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Colorless Polyimides Derived from Octahydro-2,3,6,7-anthracenetetracarboxylic Dianhydride 由八氢-2,3,6,7-蒽四羧酸二酐衍生的无色聚酰亚胺
Pub Date : 2023-04-28 DOI: 10.3390/macromol3020011
M. Hasegawa, Hiroki Sato, Katsuhisa Hoshino, Yasuhisa Arao, J. Ishii
A cycloaliphatic tetracarboxylic dianhydride, octahydro-2,3,6,7-anthracenetetracarboxylic dianhydride (OHADA) was synthesized to obtain novel colorless polyimides (PIs). Herein, approaches for decolorizing an OHADA prototype and simplifying the entire process are described, and a plausible steric structure for OHADA is proposed. The polyaddition of OHADA and 2,2′-bis(trifluoromethyl)benzidine (TFMB) was unsuccessful; specifically, the reaction mixture remained inhomogeneous even after prolonged stirring. However, the modified one-pot process was applicable to the OHADA/TFMB system. The isolated PI powder form, as well as those for the other OHADA-based PIs, was highly soluble in numerous solvents and afforded a homogeneous and stable solution with a high solid content (20–30 wt%). Solution casting produced a colorless and ductile PI film with a very high glass transition temperature (Tg~300 °C). Furthermore, the OHADA/TFMB system exhibited remarkable thermal stability compared with those of the other related TFMB-derived semi-cycloaliphatic PIs. However, contrary to our expectations, this PI film did not exhibit a low linear coefficient of thermal expansion (CTE). This PI film also possessed excellent thermoplasticity, probably reflecting its peculiar steric structure. The use of an amide-containing diamine significantly enhanced the Tg (355 °C) and somewhat reduced the CTE (41.5 ppm K−1) while maintaining high optical transparency and excellent solubility.
合成了环脂肪族四羧基二酐-八氢-2,3,6,7-蒽基四羧基二酐(OHADA),得到了新型无色聚酰亚胺(pi)。本文描述了OHADA原型脱色和简化整个过程的方法,并提出了OHADA的合理立体结构。OHADA与2,2′-双(三氟甲基)联苯胺(TFMB)的多加成反应不成功;具体来说,即使经过长时间的搅拌,反应混合物仍然不均匀。改进后的一锅工艺适用于OHADA/TFMB体系。分离的PI粉末形式,以及其他基于ohada的PI,在许多溶剂中都是高度可溶的,并且提供了高固含量(20-30 wt%)的均匀和稳定的溶液。溶液浇铸制得的PI薄膜无色、延展性好,玻璃化转变温度很高(Tg~300℃)。此外,与其他相关的TFMB衍生的半环脂肪族pi相比,OHADA/TFMB体系表现出显著的热稳定性。然而,与我们的预期相反,这种PI薄膜并没有表现出低的线性热膨胀系数(CTE)。该PI薄膜还具有优异的热塑性,这可能反映了其独特的立体结构。使用含二胺的酰胺显著提高了Tg(355°C),并在一定程度上降低了CTE (41.5 ppm K−1),同时保持了高光学透明度和良好的溶解度。
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引用次数: 2
Recent Advances on Glyoxylates and Related Structures as Photoinitiators of Polymerization 聚合法光引发剂乙氧基酯及其相关结构的研究进展
Pub Date : 2023-04-23 DOI: 10.3390/macromol3020010
F. Dumur
The design of photoinitiators activable under low-light intensity is an active research field, supported by the recent energetic sobriety plans imposed by numerous countries in Europe. With an aim to simplify the composition of the photocurable resins, Type I photoinitiators are actively researched as these structures can act as monocomponent systems. In this field, a family of structures has been under-investigated at present, namely, glyoxylates. Besides, the different works carried out in three years have evidenced that glyoxylates and related structures can be versatile for the design of Type I photoinitiators. In this review, an overview of the different glyoxylates and related structures reported to date is provided.
