The recovery properties under load of a shape memory polymer composite material

In many applications, shape memory alloys are being replaced by shape memory polymers as they have some better properties than shape memory alloys. Nevertheless, shape memory alloys can recover under load which shape memory polymers cannot. Shape memory polymers are not capable of giving full recovery even lifting a tiny load. The melting temperature or the glass transition temperature is the transition temperatures to which shape memory polymers are closely heated. Then a deforming force up to a certain position is applied to the heated shape memory polymers. After that shape memory polymer is permitted to cool while keeping it deformed. After the cooling, shape memory polymer obtains the temporary shape which can be recovered by reheating it at the similar transition temperature (glass transition or melting). Consequently, it recovers at its initial state. Shape memory polymer can achieve constrained recovery and unconstrained recovery, nonetheless; under stress, it is partly recovered. In current work, recovery under load has been investigated of an asymmetrical shape memory composite. It is established that it is capable to recover under various loads. Under various loads, it shows full recovery in reference to initial state. The ability to recover under load can be potentially used in diverse applications.     

Bioinspired phospholipid polymer biomaterials for making high performance artificial organs

Novel polymer biomaterials, which can be used in contact with blood, are prepared with strong inspiration from the surface structure of biomembrane. That is, the polymers with a phospholipid polar group in the side chain, 2-methacrylooyloxyethyl phosphorylcholine (MPC) polymers were synthesized. The MPC polymers can inhibit surface-induced clot formation effectively, when they are in contact with blood even in the absence of an anticoagulant. This phenomenon was due to the reduction of plasma protein and suppression of denaturation of adsorbed proteins, that is the MPC polymers interact with blood components very mildly. As the molecular structure of the MPC polymer was easily designed by changing the monomer units and their composition, it could be applied to surface modification of artificial organs and biomedical devices for improving blood and tissue compatibility. Thus, the MPC polymers are useful polymer biomaterials for manufacturing high performance artificial organs and biomedical devices to provide safe medical treatments.     

Applikationsfelder organischer Funktionspolymere,Polymeraktoren und Polymertransistoren

Prospective application fields of organic functional polymers, polymer actuators and transistors The paper gives a short survey of prospective high tech products in which conducting polymers and other polymers with special electronic properties will be applied. Such products are, for example, polymer actuators, organic field effect transistors (OFET's) and integrated plastic circuits, organic light emitting diodes (OLED's), plastic solar or photovoltaic cells, membranes for fuel cells, polymer batteries and various polymer sensors. It will be informed about structures and properties of intrinsic conducting polymers and more in detail on electro‐chemo‐mechanical polymer actuators and on polymeric field effect transistors.     

高分子材料导电性能改善研究进展

提高高分子材料导电性能的方法,主要有掺杂、与其它材料复合、改变导电高分子的结构等方式。掺杂能够改变高分子材料中已有电子能带的能级,使得高分子中能带间的能量差减小,载流子迁移的阻力随之减小。与其它材料复合多为材料能提供载流子迁移的通道、与导电高分子材料形成大的共轭体系、改善链与链之间的有序性或增加复合物的紧密度,从而提高复合材料的导电性,与导电高分子复合的材料多为金属或金属氧化物、无机非金属纳米材料以及一些普通的有机高分子。改变导电高分子的结构能改善聚合物的规整度,提高其结晶度。导电高分子材料具有广泛的应用前景,今后需要在提高导电高分子电导率的同时改善其溶解性、加工性以及稳定性等综合性能,以实现导电高分子的实用化。     

Constructing Post‐Permeation Method to Fabricate Polymer/Nanocrystals Hybrid Solar Cells with PCE Exceeding 6%

A post‐permeation method is constructed for fabricating bulk‐heterojunction hybrid solar cells. Porous CdTe film is prepared by annealing the mixture solution of aqueous CdTe nanocrystals and cetyltrimethyl ammonium bromide, after which the post‐permeation of polymer is employed. By this method, kinds of polymers can be applied regardless of the intermiscibility with the nanoparticles. The inorganic nanocrystals and the polymer can be treated under respective optimized annealing temperatures, which can facilitate the growth of nanocrystals without damaging the polymers. A high power conversion efficiency of 6.36% in the polymer/nanocrystals hybrid solar cells is obtained via systematical optimization.     

