Journal of Polymer Research最新文献

A novel gradient copolymer, poly(norbornadiene-grad-cyclohexadiene), was synthesized via ring-opening metathesis polymerization (ROMP) of norbornadiene (NBD) and vinyl-addition of cyclohexadiene (CHD) mechanism using Grubbs’ third-generation catalyst (G3). To overcome the intrinsic brittleness and limited thermal performance of cyclic olefin copolymers, the material was further modified through catalytic hydrogenation using a palladium supported on porous nickel decorated with carbon nanotubes (Pd@PN-CNT). The post-polymerization (catalytic hydrogenation) significantly enhanced the thermomechanical properties: the glass transition temperature increased from 127 ℃ to 139 ℃, and the degradation temperature rose from 438 ℃ to 519 ℃. Mechanical testing revealed improvements in tensile strength (from 14.58 MPa to 28.93 MPa), elongation at break (from 16.44% to 32.34%), and elastic modulus (from 28.61 MPa to 39.87 MPa). These improvements are attributed to the saturation of unsaturated bonds, reduction in chain defects, and enhanced phase separation. The high hydrogenation efficiency of the Pd@PN-CNT catalyst also demonstrated excellent reusability. This work presents a viable route for tailoring the thermal and mechanical performance of gradient copolymers, positioning hydrogenated poly(NBD-grad-CHD) as a promising candidate for advanced applications in elastomers and high-performance engineering materials.

In the present study, we investigated the segregation behavior of a plasticizer, i.e., dibutyl phthalate (DBP) in a polymer, i.e., polystyrene, subjected to a temperature gradient. We confirmed homogeneous distribution without phase separation when the DBP content was ≤ 15%. A sample film containing 10% DBP was annealed in a compression-molding machine, in which the top and bottom plates were held 3 mm apart at 200 and 120 °C, respectively. After exposure to the temperature gradient, a DBP gradient distribution was confirmed in the thickness direction: there was a high DBP content at the high-temperature side and a low DBP content at the low-temperature side. The result indicates that a plasticized polymer adopts a plasticizer concentration gradient, i.e., a graded structure, when subjected to a temperature gradient.

Emulsified oil has dynamic stability, and its harmless treatment has become a challenging problem worldwide. Membrane filtration technology has garnered significant attention in the field of oil-water separation due to its low cost, high efficiency, and environmental friendliness. In this study, NH₂-CAU-1 was incorporated into a polyphenylsulfone (PPSU) matrix to fabricate superhydrophilic and antifouling mixed matrix membranes (MMMs) via the phase inversion method, which were subsequently used for the separation of several oil-in-water emulsions. By adjusting the NH₂-CAU-1 loading capacity, the mechanical properties, wettability, separation performance, and antifouling properties of the MMMs were optimized. The results indicated that when the NH₂-CAU-1 loading is 0.1 wt%, the MMMs exhibited superhydrophilicity (water contact angle is 4.2°) and underwater superoleophobicity (underwater oil contact angle is 153.4°), achieving a separation efficiency of over 99.55% for various oil-in-water emulsions, with an irreversible fouling rate of only 2.66%.

Imidazolium-based ionic liquids (ILs) with different counter anions (Br⁻, BF₄⁻, PF₆⁻) were synthesized through quaternization and ion-exchange methods to explore their role as functional dopants in hybrid conducting composites. These ILs were incorporated into polyaniline (PANI) and graphite (Gr) matrices to form IL–PANI and IL–Gr nanocomposites. Comprehensive characterization—including FTIR, TEM, and TGA confirmed successful integration and structural uniformity. Dielectric spectroscopy and electrical conductivity measurements demonstrated tunable properties across a wide frequency range, with conductivity values spanning 10⁻⁹ to 10⁻5 S/cm, ideal for electrostatic discharge (ESD)-safe applications. The materials also exhibited high thermal stability and enhanced interfacial polarization, attributed to counter anion-dependent structuring within the composite matrix. These results position IL-modified PANI/Gr systems as promising candidates for antistatic coatings, flexible printed electronics, and next-generation high-k dielectric components. The approach offers a scalable strategy to engineer multifunctional composites with tailored electrical properties for use in advanced energy and electronic applications.