在低光强度下可激活的光引发剂的设计是一个活跃的研究领域,受到最近欧洲许多国家实施的能量清醒计划的支持。为了简化光固化树脂的组成,人们积极研究I型光引发剂,因为这些结构可以作为单组分体系。在这一领域,目前有一类结构得到了充分的研究,即乙氧基酸酯。此外,三年来开展的不同工作证明了乙氧基酸酯及其相关结构可用于I型光引发剂的设计。在这篇综述中,综述了迄今为止报道的不同的乙醛酸酯和相关结构。
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引用次数: 3
Opportunities and Limitations in Recycling Fossil Polymers from Textiles 从纺织品中回收化石聚合物的机会和限制
Pub Date : 2023-04-15 DOI: 10.3390/macromol3020009
S. Bianchi, F. Bartoli, Cosimo Bruni, C. Fernandez-Avila, L. Rodriguez-Turienzo, Jorge Mellado-Carretero, Daniele Spinelli, M. Coltelli
The recovery and recycling of textile waste is becoming urgent since textiles are generating more and more waste. In one year, about 92 million tons of textile waste are produced and the fashion industry accounts for 58 million tons of plastic waste per year. Several different synthetic fibres are used in textiles, thanks to their excellent processability and mechanical properties, but on the other hand, the difficulties linked to their end of life and the release of microplastics from them during washing is currently a cause of great concern. In this context, policy actions have been aimed at promoting recycling of waste and replacing fossil-based fibres with biobased fibres. The current review, considering both scientific papers published on international journals and web sources, considers the sorting of textiles and the possible recycling of polyesters, polyamides and acrylics. Nevertheless, the contamination and presence of mixed fibres in fabrics is another issue to face for recycling. Methodologies to solve the issue linked to the presence of elastane, present in the stretch fabrics, as well as the possibility of recycling textiles in the non-woven and composite sector are investigated. Moreover, chemical recycling and enzymatic recycling of fossil polymers are also considered. Thanks to the comprehensive scheme of this review, it is possible to deduce that, while the use of biobased materials should rapidly increase in textile applications, the perspective of recycling materials obtained from waste textile into durable and/or high-performance products seems the most promising.
由于纺织品产生的废物越来越多,纺织废物的回收和再利用变得迫在眉睫。每年大约产生9200万吨纺织废料,时尚行业每年产生5800万吨塑料废料。由于优异的加工性能和机械性能,几种不同的合成纤维被用于纺织品中,但另一方面,与它们的使用寿命和洗涤过程中释放的微塑料有关的困难是目前引起极大关注的一个原因。在这方面,政策行动的目的是促进废物的再循环和用生物基纤维代替化石基纤维。目前的审查考虑了发表在国际期刊和网络资源上的科学论文,考虑了纺织品的分类和聚酯、聚酰胺和丙烯酸的可能回收。然而,织物中的污染和混合纤维的存在是回收面临的另一个问题。研究了解决弹性织物中存在的弹性纤维问题的方法,以及非织造布和复合材料部门回收纺织品的可能性。此外,化石聚合物的化学回收和酶回收也被考虑。由于本综述的综合方案,可以推断,虽然生物基材料在纺织品应用中的使用将迅速增加,但从废弃纺织品中获得的材料回收利用到耐用和/或高性能产品的前景似乎是最有希望的。
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引用次数: 2
Perspectives of Polymers in Forensic Analysis 聚合物在法医分析中的前景
Pub Date : 2023-04-10 DOI: 10.3390/macromol3020008
A. Díez-Pascual
Polymeric materials have recently attracted a lot of attention due to their potential applications in many fields, ranging from biomedicine, the food industry and environmental monitoring to electronic, energy storage and sensing devices. Their versatility, functionalization capability, chemical/physical stability, reusability, long shelf-life, as well as good mechanical and thermal properties, also make them idoneous candidates for use in forensic sciences, which deal with the investigation of crimes, finding relations between evidence and criminals. In particular, molecularly imprinted polymers (MIPs), designed based on the principle of generating template-specific polymeric cavities fitted to the target molecules in the presence of selected chemicals via non-covalent or covalent interactions, are highly suitable for forensic analysis. In addition, their combination with other compounds such as carbon nanomaterials can provide composites with improved properties to be used in the analysis of illicit drugs, doping substances, biological agents, toxins and so forth. In this article, recent applications of polymeric materials in the field of forensic analysis are discussed. The goal is to summarize their current uses and put forth a projection of their potential as promising alternatives for standard competitors.
