Binary Blends Of Poly Research Articles

Binary blends of poly(lactic acid) and poly(methyl methacrylate) for high energy density and charge/discharge efficiency capacitors

Polymer dielectrics are widely used in modern power electronics due to their high flexibility and high breakdown strength. However, the limited energy density of current polymer dielectrics limits their wider applications, and there is an urgent need to develop novel polymer dielectric materials. Poly(lactic acid) (PLA) is favored for biological applications due to its biocompatibility and biodegradability. In general, PLA has three optical isomers, namely poly(L-lactide) (PLLA), poly(D-lactide) (PDLA), and poly(DL-lactide) (PDLLA), but the investigation of their dielectric properties remains limited. In this study, a significant increase in energy storage density and charge/discharge efficiency in poly(methyl methacrylate) (PMMA) was achieved by incorporating isomers of PLA into PMMA. Experimental results indicate that the introduction of PLA creates a phase-separated structure within PMMA, and in particular, the introduction of the crystalline region significantly improved the breakdown strength (Eb). Finally, PLLA/PMMA 50/50 and PDLA/PMMA 50/50 exhibit the discharged energy densities of 8.55 J cm−3 and 8.18 J cm−3, respectively, with charge/discharge efficiencies of 89.6% and 90.9%. This work enables the achievement of all-organic dielectrics with high energy storage density and high efficiency through the construction of phase-separated structures and demonstrates the great potential of biodegradable polymers in electronic devices.

Obvious improvement of dispersion of multiwall carbon nanotubes in polymer matrix through careful interface design

AbstractHerein, a simple and effective approach has been proposed to enhance the interfacial strength between multiwall carbon nanotubes (MWCNTs) and polymer matrix for improving the dispersion of MWCNTs. In more detail, a soluble polyaniline derivate containing polar group (POMA) was selectively incorporated into the binary blend of poly(amide‐imide) (PAI) and MWCNTs. The surface energy and atomic force microscope measurements suggested that POMA was located at the interface of PAI and MWCNTs. Fourier transform infrared measurement indicated that POMA simultaneously interacted with MWCNTs and PAI by hydrogen bonding and π–π interaction, providing stronger interfacial strength between conductive filler and polymer matrix. As a result, the dispersion of MWCNTs and the surface roughness of PAI composites were obviously improved, which is helpful for charge and load transfer in the PAI/MWCNTs/POMA ternary films. As a result, the conductivity increased by 250% from 13 S m−1 for PAI/MWCNTs binary composites to 48 S m−1 for PAI/MWCNTs/POMA ternary composites, and the tensile strength increased from 52 MPa for PAI/MWCNTs binary composites to 66 MPa for PAI/MWCNTs/POMA ternary composites. These findings imply that polar aromatic polymers with suitable surface energy will be a desirable compatibilizer for optimizing the dispersion of carbon nanotubes in the polymer matrix.

Thin Films with Perpendicular Tetragonally Packed Rectangular Rods Obtained from Blends of Linear ABC Block Terpolymers.

A binary blend of poly(isoprene-block-styrene-block-(2-vinylpyridine)) (ISP) triblock terpolymers, having the same chain length but different compositions, was used to achieve an ordered lattice with 4-fold symmetry of rectangular-shaped rods of poly(isoprene) (I) and poly(2-vinylpyridine) (P). In given conditions, the I and P domains were oriented perpendicularly to the substrate, providing an appealing type of templates for nanopatterning. Thin films were prepared by spin coating, exposed to solvent vapor (providing morphological reorganization), and then characterized by atomic force microscopy, transmission electron microscopy, and grazing-incidence small-angle X-ray scattering. Selective I and P identifications were carried out by AFM and TEM on a model ISP, as well as development of a technique of electronic contrast enhancement to better assign the self-assembly structure in GISAXS.

