Showing papers on "Miscibility published in 2019"

Miscibility Tuning for Optimizing Phase Separation and Vertical Distribution toward Highly Efficient Organic Solar Cells.

Abstract: Blending multidonor or multiacceptor organic materials as ternary devices has been recognized as an efficient and potential method to improve the power conversion efficiency of bulk heterojunction devices or single-junction components in tandem design. In this work, a highly crystalline molecule, DRCN5T, is involved into a PTB7-Th:PC70BM system to fabricate large-area organic solar cells (OSCs) whose blend film thickness is up to 270 nm, achieving an impressive performance of 11.1%. The significant improvement of OSCs after adding DRCN5T is due to the formation of an interconnected fibrous network with decreased π-π stacking and enhanced domain purity, in addition to the optimized vertical distribution of PTB7-Th and PC70BM, producing more effective charge separation, transport, and collection. The optimized morphology and performance are actually determined by the miscibility in different components, which can be quantitatively described by the Flory-Huggins interaction parameter of -0.80 and 2.94 in DRCN5T:PTB7-Th and DRCN5T:PC70BM blends, respectively. The findings in this work can potentially guide the selection of an appropriate third additive for high-performance OSCs for the sake of large-area printing and roll-to-roll fabrication from the view of miscibility.

The Influence of Compatibility on the Structure and Properties of PLA/Lignin Biocomposites by Chemical Modification.

Abstract: Lignin, a natural amorphous three-dimensional aromatic polymer, is investigated as an appropriate filler for biocomposites. The chemical modification of firsthand lignin is an effective pathway to accomplish acetoacetate functional groups replacing polar hydroxyl (-OH) groups, which capacitates lignin to possess better miscibility with poly(lactic acid) (PLA), compared with acidified lignin (Ac-lignin) and butyric lignin (By-lignin), for the sake of blending with poly(lactic acid) (PLA) to constitute a new biopolymer based composites. Generally speaking, the characterization of all PLA composites has been performed taking advantage of Fourier transform infrared (FTIR), scanning electron microscopy (SEM), dynamic Mechanical analysis (DMA), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), rheological analysis, and tensile test. Visibly, it is significant to highlight that the existence of acetoacetate functional groups enhances the miscibility, interfacial compatibility, and interface interaction between acetoacetate lignin (At-lignin) and PLA. Identical conclusions were obtained in this study where PLA/At-lignin biocomposites furthest maintain the tensile strength of pure PLA.

Enhancing Impact Toughness of Renewable Poly(lactic acid)/Thermoplastic Polyurethane Blends via Constructing Cocontinuous-like Phase Morphology Assisted by Ethylene–Methyl Acrylate–Glycidyl Methacrylate Copolymer

Abstract: Poly(lactic acid) (PLA)/thermoplastic polyurethane (TPU) blends and their ternary blends with the incorporation of ethylene–methyl acrylate–glycidyl methacrylate copolymer (E–MA–GMA) were prepared by melt blending. The PLA/TPU (70/30) blend exhibited optimum elongation at break of 615% and impact strength of 53.6 kJ/m2. Compared with PLA/TPU (90/10) blend, the impact strength of PLA/TPU/E–MA–GMA (80/10/10) blend increased by more than 15 times; meanwhile, the elongation at break did not suffer apparent reduction. Fourier transform infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMA) revealed the reaction and miscibility between components. Morphological observation by scanning electron microscopy (SEM) confirmed the transition from typical sea–island to cocontinuous-like structure due to the addition of E–MA–GMA. The toughening mechanism behind the supertoughened PLA ternary blends was established. The cocontinuous-like structure followed by massive plastic deformation of PLA matrix was beli...

