Journal of Polymer Science最新文献

The heat dissipation problem brought about by high heat density components is a key bottleneck restricting the development of the new electronics industry. At present, traditional low thermal conductivity (TC) polymer composites can no longer meet the heat dissipation demand. The requirements for their thermal performance are also increasing. In this work, the epoxy resin/carbon fiber /graphene hybrid felt (Epoxy/CF/G) composites with high in-plane TC were constructed through the synergistic interaction of one-dimensional carbon fiber (CF) and two-dimensional graphene (G). The synergistic effect of CF and G on thermal conductivity is explored. Graphene can bridge adjacent carbon fibers (CFs) to reduce phonon scattering and build multistage heat transfer paths, facilitating the thermal properties. The thermal conductivity value (K) of the prepared composites reaches 24.09 W/mK at a packing load of 35.25 wt%, which is superior to that of Epoxy/CF composites (12.73 W/mK). The heat transport mechanism is analyzed using infrared thermography. The heat dissipation effect is verified by light emitting diodes, further understanding the internal heat flow conduction process. This synergistic effect strategy provides a promising approach for further constructing thermal conduction networks with industrial application value.

Eutectic gels have great advantages in the application of flexible wearable electronic devices due to their good stability and flexibility. However, the adhesion properties of current eutectic gels are poor and the processing process is complicated. Based on this, this study proposed a eutectic gel with excellent adhesion properties that can be photocurable for 3D printing. We designed a polymerizable deep eutectic solvent (PDES) using acrylic acid as the main monomer, acrylic acid/choline chloride (AA/ChCl) as the eutectic solvent, and dopamine-grafted cellulose nanocrystals (DC) as the nanoscale crosslinking agent. The introduction of DC endows the gel with a denser hydrogen bond network, which can effectively provide energy dissipation and improve the mechanical properties of the gel. The introduction of mussel-inspired dopamine into the gel network gives the gel good adhesion. The low freezing point and low volatility of PDES give the gel excellent freezing resistance and long-term storage stability. Furthermore, the gel has a sensitivity factor of up to 9.5 (at 0%–900% strain), showing excellent strain sensing performance. In addition, the gel can not only realize the customization of various complex structures through digital light processing (DLP) 3D printing technology, but also the manufactured wearable devices can complete the accurate sensing of various strain signals of the human body. Therefore, the combination of multi-performance compatible eutectic gel materials and photocurable 3D printing technology will provide a new idea for the design and manufacture of flexible wearable devices.

Dye-containing wastewater (DCW) has become a serious environmental issue worldwide. In this work, thepoly(cyclotriphosphazene-co-2,4-diamino-6-phenyl-1,3,5-triazine) (PBMA) material was synthesized by precipitation polymerization method to probe the adsorptive removal of methylene blue (MB) from DCW. The adsorption conditions were optimized as pH = 7, initial MB concentration = 100 mg L⁻¹, and adsorption time = 800 min. Based on the acid–base interaction, the MB molecules in the DCW was adsorbed over the surface of PBMA. The surface morphology, surface elemental composition and surface functional group changes of PBMA were monitored by scanning electron microscopy images, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy, respectively. The thermodynamic analysis showed that the removal of MB prefers a single-layer adsorption over PBMA surface according to the good fitness of the adsorption results by using Langmuir isotherm (R ² = 0.9906). The kinetic analysis revealed that the adsorptive removal of MB follows the pseudo-second-order kinetics, with intra-particle diffusion and external diffusion as the dominant factors. The PBMA maintained a high adsorption capacity even after undergoing five consecutive adsorption–desorption experiments (Over 90%). The development of polyphosphazene material provides potential application in the field of dye removal from DCW.

We investigated the photovoltaic and piezoelectric power generation characteristics of ferroelectric poly(vinylidene fluoride-ran-trifluoroethylene, PVDF-TrFE) thin films on flexible indium tin oxide (ITO)/polyethylene terephthalate (PET) substrates. The solar cells and piezoelectric hybrid devices provide consistent energy to extend battery life and improve self-charging. The flexible PVDF-TrFE thin films with a transmittance of about 60% in the visible region showed a remanent polarization of about 10.5 μC/cm² (2P_r ~ 21.0 μC/cm²) with excellent β-phase formation. The flexible PVDF-TrFE thin films exhibited optimal ferroelectric and piezoelectric properties by exhibiting β-phase without α-phase. Since β-phase is the phase that carries high dipole alignment of the material, which is important for maximizing power output, the performance of the material in photovoltaic and piezoelectric applications is enhanced. The PVDF-TrFE capacitor exhibited not only a piezoelectric generation characteristic with an approximate voltage of 1.1 V under compression, but also a photovoltaic generation feature with an open-circuit voltage of about 0.23 V and a short-circuit current of approximately 0.13 mA/cm².

This study reports the synthesis and characterization of ABCBA-type pentablock copolymers comprising poly(cyclohexene oxide) (PCHO) as the A block, poly(ε-caprolactone) (PCL) or poly(L-lactide) (PLLA) as the B block, and polystyrene (PSt) as the C block. The target pentablock copolymers, PCHO-PCL-PSt-PCL-PCHO and PCHO-PLLA-PSt-PLLA-PCHO, were synthesized through a sequential combination of ring-opening polymerization (ROP), free radical polymerization (FRP), and, for the first time to the best of our knowledge, photoinduced free-radical-promoted cationic polymerization (FRPCP) in pentablock copolymer synthesis. In the initial ROP step, well-defined Bz-PCL and Bz-PLLA macrophotoinitiators were synthesized with photoactive benzoin (Bz) end groups. Next, Bz-PCL and Bz-PLLA were converted to the macro-azo initiators, Bz-PCL-NN-PCL-Bz and Bz-PLLA-NN-PLLA-Bz, by esterification with 4,4′-azobis(4-cyanovaleric acid) (ACVA). These macro-azo initiators were employed as initiators in the FRP of styrene to form triblock copolymers, which were then used as prepolymers in the photoinduced FRPCP of cyclohexene oxide (CHO) to produce the pentablock structures. Structural characterization conducted via FT-IR and ¹H NMR spectroscopy confirmed the presence of each polymer segment within the pentablock architecture, and gel permeation chromatography (GPC) analysis further validated pentablock formation, showing unimodal distributions. UV–Vis and fluorescence measurements also verified the successful incorporation of the benzoin groups. This multistep synthetic strategy introduces an effective approach for constructing ABCBA-type pentablock copolymers, which might find the potential uses in advanced material design.

