Polymer最新文献_第10页

Study on the preparation of side-by-side micro-nano composite fibers by centrifugal spinning based on improved spinneret cavity structure

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-25 DOI: 10.1016/j.polymer.2025.128077

Hao Ye, Jingying Xu, Yaru Wang, Mengyao Zhao, Wanjing Li, Xianglong Li, Bin Yang

Centrifugal spinning of nanofibers has garnered significant attention due to its numerous advantages and industrial potential. However, meeting diverse needs with a single material is challenging, and the production of mixed material fibers often compromises fiber quality due to miscibility issues with different materials. Therefore, this study introduces a novel approach for efficiently preparing side-by-side micro-nano composite fibers by modifying the cavity structure of the centrifugal spinneret. Based on the experimental analysis of fiber spinnability, we derive the motion equation of polymer solution in the spinneret and analyze how the position of cavity plate influences the force exerted on the polymer solution. The optimal spinneret structure was determined through simulation of the solution motion mechanism in various types of spinnerets. Subsequently, polyvinylpyrrolidone (PVP)/ethylene oxide (PEO) composite micro-nanofibers were prepared using a centrifugal spinning device for experimental validation. The results indicate that the left and right cavity structure results in a significant disparity in flow between the two cavities at the nozzle, rendering it unsuitable for producing juxtaposed micro-nano composite fibers. The upper and lower cavity configuration does not impact the flow rate of the two cavities, making it suitable for stable and efficient preparation of side-by-side micro-nano composite fibers.

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引用次数: 0

Ultra-high Tg colorless polyimide film with balanced optical retardation and coefficient of thermal expansion for flexible display

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-25 DOI: 10.1016/j.polymer.2025.128085

Nafeesa Mushtaq, Yujie Zhang, Maria Nazir, Liyun Tan, Guofei Chen, Xingzhong Fang

Traditional colorless polyimide (CPI) films often have high coefficient of thermal expansion (CTE), high optical retardation (R_th) or low glass transition temperature (T_g) values. However, it remains challengeable to establish a balance between low R_th and low CTE without sacrificing the high T_g of CPI film for flexible display applications, especially for flexible thin-film-transistor liquid-crystal display (TFT-LCD) substrate. A set of colorless polyimides films are prepared from copolymerization of alicyclic dianhydrides hydrogenated pyromellitic dianhydride (HPMDA) and cyclopentanone bis-spironorbornane tetracarboxylic dianhydride (CpODA) with aromatic diamines 9,9′-bis (4-aminophenyl) fluorene (FDA) and 4,4′-diaminobenzanilide (DABA). The optical transparency, anisotropy and dimension stability of CPI films are initially optimized by adjusting the DABA-to-FDA molar ratios, and later by HMPDA-to-CpODA ratios. T_g trend analysis, d-spacing calculated from WAXD patterns, and the FTIR wavenumber shifts of the functional groups implied that the strength of hydrogen bonding is relatively higher in CpODA-based CPIs than the HPMDA systems, which may resulted in improved thermal properties of CPI films. It is shown that the polyimide PI-7-5 film displayed excellent comprehensive properties with an ultra-high T_g of 458 °C, low CTE of 29.0 ppm/K, and also a low R_th of 187 nm. Notably, it has a 90 % transmittance in the visible region, along with robust mechanical properties such as a tensile strength of 111 MPa, and an elastic modulus of 3.8 GPa, and good film folding reliability against extensive folding/unfolding cycles, making it an excellent choice for flexible TFT-LCD substrate.