Synthesis and structural-biological correlation of PVC\PVAc polymer blends

Abstract: PVC\PVAc polymer blend with different mass fraction concentration were prepared using traditional solvent casting technique. Fourier transform infrared FTIR used to identify various vibrational groups presented in associated with structural changes. X-ray diffraction data approve the amorphous nature of all samples despite their concentration while optical (UV\vis) spectra confirm the complexation behavior of blend system and their miscibility. Optical energy gap and Urbach energy were calculated for further data interpretation. The obtained energy gap data determine the direct transition which suggests that a prepared blend is a conductive material. However, Urbach energy shows no crystal lattice disorder change that ensures X-ray results. The Scanning electron microscope (SEM) reveals the smooth and homogenous nature of the surface morphology for all proportions. Prepared films showed good antibacterial characteristics against gram-positive pathogenic grams in contrast with gram-negative, fungal, and yeast.

Analytical and Computational Methods for the Estimation of Drug-Polymer Solubility and Miscibility in Solid Dispersions Development

Abstract: The development of stable solid dispersion formulations that maintain desired improvement of drug dissolution rate during the entire shelf life requires the analysis of drug-polymer solubility and miscibility. Only if the drug concentration is below the solubility limit in the polymer, the physical stability of solid dispersions is guaranteed without risk for drug (re)crystallization. If the drug concentration is above the solubility, but below the miscibility limit, the system is stabilized through intimate drug-polymer mixing, with additional kinetic stabilization if stored sufficiently below the mixture glass transition temperature. Therefore, it is of particular importance to assess the drug-polymer solubility and miscibility, to select suitable formulation (a type of polymer and drug loading), manufacturing process, and storage conditions, with the aim to ensure physical stability during the product shelf life. Drug-polymer solubility and miscibility can be assessed using analytical methods, which can detect whether the system is single-phase or not. Thermodynamic modeling enables a mechanistic understanding of drug-polymer solubility and miscibility and identification of formulation compositions with the expected formation of the stable single-phase system. Advance molecular modeling and simulation techniques enable getting insight into interactions between the drug and polymer at the molecular level, which determine whether the single-phase system formation will occur or not.

PLA/PHB Blends: Biocompatibilizer Effects

Abstract: The purpose of this work was to formulate a fully bio-based blend with superior properties, based on two immiscible polymers: polylactic acid (PLA) and poly-hydroxy butyrate (PHB). To improve the miscibility between the polymeric phases, two different kinds of compatibilizers with a different chemical structure were used, namely, an ethylene oxide/propylene oxide block copolymer in the form of flakes and a mixture of two liquid surfactants with a variable lipophilic–hydrophilic index. The morphology of the blends and their thermal, mechanical, and rheological behavior were evaluated, aiming at assessing the influence of the selected compatibilizers on the microstructure and final properties of the systems. Morphological analyses of the compatibilized blends indicated that the liquid surfactant is more effective than the solid copolymer in inducing morphology refinement, as also suggested by results coming from rheological measurements. Furthermore, thermal analyses demonstrated that the presence of both kinds of compatibilizers induced an enhancement of the crystallinity content of blends. Finally, a remarkable increase of the elastic modulus values was obtained for the compatibilized blends as compared to the pure counterparts, with a consequent significant enhancement of the HDT values.

Exploring Next-Generation Engineering Bioplastics: Poly(alkylene furanoate)/Poly(alkylene terephthalate) (PAF/PAT) Blends

Abstract: Polymers from renewable resources and especially strong engineering partially aromatic biobased polyesters are of special importance for the evolution of bioeconomy. The fabrication of polymer blends is a creative method for the production of tailor-made materials for advanced applications that are able to combine functionalities from both components. In this study, poly(alkylene furanoate)/poly(alkylene terephthalate) blends with different compositions were prepared by solution blending in a mixture of trifluoroacetic acid and chloroform. Three different types of blends were initially prepared, namely, poly(ethylene furanoate)/poly(ethylene terephthalate) (PEF/PET), poly(propylene furanoate)/poly(propylene terephthalate) (PPF/PPT), and poly(1,4-cyclohenedimethylene furanoate)/poly(1,4-cycloxehane terephthalate) (PCHDMF/PCHDMT). These blends’ miscibility characteristics were evaluated by examining the glass transition temperature of each blend. Moreover, reactive blending was utilized for the enhancement of miscibility and dynamic homogeneity and the formation of copolymers through transesterification reactions at high temperatures. PEF–PET and PPF–PPT blends formed a copolymer at relatively low reactive blending times. Finally, poly(ethylene terephthalate-co-ethylene furanoate) (PETF) random copolymers were successfully introduced as compatibilizers for the PEF/PET immiscible blends, which resulted in enhanced miscibility.

