Polymer Composites with Plasmonic Metal Nanoparticles

Summary: A two-phase method has been adapted for the preparation of polymer composites consisting of regioregular poly(3-octylthiophene-2,5-diyl) and Au or Ag nanoparticles. This work compares optical and morphological properties of nanocomposites formed by mixing metal organosols and polymer solution (type I composites) with nanocomposites formed by in-situ reduction in polymer solutions (type II composites). Both types contained very small metal nanoparticles (1–10 nm). Interestingly, more than ten-fold enhancement of Raman scattering of the polymer by the electromagnetic (EM) mechanism of SERS (surface-enhanced Raman scattering) resulted from the coupling of the polymer with plasmonic Au nanoparticles into a nanocomposite system.     

Catalytic and Optical Behavior of Polymer Embedded Metal Nanoparticles

Very small metal aggregates (nanoaggregates) embedded in an inert polymer matrix, which simply stabilizes the nanodispersion, show unique catalytic and optical behaviour. Indeed Ru-nanoparticles in vinyl-aromatic polymers or polyphosphazenes display an enhanced reactivity for hydrogenation of different groups, such as aromatic rings, keto and nitro groups, oximes and nitriles which are converted into the corresponding saturated derivatives under mild conditions. The optical properties of terthiophenethiol-coated gold nanoparticles in UHMWPE (concentration lower than 4 wt.%) are characterized by poor dichroism due to their centrosymmetric structure. High dichroism (R = 30 at 400 nm, DR = 30) is on the contrary recorded for the terthiophene band showing the chromophores to be sensitive to mechanical orientation also when complexed with gold. On the other hand, nanocomposites based on polymers containing vinyl alcohol units and dispersed gold nanoparticles with average diameter ranging from 3 to 20 nm have been efficiently prepared by an UV photo-reduction process. Uniaxial drawing of the irradiated Au/polymer nanocomposites favours the anisotropic distribution of packed assemblies of gold particles, providing oriented films with polarization-dependent tunable optical properties.     

Polymer nanocomposites

Polymer nanocomposites are distinguished by the convergence of length scales corresponding to the radius of gyration of the polymer chains, a dimension of the nanoparticle and the mean distance between the nanoparticles. The consequences of this convergence on the physics of the polymer chains are considered, and some of the outstanding issues and their potential consequences on structure—property relations for polymer nanocomposites are highlighted. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3252–3256, 2007     

粒子-聚合物相互作用与粒子-粒子相互作用对聚合物基纳米复合物力学性能的影响

聚合物基纳米复合物(PNCs)具有比传统高分子材料更加优异的光学、力学、热力学等性能,广泛应用于各个工程领域.而纳米粒子(NPs)对材料性能提高的机理则是当前聚合物纳米复合物领域研究的重要问题,聚合物纳米复合体系相互作用的影响因素众多,至今尚未明确并完整建立复合体系相互作用与性能增强之间的关系.本文总结了近年来关于纳米粒子填充聚合物基体力学性能的研究,从粒子-聚合物相互作用和粒子-粒子相互作用角度阐述了聚合物纳米复合体系力学性能的增强机理,并根据体系中不同的结构关系分别总结了聚合物/未改性纳米粒子复合体系和聚合物/聚合物接枝纳米粒子复合体系中影响力学性能的因素.该部分内容具有重要的理论和实践意义,有助于构建复合体系微观结构与宏观性能之间的关系,进而对微观层面调控PNCs的力学性能提供指导.     

层状仿生高分子纳米复合材料

自然界中,鲍鱼壳具有有机-无机多级次层状结构以及大量的复合界面作用,力学性能优异。这一独特的层状结构主要由霰石碳酸钙片层构成,并通过体积分数约为5%的生物高分子在层间进行粘合。受鲍鱼壳这一微观结构的启发,我们利用不同的基元材料如纳米蒙脱土、碳纳米管以及氧化石墨烯等构筑仿鲍鱼壳层状结构,并结合多种界面设计,实现不同界面、不同基元材料之间的协同作用,得到了力学性能优异的高分子纳米复合材料。仿生高分子纳米复合材料的成功制备,为今后的研究提供了崭新的思路,拓宽了高分子纳米复合材料的应用前景。     

