IL enrichment. Moreover, alkyl length aggravates external concentration polarization caused by the enhanced adsorption of ILs onto the skin layer via electrostatic and alkyl-π interactions. Meanwhile, such adsorbed ILs further enhance the IL retention but decrease the reverse salt diffusion. Therefore, imidazolium ILs with varied alkyl lengths are ultimately enriched with a 100-fold increase in concentration from their dilute aqueous solutions with high IL/NaCl rejection and low IL loss. Remarkably, the final concentration of IL with longest alkyl length reaches the highest (6.4 mol·L^–1). This work provides the insights in respect to material preparation and process amelioration for IL recovery with high scalability at mild conditions.

In this study, a novel CS@SA@ZIF-67 core-shell nano-hybrid was synthesized using zeolitic imidazole framework-67 (ZIF-67) as a template and CS@SA@ZIF-67 as a modifier. Then, flame-retardant nanocomposites (EP/CS@SA@ZIF-67) were obtained by combining the hybrid with epoxy resins. The microstructure and morphology of CS@SA@ZIF-67 and the residual chars were explored using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), and the effect of the obtained hybrid materials on the fire performance of the epoxy resins was characterized. Compared with the flame retardant system composed of ZIF-67 and pure EP, the hybrid flame retardant composites exhibited low total heat release and smoke production. The thermogravimetric analysis (TGA) results showed that the maximum thermal decomposition temperature of the EP/CS@SA@ZIF-67 based composite coating was stabilized at the highest value (378.2 and 563.9 °C) so that the introduction of CS@SA@ZIF-67 could improve the thermal properties of the EP/CS@SA@ZIF-67 composites to a certain extent. Meanwhile, the cone test results indicated that the peak heat release rate pHRR of the CS@SA@ZIF-67 filled EP composite was reduced by 18.43% compared to that of pure EP, implying enhanced flame retardancy. The enhanced thermal stability and flame retardancy of the CS@SA@ZIF-67 composites were mainly ascribed to the catalytic effect and carbonization ability of CS@SA@ZIF-67.

Molecular dynamics simulations were performed to investigate the sliding dynamics of a small charged ring chain along rigid cyclic diblock polyelectrolyte in catenane immersed in salt solution. We found that both the mean-square displacement $ {g}_{3} \left(t\right) $ and diffusion coefficient D of ring are influenced by the salt type, electrostatic interaction strength A and salt concentration $ {c}_{{\mathrm{s}}} $. $ D $ first decreases and then increases as $ A $ increases when $ A $ is not large. At large $ A $, $ D $ decreases with an increase in $ A $ owing to the polyelectrolyte charge reversal caused by the aggregation of ions near it. Meanwhile, $ {g}_{3} \left(t\right) $ exhibited intermediate oscillating behavior at moderate $ A $ in monovalent cation salt solution. The sliding dynamics of ring can be attributed to the free energy landscape for diffusion. According to the potential of mean force (PMF) of ring chain, we found that our simulation results agreed well with the theoretical results of Lifson-Jackson formula. This study can provide a practical model for the diffusion of charged particles in different dielectric and periodic media, and provides a new perspective for regulating the sliding dynamics of mechanically interlocked molecules in electrolyte solutions.

Silicone material extrusion (MEX) is widely used for processing liquids and pastes. Owing to the uneven linewidth and elastic extrusion deformation caused by material accumulation, products may exhibit geometric errors and performance defects, leading to a decline in product quality and affecting its service life. This study proposes a process parameter optimization method that considers the mechanical properties of printed specimens and production costs. To improve the quality of silicone printing samples and reduce production costs, three machine learning models, kernel extreme learning machine (KELM), support vector regression (SVR), and random forest (RF), were developed to predict these three factors. Training data were obtained through a complete factorial experiment. A new dataset is obtained using the Euclidean distance method, which assigns the elimination factor. It is trained with Bayesian optimization algorithms for parameter optimization, the new dataset is input into the improved double Gaussian extreme learning machine, and finally obtains the improved KELM model. The results showed improved prediction accuracy over SVR and RF. Furthermore, a multi-objective optimization framework was proposed by combining genetic algorithm technology with the improved KELM model. The effectiveness and reasonableness of the model algorithm were verified by comparing the optimized results with the experimental results.

Polyimide (PI) is widely used in high-tech fields such as microelectronics, aerospace, and national defense because of its excellent optical properties, high- and low-temperature resistance, and good dimensional stability. To achieve the desired properties of PI, the monomers 2,6-diaminopyrimidin-4-ol (DAPD) and 6-(2,3,5,6-tetrafluoro-4-vinylphenoxy) pyrimidin-2,4-diamine (DAFPD), which contains crosslinkable functional groups, were designed and synthesized successfully and copolymerized with 4,4'-oxydianiline (ODA) and 4,4-hexafluoroisopropylphthalic anhydride (6FDA). The prepared PI film (PI-3), with rigid backbones and loose packing had excellent heat resistance (T_d5%=489 °C) and optical properties (T₄₅₀=82%). Furthermore, a crosslinked PI film (c-PI-3) with more heat-resistant (T_d5%=524 °C) and better mechanical properties (σ=125.46 MPa), can be obtained through thermal crosslinking of tetrafluorostyrene. In addition, the changes in the properties caused by the proportion of DAFPD added during copolymerization are discussed comprehensively. This study provides a promising candidate for heat-resistant PI materials.