Host Polymer Matrices Research Articles

TiO2 DOPED PDPP3T NANOCOMPOSITE THIN FILM FOR PHOTOVOLTAIC APPLICATION

In present work, an inorganic dopant TiO2 nanoparticles are introduced into the PDPP3T polymer host material and deposited as thin films via spin coating. Different solvent are investigated to get efficient dispersion of TiO2 nanoparticles as well as effective dissolution of PDPP3T material. The role of TiO2 particles towards optical absorption of PDPP3T material is studied by preparing different PDPP3T/TiO2 blend ratios and annealed at different temperatures. Toluene is found an efficient solvent for the dispersion of TiO2 nanoparticles as well as dissolution of PDPP3T material. Significant increase in optical absorption in UV region 300-400nm is observed for the PDPP3T/TiO2 blend ratio 1:0.2 and the annealing temperature 310oC. The deposited thin film with four layers have demonstrated significant blue shift in peak wavelength and increase in the absorption in UV region (300-400nm). XRD analysis reveals amorphous nature of all deposited thin film. No significant variations in chemical structure are observed with increase in thickness of deposited layer. The addition of TiO2 particle in PDPP3T material significantly enhanced the optical absorption in UV region.

Compact shielding design for 740 GBq 241Am-Be neutron source transport container

For transport and storage of neutron sources, shielding materials like polymers and multi layer shields are used. A compact shielding design for 740 GBq portable 241Am-Be neutron source transport container using Monte Carlo technique is presented. In the design, a polymer host material with lead and natural boron (NB) as fillers is chosen as the shielding medium. Monte Carlo simulation (MCS) is performed for optimizing the quantity of fillers in the polymer. The total dose rate (TDR) on the surface of the container due to neutrons and gamma rays emanating from source as well as polymer shield, is considered as the optimization criterion. MCS studies indicate that a polymer material with 5% of lead and 1% of NB as fillers is observed to give optimized composition of polymer (OCP). Statistical factorial design analysis (FDA) technique is employed for the first time in the shielding design to investigate the impact of fillers in the polymer. FDA studies reveal that the quantity of lead has more significant impact compared to NB in the polymer. MCS results are validated by carrying out shielding experiments with high density polyethylene (HDPE) and composite polymer (CP) based containers. The computed and experimental dose rates are observed to be within ±12%. A shielding container made of OCP for the transport of 740 GBq 241Am-Be source provides 25% reduction in the volume as compared to HDPE and CP. The mass of the OCP container is lower by 18% and 26% compared to the containers made of HDPE and CP respectively. The surface dose rate of the OCP container adheres to the IAEA transport regulations.

Encapsulation of colloid perovskite nanocrystals into solid polymer matrices: Impact on electronic transition and photoluminescence

To improve the stability and enable luminescent devices, colloidal perovskite nanocrystals (NCs) are usually encapsulated by polymer host matrices. Here, colloidal CsPbX3 (X = Cl, Br or I, or mixture) NCs with bright emissions covering wide color gamut (~410–700 nm) are incorporated into the off-stoichiometry thiol-ene (OSTE) for solid state luminescence. The impact of polymer encapsulation on electronic transitions is investigated by comparison of absorption, photoluminescence (PL), and time resolved PL (TRPL) of the CsPbX3 NCs before and after the encapsulation by the OSTE. The PL bandwidth increase pronouncedly, while the PL peak position apparently blue shifts after encapsulation. The spectral changes suggest the energy transfer between the CsPbX3 NCs and OSTE matrix and decreased exciton binding energy due to the suppressed dielectric screen effect, which are further validated by the TRPL results. This work sheds light on the fluorescence of CsPbX3 NCs incorporated in the polymer host matrices, which will facilitate their future applications in light-emitting and other optoelectronic devices.

Supramolecular Polymer Systems: Efficient Aggregation‐Induced Emission Manipulated by Polymer Host Materials (Adv. Mater. 37/2019)

Supramolecular Polymer Systems: Efficient Aggregation‐Induced Emission Manipulated by Polymer Host Materials (Adv. Mater. 37/2019)

Efficient Aggregation-Induced Emission Manipulated by Polymer Host Materials.