Polymer grafted nanoparticles: Effect of chemical and physical heterogeneity in polymer grafts on particle assembly and dispersion

Macroscopic properties of polymer nanocomposites depend on the microscopic composite morphology of the constituent nanoparticles and polymer matrix. One way to control the spatial arrangement of the nanoparticles in the polymer matrix is by grafting the nanoparticle surfaces with polymers that can tune the effective interparticle interactions in the polymer matrix. A fundamental understanding of how graft and matrix polymer chemistries and molecular weight, grafting density, and nanoparticle size, and chemistry affect interparticle interactions is needed to design the appropriate polymer ligands to achieve the target morphology. Theory and simulations have proven to be useful tools in this regard due to their ability to link molecular level interactions to the morphology. In this feature article, we present our recent theory and simulation studies of polymer grafted nanoparticles with chemical and physical heterogeneity in grafts to calculate the effective interactions and morphology as a function of chemistry, molecular weights, grafting densities, and so forth. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

聚合物纳米复合体系中聚合物结构及动力学研究进展

从计算模拟及实验角度系统总结了聚合物结构、 聚合物构象、 聚合物扩散及聚合物多尺度动力学的研究进展, 阐述了各影响因素及其变化规律, 并对聚合物动力学的未来研究进行了展望.     

Biodegradable polymer nanocomposites: An overview

Biodegradable polymer nanocomposites, due to their biodegradability and other improved properties possess tremendous scope in the industrial sector. This current article reviews the recent studies carried out over biodegradable polymer nanocomposites that includes preparation, characterization, properties, and applications of nanocomposites based on biodegradable polymers. An orderly introduction of nanocomposites prepared by using various biodegradable aliphatic polyesters and polymers obtained from biomass products has been brought about. A wide range of organic and inorganic nanoparticles was used as additives or fillers to prepare nanocomposites with improved desired properties. Considering vast research on layered silicates/polymer nanocomposites, a special emphasis has been summarized at the end of the review.     

碳纳米管/聚合物纳米复合材料研究进展

碳纳米管/聚合物纳米复合材料是近几年发展起来的一个新的研究方向。本文从增强和功能性两个方面评述了碳纳米管/聚合物纳米复合材料的发展过程以及最新进展，详细讨论了碳纳米管在聚合物中的分散、取向和胃面相互作用对复合材料力学性能的影响，介绍了碳纳米管的加入赋予聚合物的一些新的光电性能，并对今后的研究方向进行了展望。     

Ordered Toroid Structures of Nanoparticles in Self-attractive Semi exible Polymer/Nanoparticle Composites

By employing dynamic Monte Carlo simulations, we investigate a coil-to-toroid transition of self-attractive semiflexible polymers and the spatial distributions of nanoparticles in selfattractive semiflexible polymer/nanoparticle composites. The conformation of self-attractive semiflexible polymers depends on bending energy and self-attractive interactions between monomers in polymer chains. A three-stage process of toroid formation for self-attractive semiflexible chains is shown: several isolated toroids, a loose toroid structure, and a compact toroid structure. Utilizing the compact toroid conformations of self-attractive semiflexible chains, we can control effectively the spatial distributions of nanoparticles in self-attractive semiflexible polymer nanocomposites, and an unconventional toroid structure of nanoparticles is observed.     

聚合物/层状硅酸盐插层纳米复合材料的研究

简述了聚合物 /层状硅酸盐插层纳米复合材料方面的研究进展。阐述了层状硅酸盐的结构与性质以及纳米复合材料形成过程的热力学原理。重点介绍了尼龙、聚丙烯等聚合物的层状硅酸盐插层纳米复合材料的现状和技术发展趋势     

Reactive Polymer as a Versatile Toolbox for Construction of Multifunctional Superparamagnetic Nanocomposites

