Journal of Polymer Research最新文献

The incorporation of conducting polymers with nanostructure materials offers a promising route to multifunctional materials with improved electrochemical and thermal properties. In this study, poly(2-anisidine) (P(2-ANIS)), a methoxy-subst ituted derivative of polyaniline, was synthesized via oxidative polymerization and combined with titanium carbide(TiC) nanoparticles to form hybrid nanocomposites. Two methods were used : in situ polymerization, where TiC was present during polymer preparation, and ex situ method, where TiC was introduced after polymer obtained. Comprehensive characterization including XRD, FTIR, TEM, TGA, UV–Vis, cyclic voltammetry, and electrical con ductivity measurements was carried out to evaluate the effect of each method on the structural, thermal, and electronic properties of the composites. Results display that the in-situ method yields high particle dispersion, stronger interfacial interaction, enhanced electrochemical redox activity, and higher thermal stability compared to the ex-situ polymerization. However, the incorporation of TiC nanoparticles into the P(2-ANIS) matrix resulted in an increase in the optical band gap and a moderate decrease in electrical conductivity compared to the pure P(2-ANIS). These results demonstrate the influence of the synthesis method on the structural properties of P(2-ANIS)@TiC nanocomposites and provide valuable insight into tailoring polymer nanoparticle interfaces for advanced functional applications.

This work presents the synthesis of hyperbranched oligohydroxyethylaminourea(methyl)urethanes of the second, third and fourth generations by a two-step divergent scheme using triethanolamine, dimethyl carbonate and monoethanolamine. The proposed method provides high yields of the target products (95.56–97.74%). The structure of the synthesized compounds was confirmed by a comprehensive analysis using IR spectroscopy, NMR (¹H, ¹³C), titrimetry and elemental analysis, which made it possible to reliably determine the composition of functional groups (OH – 5, 9, 17; NH – 4, 8, 16), molecular weight (697, 1318, 2459 g/mol) and the degree of branching of molecules (0.875, 0.88, 0.91) for the 2nd, 3rd and 4th generations. Thermogravimetric analysis revealed high thermal stability of the oligomers up to 135–137°C, while X-ray diffraction analysis revealed an amorphous phase state with partial crystallinity in the fourth-generation macromolecules. Molecular modeling using the PM3 method demonstrated an increase in macromolecular size with increasing generation, while DLS and SEM methods revealed a spherical particle morphology exceeding the size of single molecules due to intermolecular bonding. The obtained results open up prospects for the application of the synthesized hyperbranched oligomers in catalysis, active substance carriers, and other areas of materials science requiring structurally controlled polymer systems with controlled properties.

Degradation is heavily influenced by the polymer’s molecular structure, morphology, and the presence or absence of additives. Long-term accelerated weathering experiments, lasting up to 10,000 h, were conducted on various commercial polyethylene (PE) and polypropylene (PP) resins in a Weatherometer (WOM). Dumbbell-shaped test pieces were produced from various resins, including both virgin grades with and without antioxidant additives, as well as recycled high-density polyethylene (HDPE). Throughout the experiment, test specimens were removed from the WOM at regular intervals of 2000 h and analysed for molecular weight, carbonyl index, additive content, and morphological changes. The results indicated the effectiveness of antioxidants and UV stabilisers in protecting polyolefins from significant degradation. In contrast, polyolefins with limited or no UV stabilisers and antioxidants exhibited severe degradation. The PP materials were found to degrade more rapidly than their PE counterparts. Among the virgin PE grades, low-density polyethylene (LDPE) experienced a higher rate of degradation than HDPE. Interestingly, HDPE with an adequate concentration of UV and antioxidant additives showed no signs of deterioration over the test period of 10,000 h. Notably, recycled HDPE containing antioxidant additives degraded more quickly than additive-free HDPE, possibly due to pre-existing free radicals in the recycled material. Oxidative degradation was characterised by a pronounced decline in molecular weight and a marked increase in carbonyl functionalities. Surface deterioration, especially the development of microcracks, was a clear indicator of weathering. The PE samples with microcracks demonstrated a significant drop in impact strength, suggesting that such cracks serve as stress concentrators or notches. This finding highlights the direct relationship between microcrack formation and diminished impact performance. The mechanisms of crack propagation in PE and PP resins appeared to differ, likely reflecting differences in their crystalline morphologies.