传统的无色聚酰亚胺（CPI）薄膜通常具有高热膨胀系数（CTE）、高光阻（Rth）或低玻璃化转变温度（Tg）值。然而，在柔性显示应用中，尤其是柔性薄膜晶体管液晶显示器（TFT-LCD）基板中，如何在低 Rth 和低 CTE 之间取得平衡，同时又不牺牲 CPI 薄膜的高 Tg 值，仍然是一项挑战。由脂环族二酐氢化吡咯烷二酐（HPMDA）和环戊酮双铁硼烷四羧酸二酐（CpODA）与芳香族二胺 9,9'-双（4-氨基苯基）芴（FDA）和 4,4'-二氨基苯甲酰苯胺（DABA）共聚制备了一组无色聚酰亚胺薄膜。最初是通过调整 DABA 与 FDA 的摩尔比来优化 CPI 薄膜的光学透明度、各向异性和尺寸稳定性，后来又通过调整 HMPDA 与 CpODA 的摩尔比来优化 CPI 薄膜的光学透明度、各向异性和尺寸稳定性。Tg 趋势分析、WAXD 图谱计算出的 d 间距以及官能团的傅立叶变换红外波长移动表明，与 HPMDA 系统相比，CpODA 基 CPI 的氢键强度相对较高，这可能会改善 CPI 薄膜的热性能。研究表明，聚酰亚胺 PI-7-5 薄膜具有优异的综合性能，其超高 Tg 为 458 ℃，低 CTE 为 29.0 ppm/K，低 Rth 为 187 nm。值得注意的是，它在可见光区域的透射率高达 90%，同时还具有强大的机械性能，如 111 兆帕的拉伸强度和 3.8 GPa 的弹性模量，以及良好的薄膜折叠可靠性，可承受大量的折叠/展开循环，因此是柔性 TFT-LCD 衬底的绝佳选择。

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引用次数: 0

AM/AMPS delignified wood-based hydrogel with enhanced mechanical strength and fatigue resistance for wearable strain sensing and energy harvesting

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-25 DOI: 10.1016/j.polymer.2025.128075

Yanyang He , Jiuming Xiong , Yufang Hu , Zhiyong Guo , Sui Wang , Jie Mao

Hydrogels with enhanced mechanical strength and fatigue resistance have attracted considerable attention in the development of advanced triboelectric nanogenerators (TENGs). Flexible electrode is the key to the preparation of TENG. However, the preparation process of traditional flexible electrode is complex, the mechanical strength is poor, and the cost is high. These factors limit its application and development. In this work, a composite material named AM/AMPS wood-based hydrogel (AWH) was reported, which was composed of acrylamide (AM)/2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) hydrogel and delignification wood. AWH combines the natural fiber structure of wood and the softness of hydrogel, and has excellent mechanical properties and fatigue resistance. AWH is assembled into a triboelectric nanogenerator (AWH-TENG), which has high power generation performance and low cost. The AWH-TENG has an open circuit voltage of 60 V and can light up 113 LED bulbs. At the same time, AWH is sensitive to mechanical stimuli, so we have carried out research on its application in the field of wearable motion monitoring and writing sensing and achieved good results. In addition, the writing sensing system based on AWH-TENG is expected to be combined with deep learning to develop a new handwriting recognition system.

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引用次数: 0

COMFO: Integrated deep learning model facilitates discovery of multifunctional polyimide materials

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-24 DOI: 10.1016/j.polymer.2025.128081

Bo Zhang , Xueqing Li , Ming Zeng , Jingguo Cao

Rapid development in 5G and electronic appliance fields places higher demands on the dielectric, thermal and mechanical properties of materials. Dielectric materials with excellent comprehensive properties have become an urgent need of the times. Emerging machine learning techniques could greatly accelerate the discovery of high-performance dielectric materials. However, it remains unknown whether traditional 2D fingerprints or descriptors can extract molecular structure information more completely. In this study, data on four types of properties of polyimide (PI), including dielectric constant, glass transition temperature, tensile modulus and coefficient of thermal expansion, were collected to construct a deep learning model-COMFO to explore polyimide dielectric materials with excellent comprehensive performance. Our COMFO model could extract the key feature information in the molecule from three perspective learning tasks as well as process and learn them. Specifically, the three learning tasks include extracting the feature information in the SMILES sequence using a large language model, the bidirectional encoder Transformer; extracting the information about the atoms and bonds of polymer molecules from molecular graph using the Attentive FP network; and extracting the information about the substructures of polymer molecules through molecular fingerprints. The multi-perspective feature extraction task gave our model a more excellent performance (R² > 0.90). The performance of the model was confirmed by various ways, including experimental validation, MD simulation validation, and comparison with 12 other models. Design guidelines for low dielectric constant PIs were discovered by monomer structure analysis. High-throughput virtual screening of 158,022 unknown PIs was performed and three PIs with excellent comprehensive properties (especially dielectric properties) were identified. MD and DFT approaches verified and analyzed the properties of these three potential high-performance PIs. In the future, this research could also contribute to the forward development of materials in other fields.