Carbon Dots as Fillers Inducing Healing/Self‐Healing and Anticorrosion Properties in Polymers

Self‐healing is the way by which nature repairs damage and prolongs the life of bio entities. A variety of practical applications require self‐healing materials in general and self‐healing polymers in particular. Different (complex) methods provide the rebonding of broken bonds, suppressing crack, or local damage propagation. Here, a simple, versatile, and cost‐effective methodology is reported for initiating healing in bulk polymers and self‐healing and anticorrosion properties in polymer coatings: introduction of carbon dots (CDs), 5 nm sized carbon nanocrystallites, into the polymer matrix forming a composite. The CDs are blended into polymethacrylate, polyurethane, and other common polymers. The healing/self‐healing process is initiated by interfacial bonding (covalent, hydrogen, and van der Waals bonding) between the CDs and the polymer matrix and can be optimized by modifying the functional groups which terminate the CDs. The healing properties of the bulk polymer–CD composites are evaluated by comparing the tensile strength of pristine (bulk and coatings) composites to those of fractured composites that are healed and by following the self‐healing of scratches intentionally introduced to polymer–CD composite coatings. The composite coatings not only possess self‐healing properties but also have superior anticorrosion properties compared to those of the pure polymer coatings.     

Conjugated Polymer Shells on Colloidal Templates by Seeded Suzuki–Miyaura Dispersion Polymerization

The self‐assembly of colloidal conjugated polymers presents a versatile and powerful oute towards new functional optoelectronic materials and devices. However, this strategy relies on the existence of chemical protocols to prepare highly monodisperse colloids of conjugated polymers in high yields. Here, a recently developed Suzuki–Miyaura dispersion polymerization method is adopted to synthesize core–shell particles, in which a conjugated polymer shell is grown onto non‐conjugated organic and inorganic colloidal templates. By chemically anchoring aryl halide groups at the particle surface, a conjugated polymer shell can be attached to a wide variety of organic and inorganic microparticles. In this way, both spherical and non‐spherical hybrid conjugated polymer particles are prepared, and it is shown that the method can be applied to a variety of conjugated polymers. This new method offers independent control of the size, shape and photophysical properties of these novel conjugated polymer particles.     

原子转移自由基聚合在超支化大分子合成中的应用进展

超支化聚合物是一类具有不同于线性聚合物性质的新型高分子材料,原子转移自由基聚合(ATRP)作为一种活性可控聚合方法,在超支化聚合物合成领域发挥着重要的作用。ATRP在Cu(I)催化体系下不仅可以催化AB~*型单体生成超支化聚合物,而且还可以多官能团的大分子为引发剂,生成具有"核-壳"结构的两亲性共聚物或其它特殊结构大分子。文中主要介绍了近年来采用ATRP法合成的不同结构超支化聚合物,并对ATRP在超支化大分子合成中的应用前景进行了展望。     

Stacking layered structure of polymer light emitting diodes prepared by evaporative spray deposition using ultradilute solution for improving carrier balance

Polymer light-emitting diodes (PLEDs) with staking layered structures are prepared by the evaporative spray deposition using ultradilute solution (ESDUS) method, which has enabled forming a polymer layer onto another polymer layer even if both polymers are soluble in a solvent used for the preparation. By this method, polymers having various HOMO and LUMO levels can be stacked as a hole transport layer, an emitting layer and an electron transport layer as commonly employed in small molecule-based organic light emitting diodes. Here we demonstrated that a PLED having a tri-layer structure using three kinds of polymers showed significant improvement in quantum efficiency compared with those having a single or bi-layer structure of corresponding polymers.     

Approaches to improve compatibility of starch filled polymer system: A review

When hydrophilic starch is incorporated into synthetic polymers, the resulting products are weakened, especially blending with hydrophobic polymers. Many researchers have been undertaking various approaches to improve compatibility of starch and synthetic polymers. However, no ultimate and comprehensive approach can be determined. This paper aims to investigate and discuss the improvement approaches which have been recently developed by researchers. Also, the extents of improvement are summarized as well. In order to simplify this review, synthetic polymers are categorized into polar and non-polar types. Low density polyethylene was studied as non-polar type polymer, while polyvinyl alcohol was studied to represent as polar type polymer. Both types of synthetic polymers were blended with starches and their results were reported well by researchers. All findings are very informative and further encourage research for other starch filled polymer systems as well. In short, appropriate modifications to starch filled polymer system would induce polarity of the materials and subsequently create harmonious intermolecular interactions among blending components for better product properties.     

