Search query: semiconductor nanoparticles in polymer blends

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abstract: Polymeric blends of Poly (p anisidine) with ZnO nanoparticles was prepared by chemical oxidative polymerization. Zinc oxide doped PPA polymer nanocomposite (ZPPA) and Magnesium doped Zinc oxide PPA polymer nanocomposite (MZPPA) were synthesized with the addition of semiconductor metal oxide to the polymeric solution. The X ray diffraction studies of ZnO nanoparticles showed hexagonal wurzite structure. The surface morphological study also confirms the formation of hexagonal structured nanoparticles. The peak for Magnesium and Zinc in EDS spectra confirms the formation of Magnesium doped polymer nanocomposite. The addition of ZnO/MgZnO onto PPA conducting polymer showed agglomeration of semiconductor material results in spherical shaped polymer nanocomposite and irregular overlapping over the PPA polymeric surface. The electrochemical conductivity studies suggested that the doped PPA conducting polymeric blends showed enhanced conductivity nature.
author_names: Rathidevi K

Velmani N

Tamilselvi D
title: Electrical conductivity study of poly(p anisidine) doped and undoped ZnO nanocomposite
year: 2019

abstract: Abstract A theoretical macrokinetic model for photoinduced growth of semiconductor nanoparticles was developed with allowance for specific features of their optical properties in the near ultraviolet region. In [A. A. Smirnov et al. Optical Materials Express, 8 (2018) 1603 1612] the Polymethylmethacrylate (PMMA) film containing good soluble CdS precursors [Cd(N(SCNEt2)2)2] (TEDBCd) was irradiated by an ultraviolet light emitting diode (UV LED) with a central wavelength of 365 nm at different fixed temperatures and at different fixed intensities. The authors in situ followed the evolution of absorbance at a wavelength of 405 nm where the film is initially transparent. The corresponding photon energy is larger than the bandgap of the bulk CdS crystals. The increase in absorbance of the irradiated film at this wavelength was associated with the CdS nanoparticle growth. The main result is that at a given temperature, the effect of UV radiation on the sample is determined by the exposure (dose) rather than the light intensity and the irradiation time separately. The presented paper aims at constructing a model of the semiconductor particle growth initiated by the light induced destruction of good soluble precursor molecules and fitting this model to the experimental data, making it possible to estimate the most important parameters of the process. The photoinduced formation of CdS nanoparticles is a complicated process that includes photo mediated destruction of the precursor molecules followed by diffusion assisted growth of nanoclusters. The feature of the growing semiconductor nanoparticles is that rather small particles do not absorb radiation at a particular wavelength because of the quantum confinement. The theory also takes into account the finite thickness of the sample and the nonlinear effects of radiation shielding.
author_names: Nikita Bityurin

Anton A Smirnov
title: Model for UV induced growth of semiconductor nanoparticles in polymer films
venue: Applied Surface Science
year: 2019

abstract: Abstract The aim of this work was to obtain Janus nanoparticles from known methods using easily accessible cation modifiers. In addition, the intent was to study the use of these particles in polystyrene/poly (methyl methacrylate) (PS/PMMA) polymer blends and to perform a complete study of their properties. Two types of Janus nanoparticles were obtained using kaolinite. The octahedral and tetrahedral layers of the clay mineral were modified with a PMMA hairy copolymer and two species of amines, in order to interact with PMMA and PS phases in a polymer blend. The blends were obtained by solution processing using a mixer with high rotation and then evaluated by their morphology and thermo mechanical, mechanical, and thermal properties. The microscopic analysis showed that the incorporation of Janus nanoparticles improved the interaction between phases and the size of the domains was reduced which increased their compatibility. This increase in compatibility had an influence on the mechanical, thermal, and thermo mechanical properties. In relation to a pure blend, it increased the storage modulus, Young's modulus, and strain of break up to 50% 35% and 70% respectively. The construction of different types of Janus nanoparticles as well as their application in PS/PMMA blends resulted in an interesting material with enhanced properties which indicated that these nanoparticles have a compatibilizing effect in polymeric systems.
author_names: Tales S Daitx