近年来,高分子材料因其在生物医药、食品工业、环境监测、电子、储能和传感器件等诸多领域的潜在应用而备受关注。它们的通用性、功能化能力、化学/物理稳定性、可重复使用性、长保质期以及良好的机械和热性能,也使它们在法医科学中也成为献献性的候选人,法医科学涉及犯罪调查,寻找证据和罪犯之间的关系。特别是,分子印迹聚合物(MIPs)是基于通过非共价或共价相互作用在选定化学物质存在的情况下产生适合靶分子的模板特异性聚合物空腔的原理设计的,非常适合法医分析。此外,它们与碳纳米材料等其他化合物结合,可以提供性能更好的复合材料,用于分析违禁药物、兴奋剂、生物制剂、毒素等。本文综述了高分子材料在法医分析领域的最新应用。目的是总结它们目前的用途,并预测它们作为标准竞争者的有希望的替代品的潜力。
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引用次数: 1
A Comprehensive Study on the Styrene–GTR Radical Graft Polymerization: Combination of an Experimental Approach, on Different Scales, with Machine Learning Modeling 苯乙烯- gtr自由基接枝聚合的综合研究:不同尺度的实验方法与机器学习建模的结合
Pub Date : 2023-02-22 DOI: 10.3390/macromol3010007
Cindy Trinh, S. Hoppe, R. Laine, D. Meimaroglou
The study of the styrene–Ground Tire Rubber (GTR) graft radical polymerization is particularly challenging due to the complexity of the underlying kinetic mechanisms and nature of GTR. In this work, an experimental study on two scales (∼10 mL and ∼100 mL) and a machine learning (ML) modeling approach are combined to establish a quantitative relationship between operating conditions and styrene conversion. The two-scale experimental approach enables to verify the impact of upscaling on thermal and mixing effects that are particularly important in this heterogeneous system, as also evidenced in previous works. The adopted experimental setups are designed in view of multiple data production, while paying specific attention in data reliability by eliminating the uncertainty related to sampling for analyses. At the same time, all the potential sources of uncertainty, such as the mass loss along the different steps of the process and the precision of the experimental equipment, are also carefully identified and monitored. The experimental results on both scales validate previously observed effects of GTR, benzoyl peroxide initiator and temperature on styrene conversion but, at the same time, reveal the need of an efficient design of the experimental procedure in terms of mixing and of monitoring uncertainties. Subsequently, the most reliable experimental data (i.e., 69 data from the 10 mL system) are used for the screening of a series of diverse supervised-learning regression ML models and the optimization of the hyperparameters of the best-performing ones. These are gradient boosting, multilayer perceptrons and random forest with, respectively, a test R2 of 0.91 ± 0.04, 0.90 ± 0.04 and 0.89 ± 0.05. Finally, the effect of additional parameters, such as the scaling method, the number of folds and the random partitioning of data in the train/test splits, as well as the integration of the experimental uncertainties in the learning procedure, are exploited as means to improve the performance of the developed models.
苯乙烯-磨胎橡胶(GTR)接枝自由基聚合的研究尤其具有挑战性,因为GTR的潜在动力学机制和性质的复杂性。在这项工作中,结合了两个尺度(~ 10 mL和~ 100 mL)的实验研究和机器学习(mL)建模方法,建立了操作条件和苯乙烯转化之间的定量关系。双尺度实验方法能够验证升尺度对热效应和混合效应的影响,这在这种非均质系统中尤为重要,正如之前的工作所证明的那样。所采用的实验设置是针对多种数据产生而设计的,同时特别注意数据的可靠性,消除了与采样分析相关的不确定性。同时,所有潜在的不确定性来源,如过程中不同步骤的质量损失和实验设备的精度,也被仔细识别和监测。两个尺度上的实验结果验证了之前观察到的GTR、过氧化苯甲酰引发剂和温度对苯乙烯转化的影响,但同时也揭示了在混合和监测不确定性方面需要有效设计实验程序。随后,使用最可靠的实验数据(即来自10 mL系统的69个数据)筛选一系列不同的监督学习回归mL模型,并优化表现最佳的模型的超参数。它们分别是梯度增强、多层感知器和随机森林,检验R2分别为0.91±0.04、0.90±0.04和0.89±0.05。最后,利用其他参数的影响,如缩放方法、折叠次数和训练/测试分割中数据的随机划分,以及学习过程中实验不确定性的集成,作为提高所开发模型性能的手段。
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引用次数: 0
The Role of Coupling Agents in the Mechanical and Thermal Properties of Polypropylene/Wood Flour Composites 偶联剂对聚丙烯/木粉复合材料力学和热性能的影响
Pub Date : 2023-02-03 DOI: 10.3390/macromol3010006
Cecilia Zárate-Pérez, R. Ramírez-Aguilar, E. Franco-Urquiza, Carlos Sánchez-Alvarado
This work is a collaborative effort between academia and industry to promote the development of new sustainable and profitable materials for manufacturing products. Incorporating wood flour particles (WF) in polypropylene (PP) grants environmental advantages in developing products that use renewable resources to manufacture PP/WF composites using the melt intercalation process. However, the interaction between a hydrophilic strengthening phase (wood flour) with a nonpolar polymer matrix (PP) is poor, resulting in deficient mechanical performance. This investigation details the use of graft and masterbatch coupling agents to evaluate their effects on mechanical parameters. The low compatibility between the constituents favors increasing the composites’ thermal properties because the reinforcing phase acts as a nucleating agent. PP showed typical mechanical behavior, with a marked necking and a wide deformation capacity of approximately 180%. The mechanical behavior of the PP/WF composites revealed an elastic region followed by a termination after their yield point, shortening the stress–strain curves and reducing their ductility at strain values of approximately 2–4%. Graft coupling agents have better intermolecular performance with PP than masterbatch coupling agents. The modulus of elasticity of the composites increased to around 82% relative to PP. Processing methods influenced the thermal properties of the composites. The melt-blending process promoted molecular orientation, while injection molding erased the thermomechanical history of the extruded pellets. The melting temperature was similar in the composites, so there was no evidence of thermal degradation. The results showed that the coupling agents favor the crystallinity of the PP over tensile strength. SEM observations showed insufficient adhesion between the WF and PP, which promotes a reduction in stress transfer during tensile testing. The WF particles act as fillers that increase the stiffness and reduce the ductility of composites.