We present a heat-resistant strong adhesive system consisting of aromatic polyamide substituted with N-tert-butoxycarbonyl (Boc) groups, synthesized by polycondensation of bis(4-Boc-aminophenyl) ether (1) and isophthaloyl chloride (2), together with a thermal acid generator (TAG). Upon heating, the Boc groups are readily removed by the TAG-generated acid, affording N-H polyamide. Adhesion was conducted at 150°C or 250°C under a pressure of 10 kgf/cm² for 7 h to eliminate voids due to Boc-derived gaseous CO₂ and isobutene. For metal adherends treated at 150°C, the adhesion strength was 2–3 MPa. However, upon treatment at 250°C, above the T _g of N-H polyamide (236°C), the adhesion strength reached 7.43–6.25 MPa for sandblasted steel plate, cold commercial (SPCC) and stainless steel. Next, we prepared copolyamides with lower T _g values from 1, bis(4-methylaminophenyl) ether (3), and 2. Upon treatment at 150°C, the adhesion strength of SPCC with copolyamide consisting of 30% 1 and 70% 3 reached 6.83 MPa. As regards heat resistance, SPCC treated with N-Boc polyamide/TAG at 250°C maintained an adhesion strength of 7.0–7.5 MPa from room temperature to 250°C, whereas SPCC treated with copolyamide/TAG at 150°C maintained an adhesion strength of 6.8–8.2 MPa up to 200°C.

The reaction of organogallium amide LGa(NEt2)2 (1) and organotin carbonate L(Ph)SnCO3 (2), where L = 2,6-(Me2NCH2)2C6H3, with organoboronic acids RB(OH)2 yielded molecular gallium- and stannaboroxines LM(O3B2R2) (3–8) (3: M = Ga, R = 4-tBu-C6H4; 4: M = Ga, R = 4-CF3-C6H4; 5: M = Ga, R = 3,5-(CF3)2-C6H3; 6: M = PhSn, R = 4-tBu-C6H4; 7: M = PhSn, R = 4-CF3-C6H4; 8: M = PhSn, R = 3,5-(CF3)2-C6H3). The Lewis acidity of boron atom (especially in 8) allowed to form N → B coordination bond with bases such as 4-Me2N-pyridine (DMAP) or poly(4-vinylpyridine-co-styrene) (PVPS) yielding new compounds DMAP→8 (9) and PVPS→8 (10). The good film forming properties of 10 allowed the deposition of transparent thin layers by spin-coating method and the determination of their hydrophobic properties by the sessile drop method. The study of hydrophobicity was subsequently focused on the content of stannaboroxine 8 in PVPS and on the concentration influence of the deposited PVPS:8 mixture solution. The parameters of thin layers such as thickness, transparency, and roughness were also determined.

Transparent polyimides were expected to be an alternative to glass substrates. To meet the requirements of high transparency, high heat resistance, and low coefficients of thermal expansion (CTE) for substrate materials, a series of poly(amide-imide)s (PAIs) were synthesized from 2,2′-bis(trifluoromethyl)benzidine (TFDB), (hexafluoroisopropylidene)diphthalic anhydride (6FDA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), terephthaloyl chloride (TPC) and 9,9-bis(4-aminophenyl)fluorene (FDA) with different substituents. And the corresponding films were prepared by adding 0 or 2 pph lithium chloride (LiCl). Through the adjustment of monomer ratio, regulation of the amino ortho-position of diamine monomer, and coordination of Li ions, all PAIs exhibited high glass transition temperatures (T _g) of 390°C–436°C, low CTE of 12.5–60.9 ppm K⁻¹, excellent optical transmittances of 71%–84% at 400 nm, high tensile strengths of 140–204 MPa, and high tensile moduli of 4.4–7.2 GPa. In particular, PAI-M-1-2-2Li showed the best comprehensive properties with the transmittance of 83% at 400 nm, T _g of 432°C, CTE of 18.7 ppm K⁻¹, tensile modulus of 6.9 GPa and tensile strength of 204 MPa, which made it competitive in flexible display applications.

To improve the modulus and tensile strength of polyimide films, this study utilized diamines with amide bonds as monomers, introducing hydrogen bonding into the material. Additionally, a microbranched cross-linked structure was created by incorporating a triamino compound, and its effect on film properties was analyzed. The results showed that the microbranched cross-linked structure and amide bonding significantly improved the storage modulus, tensile strength, shape memory properties, and toughness of the polyimide films. Specifically, at 2% concentration of 1,3,5-tris(4-aminophenoxy)benzene, the storage modulus of the polyimide films reached 12.97GPa, the tensile strength was 243 MPa, the elongation at break was 5.58%, and the toughness was improved by 2.59 times. At this concentration, the shape fixation rate of normal polyimide was 96.7%, and the shape recovery rate was 92%. These findings suggest that the modified polyimide films exhibit high strength and are suitable for applications in high-temperature environments.