The development of magnetic nanoparticles with multiple functions has been an ever‐growing field because of their diverse applications in drug delivery, biosensing, cell labeling, and so on. In this study, a facile method was developed to construct multifunctional magnetic nanocomposites. The approach is based on the use of poly(glycidyl methacrylate), PGMA, with numerous epoxy groups as reactive polymer to combine with fluorescent dye, the surface of magnetic nanoparticles, and targeting ligands directly without expatiatory functionality design. The resultant nanocomposites with good superparamagnetic and fluorescent properties could be exploited for bioimaging. Moreover, after conjugation with a model protein, namely, transferrin, which specifically targets cells overexpressing transferrin receptors, the nanocomposites could be used selectively to recognize Hela cells in comparison with nonconjugated ones. These results indicate that the newly designed magnetic nanocomposites with PGMA as functional polymer could serve as a novel versatile platform to conjugate with various molecules for construction of diverse multifunctional magnetic nanocomposites to meet different requirements and potential uses in nanomedicine and biological chemistry.     

A novel method to synthesize polystyrene nanospheres immobilized with silver nanoparticles by using compressed CO2

In this work, a novel route to synthesize polymer/metal composite nanospheres has been proposed. This method combines the advantages that the polymer chains collapse and entangle in the presence of compressed CO(2), which acts as antisolvent, and the metal nanoparticles and polymers can be precipitated simultaneously from micellar solutions by the easy control of CO(2) pressure. Ag/polystyrene (PS) nanocomposites have been successfully prepared using this method. The transmission electronic micrographs (TEM) of the obtained nanocomposites show that the smaller Ag nanoparticles are immobilized by PS nanospheres of about 50 nm; the phase structure was characterized by X-ray diffraction (XRD). The Ag/PS nanocomposites show absorption properties at a wavelength of approximately 417 nm. The results of X-ray photoelectron spectra (XPS) and FT-IR spectra indicate that there is no chemical linkage or strong interaction between PS and Ag nanoparticles in the resultant products. This method has many potential advantages for applications and may easily be applied to the preparation of a range of inorganic/ polymer composite nanoparticles.     

Polymer nanocomposites for electrical energy storage

This review highlights the frontier scientific research in the development of polymer nanocomposites for electrical energy storage applications. Considerable progress has been made over the past several years in the enhancement of the energy densities of the polymer nanocomposites via tuning the chemical structures of ceramic fillers and polymer matrix and engineering the polymer–ceramic interfaces. This article summarizes a range of current approaches to dielectric polymer nanocomposites, including the ferroelectric polymer matrix, increase of the dielectric permittivity using high‐permittivity ceramic fillers and conductive dopants, preparation of uniform composite films based on surface‐functionalized fillers, and utilization of the interfacial coupling effect. Primary attentions have been paid to the dielectric properties at different electric fields and their correlation with film morphology, chemical structure, and filler concentration. This article concludes with a discussion of scientific issues that remain to be addressed as well as recommendations for future research. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1421–1429, 2011     

Polymer/montmorillonite nanocomposites with improved thermal properties: Part I. Factors influencing thermal stability and mechanisms of thermal stability improvement

The results of recent research indicate that the introduction of layered silicate - montmorillonite - into polymer matrix results in increase of thermal stability of a number of polymer nanocomposites. Due to characteristic structure of layers in polymer matrix and nanoscopic dimensions of filler particles, several effects have been observed that can explain the changes in thermal properties. The level of surface activity may be directly influenced by the mechanical interfacial adhesion or thermal stability of organic compound used to modify montmorillonite. Thus, increasing the thermal stability of montmorillonite and resultant nanocomposites is one of the key points in the successful technical application of polymer-clay nanocomposites on the industrial scale. Basing on most recent research, this work presents a detailed examination of factors influencing thermal stability, including the role of chemical constitution of organic modifier, composition and structure of nanocomposites, and mechanisms of improvement of thermal stability in polymer/montmorillonite nanocomposites.     