Caroline Gross Jacoby

Creusa Iara Ferreira

Paulo Henrique Schneider

Raquel Santos Mauler
title: Kaolinite based Janus nanoparticles as a compatibilizing agent in polymer blends
year: 2019

abstract: Surface modified boehmite nanorods have been synthesized by binary grafting of reactive epoxide groups and long poly(methyl methacrylate) (PMMA) tails. The prepared nanoparticles have been incorporated into the immiscible poly(vinylidene fluoride)/poly(L lactide) (PVDF/PLLA) blends. Unlike the traditional metal hydroxide flame retardants, a small amount of surface modified boehmite nanorods (5 wt% can simultaneously enhance both the flame retardancy (with the LOI increasing 33% and mechanical performance (with elongation at break increasing more than 10 times) of the PVDF/PLLA (70/30) blends. It is found that the boehmite nanorods are dominantly located at the interface between PVDF and PLLA phases. The reactive boehmite nanorods improve the compatibility of PVDF/PLLA blends by physical entanglement and in situ chemical reaction during melt blending. At the same time, the nanorods at the interface reduce the surface temperature and form a dense metal oxide layer which isolates the flame and oxygen through their thermal decomposition during combustion. Therefore, simultaneous enhancements in both mechanical properties and flame retardancy using flame retarding metal hydroxides have been achieved for the first time.
author_names: Zhiang Fu

Hengti Wang

Xuewen Zhao

Xuan Li

Xiaoying Gu

Yongjin Li
title: Flame retarding nanoparticles as the compatibilizers for immiscible polymer blends: simultaneously enhanced mechanical performance and flame retardancy
year: 2019

abstract: Janus nanoparticles (JPs) which are anisotropic nanoparticles with at least two opposite surface regions, have been demonstrated as highly efficient compatibilizers for polymer blends. However, there are still a number of open questions concerning the mechanism behind the influence of JPs on the phase separation dynamics of polymer blends. Herein, we report a counter intuitive feature of JPs concerning their roles during spinodal decomposition (SD) that is, they promote the decomposition of unlike polymers in the early stage of SD but retard it during the late stage. This is in remarkable contrast to traditional compatibilizers such as block copolymers and homogenous nanoparticles, which impede phase separation during both stages. We further demonstrate that the unique promoting effect of JPs at early times is due to the formation of microphase separated homopolymer rich regions in the vicinity of opposite JP surface regions. Our findings are expected to have important implications for the phase separation behavior of JP compatibilized polymer blends, whose morphologies and performance could be controlled by tuning the interactions between the constituent polymers and JP based compatibilizers.
author_names: Qing Li

Liquan Wang

Jiaping Lin

Liangshun Zhang
title: Distinctive phase separation dynamics of polymer blends: roles of Janus nanoparticles.
venue: Physical chemistry chemical physics PCCP
year: 2019

abstract: Molecular dynamics simulations were performed to study the fabrication of polymeric colloids containing inorganic nanoparticles (NPs) via the flash nanoprecipitation (FNP) technique. During this process, a binary polymer blend, initially in a good solvent for the polymers, is rapidly mixed with NPs and a poor solvent for the polymers that is miscible with the good solvent. The simulations reveal that the polymers formed Janus particles with NPs distributed either on the surface of the aggregates, throughout their interior, or aligned at the interface between the two polymer domains, depending on the NP polymer and NP solvent interactions. The loading and surface density of NPs can be controlled by the polymer feed concentration, the NP feed concentration, and their ratio in the feed streams. Selective localization of NPs by incorporating electrostatic interactions between polymers and NPs has also been investigated, and was shown to be an effective way to enhance NP loading and surface density as compared to the case with only van der Waals attractions. This work demonstrates that the FNP process is promising for the production of structured and hybrid nanocolloids in a continuous and scalable way, with independent control over particle properties such as size, NP location, loading, and surface density. Our results provide useful guidelines for experimental fabrication of such hybrid nanoparticles.
author_names: Nannan Li

Arash Nikoubashman

Athanassios Z Panagiotopoulos
title: Self Assembly of Polymer Blends and Nanoparticles through Rapid Solvent Exchange.
venue: Langmuir the ACS journal of surfaces and colloids
year: 2019