A diamide-preformed diamine monomer, N,N’-bis(4-(4-aminobenzamido)phenyl)-N,N’-diphenylbenzidine, was successfully synthesized and subsequently employed to produce electroactive aromatic poly(amide-imide)s (PAIs) through two-step polycondensation reactions with commercially available tetracarboxylic dianhydrides. The resulting PAIs exhibit good solubility in various organic solvents and can be solution-cast into smooth, flexible thin films. They demonstrate high thermal stability, with glass transition temperatures ranging from 292 to 304 °C and no significant decomposition observed before 450 °C. Their cyclic voltammograms reveal two closely spaced oxidation waves at approximately 0.87 V and 1.04 V (vs. Ag/AgCl), indicating a reversible electrochemical oxidation process accompanied by color changes from a colorless neutral form to chrome yellow in the first oxidation stage, and subsequently to deep blue in the second oxidation stage. In comparison to the polyimide derived from N,N’-bis(4-aminophenyl)-N,N’-diphenylbenzidine and 4,4’-oxydiphthalic anhydride, the corresponding PAI exhibits a lower oxidation potential and higher solubility in organic solvents. The PAIs demonstrate promising electrochromic performance, characterized by rapid response time, high optical contrast, high coloration efficiency, and satisfactory switching stability and reversibility.

Blends of linear low-density polyethylene (LLDPE) and ethylene-octene copolymer (EOC) are prepared in various compositions by melt mixing, followed by electron beam (EB) irradiation at dose ranging from 50 to 250 kGy. The effects of blend composition and EB irradiation on the free volume of LLDPE/EOC blends are investigated using positron annihilation lifetime spectroscopy (PALS). Two ortho-positronium (o-Ps) lifetime components extracted from the PALS spectra indicate the presence of two distinct phases in the LLDPE/EOC blends. These components provide insights into the free volume properties of the crystalline and amorphous phases of the polymers. Analysis of the variation in o-Ps annihilation parameters (lifetime and intensity) in these phases confirms a significant increase in the crosslinked three-dimensional network with increasing irradiation dose up to 150 kGy for the LLEO82 blend (LLDPE/EOC: 80 wt%/20 wt%) and 200 kGy for the LLEO28 blend (LLDPE/EOC: 20 wt%/80 wt%). The increase in crosslinking density with EB irradiation is further supported by gel fraction measurements. The results from PALS, gel fraction and thermal analysis are consistent with each other. The study shows that o-Ps parameters are highly effective for determining the free volume hole size and relative fractional free volume in both unirradiated and irradiated LLDPE/EOC blends.

This study aimed to explore the effects of ester-based internal electron donors on the efficacy and characteristics of SiO₂@MgCl₂ bi-supported Ziegler-Natta (ZN) catalysts. Four distinct ester-based electron donors were used during catalyst synthesis, including linear diesters with varying carbon chain lengths (diethyl succinate and diethyl malonate), aromatic diesters (di-n-butyl phthalate), and aromatic monoesters (ethyl benzoate). Synthesized catalysts were employed in ethylene polymerizations using H₂ as a molar mass moderator. Various analytical techniques and measurement of bulk density was employed to analyze the prepared catalysts and polymers. SEM analysis revealed that most catalyst particles had a spherical morphology, except for the catalyst incorporating malonate as an internal electron donor. The phthalate catalyst showed a larger diameter, mainly due to its role as a binding agent. The molecular weight, activity, and bulk density of polyethylene were found to be influenced by the type of electron donor. The catalyst with SiO₂@MgCl₂/THF/TiCl₄/ethyl benzoate exhibited significantly higher catalytic activity and response to hydrogen, which can be attributed to the reduced steric hindrance surrounding the ethyl benzoate compound. These findings have implications for the development of more efficient and sustainable polymerization processes, with potential applications in various industries using polyethylene.