Polymer nanocomposites in medicine

A large number of recent studies deal with the application of nano materials to different medicine areas, application that led to a new discipline known as nanomedicine. It comprises the processes of diagnosing, treating, curing, preventing diseases and also dealing with traumatic injury, relieving pain and preserving/improving human health by using nano materials. Among nano materials, an important place belongs to the group of natural and synthetic polymer nanocomposites. These are made up of an organic polymer matrix and a mineral, organic or metallic nanofiller. The properties of polymer nanocomposites depend on the characteristics of the components and on the interaction polymer-nanofiller. Polymer nanocomposites offer to modern medicine new opportunities for generate products for antibacterial treatment, tissues engineering, cancer therapy, medical imaging, dental applications, drug delivery, etc.     

高分子/棒状纳米粒子复合物的分子动力学模拟

采用非平衡态分子动力学模拟研究了剪切场下棒状纳米粒子对高分子基体的结构、 动力学和流变性质的影响. 通过比较多种体积分数(0.8%~10%)的纳米复合物及纯熔体的模拟结果发现, 随着纳米粒子的增加, 高分子链的扩散和松弛逐渐受到抑制, 而链尺寸几乎保持不变. 从Weissenberg number(W_i)角度看, 在剪切流场下, 高分子链的结构性质(如归一化的均方回转半径、 回转张量和取向抑制参数)几乎与纳米粒子的体积分数无关, 而高分子链的Tumbling运动受到抑制. 研究还发现, 纳米复合物与纯熔体的剪切黏度曲线趋势基本一致, 即W_i=1将曲线分为平台区和剪切变稀区. 纳米棒的加入仅定量地改变了流体的剪切黏度.     

Nanocomposites of polymers and metals or semiconductors: Historical background and optical properties

Upon transmission of visible light through composites comprising of a transparent polymer matrix with embedded particles, the intensity loss by scattering is substantially reduced for particle diameters below 50–100 nm (nanoparticles, nanosized particles). As a consequence, related materials (nanocomposites) have found particular interest in optical studies. The first part of this article deals with a historical survey on nanoparticles and nanocomposites and the importance of small particle sizes on their optical properties. The second part focuses on results from our laboratory concerning nanocomposites with extremely high or low refractive indices and dichroic nanocomposites and their application in bicolored liquid crystal displays (LCD). The inorganic colloids required for these studies (lead sulfide, iron sulfides, gold, and silver) were prepared in situ in presence of a polymer or isolated as redispersable metal colloids modified at the surface with a self‐assembled monolayer (SAM) of an alkanethiol. The nanocomposites themselves were finally obtained by coprecipitation, spin coating, solvent casting or melt extrusion, with poly(ethylene oxide), gelatin, poly(vinyl alcohol) and polyethylene as matrix polymers.     

聚合物纳米复合电介质

聚合物纳米复合材料能够发挥纳米材料在电、磁、光等方面的优越性,也具有聚合物的易成型等方面的优点,正成为电介质领域研究的热点.本文综述了聚合物纳米复合材料在介电性能方面的研究概况,主要涉及了电导、介电强度与空间电荷、介电常数、介电损耗以及局部放电等方面的研究.最后展望了今后的研究方向.     

Broadband Dielectric Relaxation Spectroscopy in Polymer Nanocomposites

Summary: Dielectric spectroscopy in the frequency domain and thermally stimulated depolarization currents techniques, covering together a broad frequency range (10⁻⁴–10⁹ Hz), were employed to investigate molecular dynamics in relation to structure and morphology in polymeric nanocomposites. Several systems were investigated, three of them with the same epoxy resin matrix and different inclusions (modified smectite clay, conducting carbon nanoparticles and diamond nanoparticles) and two with silica nanofiller (styrene-butadiene rubber/silica and polyimide/silica nanocomposites). Special attention was paid to the investigation of segmental dynamics associated with the glass transition of the polymer matrix, in combination also with differential scanning calorimetry measurements. Effects of nanoparticles on local (secondary) relaxations and on the overall dielectric behavior were, however, also investigated. Several interesting results were obtained and discussed for each of the particular systems. Two opposite effects seem to be common to the nanocomposites studied and dominate their behavior: (1) immobilization/reduction of mobility of a fraction of the chains at the interface to the inorganic nanoparticles, due to chemical or physical bonds with the particles, and (2) loosened molecular packing of the chains, due to tethering and geometrical confinement, resulting in an increase of free volume and of molecular mobility.