abstract: Nanoparticles (NPs) have had increasingly successful applications including in emissive or photovoltaic devices; however, trap states associated with the surface of NPs often drastically reduce the efficiency of devices and are difficult to detect spectroscopically. We show the applicability of photoconduction as means of detecting and quantifying trap states in NPs. We performed Time of Flight (ToF) photoconduction measurements, using semiconducting poly[bis(4 phenyl)(4 butyphenyl)amine] (P TPD) doped with either core/shell CdSeS/CdS quantum dots (QDs) or perovskite CsPbBr3 NPs, both of which are carefully designed to be energetically matched. In the case of the QDs, a drop in hole mobility from ~10 3 to ~10 4 cm2V 1s 1 was observed when compared to a control sample, suggesting the presence of hole trapping. These trap states were found to be around 5.0 to 4.9 eV from the vacuum level. The presence of the trap states was further supported by a coincident reduction in photoluminescence (PL) quantum yield (QY) and lifetime of the core/shell QDs after purification. Using the measured reductions in the PL QY and lifetime, the surface trap state density was estimated to increase by between 20 and 40% most likely due to ligand detachment. In the case of the perovskite NP doped samples, a mobility of ~10 3 cm2V 1s 1 was measured. Thus, doping with perovskite NPs did not generate any obvious hole trapping from the P TPD matrix. The absence of trapping may be related to the reduced surface to volume ratio and NP number density of the perovskite NPs compared to the core/shell QDs, since the perovskite NPs are approximately 10 times larger in radius than that of the core/shell QDs. Our results suggest that to minimize the presence of trap states with a view to improving device performance, large size perovskite NPs appear to be better than small size QDs.
author_names: Xiaoqing Guo

Qianxun Gong

Joanna Borowiec

Sijie Zhang

Shuo Han

Meng Zhang

Maureen Willis

Theo Kreouzis

Kui Yu
title: Energetics of Non Radiative Surface Trap States in Nanoparticles Monitored by Time of Flight Photoconduction Measurements on Nanoparticle Polymer Blends.
venue: ACS applied materials interfaces
year: 2019

abstract: Abstract Solution processed polymer semiconductors are key materials in the fabrication of lightweight, low cost, and flexible electronic devices without using the high vacuum process. For practical applications, reliable device operations based on these materials are required. In this study, we propose a strategy to improve the operation stability of organic field effect transistors (OFETs) using solution processed polymer semiconductor/insulator blends as the active channel prepared by introducing a fluorinated insulating polymer in the blends. The semiconducting polymer forms nanowire networks in spin coated ternary blend films, which serve as charge transport pathways in the insulating polymer matrix consisting of the fluorinated polymer and polystyrene. Owing to its high surface potential attributed to the strongly electron withdrawing structure, the fluorinated polymer provides a large energy barrier for suppression of the hole trapping at the semiconductor/insulator interface. Consequently, OFETs based on the ternary blend films with an optimized polymer composition exhibit almost hysteresis free transfer and output characteristics and superior electrical stabilities under sustained gate bias stresses in both N2 and air atmospheres. We believe that our study provides a practical route to the fabrication of OFETs based on polymer semiconductor/insulator blend systems with high operation stabilities.
author_names: Dong-Jin Yun
title: Enhanced gate bias stress stability of organic field effect transistors by introducing a fluorinated polymer in semiconductor/insulator ternary blends
venue: Applied Surface Science
year: 2019

abstract: Nanoparticles in polymer nanocomposites can be dielectric quantum dots (DQDs) A quantum dot model is proposed for nanoparticles imbedded in polymers based on both this new concept and the multicore model proposed in 2005. QDs should be as small as de Broglie's wavelength and the exciton Bohr diameter, and accommodate a countable number of charge carriers. DQDs are a little bit larger than metal and semiconductor QDs. Some of dielectric performances such as permittivity, charge transport, space charge and treeing can be explained in terms of nonlinear multi functional traps derived from the DQD model. It was verified that different combination of polymers and nanoparticles lead to different characteristics.
author_names: Toshikatsu Tanaka
title: A quantum dot model for nanoparticles in polymer nanocomposites
venue: IEEE Transactions on Dielectrics and Electrical Insulation
year: 2019

abstract: The electrical properties of composite films based on polymer PEDOT:PSS with a addition of Ag nanoparticles or Ag TiO2 nanostructures have been studied. A current voltage characteristic is observed for polymer solar cells. A short circuit current increased after adding of Ag nanoparticles or Ag TiO2 nanostructures to the PEDOT:PSS polymer. Also, an increase in the recombination rate in cells with silver nanoparticles is observed. An electrical impedance is measured for polymer solar cells. A significant increase in the dielectric constant of a PEDOT:PSS film containing silver nanoparticles was detected.
author_names: Ibrayev N Kh

Afanasyev D A
title: ELECTRICAL CHARACTERISTICS OF SEMICONDUCTOR POLYMER FILMS DOPED WITH SILVER NANOPARTICLES
year: 2019