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引用次数: 0

Mass-produce sub-15 nm polymeric soft-nanoparticles and cold-flow conditions

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-23 DOI: 10.1016/j.polymer.2025.128082

Chunhua Li, Yifu Ruan, GengXin Liu

Polymeric soft-nanoparticles (SNPs) synthesized via microemulsion polymerization, are widely used in both academia and industry. However, achieving a significantly smaller diameter still presents a challenge. Despite the use of excess surfactants, surface tension constraints prevent microemulsion droplets from decreasing in diameter below 20 nm. Still using conventional surfactants, we introduce a simple and efficient method for mass production of SNPs down to 10–15 nm in diameter. The microemulsion is prepared by incorporating solvents that are good for both monomers and polymers. This method effectively yields significantly smaller SNPs. In the melts of such small SNPs, the Rouse-like viscous-dominant behavior is observed and fully mapped with respect to the diameter and degree of cross-linking. This was previously not observed in microemulsion polymerized SNPs. We assess the cold flow conditions by determining the ability to form transparent sheets from the powder at room temperature when subjected to pressure. It is governed by the diameter and degree of crosslinking. The ultrasmall SNPs thus have the potential to be used as fillers in various industries.

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引用次数: 0

Impact of uniaxial strain programming on morphology and electrical properties of PET from amorphous precursors

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-23 DOI: 10.1016/j.polymer.2025.128078

Jiahao Mao , Jierui Zhou , Yang Cao , Mukerrem Cakmak

This study examines the morphological evolution of melt-cast Poly (ethylene terephthalate) (PET) thin films under nonlinear deformation strategies, specifically stretching and cycling, to analyze their structural, mechanical, and electrical properties. Capacitor-grade thin films were melt-cast and subjected to uniaxial deformation using an instrumented stretching machine that applied programmable deformations. During deformation, real-time mechano-optical data, including birefringence, true strain, and true stress, were collected above the glass transition temperature (Tg).

Stress-induced crystallization emerged as the primary mechanism during stretching, as thermally induced crystallization was suppressed due to high viscosity in the rubbery temperatures near Tg. Strain oscillations after steady deformations at various strain levels promoted crystallization and relaxed oriented amorphous chains. This process enhanced crystalline orientation and crystallinity, particularly in stretching and oscillation tests compared to stretching and holding tests. At higher deformation levels, the orientation of amorphous domains transitioned to oriented crystalline structures. Increased crystallinity and crystalline and amorphous chain orientation enhanced electrical breakdown. The strain oscillation played a crucial role in promoting crystallinity enhancement while minimizing amorphous chain orientation, leading to lower electrical breakdown. These results highlight the substantial influence of the amorphous phase and its chain orientation on the electrical breakdown of PET films.

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引用次数: 0

Effects of dopant solution solvent on the stability of doped P3HT films

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-23 DOI: 10.1016/j.polymer.2025.128079