Framework for deformation induced anisotropy in glassy polymers

In this paper a constitutive model for glassy polymers is developed. Glassy polymers consist of a number of polymer chains that at a microscopic level form a network. If the distribution of the polymer chains shows some preferred direction, the mechanical response at a global macroscopic level will be anisotropic. To incorporate the orientational distribution of the polymer chains, a homogenization procedure involving a chain orientation distribution function was undertaken. When polymers are exposed to external loading, the chains at the microscopic level orient in a certain manner, leading to an evolution of the macroscopic anisotropic properties. This phenomenon was modeled by use of evolution equations for the chains at a microscopic level and are then—by using the orientation distribution function—transformed to the macroscopic level. The theories involved are developed in a large strain setting in which a multiplicative split of the deformation gradient for the elastic-viscoplastic response is adopted. Various numerical experiments were conducted to evaluate the model that was developed.     

新型梳形抗盐聚合物的流变性

进行了不同条件下聚丙烯酰胺和梳形抗盐聚合物溶液的粘度及流变性测定,发现根据不同条件下聚合物溶液的流变参数可以定性地判断三次采油用聚合物的抗盐能力大小和趋势。聚合物的流变性分析可作为评价聚合物抗盐性能的一条新途径,具有一定的实用价值。     

梯度高分子溶液的声衰减

聚合物在溶解过程中形成聚合物膜、溶胀层、高浓度溶解层及低浓度溶解层,从而形成梯度高分子溶液,此种梯度高分子溶液对声信号有很好的衰减效果．文中详细研究了梯度高分子溶液在不同频率下,聚合物厚度及梯度结构的变化对反射声衰减效果的影响．结果表明,梯度高分子溶液浓度梯度的形成是声衰减效果好坏的关键。溶液浓度梯度很大或很小时,声衰减效果均不好,只有当浓度梯度适当时,其声衰减效果才最佳。     

Biokompatible und bioaktive polymere Beschichtungen

Biocompatible and bioactive polymer surface for most biomedical applications of polymers biocompatible surface properties are highly needed. here we present various methods to immobilize biocompatible and also bioactive hydrogels on polymer surfaces. In one approach, macroinitiator‐based reactive layers are attached to polycondensates which are able to allow the grafting‐from of various hydrogels. on the other hand, it is possible to immobilize hydrophilic polymers on various substrates by plasma and e‐beam treatment. Stability, swelling and biocompatibility of the polymer films could be verified. by incorporating ph and thermo‐responsive groups, it is possible additionally to control the swelling behaviour by external triggers.     

An activated rate theory approach to the hydrostatic extrusion of polymers

An analysis of the mechanics of the hydrostatic extrusion process for polymers is presented, in which the predicted extrusion pressure is considered to be influenced by the effects of strain, strain rate and pressure on the material flow stress, as well as by the billet—die friction. The extrusion behaviour of both crystalline and amorphous polymers is discussed with reference to experimental results for linear polyethylene, polyoxymethylene and polymethylmethacrylate. Particular attention is paid to the method of incorporating the flow behaviour of the polymer into the analysis. A modified form of the Eyring equation for an activated rate process is proposed, in which the effects of strain rate and pressure on the flow stress are assumed to be separable, but related to strain by the large strain dependence of the stress activation volume. Moreover, a direct equivalence between the pressure effect and the friction between the polymer and the die is proposed for hydrostatic extrusion, following previous work on the adhesive mechanism for friction in polymers. This results in a formally identical analysis for both crystalline and amorphous polymers, in which the strain rate sensitivity, pressure sensitivity and friction coefficients all increase markedly with material strain during the process.     

Anisotropy of Charge Transport in a Uniaxially Aligned Fused Electron-Deficient Polymer Processed by Solution Shear Coating

Precise control of the microstructure in organic semiconductors (OSCs) is essential for developing high-performance organic electronic devices. Here, a comprehensive charge transport characterization of two recently reported rigid-rod conjugated polymers that do not contain single bonds in the main chain is reported. It is demonstrated that the molecular design of the polymer makes it possible to achieve an extended linear backbone structure, which can be directly visualized by high-resolution scanning tunneling microscopy (STM). The rigid structure of the polymers allows the formation of thin films with uniaxially aligned polymer chains by using a simple one-step solution-shear/bar coating technique. These aligned films show a high optical anisotropy with a dichroic ratio of up to a factor of 6. Transport measurements performed using top-gate bottom-contact field-effect transistors exhibit a high saturation electron mobility of 0.2 cm² V⁻¹ s⁻¹ along the alignment direction, which is more than six times higher than the value reported in the previous work. This work demonstrates that this new class of polymers is able to achieve mobility values comparable to state-of-the-art n-type polymers and identifies an effective processing strategy for this class of rigid-rod polymer system to optimize their charge transport properties.     

