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Polyurethane (PU) materials with high strength, toughness, anti‐wear properties, and high heat resistance are in high demand for dynamic sealing applications. In this study, a series of high‐performance crosslinking polyurethanes (CPUs) were prepared by pre‐polymerization of polycarbonate diol (PCDL) with toluene‐2,4‐diisocyanate (TDI), followed by crosslinking with trimethylolpropane (TMP). The molar ratio (R) of PCDL/ TDI and the degree of cross‐linking were found to significantly affect the microphase separation. The results indicate that as the R‐value increases, the transition temperature of CPUs increases from 6.0°C to 82.4°C, and the tensile strength increases from 21.1 ± 2.5 MPa to 46.0 ± 3.6 MPa. Moreover, the CPUs exhibit excellent heat resistance (with a heat resistance index of ~150°C) and hydrolysis resistance, attributed to the high crystallinity of PCDL and the synergistic effect of chemical crosslinking. Additionally, the CPUs demonstrate low friction coefficient (COF = 0.01–0.062), exceptional anti‐wear properties (Akron wear, 0.11–0.07 cm3/1.61 km), and outstanding fatigue resistance. These desirable characteristics make CPUs suitable for use as dynamic sealing or lubricating materials in harsh conditions, thereby extending the service life of seals and preventing leakage and other related issues. [ABSTRACT FROM AUTHOR]

Self‐rolling allows the bilayer to transform into a 3D structure in response to specific external stimulation, such as heat, humidity, ions, etc. Herein, we report a 4D printing bilayer with a top sodium alginate layer and bottom polycaprolactone layer that could be rolled up to a tubular structure upon exposure to heat and Ca2+ solution stimulation. The discrepancy in the swelling and thermal‐responsiveness between alginate and polycaprolactone induced the self‐rolling under different stimuli. The self‐rolling behavior of the bilayer depends on the aspect ratio, thickness ratio of the bilayer film, the pattern, and external stimuli. Thus, a tailorable surface of the self‐rolled tube was obtained by tuning the bilayer parameter and the stimuli medium to meet varied demands. This controllable shape changing provides a strategy for the preparation of well‐defined tubular structures. Besides, the biocompatibility of bilayer film suggests the potential application in the field of biomedical device such as vascular stent. [ABSTRACT FROM AUTHOR]

The 4D‐printing technology is applied to fabricate a shape memory peripheral stent with good biocompatibility, which sustains long‐term drug release. The star polymer s‐PCL is prepared by ring opening polymerization of ε‐caprolactone with the ‐OH of β‐cyclodextrin (βCD) as initiator, and then the s‐PCL is modified with acrylate endgroup which allows the polymerization under UV light to form the crosslinking network c‐PCL. Attributed to the feature of the high crosslinked structure and chemical nature of polycaprolactone (PCL) and βCD, the composite exhibits appropriate tensile strength and sufficient elasticity and bursting pressure, and it is comparable with great saphenous vein in human body. The radial support of the 4D‐printed stent is 0.56 ± 0.11 N and is equivalent to that of commercial stent. The cell adhesion and proliferation results show a good biocompatibility of the stent with human umbilical vein endothelial cells. Due to the presence of βCD, the wettability and biocompatibility of the materials are improved, and the sustained paclitaxel release based on the host–guest complexion shows the potential of the drug‐loaded stent for long‐term release. This study provides a new strategy to solve the urgent need of small‐diameter scaffolds to treat critical limb ischemia. [ABSTRACT FROM AUTHOR]

Addressing the demand for integrating strength and durability reinforcement in shape memory polyurethane (SMPU) for diverse applications remains a significant challenge. Here a series of SMPUs with ultra‐high strength, self‐healing and recyclability, and excellent shape memory properties through introducing dynamic boron–urethane bonds are synthesized. The introducing of boric acid (BA) to polyurethane leading to the formation of dynamic covalent bonds (DCB) boron–urethane, that confer a robust cross‐linking structure on the SMPUs led to the formation of ordered stable hydrogen‐bonding network within the SMPUs. The flexible crosslinking with DCB represents a novel strategy for balancing the trade‐off between strength and durability, with their strengths reaching up to 82.2 MPa while also addressing the issue of durability in prolonged usage through the provision of self‐healing and recyclability. The self‐healing and recyclability of SMPU are demonstrated through rapid dynamic exchange reaction of boron–urethane bonds, systematically investigated by dynamic mechanical analysis (DMA). This study sheds light on the essential role of such PU with self‐healing and recyclability, contributing to the extension of the PU's service life. The findings of this work provide a general strategy for overcoming traditional trade‐offs in preparing SMPUs with both high strength and good durability. [ABSTRACT FROM AUTHOR]

Fluorescence excitation and emission matrices (EEMs) and parallel factor analysis (PARAFAC) were used to explore the organic matter removal from micro-polluted raw water in Zhongqiao water treatment plant. Based on PARAFAC analysis, four fluorescent components were extracted, including tyrosine-like, tryptophan-like, UV humic-like and visible humic-like substances. The water samples were dominated by protein-like substances, including tryptophan-like and tyrosine-like substances. The fluorescent components have the spectral features similar to those previously identified from EEMs of diverse aquatic environmental samples. The changes of maximum fluorescence intensities (Fmax) illustrated that the fluorescent components could be effectively removed during the water treatment process. Ozonation and BAC filtration played an important role in the removal of organic components, with the reduction of Fmax by 76.4% for tyrosine-like, 74.2% for tryptophan-like, 60.1% for TJV humic-like, and 46.7% for visible humic-like. Protein-like substances were more readily eliminated than humic-like substances during BAC (biological activated carbon) filtration. PARAFAC analysis and Fmax could be regarded as an effective tool and indicator for water quality analysis and water treatment plant evaluation. [ABSTRACT FROM AUTHOR]