Continuity, morphology and surface resistivity in binary blends of poly(ether-block-amide) with polyethylene and polystyrene

Binary blends of low-density polyethylene (LDPE)/poly(ether-block-amide) (PEBA) and polystyrene (PS)/PEBA were prepared by melt blending. The interfacial tensions were measured by the breaking thread method with a value of 8.0mN/m for LDPE/PEBA and 1.6mN/m for PS/PEBA. The modulated DSC results show a partial miscibility between PS and PEBA at low PEBA concentrations. The continuity development in the LDPE/PEBA blend follows a droplet-droplet coalescence mechanism. However, in the case of the low interfacial tension PS/PEBA blend, a frozen capillary instability morphology was observed for the first time and a new continuity development mechanism was proposed. The continuity and morphology of the blends, and their effect on surface resistivity was examined. Our results indicate that although the continuity is crucial to controlling surface resistivity, other factors, such as the morphology (e.g., constriction) and interfacial properties also play an important role.

Topological and morphological analysis of gamma rays irradiated chitosan-poly (vinyl alcohol) blends using atomic force microscopy

In the present communication, binary blends of poly (vinyl alcohol) (PVA) and chitosan (CS) were prepared by solution cast method and the roughness parameters of PVA, native CS and CS-PVA blend films were determined using atomic force microscopy (AFM). Moreover, the changes in the morphology of the samples were also investigated after irradiation of gamma rays at absorbed dose of 1Mrad and 10Mrad for the scanning areas of 5×5µm2, 10×10µm2 and 20×20µm2. Amplitude, statistical and spatial parameters, including line, 3D and 2D image profiles of the experimental surfaces were examined and compared to un-irradiated samples. For gamma irradiated CS-PVA blends the larger waviness over the surface was found as compared to un-irradiated CS-PVA blends but the values of average roughness for both the films were found almost same. The coefficient of skewness was positive for gamma irradiated CS-PVA blends which revealed the presence of more peaks than valleys on the blend surfaces.

Excellent Electroactive Shape Memory Performance of EVA/PCL/CNT Blend Composites with Selectively Localized CNTs

In this work, the binary blend of poly(ethylene vinyl acetate) (EVA)/poly(e-caprolactone) (PCL) with different compositions were prepared and the shape memory behaviors were evaluated first. Then, carbon nanotubes (CNTs) were introduced into the composition that exhibited relatively better shape memory effect (SME) to prepare the ternary blend composites with electrically actuated SME. The morphologies of the blend and/or blend composites, the crystallization of the component, and the selective location states of CNTs in the blend composites were comparatively investigated. The results demonstrated that the binary EVA/PCL blends exhibit a typical sea–island structure at low PCL content, a quasi-cocontinuous structure at mediate PCL content and then the sea–island structure at high PCL content. Among these binary blends, the EVA/PCL (60/40) sample exhibits relatively better SME with not only high shape fixing ratio but also shape recovery ratio. The presence of the CNTs further induces the changes of morph...

The influence of polymer purification on the efficiency of poly(3-hexylthiophene):fullerene organic solar cells.

We report the influence of different polymer purification procedures on the photovoltaic performance of bulk heterojunction solar cells formed from binary blends of poly(3-hexylthiophene) (P3HT) and fullerenes. Selective Soxhlet extractions and metal scavenging agents were used to remove residual monomer, magnesium salt by-products and catalyst from high-weight P3HT (Mw 121 kg/mol, PDI 1.8, RR 99%) synthesised by the Grignard metathesis (GRIM) polymerization route. Using phenyl-C61-butyric acid methyl ester (PC60BM) as an electron acceptor, we observed an increase in average power conversion efficiency from 2.3 to 4.8% in going from crude to fully purified material. Using indene-C60 bisadduct (IC60BA) in place of PC60BM, we observed a further increase to an average value of 6.6% - high for a bulk heterojunction formed from a binary blend of P3HT and C60 fullerene derivatives.