Multifaceted bio-contamination, including natural organic matter (NOM) and microbial colonization, challenges the application of hydrophobic polyvinylidene fluoride (PVDF) membranes in water purification. To address organic and biofouling, a UV irradiation grafting strategy is developed to fabricate dual-functional PVDF membranes with integrated antibacterial and anti-fouling capabilities. Two quaternary ammonium salts (QAS)—short-chain allyltrimethylammonium chloride (ATMAC, C6) and long-chain methacryloxyethyltrimethylammonium chloride (DMC, C9)—are grafted onto PVDF membranes. Herein, C6 and C9 denote quaternary ammonium salts bearing hexyl and nonyl alkyl substituents, respectively. The best surface modification induced a 43.4% reduction in water contact angle (88.5° to 45.1°), demonstrating significantly enhanced hydrophilic characteristics of the modified membranes, surfaces with enhanced positive character (zeta potential shifted from − 30.22 mV to − 20.15 mV), and dual antifouling mechanisms via pore-clogging mitigation and hydration layer formation. The PVDF membrane grafted with 7.5 wt% DMC demonstrates optimal performance, achieving a 98.5% flux recovery ratio during sodium alginate filtration and > 99% bactericidal efficiency against E. coli and S. aureus. By grafting QAS(e.g., DMC/ATMAC) onto PVDF membranes, this approach mitigates irreversible fouling while sustaining long-term antimicrobial activity, providing a robust solution for biofouling-resistant membranes in sustainable water treatment.

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A novel diamide-diamine monomer, N, N’-bis[4-(4-aminobenzamido)]-N, N’-di(2-naphthyl)-1,4-phenylenediamine, was synthesized and polymerized with three aromatic tetracarboxylic dianhydrides to produce three new poly(amide-imide)s (PAIs), each featuring two redox-active triarylamino cores in its repeating unit. The resulting polymers exhibited excellent solubility in polar organic solvents and could be solution-cast into strong, flexible films with high thermal stability. Their cyclic voltammograms revealed two distinct and reversible redox processes within a potential range of 0 to 1.5 V. Upon oxidation, all the PAIs exhibited visible and near-infrared dual-band electrochromic behavior. The polymer films underwent a color change from a colorless neutral state to grass green at the first oxidation stage, and then further transformed to dark blue at the second stage. All the PAIs demonstrated high electrochemical and electrochromic stability during both the first and second redox processes.

This paper breaks through the traditional hydrophobic design concept of antifouling coatings by combining aggregated state structure, interface structure, and coating micro-nano surface structure to prepare an organic-inorganic hybrid epoxy resin with a mesogenic structure, addressing the defects of poor coating toughness and insufficient antifouling performance in complex marine environments. Firstly, a liquid crystalline epoxy curing agent and Ag@SiO₂ antifouling particles with both reactivity and hydrophobicity were designed and prepared. By blending the self-made curing agent, modified nano-Ag, and E-44, an organic-inorganic hybrid epoxy resin integrating microbial attachment inhibition, hydrophobicity, liquid crystallinity, and micro-nano surface structure was successfully prepared. Results showed that the adhesion of the composite coatings reached grade B or above, and the hardness reached grade H or above. Due to the increase in the number of flexible C atoms in the side chain of the curing agent molecule, ordered liquid crystal microdomains are induced during the curing process. The synergistic effect of the rigid liquid crystal mesogenic units and the flexible side chains effectively promotes stress dispersion and increases the mobility of molecular segments, thereby increasing the elongation at break from 0.51% to 5.3%, achieving a transition from brittle fracture to ductile fracture. The composite coating (TC-20) surface possessed a complex micro-nano rough structure, with a contact angle of 127° and a surface energy of 8.9 mJ/m², exhibiting significant self-cleaning performance. After continuous abrasion and acid-base corrosion, the surface structure of the composite coating remained intact, demonstrating persistent hydrophobic and barrier properties. When the addition amount of SG-1 was only 1.5%, the antibacterial rates of the composite coating against E. coli and S. aureus reached 99% and 99.4%, respectively; when the addition amount of SG-1 was 2%, the anti-protein adsorption efficiency reached 82.5%, indicating high-efficiency antifouling performance.

Polymer composites have different properties due to different molding processes. Exploring the best molding process is a key challenge currently faced by research. This study simultaneously investigated the effects of injection molding and 3D printing on the chemical structure, thermal stability, microstructure and mechanical properties of rice husk (RH)/polylactic acid (PLA) composites, aiming to explore the optimal process for the preparation of RH/PLA composites. The results showed that RH successfully bonded with PLA (FTIR), and as the RH content in PLA increased, the thermal stability of the composite gradually decreased (TGA). The distribution of RH in the injection molded composites was more uniform than that in the 3D printed composites under the microscopic morphology (SEM), and the mechanical properties of the injection molded composites were better than 3D printed composites under the same RH content. Among them, the maximum tensile strength and bending strength of the composites with 15% RH content by injection molding reached 72.63 MPa and 99.66 MPa, respectively 71% and 22% higher than that of the composites with 15% RH content by 3D printing.