Jiaxin He, Hongtao Shan, Xueting Cao, Jianjun Zhou, Hong Huo

Understanding the factors affecting stability is crucial for achieving commercial success with doped conjugated polymers (CPs). In this work, we sequentially doped poly(3-hexylthiophene) (P3HT) films with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) from chlorobenzene/acetonitrile (CB/AN) solvent blends and stored the doped P3HT films under inert conditions at room temperature. The sequential doping of the P3HT film was accompanied by solution doping when CB was used to prepare the F4TCNQ solution. By combining UV–visible–near infrared (UV–vis–NIR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and grazing-incidence wide-angle X-ray diffraction (GIXRD) measurements, we found that with prolonged storage time, the microstructures of doped P3HT produced by sequential doping could retain crystalline structures; however, the crystalline aggregates produced by solution doping would recover back to amorphous chains. The diffidence between the microstructures leads to the conductivity σ, the carrier density n and mobility μ of the P3HT film doped with F4TCNQ from CB/AN blend decreased faster than that doped from pure AN. Two doping mechanisms, namely, integer charge transfer (ICT) and charge transfer complexes (CTCs), occurred in each freshly doped P3HT film. The order of the ICT phase influenced its stability, regardless of its formation from solution doping or sequential doping. The lower the order of the ICT phase is, the better its stability. Both the ICT and CTC phases were unstable at room temperature, yet no interconversion between them was observed.

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引用次数: 0

Highly insulating LDPE compounds at high temperature: The effect of electron-withdrawing PCBM on DC dielectric properties

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-23 DOI: 10.1016/j.polymer.2025.128052

Minhui Zhu, Daomin Min, Shihang Wang, Yihang Jiang

Low-density polyethylene (LDPE) is an excellent insulating material that ensures the safe and reliable operation of high-voltage direct current (HVDC) cables. The insulation properties of LDPE can be improved by doping with voltage stabilizers. Due to its electron-withdrawing property, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) has the potential to be used as a voltage stabilizer to improve the DC insulation performance of LDPE, especially the high temperature insulation performance of cable insulation. Therefore, the impact of PCBM on carrier trap characteristics and micro charge transport at high temperatures and high fields requires further study. LDPE is used as the matrix material to prepare composites with concentrations of 0.5 and 1 wt%. The experimental results show that the Weibull characteristic breakdown strength can be increased by 10.5 % and the DC electrical conductivity can be reduced by 73.6 % at 90 °C, when the PCBM doping concentration is 0.5 wt%. These results can be explained by trap characteristics and molecular chain displacement. It reveals that the introduction of PCBM can effectively increase the trap density, which can capture more charge carriers, resulting in a decrease in carrier mobility and electrical conductivity. Quantum chemical calculations indicate that owing to the high electron affinity and low ionization potential of PCBM, it is more prone to attracting and capturing electrons, thereby efficiently absorbing high-energy electron energy. Moreover, PCBM makes the amorphous region more tightly ordered, which manifests as an improvement in crystallinity. It also enhances the friction coefficient of the molecular chain and suppresses the molecular chain displacement in LDPE, which is verified by charge transport and molecular displacement modulated model simulations. This study provides a new method for improving the properties of cable insulation materials.

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引用次数: 0

Preparation of high elastic bimodal cells biodegradable foam 高弹性双峰细胞可生物降解泡沫的制备

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-22 DOI: 10.1016/j.polymer.2024.127987

Hanlin Tian , Zepeng Wang , Jinshuo Yu , Yan Zhao , Hongwei Pan , Junjia Bian , Huili Yang , Zhibing Wang , Huiliang Zhang

Poly(butylene adipate-co-terephthalate) (PBAT) and polybutylene succinate (PBS) are advanced biodegradable thermoplastic elastomer with excellent application prospects. There is a growing interest in developing PBAT foam products as effective alternatives to traditional foams for sports, shock absorption, and safety protection. In this study, high compression strength and high elasticity PBAT/PBS foam materials was prepared by supercritical CO₂ foam, the effects of the crystallization nucleation agent TMC and the chain extender ADR on crystallization and melt strength of blends was investigated by varying temperature-pressure modes (VT-PM). The rheological results showed that with the increase of ADR, the storage modulus and viscosity of PBAT/PBS blends increased significantly, transitioning from a viscous liquid-like to an elastic state. TMC could promote polymer crystallization, crystal size reduced, and small size cell was obtained during the foaming. Finally, a high elastic foam T/S-0.2-1.5 with 12 times and the compressive strength about 0.59 MPa and energy loss of 14.3 % can be prepared due to synergistic effect of ADR and TMC. This provides a promising application prospect for biodegradable foams.

