Xinyan Shi

Conventional microfluidic chips fabricated from polydimethylsiloxane (PDMS), glass, and silicon suffer from intrinsically fixed surface wettability, tedious post-modification, and inhomogeneous wetting inside enclosed three-dimensional (3D) microchannels, which severely restrict their applications in biphasic fluid manipulation. Herein, we develop a photocurable poly(vinyl alcohol) (PVA)-based hydrogel featuring a triple synergistic network for digital light processing (DLP) 3D printing of integrated microfluidic devices. Under acidic catalysis, glutaraldehyde (GA) undergoes acetalization with PVA to form the first crosslinked network, which consumes hydrophilic hydroxyl groups and introduces hydrophobic alkyl segments. Subsequently, the hydrogel framework is co-constructed by a PVA hydrogen-bonding physical network and a UV-initiated covalent network derived from acrylamide (AAm), acrylic acid (AAc), and poly(ethylene glycol) diacrylate (PEGDA), ultimately yielding a triple-crosslinked network. By adjusting the GA loading, the water contact angle of the hydrogel can be continuously tuned from 15.42° (hydrophilic) to 111.66° (hydrophobic). Benefiting from the interpenetrating multi-network architecture, the tensile strength increases from 48.76 kPa to 118.27 kPa, and the elastic modulus increases from 14.72 to 63.84 kPa. DLP 3D printing enables the direct fabrication of monolithic microfluidic chips with smooth microchannels down to approximately 160 μm in width, without requiring any post-treatment. Fluorescence characterization confirms that the hydrophilic channels allow stable laminar flow of deionized water, while the hydrophobic channels enable low-friction transport of mineral oil. This work establishes a comprehensive strategy integrating molecular design, wettability programming, and 3D additive manufacturing, providing a scalable platform for applications in fluid transportation, biochemical detection, environmental monitoring, and wearable microfluidics.

This study investigates hydrogenated nitrile butadiene rubber (HNBR) as the research object, using polytetrafluoroethylene (PTFE) combined with different amounts of zinc dimethacrylate (ZDMA) as variables. The behavior of hydrogenated nitrile butadiene rubber was analyzed through mechanical property tests, compression set tests, dynamic mechanical property tests, SEM tests, MTS compression fatigue tests, and supercritical carbon dioxide aging tests, and a comparison of four formulations was conducted. The results show that the mechanical properties of HNBR compounds containing only PTFE did not improve significantly, and performance even slightly decreased under tensile testing. The compression set and compression fatigue performance of HNBR compounds containing ZDMA decreased. The HNBR compound containing both PTFE and ZDMA showed optimal dynamic mechanical properties and performance after supercritical carbon dioxide aging. The experimental findings indicate that hydrogenated nitrile butadiene rubber containing 10 parts of PTFE and 10 parts of ZDMA exhibits superior mechanical properties and resistance to supercritical carbon dioxide aging under the same conditions.

Soft‐grade ethylene propylene diene monomer/polypropylene (EPDM/PP) thermoplastic vulcanizates (TPVs) suffer from compromised processability and unstable phase morphology due to high rubber loading and oil extension. Herein, we report a concentrated thermoplastic vulcanizate (TPVC) masterbatch strategy via peroxide‐mediated dynamic vulcanization of highly oil‐extended EPDM and PP, enabling flexible hardness tuning via PP dilution. The nonisothermal crystallization kinetics of the PP matrix in TPVC was systematically quantified via the Jeziorny‐modified Avrami model, Mo model, and Kissinger method, revealing a dual effect of dispersed EPDM phase: accelerating PP crystallization via heterogeneous nucleation (crystallization activation energy reduced by 22.36 kJ/mol vs. pure PP) while restricting chain mobility. Dynamic rheological tests combined with time–temperature superposition (TTS) analysis (Han and van Gurp‐Palmen curves) confirmed that the T80P20 system fully conforms to the TTS principle with a broad processability window, and all formulations exhibit elasticity‐dominated viscoelastic behavior (phase angle ≤ 20°). This work provides quantitative kinetic and rheological guidance for industrial processing optimization of soft TPVs.

