Chinese Journal of Polymer Science最新文献

In this work, poly(3-hexylthiophene) (P3HT) ultrathin films (P3HT-T) were prepared by spin-coating a dilute P3HT solution (in a toluene: o-dichlorobenzene (Tol:ODCB) blend with a volume ratio of 80:20) with ultrasonication and the addition of the nucleating agent bicycle [2.2.1] heptane-2,3-dicarboxylic acid disodium salt (HPN-68L) on glass, Si wafers and indium tin oxide (ITO) substrates. The electrical and mechanical properties of the P3HT-T ultrathin films were investigated, and it was found that the conductivity and crack onset strain (COS) were simultaneously improved in comparison with those of the corresponding pristine P3HT film (P3HT-0, without ultrasonication and nucleating agent) on the same substrate, regardless of what substrate was used. Moreover, the conductivity of P3HT-T ultrathin films on different substrates was similar (varying from 3.7 S·cm⁻¹ to 4.4 S·cm⁻¹), yet the COS increased from 97% to 138% by varying the substrate from a Si wafer to ITO. Combining grazing-incidence wide-angle X-ray diffraction (GIXRD), UV-visible (UV-Vis) spectroscopy and atomic force microscopy (AFM), we found that the solid order and crystallinity of the P3HT-T ultrathin film on the Si wafer are highest, followed by those on glass, and much lower on ITO. Finally, the surface energy and roughness of three substrates were investigated, and it was found that the polar component of the surface energy γ^p plays a critical role in determining the crystalline microstructures of P3HT ultrathin films on different substrates. Our work indicates that the P3HT ultrathin film can obviously improve the stretchability and simultaneously retain similar electrical performance when a suitable substrate is chosen. These findings offer a new direction for research on stretchable CP ultrathin films to facilitate future practical applications.

Non-aromatic fluorescent and multi-responsive materials, exhibiting inherent fluorescence emission and controlled phase change, have garnered significant attention in recent years. However, the underlying interaction between their fluorescent properties and phase transition remains unclear. In this study, we synthesized a series of catalyst-free aza-Michael addition-based polyethyleneimine (RFPEI) materials by reacting polyethyleneimine (PEI) with N-isopropyl acrylamide (NIPAM). The resulting RFPEI was comprehensively characterized, and demonstrated dual-phase transition behavior (LCST and UCST) in water, which could be finely tuned by adjusting its composition or external factors such as pH. Notably, upon UV irradiation (365 nm), RFPEI exhibited strong fluorescence emission. We further investigated the effects of NIPAM grafting percentage to PEI, polymer concentration, and pH on the LCST/UCST and fluorescent properties of RFPEI aqueous solutions. Moreover, we showcased the great potential of RFPEI as a versatile tool for physiological cell imaging, trace detection, and controlled release of doxorubicin. Our study presents a novel class of stimuli-responsive fluorescent materials with promising applications in the field of biomedicine.

In this study, a series of hindered urea bond (HUB) containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the reactive diluent via one-pot procedure. The prepolymers were characterized fully by various techniques. Then, their thermosets were fabricated via UV curing in presence of a photo initiator, and their mechanical property and thermal behavior were investigated and compared. Different from the none HUB containing thermoset, the HUB containing thermosets (defined as PUT) could be recycled and reprocessed by hot press under relatively mild conditions with high recovery ratio of mechanical property. Furthermore, zinc oxide (ZnO) nanoparticles were modified with 3-(trimethoxysilyl) propyl methacrylate and the modified ZnO (defined as ZnO-TPM) was dispersed and polymerized into PUT matrix to prepare their nanocomposites. The influence of ZnO-TPM on the mechanical performance of the composites was evaluated, which indicated that the Young’s modulus and tensile strength increased gradually to the maximum values at ZnO-TPM content of 1 wt% and then decreased. The composites also displayed good reprocessability with improved recovery ratio compared to the pure PUT sample. In addition, the composite materials exhibited strong UV absorption capacity, implying their potential application in the circumstance where UV-shielding was required.

Holographic optical elements (HOEs) based on polymer composites have become a research hot spot in recent years for augmented reality (AR) due to the significant improvement of optical performance, dynamic range, ease of processing and high yield rate. Nevertheless, it remains a formidable challenge to obtain a large field of view (FOV) and brightness due to the limited refractive index modulation. Herein, we report an effective method to tackle the challenge by doping an epoxy liquid crystal termed E6M, which enables a large refractive index modulation of 0.050 @ 633 nm and low haze of 5.0% at a doping concentration of 5 wt%. This achievement may be ascribed to the improved molecular ordering of liquid crystals within the holographic polymer composites. The high refractive index modulation can endow transmission-type holographic polymer composites with a high diffraction efficiency of 96.2% at a small thickness of 5 µm, which would promise the design of thin and lightweight AR devices.

Since electromagnetic pollution is detrimental to human health and the environment, numerous efforts have been successively made to achieve excellent electromagnetic interference shielding effectiveness (EMI SE) via designing the hierarchical structures for electromagnetic interference (EMI) shielding polymer composites. Among the plentiful structures, the asymmetric structures are currently a hot spot, principally categorizing into multi-layered, porous, fibrous, and segregated asymmetric structures, which endows the high EMI shielding performance for polymer composites incorporated with magnetic, conductive, and/or dielectric micro/nano-fillers, due to the “absorption-reflection-reabsorption” shielding mechanism. Therefore, this review provides the retrospection and summary of the efforts with respect to abundant asymmetric structures and multifunctional micro/nano-fillers for enhancing EMI shielding properties, which is conducive to the booming development of polymeric EMI shielding materials for the promising prospect in modern electronics and 5-generation (5G) technology.