The aim of this work was to investigate and analyse the feasibility of pyrolytic tyre char (PT-char) as filler in polypropylene (PP) composites. Untreated PT-char was first demineralised with acid-base lixiviants (nitric acid and sodium hydroxide) to remove impurities. Thereafter, surface modification was done using either 3-methacryloxypropyletrimethoxysilane (3-MPTS) or titanium IV 2,2 (bis-2-propenolatomethyl) butanolato, tris (dioctyl) pyrophosphato-O (LICA 12) coupling agents, or maleic anhydride-grafted polypropylene (MAgPP) compatibiliser to improve surface compatibility. PP composites filled with varying amounts of unmodified or modified PT-char were produced following which impact strength, surface fracture and tensile properties were tested to evaluate the feasibility of using PT-char as filler. Unmodified PT-char showed moderate improvements in some mechanical properties. On the other hand, demineralisation of PT-char generally reduced the mechanical properties. Surface modification with 3-MPTS and LICA 12 improved the mechanical properties of PP composites due to enhancement of the interface between PT-char and the PP matrix. High PT-char loadings reduced the mechanical properties of PP composites particularly with demineralised PT-char, presumably due to aggregation of small particles which caused defects in the composites system. PT-char demonstrated good potential for use as a filler in PP composites; however, application of a suitable surface modifier is imperative to enhance compatibility between the PT-char and the PP matrix and reduce the impact of aggregation of the PT-char particles. A technically feasible solution was presented for valorisation of waste PT-char, while simultaneously enhancing the mechanical properties of everyday PP composites.

The growing market of efficient thermal management materials in architectural and energy systems has led to the creation of polymer composite materials with better heat dissipation properties. In this work, the high-density polyethylene (HDPE) composites loaded with graphite and different metal (Cu, Mg, Bi, Fe, Sr, Na) nitrate doped carbon quantum dots (CQDs) are presented. The metal nitrate doped CQD is synthesized using pulsed thermal treatment using citric acid, urea, and metal nitrates. The Cu-doped CQD composite exhibited a substantial enhancement in thermal conductivity compared to bare HDPE, with an improvement of approximately 10.5%. Additionally, dielectric measurements revealed that Bi-, Fe-, and Cu-doped composites exhibited the highest improvements in conductivity, indicating strong interfacial interactions and effective charge transport pathways within the composite matrix. Analysis such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and dielectric spectroscopy analyses further revealed extensive interaction between filler matrices, a decrease in phonon scattering, and a positive increase in crystallinity which led to the improved thermal performance.The TGA results showed that the composite exhibited greater thermal stability, and the residue mass after the decomposition process was 9%, indicating increased carbonization and structural integrity. These results point to a scalable approach for developing lightweight corrosion resistant thermal management composites that can be used in the design of energy efficient wall panels and heat-dissipative building materials.

This study is inspired by the exquisite multi-level structure of trabecular bone, and innovatively proposes a design and preparation strategy for nonlinear oriented (irregular arrangement of microstructure) reinforced hydrogels with micro-zone limitation (precise regulation of mechanical property in mirco-zone), achieving precise regulation of the internal structure of hydrogels. Based on the force-bearing model of the porous structure of trabecular bone, this study uses polyvinyl alcohol (PVA) as the raw material to successfully prepare a porous hydrogel framework (PHF) at the macroscopic scale. The framework is composed of multiple tricorn micro-zone (TMZ) units, laying a foundation for subsequent structural regulation. At the mesoscopic level, with the aid of mechanical training methods, nonlinear oriented fibers along the contour direction spontaneously form inside the TMZ units, with the fiber orientation degree reaching 0.9788. The correctness of this force-bearing mode is verified through finite element mechanical simulation. At the microscopic level, point-by-point scanning of TMZ units using the synchrotron radiation light source confirms that the maximum molecular chain orientation degree reaches 86.5%, and the crystallinity reaches up to 50.4%. According to mechanical property tests, the hydrogel with outstanding mechanical characteristics is endowed by the non-linear orientation structure. The tensile breaking strength of this hydrogel can reach up to 8.83 ± 0.62 MPa, and the compressive strength at 80% strain reaches 6.91 ± 0.48 MPa, achieving a significant improvement compared with the regular hydrogel system, and conceptually opening up new ideas for the hydrogel field of structural mechanics enhancement.