这项工作是学术界和工业界的共同努力,旨在促进新的可持续和有利可图的制造产品材料的发展。在聚丙烯(PP)中加入木粉颗粒(WF),在开发利用可再生资源生产PP/WF复合材料的产品中具有环境优势。然而,亲水强化相(木粉)与非极性聚合物基体(PP)之间的相互作用较差,导致机械性能不足。本研究详细介绍了接枝剂和母粒偶联剂的使用,以评估它们对力学参数的影响。组分之间的低相容性有利于提高复合材料的热性能,因为增强相起成核剂的作用。PP表现出典型的力学行为,颈缩明显,变形能力约为180%。PP/WF复合材料的力学行为表现为在屈服点后出现弹性区,应力-应变曲线缩短,在应变值约为2-4%时塑性降低。接枝偶联剂与PP的分子间性能优于母粒偶联剂。与PP相比,复合材料的弹性模量提高到82%左右。加工方法影响复合材料的热性能。熔融共混工艺促进了分子取向,而注射成型消除了挤出颗粒的热力学历史。复合材料的熔融温度相似,因此没有热降解的迹象。结果表明,偶联剂对PP结晶度的影响大于对拉伸强度的影响。扫描电镜观察显示,WF和PP之间的粘合不足,这有助于减少拉伸测试过程中的应力传递。WF颗粒作为填料,增加了复合材料的刚度,降低了复合材料的延性。
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引用次数: 2
Experimental Studies on the Phase Separation Behavior of Molten Benzenesulfonate-Modified PET/PA6 Blends 熔融苯磺酸改性PET/PA6共混物相分离行为的实验研究
Pub Date : 2023-01-31 DOI: 10.3390/macromol3010005
Xiaoling Ma, Qingqing Ye, Shao-jie Zheng, Ji-jiang Hu, Zhen Yao
In this work, nylon 6 (PA6) and cationic dyeable polyester (CDP) modified with benzenesulfonate groups were reactively blended in a twin-screw extruder. The well-mixed CDP/PA6 blends were re-molten and statically kept for various amounts of time. The morphology evolution caused by phase separation was observed by a scanning electron microscope (SEM) and an atomic force microscopy-infrared (AFM-IR) technique. In the absence of shear force, the homogeneously mixed blends were found to separate rapidly into two phases because of the poor miscibility between polyester and polyamide. In the early stage, the dispersed phase was small in size and irregular in shape. With prolongation of the phase separation time, the dispersed phase turned into larger and spherical particles to minimize the interface between phases. The phase separation process typically lasted 2 to 7 min. This means that the effects of phase separation on the morphology of the blends cannot be ignored in injection molding, compression molding, or other processing processes short of shear force. The effects of the ratio between polyester and polyamide, the benzenesulfonate content, and the molecular weight of polymers on phase separation behavior were investigated.