A series of new fluorenyl-tethered oxazoline based ligands, L = 2-(1-(9 H-fluoren-9-yl)alkyl)-4,5-dihydrooxazole [alkyl = butyl (5a), propyl (5b), ethyl (5c), methyl (5d)] were prepared via an effective synthetic strategy starting from fluorene and ethyl 2-bromoalkanoates, followed by four consecutive reaction steps. Ligands were thoroughly characterized by ¹H NMR, ¹³C NMR, FTIR, HRMS and elemental analyses. The molecular structure of 5a and 5d were determined by single crystal X-ray diffraction analysis. Deprotonation of the ligands 5a-d with n-BuLi, followed by subsequent metallation with TiCl₄ afforded the corresponding titanium(IV) complexes Ti1–Ti4. These complexes were characterized unambiguously by NMR spectroscopy, mass spectrometry, and elemental analysis. Upon activation with TIBA/[Ph₃C][B(C₆F₅)₄], these half-sandwich titanium(IV) complexes showed catalytic activity toward ethylene polymerization producing polyethylene with ultrahigh molecular weight up to 2.09 × 10⁶ g.mol^− 1. The relatively broad PDI range (4–6) for the polyethylene obtained by these catalytic systems may help to improve flow properties of the polymers. Notably, complex Ti1, containing a bulky propyl substituent on the bridging carbon, exhibited the highest catalytic activity among the synthesized titanium complexes under the optimized conditions of 50 °C and an Al/Ti molar ratio of 200. The well-defined melting temperature (T_m) of the resulting polymers, observed in the range of 131–134 °C, indicates the formation of predominantly linear polyethylene chain architecture.

Shaping of polymer sheets into complex shapes has been traditionally achieved using thermoforming process. However, for customized and complex geometries it is not economical to make dedicated moulds. Thus, Incremental Sheet Forming (ISF) has been explored for polymer sheet forming without the need of a dedicated moulds. ISF is a die-less and an adaptable manufacturing process, which offers unique advantages over other forming methods, due to its low tooling cost, rapid geometric customization, and the ability to form complex shapes through localized plastic deformation. Polycarbonate (PC), an engineering-grade amorphous polymer, is widely utilized for automotive, aerospace, and biomedical applications, etc., owing to its good impact resistance, optical transparency, and thermal stability. This work experimentally studies the formability of PC sheets with respect to the variation in the process parameters of incremental step depths and toolpaths during the ISF process. Furthermore, to improve the usability and industrial adoption of this process, a MATLAB^®-based-graphical user interface (GUI) was developed, enabling users to input geometrical parameters, and generate different toolpaths to fabricate various geometrical 3D shapes. The study demonstrated that the spiral toolpath yielded higher tensile strength, better elongation through thermo-mechanical softening, and improved geometrical deformation compared to the conventional contour toolpath. Moreover, the smallest step depth of 0.1 mm assisted in achieving uniform surface finish with minimal tool markings on the formed part. With spiral strategy, lower average surface roughness of 0.97 μm were observed with lesser strain accumulation, relative to the contour, having the roughness of 1.4 μm. Whereas, increasing the wall angle from 30° to 60° also enhanced the viscoelastic material flow and surface quality with less deformation gradients, leading to higher formability and delay in localized fracture. Overall, these outcomes showed that with optimized parameters and incorporation of the GUI, can strengthen the potential of the ISF process for industrial-scale polymer forming applications.

In this study, the effect of thermal and UV-ozone/ozone-induced oxidation on the electrical conductivity of poly(2,3-dihydrothieno-1,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS) film was systematically studied by varying two dry oxidation mechanisms: annealing of PEDOT:PSS from 120 to 240 °C and UV-ozone/ozone exposures at different time intervals (i.e., 0 to 32 min). The comparative maximum electrical conductivity was achieved in the 200 to 240 °C annealing range, with conductivity showing a dynamic, complex dependence on temperature: initial reduction at lower temperatures, followed by a dramatic increase around 200 °C, and subsequent saturation at 220–240 °C. This behavior is attributed to the temperature’s influence on the organization and cross-linking/alignment of polymer chains. However, the high conductivity achieved at 240 °C significantly degraded within five days, contrasting with the more stable conductivity observed for films annealed at 150 °C and 200 °C. On the other hand, both UV–ozone and pure ozone treatments increased the surface energy and work function of the polymer; however, the rate of increase in surface energy was higher for UV–ozone, while the rate of increase in work function was higher for ozone-only exposure. Such changes in electronic and surface properties are likely driven by UV/ozone-induced oxidation and the resulting cross-linking within the material. The findings offer new insights into the oxidation-driven modifications of PEDOT:PSS, providing strategies to precisely tailor its electronic and surface properties for enhanced optoelectronic device performance.

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