聚己二酸丁二酸酯（PBAT）和聚丁二酸丁二酸酯（PBS）是一种先进的可生物降解热塑性弹性体，具有良好的应用前景。人们对开发PBAT泡沫产品越来越感兴趣，它可以作为传统泡沫的有效替代品，用于运动、减震和安全保护。采用超临界CO2泡沫法制备了高抗压强度、高弹性的PBAT/PBS泡沫材料，通过变温-变压模式（VT-PM）研究了结晶成核剂TMC和扩链剂ADR对共混物结晶和熔融强度的影响。流变学结果表明，随着ADR的增加，PBAT/PBS共混物的存储模量和粘度显著增加，由粘性类液体状态过渡到弹性状态。TMC能促进聚合物的结晶，使聚合物的结晶尺寸减小，发泡时得到小尺寸的晶胞。最后，由于ADR和TMC的协同作用，可制得高弹性泡沫T/S-0.2-1.5，其抗压强度为TMC的12倍，抗压强度约为0.59 MPa，能量损失为14.3%。这为生物降解泡沫材料提供了广阔的应用前景。

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引用次数: 0

Transformation of ethylene vinyl alcohol copolymer from a glassy state to a rubber state through post ester-exchange modification 乙烯乙烯醇共聚物通过酯交换后改性从玻璃态转变为橡胶态

IF 4.1 2区化学 Q2 POLYMER SCIENCE

Polymer

Pub Date : 2025-01-22 DOI: 10.1016/j.polymer.2024.127993

Zhenjing Zhou , Yihao Meng , Jiang Wu , Jieting Zhou , Xi Yu , Ningbo Yi , Qinghua Wu , Yancheng Wu , Jialin Zhang , Longfei Fan , Juxian Zhang , Feng Gan

Polyolefins and their derivatives can be modified in both phase-state and function through post-modification techniques. This study presented a novel ethylene-vinyl alcohol-acetoacetate ester copolymer (EVOH-A), synthesized via a simple post ester-exchange method. The incorporation of acetoacetic ester not only alters the polymer's phase state but also enhances its potential for further functionalization. Two-dimensional infrared spectroscopy and molecular dynamics simulations showed that the ester-exchange modification weakens hydrogen bonds in EVOH, leading to a more amorphous structure. Thermal analysis reveals that the glass transition temperature (T_g) of modified EVOH decreases from 30 °C (EVOH) to −3 °C (EVOH-A4), indicating a transformation from a glassy to a rubbery state of polymers. The tensile strength and Young's modulus of the modified EVOH-A films decrease, while tensile elongation significantly increases. Additionally, this work demonstrates the application of modified polymers in the Hantzsch reaction, endowing the photoluminescence and hydrophobicity of polymers. This study introduces a new EVOH modification method with significant potential for developing multifunctional polyolefin materials.

聚烯烃及其衍生物可通过后改性技术改变相态和功能。本研究介绍了一种新型乙烯-乙烯醇-乙酰乙酸酯共聚物（EVOH-A），它是通过一种简单的酯交换后方法合成的。乙酰乙酸酯的加入不仅改变了聚合物的相态，还增强了其进一步官能化的潜力。二维红外光谱和分子动力学模拟显示，酯交换改性削弱了 EVOH 中的氢键，使其结构更加无定形。热分析表明，改性 EVOH 的玻璃化转变温度 (Tg) 从 30 oC（EVOH）降至 -3 oC（EVOH-A4），表明聚合物从玻璃态转变为橡胶态。改性 EVOH-A 薄膜的拉伸强度和杨氏模量降低，而拉伸伸长率显著增加。此外，这项研究还证明了改性聚合物在 Hantzsch 反应中的应用，赋予了聚合物光致发光和疏水性。这项研究介绍了一种新的 EVOH 改性方法，它在开发多功能聚烯烃材料方面具有巨大潜力。

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引用次数: 0