Journal of Polymer Science最新文献

Pressure-Sensitive Adhesives (PSAs) are widely used in flexible packaging due to their rapid adhesion, excellent transparency, and mechanical flexibility. However, traditional solvent-based PSAs pose environmental hazards; although waterborne alternatives are more eco-friendly, they often suffer from limited adhesion, poor wetting on low-energy surfaces, low mechanical strength, and inadequate microbial resistance without additional additives. To overcome these challenges, two hybrid polyurethane acrylate (PUA) systems were synthesized: a conventional PUA (prepolymer-01) and a zwitterionic-based PUA (ZPUA, prepolymer-02). From these prepolymers, five PSA emulsions were formulated: one from acrylic monomers (PSA-01), one from PUA (PSA-02), and three from ZPUA (PSA-03, PSA-04, PSA-05). The incorporation of zwitterionic segments into the PUA backbone was confirmed by FTIR spectroscopy. Thermogravimetric analysis (TGA) demonstrated the superior thermal stability of ZPUA over its non-zwitterionic counterpart. ZPUA-based emulsions exhibited excellent wettability on low-energy surfaces, a key advantage for packaging applications. Moreover, tensile testing showed that zwitterionic PSA films (PSA-03 to PSA-05) outperformed their non-zwitterionic counterparts (PSA-01, PSA-02) in both tensile strength and elongation at break. Improved adhesion was also observed on difficult-to-bond surfaces, confirming the benefit of zwitterion integration. Importantly, the ZPUA emulsions displayed intrinsic antimicrobial activity, potentially eliminating the need for formalin as a preservative.

Cyanate ester resin (CER) is an excellent thermosetting polymer. However, its brittleness and poor mechanical properties limit its application. The innovation of this work lies in the smart collaborative toughening effects of Eu³⁺/Tb³⁺@uCNTs working together with phenolphthalein polyether sulfone (marked as PES-C) on dicyanate ester of bisphenol F. Tb³⁺-complex enhances Eu³⁺@uCNT-effects, and the cooperation of PES-C together with Eu³⁺-Tb³⁺@uCNTs (marked as ET-uC) functions strongly to increase flexural, tensile, and impact strengths by 209%, 120%, and 286%, respectively. When additions of ET-uC ratio at 0.6 wt% and PES-C ratio at 15% to CER. At the same time, we can get more multiple enhancing effects can be observed as below. The introduction of ET-uC reduces the curing temperature of the composite material from 342°C to 271°C. At the same time, the mass loss rate decreased from 87% to 55%. The intensity of luminescent CER/ET-uC/PES-C is much stronger compared to CER/ET-C/PES-C. If the curing temperature is 250°C, the luminescence lifetimes of CER/ET-C/PES-C and CER/ET-uC/PES-C become 411.23 and 731.91 μs, respectively. These strong data confirm that our strategy of ET-uC collaborating with the linear thermal stable polymer of PES-C functions has generated the breakthrough to improve the comprehensive properties of CER.

The forming quality of blocked polyurethane (BPU) elastomers is critically governed by their rheokinetic response during curing. Nevertheless, existing constitutive models remain constrained by Newtonian assumptions and the absence of shear-rate coupling, limiting predictive reliability. In this study, rheological characterization across multiple conversion levels, combined with phase-field normalization, enables the derivation of a power-law index model coupling temperature and normalized relative viscosity (α). This relation reveals a transition from quasi-Newtonian to non-Newtonian behavior during curing, with the power-law index scaling proportionally with lnα and temperature. Within an Arrhenius-power-law framework, a dynamic power-law multifield coupled (DPL-MFC) rheological model is developed, achieving high-accuracy prediction of apparent viscosity across broad processing conditions with a global mean absolute percentage error (MAPE) of 0.80%. By further decoupling temperature and shear effects, an α-Arrhenius relation is formulated and integrated with the rheological model to yield the DPL-MFC rheokinetic model. This model resolves the time-dependent coupling among thermal, chemical, and shear fields, achieving a MAPE of 1.85% under isothermal conditions and extending seamlessly to non-isothermal regimes. The proposed non-Newtonian rheokinetic paradigm transcends the limitations of classical models, providing a robust theoretical benchmark for precision manufacturing of advanced thermosetting polymers.

This study investigates the hydrogelation behavior of amphiphilic triblock copolymers composed of a long poly(ethylene glycol) (PEG) chain as the hydrophilic central block and various aromatic polypeptides—poly(S-benzyl-_L-cysteine) (PBLC), poly(O-benzyl-_L-tyrosine) (PBLY), poly(_L-phenylalanine) (PLF), poly(γ-benzyl-_L-glutamate) (PBLG), and poly(Z-_L-lysine) (PZLL)—as hydrophobic terminal blocks. The results reveal that the long PEG chain, polypeptide chain length, and side-chain functional group critically influence amphiphilic balance and non-covalent interactions, which govern hydrogel formation and mechanical properties. Structural analysis identified intermolecular hydrogen bonding, π–π interactions on aromatic side chains, and PEG backbone entanglement as key factors stabilizing the hydrogel network. The PBLC-PEG-PBLC and PBLY-PEG-PBLY samples with a short polypeptide segment exhibited enhanced gel network stability and stiffness, evidenced by the crossover points of the moduli at the strain values higher than 300.0%. Among all the studied samples, PBLC_4.8-PEG20000-PBLC_4.8 and PLF₆-PEG20000-PLF₆ exhibited superior hydrogelation performance due to optimal hydrophilic/hydrophobic balance. Rheological studies demonstrated shear-thinning behavior and recovery post-deformation, highlighting suitability for injectable applications. However, higher stiffness was found to hinder smooth extrusion through needles. Additionally, the in vitro cytotoxicity proved their biocompatibility for normal cells. These findings underscore the potential of PEG-based triblock copolymers with aromatic polypeptides for designing tunable hydrogels with tailored mechanical properties for biomedical applications.

Fused deposition modeling (FDM) faces significant challenges in producing unsupported overhangs, particularly regarding dimensional accuracy and surface quality. While support structures can address these issues, they increase material waste and post-processing requirements. This study investigates how process parameters affect the quality of unsupported inclined surfaces in FDM printing, aiming to optimize fabrication without support structures. Test specimens with three surface inclination angles—75° (Surface-1), 60° (Surface-2), and 45° (Surface-3)—were produced using acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and polyethylene terephthalate glycol (PETG). The study employed an L27 Taguchi orthogonal array to evaluate five key process parameters: material type (MT), infill pattern (IP), wall thickness (WT), infill density (ID), and layer thickness (LT). Dimensional deviations and surface roughness were measured across all angled regions. Dimensional deviations remained below 2.3% across all specimens. ANOVA revealed LT and MT as the most significant factors affecting both dimensional accuracy and surface roughness (p < 0.001), with LT showing the highest contribution to surface roughness variance (F values > 500). Surface roughness improved with decreasing surface angles, while dimensional accuracy showed an inverse trend. Artificial neural network (ANN) models developed for predicting quality metrics achieved R ² values exceeding 0.90. This study establishes a comprehensive framework integrating Taguchi design, statistical analysis, and machine learning (ML) for optimizing unsupported overhang fabrication in FDM. The findings reveal crucial relationships between process parameters and part quality, demonstrating that carefully controlled parameter selection can achieve acceptable quality without support structures. The developed predictive models offer a reliable tool for parameter optimization in FDM manufacturing of unsupported overhangs.