Efforts to develop innovative water harvesting strategies offer powerful solutions to alleviate the water crisis, especially in remote and arid areas. Inspired by the hydrophobic/hydrophilic pattern of desert beetles and water self-propulsion property of spider silks, a double-strand hydrophobic PVDF-HFP/hydrophilic PAN nanofibers yarn is proposed by electrospinning and twisting techniques. The double-strand cooperation approach allows for water deposition on hydrophobic PVDF-HFP segment and transport under the asymmetric capillary driving force of hydrophilic PAN segment, thus speeded up the aggregation and growth of droplets. The effects of the composition and the diameter ratio of the two primary yarns were studied and optimized for boosting fog collection performance. The double-strand anisotropic yarn not only provide an effective method for water harvesting, but also hold the potential to inspire innovative design concepts for fog collection materials in challenging environments.

To enhance the mechanical properties of polypropylene random copolymer (PPR), polystyrene (PS) with four different contents were added to the PPR matrix through melt blending. Subsequently, using the Multi-Flow Vibration Injection Molding (MFVIM) technology, PPR/PS in situ microfiber composites (MFC) with different blending ratios were prepared. The results indicated that blending ratio had a great impact on the phase morphology and crystal structure of MFVIM samples, which was different from those of conventional injection molding (CIM) samples. PS ultrafine fibers could be formed under the shear field and could absorb the PPR molecular chains to form hybrid shish-kebab structures. Meanwhile, the PPR matrix could also form shish-kebab structures under the effect of strong shear. When the PS content reached 20%, under the combined action of PS in situ microfibers and highly oriented crystal structure, the tensile strength and Young’s modulus of the sample were obviously improved and the impact strength remained at a relatively high level. So a strong and tough balanced PPR based material was obtained. These results provide valuable insights for expanding the industrial and daily-life applications of PPR and show promising development prospects.

In order to achieve efficient and durable oil-water emulsion separation, the membranes possessing high separation efficiency and mechanical strength attract extensive attention and are in great demand. In present study, a kind of polytetrafluoroethylene (PTFE)-based bilayer membrane was fabricated by electrospinning fibrous PTFE (fPTFE) on an expanded PTFE (ePTFE) substrate. The morphological observation revealed that the fibrous structure of the fPTFE layer could be tailored by controlling the formulation of spinning solution. The addition of appropriate polyoxyethylene (PEO) would make the fibers in the fPTFE layer finer and more uniform. As a result, the compounded membrane exhibited a small pore size of approximately 1.25 µm and a substantial porosity nearing 80%. This led to super-hydrophobicity, characterized by a high water contact angle (WCA) of 149.8°, and facilitated rapid oil permeation. The water-in-oil emulsion separation experiment further confirmed that the compounded membrane not only had a high separation efficiency closing 100%, but such an outstanding separation capacity could be largely retained, either through multiple cycles of use or through strong acid (pH=1), strong alkali (pH=12), or high-temperature (100 °C) treatment. Additionally, the mechanical behavior of the bilayer membrane was basically contributed by that of each layer in terms of their volume ratio. More significantly, the poor creep resistance of fPTFE layer was suppressed by compounding with ePTFE substrate. Hence, this study has laid the groundwork for a novel approach to create PTFE-based compounded membranes with exceptional overall characteristics, showing promise for applications in the realm of emulsion separation.

We utilize molecular dynamics simulations to investigate the microstructures of ions and polyelectrolytes in aqueous solutions under external electric fields. By focusing on the multi-body interactions between ionic components and H₂O molecules, as well as their responses to the external electric fields, we clarify several nontrivial molecular features of the ionic and polyelectrolyte solutions, such as the solvations of cations and anions, clustering of the ions, and dispersions/aggregations of polyelectrolyte chains, as well as the corresponding responses of H₂O molecules in these contexts. Our simulations illustrate the variations in structures of ionic solutions caused by reversing the charge sign of the ions, and elucidate the disparity in structures between anionic and cationic polyelectrolyte solutions in the presence of the external electric fields. This work clarifies the mechanism for the alternations in complex multi-body interactions in aqueous solutions caused by the application electric field, which can contribute to the fundamental understanding of the physical and chemical natures of ion-containing and charged polymeric systems.

Against the backdrop of a global paper resource shortage, there is a growing need to identify fast-growing tree species capable of producing long-lasting paper. Three plant species namely Broussonetia kazinoki, Broussonetia papyrifera and hybrid paper mulberry, belong to the Broussonetia genus, were collected from China to study their white bark suitability for pulp and papermaking. Their chemical composition revealed that the holocellulose content in Broussonetia kazinoki and Broussonetia papyrifera was more than 80%. The molecular weight distribution of several holocellulose/α-cellulose is observed by GPC, which allows us to better observe the changes of various components on the molecular weight. The yield, lignin, whiteness, and molecular weight of the pulps obtained by NaOH treatment were determined. Optical microscope was used to characterize the fiber length-width ratio and rigidity. Finally, the improvement of the fiber rigidity method based on the Kratky-Porod chain model makes it more theoretical and further reveals the influencing factors of fiber rigidity. This study demonstrates the high potentiality of these three species for papermaking applications.