含液晶基团的聚对亚苯基亚乙炔基类交替共聚物的合成、表征及性能研究

合成了两种含氰基联苯液晶基团的新型聚对亚苯基亚乙炔基(PPE)类交替共聚物,并对其进行了结构表征和性能研究.示差扫描量热仪(DSC)和偏光显微镜(POM)的结果证明了在液晶单元含量较大时聚合物才会出现明显的液晶形态.荧光光谱表明,在降温前后液晶聚合物的发光光谱发生了明显的变化.同时,对聚合物进行能量转移研究发现随着溶液浓度的增加,Frster能量转移更加完全;另外,利用原子力显微镜(AFM)对聚合物降温前后的形态变化进行了观察.结果表明,液晶性质可以导致聚合物形态的变化进而带来发光光谱的改变,为今后制备液晶可控型发光聚合物提供了理论依据.     

Application of the essential work of fracture concept to nanostructured polymer materials

The first part of the paper deals with a critical discussion of the methodical basis of essential work of fracture (EWF) concept with respect to the specimen geometry (especially the notch depth) and application to polymers. In the second part, an in situ testing device, which combines a tensile testing machine with an optical strain-field measuring system, has successfully demonstrated possibility of characterization of fracture behaviour of polystyrene-polybutadiene block copolymers and block copolymer/homopolymer blends as examples of nanostructured polymer materials. It has been shown that knowledge of the time evolution of the strain field close to the crack tips leads to a simple verification of the basic precondition for the applicability of the EWF concept, the precondition “plastic zone coalescence-before-stable crack propagation”.     

Resilient and agile engineering solutions to address societal challenges such as coronavirus pandemic

The world is witnessing tumultuous times as major economic powers including the US, UK, Russia, India, and most of Europe continue to be in a state of lockdown. The worst-hit sectors due to this lockdown are sales, production (manufacturing), transport (aerospace and automotive) and tourism. Lockdowns became necessary as a preventive measure to avoid the spread of the contagious and infectious “Coronavirus Disease 2019” (COVID-19). This newly identified disease is caused by a new strain of the virus being referred to as Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS CoV-2; formerly called 2019-nCoV). We review the current medical and manufacturing response to COVID-19, including advances in instrumentation, sensing, use of lasers, fumigation chambers and development of novel tools such as lab-on-the-chip using combinatorial additive and subtractive manufacturing techniques and use of molecular modelling and molecular docking in drug and vaccine discovery. We also offer perspectives on future considerations on climate change, outsourced versus indigenous manufacturing, automation, and antimicrobial resistance. Overall, this paper attempts to identify key areas where manufacturing can be employed to address societal challenges such as COVID-19.     

Polymer blends of polyamide-6 (PA6) and poly(phenylene ether) (PPE) compatibilized by a multifunctional epoxy coupler

A tetrafunctional epoxy monomer, N,N,N′-N′-tetraglycidyl-4,4′-diaminodiphenyl methane (TGDDM), has demonstrated to be a highly efficient reactive compatibilizer in compatibilizing the immiscible and incompatible polymer blends of polyamide-6 (PA6) and poly(2,6-dimethyl-1,4-phenylene ether) (PPE). This epoxy coupler can react with both PA6 and PPE to form various PA6-co-TGDDM-co-PPE mixed copolymers. These interfacially formed PA6-co-TGDDM-co-PPE copolymers tend to anchor along the interface to reduce the interfacial tension and result in finer phase domains and enhanced interfacial adhesion. A simple one-step melt blending has demonstrated to be more efficient in producing a better compatibilized PA6/PPE blend than a two-step sequential blending. The mechanical property improvement of the compatibilized blend over the uncompatibilized counterpart is very drastic, by considering the addition of a very small amount, a few fractions of 1%, of this epoxy coupling agent. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1805–1819, 1998     

POSS—PPE杂化材料的合成、表征及其与TNT的荧光响应

通过Heck—SonogashFT—IRa偶合法合成了含五蝶烯（Pentiptycene）基团的新型荧光共轭聚合物——聚对苯撑乙炔撑衍生物（PPE）,分别为：侧链不对称烷氧基取代的PPE1和侧链单、双一丙基七异丁基多面体齐聚倍半硅氧烷（POSS）取代的PPE2、PPE3。采用FT—IR、^1H—NMR、UVVis、荧光发射光谱、TGA等仪器对PPE的结构和性能进行了分析测试,并研究了其与TNT之间的荧光响应。结果表明：PPE1、2、3均表现出良好的荧光性能及较高的荧光量子产率;对TNT显示出很高的猝灭敏感性,其荧光猝灭效率与TNT的浓度曲线表现为非线性关系,特别是侧链引入POSS的PPE2,提高了PPE的荧光量子产率及与TNT荧光猝灭效率,同时,PPE的热稳定性得到明显提高。     