Linear copolymer hosts bearing a number of pillar[5]arene dangling side chains are synthesized for the facile construction of highly emissive supramolecular polymer networks (SPNs) upon noncovalently cross-linking with a series of tetraphenyethylene (TPE)-based tetratopic guests terminated with different functional groups through supramolecular host-guest interactions. An extremely high fluorescence quantum yield (98.22%) of the SPNs materials is obtained in tetrahydrofuran (THF) by fine-tuning the parameters, and meanwhile supramolecular light-harvesting systems based on spherical supramolecular nanoparticles are constructed by interweaving 9,10-distyrylanthracene (DSA) and TPE-based guest molecules of aggregation-induced emission (AIE) with the copolymer hosts in the mixed solvent of THF/H2 O. The present study not only illustrates the restriction of the intramolecular rotations (RIR)-ruled emission enhancement mechanism regulated particularly by macrocyclic arene-containing copolymer hosts, but also suggests a new self-assembly approach to construct high-performance light-harvesting materials.

Triplet-Triplet Annihilation Upconversion in Broadly Absorbing Layered Film Systems for Sub-Bandgap Photocatalysis.

Upconversion (UC) of sub-bandgap photons extends the effective light absorption range of photovoltaic and photocatalytic devices, allowing them to reach higher conversion efficiencies. Recent advances in polymer host materials make it possible to translate triplet-triplet annihilation (TTA)-UC, the UC mechanism most suitable for this purpose, to solid films that can be integrated into devices. The promise of these films is currently limited by the narrow light absorption of TTA-UC sensitizer chromophores, but incorporating multiple sensitizers into layered film systems presents a promising strategy for producing UC materials with broadened light absorption. This strategy is hereinapplied for photocatalytic air purification, demonstrating its use in a real-world application for the first time. We superimpose optimized red-to-blue and green-to-blue UC films within dual-layer systems and develop a new photocatalyst compatible with their fluorescence emission. By integrating the dual-layer UC film systems withfilms of this photocatalyst, we produce the first devices that use TTA-UC to harness both red and green sub-bandgap photons for hydroxyl radical generation and photocatalytic degradation of gaseous acetaldehyde, a model volatile organic compound (VOC). Under white light-emitting diode excitation, the dual-layer film systems' broadened light absorption enhances their devices' photocatalytic degradation efficiency, enabling them to degrade twice as much acetaldehyde as their single-sensitizer counterparts. We show that as a result of the different absorption profiles of the two sensitizers, the film order significantly impacts UC fluorescence and VOC degradation. By probing the influence of the excitation light source, excitation geometry, and chromophore spectral overlap on the film systems' UC performance, we propose a framework for the design of multilayer TTA-UC film systems suitable for integration with a variety of photovoltaic and photocatalytic devices.

Investigation of alumina nanofiller impact on the structural and dielectric properties of PEO/PMMA blend matrix-based polymer nanocomposites

Polymer nanocomposite (PNC) films have been prepared by the solution-cast method using a polymer blend of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) (PEO/PMMA = 50/50 wt%) as organic host matrix and x wt% Al2O3 nanoparticles (x = 0, 1, 3, and 5) as inorganic nanofiller. The morphological and structural behavior of these PNC films has been examined by employing the scanning electron microscope (SEM), X-ray diffractometer (XRD), and Fourier transform infrared (FTIR) spectrometer, whereas their dielectric polarization and relaxation processes are characterized by carrying out the dielectric relaxation spectroscopy (DRS) over the frequency range 2 × 101 to 1 × 106 Hz. Impact of Al2O3 nanofiller on the spherulite and porous morphology, degree of crystallinity, polymer-polymer and polymer-nanoparticle interactions, complex dielectric permittivity, ac electrical conductivity, and the polymers structural dynamics has been explored. It is revealed that initially 1 wt% dispersion of Al2O3 in the PEO/PMMA blend matrix significantly reduces the crystallinity and dielectric permittivity, and hinders the cooperative chain segmental dynamics of the polymers which unevenly changes with the further increase of Al2O3 concentration up to 5 wt%. The dielectric and electrical parameters of these materials have also been compared with the PNC materials based on other polar polymer host matrices containing different oxide inorganic nanoparticles. The results of this work provide a guideline to design and fabricate the alumina nanoparticles loaded flexible-type polymer nanodielectric materials for advanced technologies.