自修复聚合物的制备与应用研究进展

聚合物暴露于外部环境(光照、紫外线、热)之中会受到破坏,降低材料的性能以及使用寿命。自修复是人们模仿生物体损伤愈合的概念,解决材料损伤、延长材料使用寿命的新方法。针对近年来自修复聚合物材料的研究情况,文中根据自修复机理将其分为共价键自修复材料、超分子自修复材料两类,分别阐述了它们的化学原理与制备方法。在此基础上,对自修复性质的多样性,如形状自修复、导电性自修复、疏水性自修复、顺磁性自修复等应用性质进行综述。最后,展望了自修复聚合物材料的发展方向,指出纳米粒子、石墨烯等新颖的自修复方法已经崭露头角,有望从材料的堆积结构层次上完善并提高聚合物的自修复性能。     

Multicomponent semiconducting polymer systems with low crystallization-induced percolation threshold

Blends and other multicomponent systems are used in various polymer applications to meet multiple requirements that cannot be fulfilled by a single material. In polymer optoelectronic devices it is often desirable to combine the semiconducting properties of the conjugated species with the excellent mechanical properties of certain commodity polymers. Here we investigate bicomponent blends comprising semicrystalline regioregular poly(3-hexylthiophene) and selected semicrystalline commodity polymers, and show that, owing to a highly favourable, crystallization-induced phase segregation of the two components, during which the semiconductor is predominantly expelled to the surfaces of cast films, we can obtain vertically stratified structures in a one-step process. Incorporating these as active layers in polymer field-effect transistors, we find that the concentration of the semiconductor can be reduced to values as low as 3 wt% without any degradation in device performance. This is in stark contrast to blends containing an amorphous insulating polymer, for which significant reduction in electrical performance was reported. Crystalline-crystalline/semiconducting-insulating multicomponent systems offer expanded flexibility for realizing high-performance semiconducting architectures at drastically reduced materials cost with improved mechanical properties and environmental stability, without the need to design all performance requirements into the active semiconducting polymer itself.     

Surface modification of polymers by ion-assisted reaction

This paper deals with a new surface modification technique of polymers, the so-called ion-assisted reaction (IAR) to improve the surface properties of polymers and provides outstanding experimental results regarding wettability and adhesion of various polymers. In the IAR, polymer surfaces were subjected to low energy ion irradiation at different dosage in reactive gas environment. Dramatic improvements in wettability and surface energy are observed for the IAR-treated polymer surfaces and can be explained by the addition of functional groups, responsible for the increase of polar component in surface energy. The formation of functional groups results from the interaction among ion, reactive gas and polymer chain involved in IAR treatment, depending on the reactive ion species, the flow rate of the reactive gas and the irradiating ion fluence. The improvement in adhesion between the IAR-treated polymers and coating materials was explained in terms of the increased surface energy as well as surface roughness in the polymers modified by the IAR and possible adhesion enhancement mechanism is to be discussed.     

Synthesis, characterization, and nonlinear optical properties of donor–acceptor conjugated polymers and polymer/Ag nanocomposites

Two new donor–acceptor (D–A) conjugated polymers P1 and P2 containing 3,4-didodecyloxythiophene and 1,3,4-oxadiazole units are synthesized via Wittig reaction methodology. Cyclic voltammetry studies reveal that the polymers are both p and n dopable, and possess low-lying LUMO energy levels (?3.34?eV for P1 and ?3.46?eV for P2) and high-lying HOMO energy levels (?5.34?eV for P1 and ?5.27?eV for P2). The optical band gap of the polymers is in the range of 2.25–2.29?eV, calculated from the onset absorption edge. The polymers emit orange to yellow light in the film state when irradiated with a UV light. The synthesized polymers are used to prepare polymer nanocomposites with different wt% of silver nanoparticles. The polymer nanocomposites are characterized by UV–Vis absorption spectroscopy, field emission scanning electron microscopy, and thermogravimetric analysis. Both polymers and polymer/Ag nanocomposites show good thermal stability with onset decomposition temperature around 300?°C under nitrogen atmosphere. The nonlinear optical properties of polymers and polymer/Ag nanocomposites are measured by Z-scan technique. Both polymers and polymer nanocomposites show a good optical limiting behavior. Nearly five times enhancement in the nonlinear optical properties is observed for polymer/Ag nanocomposites. The value of effective two-photon absorption coefficient (β) is in the order of 10^?10–10^?11?m/W. These results indicate that the synthesized polymers (P1 and P2) and their Ag nanocomposites are expected to be good candidates for application in photonic devices.