在双螺杆挤出机中,对尼龙6 (PA6)和苯磺酸基改性阳离子可染聚酯(CDP)进行了反应共混。将混合良好的CDP/PA6共混物重新熔融并静态保存不同的时间。利用扫描电子显微镜(SEM)和原子力显微镜-红外(AFM-IR)技术观察了相分离引起的形貌演变。在没有剪切力的情况下,由于聚酯和聚酰胺之间的混相较差,发现均匀混合的共混物迅速分离成两相。早期分散相体积小,形状不规则。随着相分离时间的延长,弥散相变成较大的球形颗粒,使相间界面最小化。相分离过程通常持续2到7分钟。这意味着在注射成型、压缩成型或其他缺乏剪切力的加工过程中,相分离对共混物形貌的影响是不可忽视的。考察了聚酯与聚酰胺的比例、苯磺酸盐的含量和聚合物的分子量对相分离行为的影响。
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引用次数: 0
Influence of Concentration of Thiol-Substituted Poly(dimethylsiloxane)s on the Properties, Phases, and Swelling Behaviors of Their Crosslinked Disulfides 巯基取代聚二甲基硅氧烷浓度对交联二硫化物性质、物相及溶胀行为的影响
Pub Date : 2023-01-28 DOI: 10.3390/macromol3010004
Danielle M. Beaupre, A. Goroncy, R. Weiss
A simple, efficient procedure has been employed to effect intra- and inter-chain crosslinking of two commercially available thiolated poly(dimethylsiloxane) copolymers (T-PDMS) with 4–6% or 13–17% of mercaptopropyl side-chains. The thiol functional groups were converted to disulfides (D-PDMS) in chloroform solutions of I2. Importantly, the conditions employed avoid over-oxidation to other types of sulfur-containing species, and the concentration of T-PDMS during the crosslinking reaction dictated the rheological properties and liquid or solid nature of the D-PDMS. The procedure for obtaining the crosslinked copolymers is simpler than other approaches in the literature used to crosslink polysiloxane backbones and to modulate their properties. By changing the concentration of T-PDMS during the treatment with I2, the degree of intra- and inter-chain crosslinking can be controlled (as assessed qualitatively by the solid or liquid nature of the products and their viscoelastic properties). For each of the T-PDMS materials, there is a concentration threshold, above which products are solids, and below which they are oils. Liquid and solid materials were characterized using 1H and 13C solution-state and 13C solid-state NMR spectroscopy, respectively. They indicate greater than 90% conversion of thiols to disulfides in the presence of excess I2. The rheological behavior of the liquid products, solvent swelling ability of solid products, and the thermal stability of the reactants and products are described. Furthermore, the solid products exhibit some of the highest swelling values reported in the literature for poly(dimethylsiloxane) (PDMS) materials. As assessed by thermal gravimetric analyses, the disulfide-crosslinked materials are more stable thermally than the corresponding thiols.
采用一种简单、高效的方法对两种含4-6%或13-17%巯基侧链的巯基化聚二甲基硅氧烷共聚物(T-PDMS)进行了链内交联和链间交联。硫醇官能团在氯仿I2溶液中转化为二硫化物(D-PDMS)。重要的是,所采用的条件避免了对其他类型的含硫物质的过度氧化,并且在交联反应中T-PDMS的浓度决定了D-PDMS的流变性能和液体或固体性质。获得交联共聚物的程序比文献中用于交联聚硅氧烷骨架和调节其性能的其他方法更简单。在I2处理过程中,通过改变T-PDMS的浓度,可以控制链内和链间交联的程度(通过产品的固体或液体性质及其粘弹性定性评估)。对于每种T-PDMS材料,都有一个浓度阈值,高于该值的产品为固体,低于该值的产品为油。液体和固体材料分别用1H和13C溶液态和13C固态核磁共振谱进行表征。它们表明在过量I2存在的情况下,硫醇转化为二硫化物的比例大于90%。描述了液体产物的流变性能、固体产物的溶胀能力以及反应物和产物的热稳定性。此外,固体产物表现出一些文献中报道的聚二甲基硅氧烷(PDMS)材料的最高膨胀值。热重分析表明,二硫交联材料比相应的硫醇具有更大的热稳定性。
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引用次数: 0
Acknowledgment to the Reviewers of Macromol in 2022 感谢Macromol在2022年的审稿人
Pub Date : 2023-01-18 DOI: 10.3390/macromol3010003
High-quality academic publishing is built on rigorous peer review [...]
高质量的学术出版建立在严格的同行评审的基础上[…]
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引用次数: 0
Hot Topics in 2022 and Future Perspectives of Macromolecular Science 2022年大分子科学热点与展望
Pub Date : 2023-01-16 DOI: 10.3390/macromol3010002
A. Díez-Pascual
In 1920, Hermann Staudinger discovered that macromolecules consist of long chains of covalently linked building blocks and subsequently published the first paper on polymerization [...]
1920年,Hermann Staudinger发现大分子是由共价连接的长链组成的,随后发表了第一篇关于聚合的论文。
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引用次数: 1
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