Review on the Role of Polymers in Luminescent Solar Concentrators

ABSTRACTThe use of luminescent solar concentrators (LSCs) offers an alternative approach to integrating photovoltaic technologies into the built environment. The research on LSCs has bloomed in the past decade in terms of searching for novel device architectures, developing new luminescent species, and employing unique host materials. This article will provide a concise review on LSCs and focus on the polymer host materials used in LSCs. Finally, we provide a brief outlook on the future development of this research area, particularly on the polymers used as host materials and luminescent species for LSCs. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 201–215

Aliphatic Polycarbonate-Based Solid-State Polymer Electrolytes for Advanced Lithium Batteries: Advances and Perspective.

Conventional liquid electrolytes based lithium-ion batteries (LIBs) might suffer from serious safety hazards. Solid-state polymer electrolytes (SPEs) are very promising candidate with high security for advanced LIBs. However, the quintessential frailties of pristine polyethylene oxide/lithium salts SPEs are poor ionic conductivity (≈10-8 S cm-1 ) at 25 °C and narrow electrochemical window (<4 V). Many innovative researches are carried out to enhance their lithium-ion conductivity (10-4 S cm-1 at 25 °C), which is still far from meeting the needs of high-performance power LIBs at ambient temperature. Therefore, it is a pressing urgency of exploring novel polymer host materials for advanced SPEs aimed to develop high-performance solid lithium batteries. Aliphatic polycarbonate, an emerging and promising solid polymer electrolyte, has attracted much attention of academia and industry. The amorphous structure, flexible chain segments, and high dielectric constant endow this class of polymer electrolyte excellent comprehensive performance especially in ionic conductivity, electrochemical stability, and thermally dimensional stability. To date, many types of aliphatic polycarbonate solid polymer electrolyte are discovered. Herein, the latest developments on aliphatic polycarbonate SPEs for solid-state lithium batteries are summarized. Finally, main challenges and perspective of aliphatic polycarbonate solid polymer electrolytes are illustrated at the end of this review.