Miscibility Matching and Bimolecular Crystallization Affording High-Performance Ternary Nonfullerene Solar Cells

Abstract: How the interaction between a third component and a donor/acceptor affects the crystallization and phase separation of the active layer remains to be explored from the perspective of miscibility. T...

Super-Toughened Poly(lactic Acid) with Poly(ε-caprolactone) and Ethylene-Methyl Acrylate-Glycidyl Methacrylate by Reactive Melt Blending.

Abstract: In recent years, poly(lactic acid) (PLA) has attracted more and more attention as one of the most promising biobased and biodegradable polymers. However, the inherent brittleness significantly limits its wide application. Here, ternary blends of PLA, poly(e-caprolactone) (PCL) with various amounts of ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) terpolymer were fabricated through reactive melt blending in order to improve the toughness of PLA. The effect of different addition amounts of EMA-GMA on the mechanical properties, interfacial compatibility and phase morphology of PLA/PCL blends were studied. The reactions between the epoxy groups of EMA-GMA and carboxyl and hydroxyl end groups of PLA and PCL were investigated thorough a Fourier transform infrared (FT-IR). The miscibility and thermal behavior of the blends were studied through a dynamic mechanical analysis (DMA), differential scanning calorimetric (DSC) and X-ray diffraction (XRD). The phase morphology and impact fracture surface of the blends were also investigated through a scanning electron microscope (SEM). With the addition of 8 phr EMA-GMA, a PLA/PCL (90 wt %:10 wt %)/EMA-GMA ternary blend presenting a suitable multiple stacked phase structure with an optimum interfacial adhesion exhibited an elongation at break of 500.94% and a notched impact strength of 64.31 kJ/m2 with a partial break impact behavior. Finally, the toughening mechanism of the supertough PLA based polymers have been established based on the above analysis.

On the Miscibility and Immiscibility of Ionic Liquids and Water.

Abstract: Although the ?like-dissolves-like? rule is often invoked to explain why sodium chloride dissolves in water, hidden behind this explanation is the delicate balance between the very large cohesive energy of the ionic crystal and large solvation energies of the ions. Room-temperature ionic liquids (ILs) are liquid analogues of ionic crystals and, as dictated by a similar energetic balance, may either fully mix with water or be immiscible with water depending on ion type and cation/anion combination. In this work, we study three hydrophobic and three hydrophilic ILs to examine whether a priori prediction of water miscibility is possible based on analysis of bulk properties alone. We find that hydrophilic and hydrophobic ILs exhibit distinct signatures in their (reciprocal space) Coulomb interactions that indicate predisposition to water mixing. Hydrophilic ILs exhibit a prominent peak in their electrostatic interactions at ?5?8 ? length scale, largely due to repulsion between neighboring anion shells. When mixed with water, this peak is significantly reduced in magnitude, indicating that electrostatic screening by water molecules is an important driving force for mixing. In contrast, hydrophobic ILs show no such peak, indicating no predisposition to mixing. In addition to this analysis, we compute and compare solvation free energies of the six different anions in water, ion-pairing free energies at ?infinitely? dilute concentration, and water absorption free energies in the different ILs. Analyzed within the context of empirical data, our calculations suggest that hydrophobicity trends of different ILs are very sensitive to precise water content at dilute conditions. For example, we predict that bis(fluorosulfonyl)imide-based ILs exhibit anomalously large water absorption free energies at zero water content, with increasing hydrophobicity as preferential absorption sites within the IL become saturated.