To address the failure issue of nitrile butadiene rubber (NBR) in environmentally friendly white oil drilling oil‐based mud, caused by the leaching of additives, this study uses white oil as the aging medium and introduces microcrystalline graphite (CY6) to form a barrier network. Through multiscale characterizations such as ATR–FTIR, XRD, TGA, and SEM, the thermal aging behavior and mechanism in white oil are thoroughly investigated. The results show that FTIR and XRD analyses confirm the extraction of additives and reaction‐generated zinc salts (such as RD, zinc stearate, benzothiazole zinc salts, etc.), accompanied by structural changes in zinc oxide, which partially dissolves into the medium. TGA results demonstrate that thermal aging in white oil leads to the breakdown of the cross‐linked structure, resulting in a decline in heat resistance. SEM analysis reveals that the sample surface becomes rough, with a large number of white additive particles extracted and attached to the surface, while fractures exhibit varying degrees of pitting and small pores. Over‐cross‐linking during the thermal aging process reduces the tensile properties of the sample. The samples containing CY6 show the least change in tensile strength, elongation at break, and oil resistance after aging in white oil. This effectively reduces the extraction of additives and reaction‐generated zinc salts, acting as a barrier. This study systematically analyzes the formulation performance optimization and aging behavior in thermal white oil, providing theoretical and technical support for improving the heat resistance and aging performance of NBR in white oil.

Thermoplastic polyurethane (TPU) possesses excellent mechanical properties, shape memory effects, and good processability due to its unique microphase‐separated structure. Carbon nanotubes (CNTs) have shown significant advantages in enhancing the mechanical properties of polymer matrices and endowing them with intelligent responsiveness due to their unique three‐dimensional tubular structure, high interfacial activity, and photothermal conversion ability. However, achieving uniform dispersion of CNTs within the TPU matrix and fully realizing their functional potential remains a key challenge in preparing high‐performance composites via melt blending. This study successfully prepared TPU/CNTs composites with varying CNTs contents (0–0.6 wt%) using a Haake torque rheometer. The results indicate that when the CNTs content reaches 0.6 wt%, an agglomeration phenomenon occurs, adversely impacting the mechanical properties and shape memory capability of the composites. At a CNTs content of 0.4 wt%, the composite exhibited the best overall performance: melt strength and structural stability were significantly enhanced, which facilitated fused deposition modeling (FDM) printing; tensile strength reached 26.7 MPa. The composites exhibit exceptional shape memory properties with a shape fixation ratio ( R _f ) > 99% and shape recovery ratio ( R _r ) reaching 93.27%, accompanied by rapid response times (< 30 s). This performance enhancement originates from CNTs' near‐full‐spectrum absorption (> 95%) across the ultraviolet–visible‐near‐infrared range (200–2500 nm), particularly in the visible and NIR regions that constitute ~80% of solar energy. The absorbed photons are efficiently converted into lattice vibrational energy (thermal energy). Furthermore, TPU's inherently low thermal conductivity confines the heat generated by CNTs within the polymer matrix, minimizing thermal dissipation losses. Concurrently, 3D printing induces alignment of CNTs, which optimizes light capture efficiency and photothermal conversion. These synergistic effects collectively elevate the shape memory capabilities of the composites. Building on this, successful four‐dimensional (4D) printing of complex models and high‐precision negative Poisson's ratio (NPR) structures was achieved; these structures undergo programmable shape changes upon thermal and photonic stimulation. This work provides a novel strategy for developing high‐performance 4D printing smart materials and structures through straightforward melt blending.

Moisture crosslinking would be a good substitution to cure ethylene‐vinyl acetate‐glycidyl methacrylate rubber (EVM‐GMA) due to the characteristics of low cost and environmental friendliness. Our previous study found amino silane grafted onto EVM‐GMA with low degree due to the low epoxy group content in rubber matrix. Consequently, the moisture crosslinking density of rubber compound is low. So, it is necessary to find an effective method to improve the moisture crosslinking density of EVM‐GMA. In this paper, EVM‐GMA grafted with γ‐aminopropyltriethoxysilane and maleic anhydride (EVM‐GMA‐g‐APTES/MAH) composites were prepared by melt blending, and then the moisture crosslinking of composites was achieved in a 90°C water bath with the aid of catalyst dibutyltin dilaurate (DBTL). The grafting of MAH onto the EVM‐GMA molecular chain and its reaction with amino silane were confirmed by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT‐IR). Furthermore, the moisture crosslinking density of the samples before and after grafting MAH was compared. The results indicated that the moisture crosslinking density of the grafted MAH was higher than that of the unmodified rubber, thus achieving better overall mechanical properties. Therefore, grafting MAH was a feasible way to improve the moisture crosslinking density of EVM‐GMA with the existence of silane.