Effect of Inorganic Nano Fillers on Alkaline Polymer Electrolytes

Polymer electrolytes are important enablers for safe, thin, future flexible electronics. Alkaline electrolytes such as KOH have been extensively used in energy storage devices such as batteries and electrochemical capacitors (ECs). Although aqueous KOH is useful, it has limitations when serving in a polymer electrolyte due to crystallization that compromises hydroxide (OH-) ion conductivity. An alternative alkaline electrolyte, tetraethylammonium hydroxide (TEAOH) was shown to be more stable with polymers compared to KOH.[1,2] Polyacrylamide (PAM) is a promising polymer host material due to its hygroscopic nature, amorphous structure, and useful functional groups that support ion conduction. When combined with TEAOH, a good ionic conductivity (> 10 mS cm-1) was achieved under ambient conditions (room temperature and 45% relative humidity (RH)). Thin, lightweight, electrochemical double layer capacitors (EDLC) were also demonstrated with TEAOH-PAM that outperformed their liquid analogues.[3] One of the important properties of TEAOH-PAM is its OH- ion-conduction dependence on hydration. As its degree of hydration changes with environmental factors such as RH and temperature, so does the conductivity of TEAOH-PAM as shown in Fig. 1. An additional consequence of this environmental vulnerability is poor dimensional stability of the polymer electrolyte which can lead to premature failure. To address these issues, the use of inert inorganic fillers as additives is explored. Inorganic fillers such as SiO2, TiO2, and Al2O3 have been commonly used to enhance the ionic conductivity, strengthen the mechanical properties, and improve the thermal stability of polymer electrolytes.[4–6] Here, we leverage different inorganic fillers to improve the environmental stability, expand the working temperature range, and provide better structural support for TEAOH-PAM polymer electrolytes. In this talk, the effects of different inorganic fillers such as SiO2 and TiO2 on OH- ion-conduction will be presented. For example, SiO2 showed both advantageous and detrimental effects on OH- ion conductivity depending on the RH condition and the size of SiO2. The possibility to enhance the OH- ion conductivity of TEAOH-PAM in low and high temperatures using SiO2 and TiO2 will be discussed. A combination of electrochemical and spectroscopy experiments is used to study the interaction of these inorganic fillers with the TEAOH-PAM alkaline polymer electrolyte. These results will help further clarify OH- ion-conduction in polymer electrolytes. [1] H. Gao, J. Li, K. Lian, Alkaline quaternary ammonium hydroxides and their polymer electrolytes for electrochemical capacitors, RSC Adv. 4 (2014) 21332–21339. doi:10.1039/C4RA01014K. [2] J. Li, K. Lian, A comparative study of tetraethylammonium hydroxide polymer electrolytes for solid electrochemical capacitors, Polymer. 99 (2016) 140–146. doi:10.1016/j.polymer.2016.07.001. [3] J. Li, J. Qiao, K. Lian, Investigation of polyacrylamide based hydroxide ion-conducting electrolyte and its application in all-solid electrochemical capacitors, Sustain. Energy Fuels. 1 (2017) 1580–1587. doi:10.1039/C7SE00266A. [4] S. Ketabi, K. Lian, Effect of SiO2 on conductivity and structural properties of PEO-EMIHSO4 polymer electrolyte and enabled solid electrochemical capacitors, Electrochim. Acta. 103 (2013) 174–178. doi:10.1016/j.electacta.2013.04.053. [5] J.E. Weston, B.C.H. Steele, Effects of inert fillers on the mechanical and electrochemical properties of lithium salt-poly(ethylene oxide) polymer electrolytes, Solid State Ionics. 7 (1982) 75–79. doi:10.1016/0167-2738(82)90072-8. [6] J. Przyluski, M. Siekierski, W. Wieczorek, Effective medium theory in studies of conductivity of composite polymeric electrolytes, Electrochim. Acta. 40 (1995) 2101–2108. doi:10.1016/0013-4686(95)00147-7. Figure 1

The application of a high boiling point dissolution solvent on a poly(N-vinylcarbazole) host toward improving the performance of blue electrophosphorescent devices via a solution process

ODCB triggers the formation of a p-PVK conformation, a low content PVK electromer, enhancing the performance of blue phosphorescent s-PhOLEDs.

Synthesis and properties of polymeric host materials constructed by silane-carbazole backbone and electron-affinitive cyanohexyl substituent for blue phosphorescence dopant

A series of blue phosphor hosts, using 3,6-linked carbazole with δ-π tetraphenylsilane segment as the main chain and modified by peripheral cyanohexyl group with different ratios, was designed and synthesized. These polymers show good solubility in common organic solvents. They all possess wide bandgap of 3.40 eV, high thermal stabilities and good film forming abilities. The peripheral cyanohexyl substituents have no effect on the polymer backbones but enhance the electron transporting properties of the polymers in devices. Among them, doped devices using poly[(tetraphenylsilicon/9-hexyl-9H-3,6-carbazole)50-co-(tetraphenylsilicon/9-hexanenitrile-9H-3,6-carbazole)50 (PCNCzSi50) as the host and bis[(4,6-difluorophenyl)pyridinato-N,C2]-(picolinato)iridium(III)(FIrpic) as the guest show the best performance with the maximum current efficiency and power efficiency of 2.00 cd/A and 1.40 lm/W, respectively.