Structure—Property relationships for exciton transfer in conjugated polymers

The ability of conjugated polymers to function as electronic materials is dependent on the efficient transport of excitons along the polymer chain. Generally, the photophysics of the chromophore monomer dictate the excited state behavior of the corresponding conjugated polymers. Different molecular structures are examined to study the role of excited state lifetimes and molecular conformations on energy transfer. The incorporation of rigid, three‐dimensional scaffolds, such as iptycenes and cyclophanes, can encourage an oblique packing of the chromophore units of a conjugated polymer, thus allowing the formation of electronically‐coupled aggregates that retain high quantum yields of emission. Rigid iptycene scaffolds also act as excellent structural directors that encourage complete solvation of PPEs in a liquid crystal (LC) solvent. LC‐PPE mixtures display both an enhanced conformational alignment of polymer chains and extended effective conjugation lengths relative to isotropic solutions, which leads to enhanced energy transfer. Facile exciton migration in poly(p‐phenylene ethynylene)s (PPEs) allows energy absorbed over large areas to be funneled into traps created by the binding of analytes, resulting in signal amplification in sensory devices. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Synthesis,Electrochemical, and Optical Properties of a Novel PPV/PPE Block‐Copolymer

Summary: A novel poly(p‐phenylene vinylene) (PPV)/poly(p‐phenylene ethynylene) (PPE) block‐copolymer was synthesized by a cross‐coupling polycondensation with Pd(PPh₃)₂Cl₂ and a phase‐transfer catalyst, and was confirmed by ¹H NMR and IR spectroscopy and elemental analysis. The thermal, electrochemical, and photoluminescent properties of the new copolymer have been investigated. The incorporation of triple bonds into the cyano‐substituted PPV (CN‐PPV) backbone leads to higher oxidation and reduction potentials than poly(2‐methoxy‐5‐(2‐ethylhexyloxy)‐p‐phenylene vinylene) (MEH‐PPV) and CN‐PPV, potentially making the copolymer a good electron‐transporting material for use in a light‐emitting‐diode device.

The cyclic voltammogram of the novel poly(p‐phenylene vinylene) (PPV)/poly(p‐phenylene ethynylene) (PPE) block‐copolymer synthesized here.     

Numerical study of PPE source term errors in the incompressible SPH models

In a recent work by Gui et al. 13 , an incompressible SPH model was presented that employs a mixed pressure Poisson equation (PPE) source term combining both the density‐invariant and velocity divergence‐free formulations. The present work intends to apply the model to a wider range of fluid impact situations in order to quantify the numerical errors associated with different formulations of the PPE source term in incompressible SPH (ISPH) models. The good agreement achieved between the model predictions and the documented data is taken as a further demonstration that the mixed source term formulation can accurately predict the fluid impact pressures and forces, both in the magnitude and in the spatial and temporal patterns. Furthermore, an in‐depth numerical analysis using either the pure density‐invariant or velocity divergence‐free formulation has revealed that the pure density‐invariant formulation can lead to relatively large divergence errors while the velocity divergence‐free formulation may cause relatively large density errors. As compared with these two approaches, the mixed source term formulation performs much better having the minimum total errors in all test cases. Although some recent studies found that the weakly compressible SPH models perform somewhat better than the incompressible SPH models in certain fluid impact problems, we have shown that this could be largely caused by the particular formulation of PPE source term in the previous ISPH models and a better formulation of the source term can significantly improve the accuracy of ISPH models. Copyright © 2014 John Wiley & Sons, Ltd.     

Polymer BHJ solar cell performance tuning by C60 fullerene derivative alkyl side‐chain length

A systematic study on the influence of the alkyl side‐chain length of C₆₀ based fullerene derivatives in polymer solar cells based on an anthracene‐containing poly(p‐phenylene‐ethynylene)‐alt‐poly(p‐phenylene‐vinylene) (PPE‐PPV) copolymer (AnE‐PV) is reported. It is shown that the alkyl side‐chain length of the fullerene derivative strongly correlates with the individual photovoltaic parameters. The most pronounced dependence on the side‐chain length is found for the fill factor, spanning the range between 50–72%, which dominantly controls in combination with the short‐circuit current the power conversion efficiency. The maximum performance of 4.8% was found for an ethyl terminated side‐chain, whereas larger alkyl groups resulted in a gradually decreasing power conversion efficiency. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Poly(p‐phenylene ethynylene) Incorporating Sterically Enshrouding m‐Terphenyl Oxacyclophane Canopies

A sterically encumbered m‐terphenyl oxacyclophane substituted with two aryl iodide substituents has been prepared as a versatile monomer for the preparation of π‐conjugated polymers. The monomer has been used to prepare a poly(p‐phenylene ethynylene) derivative (P1) incorporating oxacyclophane units as canopies that shield one side of the π‐system from inter‐chain interactions. The photophysical properties of P1 in dilute solution compare well to those of a poly(p‐phenylene ethynylene) derivative (P2) that lacks the canopy. The presence of the steric canopy leads to a diminished inter‐chain interaction in the solid state and enhances the kinetic response of P1 to vapors of nitro‐organics such as TNT, presumably by increasing the permeability of P1 to these analytes over that of P2.