Triphenyl phosphine oxide and carbazole-based polymer host materials for green phosphorescent organic light-emitting diodes

Four novel polymers, poly(3,6-9-decyl-carbazole-alt-1,3-benzene) (PB13CZ), poly(3,6-9-decyl-carbazole-alt-bis(4-phenyl) (phenyl) phosphine oxide) (PTPPO38CZ), poly(3,6-9-decyl-carbazole-alt-2,4-phenyl(diphenyl) phosphine oxide) (PTPPO13CZ) and poly(3,6-9-decyl-carbazole-alt-bis(3-phenyl) (phenyl) phosphine oxide) (PTTPO27CZ) were synthesized, and their thermal, photophysical properties and device applications were further investigated to correlate the chemical structures with the photoelectric performance of bipolar host materials for phosphorescent organic light emitting diodes. All of them show high thermal stability as revealed by their high glass transition temperatures and thermal decomposition temperatures at 5% weight loss. These polymers have wide band gaps and relatively high triplet energy levels. As a result, the spin coating method was used to prepare the green phosphorescent organic light emitting diodes with polymers PTPPO38CZ, PTPPO13CZ and PTTPO27CZ as the typical host materials. The green device of polymer PTPPO38CZ as host material shows electroluminescent performance with maximum current efficiency of 2.16 cd·A−1, maximum external quantum efficiency of 0.7%, maximum brightness of 1475 cd·m−2 and reduced efficiency roll-off of 7.14% at 600 cd·m−2, which are much better than those of the same devices hosted by polymers PTTPO27CZ and PTPPO13CZ.

A simulation study on p-doping level of polymer host material in P3HT:PCBM bulk heterojunction solar cells

In this study, we investigate the influence of doping on the charge transfer and device characteristics parameters in the bulk heterojunction solar cells based on poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM). Organic semiconductors are also known to be not pure and they have defects and impurities, some of them are being charged and act as p-type or n-type dopants. Calculations of the solar cell characteristics parameters versus the p-doping level have been done at three different n-dopings () that consist of , , and . We perform the analysis of the doping concentration through the drift-diffusion model, and calculate the current and voltage doping dependency. We find that at three different n-dopant levels, optimum p-type doping is about . Simulation results have shown that by increasing doping level, monotonically increases by doping. Cell efficiency reaches its maximum at somewhat higher doping as FF has its peak at . Moreover, this paper demonstrates that the optimum value for the p-doping is about and optimum value for n-dopant is , respectively. The simulated results confirm that doping considerably affects the performance of organic solar cells.

Quantum dot–polymer composites based on nanoporous polypropylene films with different draw ratios

Hybrid composites of polymers with fluorescent nanoparticles are unique materials combining good mechanical properties of the host polymer matrices and luminescent properties of the embedded nanoparticles. Here, we report on the optical characterization of novel inorganic–organic hybrid composites based on nanoporous polypropylene (PP) as a polymer matrix and quantum dots (QDs) as a fluorescent inorganic component. The first type of the composite films is prepared by absorption of CdSe/ZnS QDs onto the porous structure of the PP films, followed by annealing at 170°C, i.e., above the melting point of the PP. The second type of the composite films is obtained by filling of porous QD–PP composites with a nematic liquid crystalline (LC) mixture. Both types of composites are characterized by low light scattering, which makes it possible to study their optical properties by absorbance and fluorescence spectroscopies. TEM and confocal fluorescence microscopy have been used to analyze the aggregation of QDs in composites of different types. It has been shown that introduction of QDs into PP with a low draw ratio decreases the degree of alignment of LC molecules embedded into the pores of QD–PP composite films.

Functional Solid-State Polymer Electrolytes through Utilization of Polycarbonates

Solid polymer electrolytes (SPEs) have since their discovery in the 1970s been considered a promising class of Li-battery materials due to their mechanical flexibility, chemical and electrochemical stability, non-toxicity and the safety of the resulting devices – also possible to function with Li-metal anodes. SPEs have, however, not yet been realized to any great extent due to several shortcomings, primarily their inherent low ionic conductivity. This is likely associated to the limited number of polymer host materials which have been explored: the overwhelming majority of relevant publications and patents have been on poly(ethylene oxide) (PEO) materials. PEO displays some appealing properties such as low Tg and a good dissolution of many Li-salts, but are also associated with problems: semi-crystallinity, low cation transference numbers, and temperature sensitivity. Despite intense research on this category of materials during several decades, the conductivity values have not yet reached the levels which are considered necessary for most commercial applications (10-2-10-3 S/cm). The rapidly expanding market for electric vehicles (EVs) demand batteries with higher energy density, improved safety, and prolonged lifetime. These criteria are largely met by SPEs, and the research field could therefore experience a true renaissance if some of the inherent problems for this class of materials are properly solved. Alternative polymer materials to PEO could in this context provide a route forward.We have been targeting polycarbonates – specifically, poly(trimethylene carbonate) (PTMC) – for Li- and Li-ion batteries. PTMC has a somewhat higher Tg than PEO, but is amorphous and display better mechanical integrity, not least at higher temperatures. The Li+ transference numbers are also much higher than for PEO. We have recently shown that functional Li-batteries can be constructed using PTMC as an electrolyte host for LiTFSI salt [1]. We have also shown that the ion transport and/or mechanical properties can be improved by lowering the Tg through monomer functionalization, cross-linking [2] or through co-polymerization with polyesters [3,4], rendering Li-batteries with room temperature functionality. Moreover, we have been able to significantly improve the device performance by tailoring the battery fabrication procedure using oligomer components [5] and utilized X-ray Photoelectron Spectroscopy to better understand the interfacial chemistry between the SPE and common Li-battery electrode materials [6].

Third order non-linear response of II-VI semiconductor polymer nanocomposites with different polymers

Effect of two different host polymer matrices: Polyvinyl pyrrolidone (PVP) and Poly(vinylcarbazole) (PVK) on third order nonlinear optical properties of Ag:CdSe hybrid polymer nanocomposites has been investigated and discussed. Higher nonlinear behaviour of the PVK based nanocomposites as compared to PVP based nanocomposites is attributed to large electron delocalization in PVK matrix due to the two additional benzene rings. Nanocomposites show self focussing behaviour with two photon absorption processes. Large nonlinearity of CdSe hybrid polymer nanocomposites is the collective outcome of dielectric & Quantum confinement and surface Plasmon-exciton interaction effects. Third order nonlinear refraction parameters of these nanocomposites have been found to be improved with metal doping upto specific doping concentration due to the increased electron density.

The effect of molecular structure on the secondary transitions and their influence on the decoloration kinetics of photochromic dyes in co‐polycarbonates

ABSTRACTPhotochromic dyes have restricted use in rigid polycarbonates because of slow coloration and decoloration kinetics. In this study, it is shown that the decoloration kinetics of two photochromic dyes can be controlled by tuning the chain stiffness and free volume of the host matrix. The introduction of flexible moieties in rigid BPA‐based polycarbonate chain accelerates the decoloration of these dyes whereas a rigid co‐monomer delays the decoloration kinetics. Although Tg might be used as a parameter to improve photochromism in polymer matrices, dynamic mechanical analysis demonstrates that the decoloration kinetics of the dyes in host polymer matrices having similar Tg depends primarily on the secondary relaxations and, thus, on the polymer architecture. The effect of the co‐monomer type on the characteristic ratio is also discussed underlining the potential relationship between the free volume and chain stiffness. These results open the possibility to develop transparent or semitransparent photochromic materials based on tailor‐made co‐polycarbonates. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1593–1601

Effect of Zinc Oxide Nanoparticles on Mechanical Properties of Diglycidyl Ether of Bisphenol-A

This study reports on the synthesis of zinc oxide (ZnO) nanostructures and examines the performance of polymer nanocomposites fabricated using ZnO dispersed in polymer host matrices. The polymer matrix used was an epoxy based thermosetting polymer known as Diglycidyl Ether of Bisphenol-A(DGEBA). Zinc oxide nano particles were prepared by precipitation method using Poly Vinyl Alcohol as the surface modifier. It was characterized using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). And the average particle size has been found to be 25 nm. The main objective of this study is to investigate the simultaneous effect of the additive ZnO nanoparticles and curing agent on the curing kinetics, mechanical and morphological properties of Diglycidyl ether of bisphenol-A system. The mechanical properties of epoxy resin based on diglycidyl ether of bisphenol-A and Zinc Oxide were also investigated and improved mechanical properties were obtained for epoxy resin with 2% filler concentration.

Sensitized, Thermally Activated, Delayed Fluorescence Devices Based on a Polymer Host Material

Sensitized, Thermally Activated, Delayed Fluorescence Devices Based on a Polymer Host Material