Novel highly sensitive and reversible electrospun nanofibrous chemosensor-filters composed of poly(HEMA-co-MNA) and bpy-F-bpy with metal-ion-modulated multicolor fluorescence emission

Novel multifunctional fluorescent electrospun (ES) nanofibers exhibiting high sensitivity for various metal ions were prepared from binary blends of poly(2-hydroxyethyl methacrylate-co-N-methylolacrylamide) (poly(HEMA-co-NMA)) and 9,9-dihexylfluorene-2,7-bipyridine (bpy-F-bpy) by using a single-capillary spinneret. Different compositions of poly(HEMA-co-NMA) were synthesized through free-radical polymerization. The HEMA moieties were designed to exhibit hydrophilic properties, and the NMA content substantially affected the stability of the ES nanofibers in water. Experimental optical spectra and simulation results demonstrated that the fluorescent sensing probe bpy-polyfluorene-bpy could detect various metal ions. ES nanofibers prepared from copolymers with a 77:23 HEMA:NMA ratio blended with 5% bpy-F-bpy (P2–5) exhibited apparent color change from blue to green, color change from blue to blue-green and fluorescence quenching when detecting Zn2+, Hg2+ and Cu2+, respectively. The P2–5 ES nanofibers exhibited ultrasensitivity for Zn2+ (10−7–10−3 m) because of the 70 nm red shift of the emission maximum, and high reversibility because of their on–off switchable fluorescence emission upon the sequential addition of Zn2+ and ethylenediaminetetraacetic acid cycled several times. These results and a microfluidics system study indicated that the nanofibers, which have a high surface-to-volume ratio, can be used as ‘naked eye’ sensors for sensing various metal ions and as efficient multifunctional chemosensor-filtering devices. The chemosensor-filter based on novel multifunctional fluorescent electrospun (ES) nanofibers exhibiting high sensitivity for various metal ions were prepared from binary blends poly(HEMA-co-NMA) and bpy-F-bpy by using a single-capillary spinneret. It shows apparent color change from blue (blank) to green, to blue-green and to be fluorescence quenching when detecting Zn2+, Hg2+ and Cu2+, respectively, and high reversibility. A microfluidics system study indicated that these nanofibers can be used as ‘naked eye’ sensors for sensing various metal ions and as efficient multifunctional chemosensor-filtering devices.

Novel highly selective and reversible chemosensors based on dual-ratiometric fluorescent electrospun nanofibers with pH- and Fe(3+)-modulated multicolor fluorescence emission.

Novel dual-ratiometric fluorescent electrospun (ES) nanofibers featuring high sensitivity for pH and ferric ion (Fe(3+)) were prepared using binary blends of poly(2-hydroxyethyl methacrylate-co-N-methylolacrylamide-co-nitrobenzoxadiazolyl derivative) (poly(HEMA-co-NMA-co-NBD)) and a spirolactam rhodamine derivative (SRhBOH) by employing a single-capillary spinneret. The HEMA, NMA, and NBD moieties were designed to exhibit hydrophilic properties, chemical cross-linking, and fluorescence (fluorescence resonance energy transfer (FRET) donor), respectively. The fluorescence emission of SRhBOH was highly selective for pH and Fe(3+); when SRhBOH detected acidic media and Fe(3+), the spirocyclic form of SRhBOH, which is nonfluorescent, was transformed into the opened cyclic form and exhibited strong fluorescence emission. The emission colors of ES nanofibers in acidic or Fe(3+) aqueous solutions changed from green to red because of FRET from NBD (donor) to SRhBOH (acceptor). The off/on switching of the FRET process was modulated by adjusting the SRhBOH blending ratio, pH, and Fe(3+) concentration. Poly(HEMA-co-NMA-co-NBD) ES fibers blended with 20% SRhBOH showed high sensitivity in sensing Fe(3+) and pH because of the substantial 57 nm red shift in emission as well as substantial reversible dual photoluminescence. The prepared FRET-based dual-ratiometric fluorescent ES nanofibrous membranes can be used as "naked eye" sensors and have potential for application in multifunctional environment sensing devices.

Peculiar crystallization kinetics of biodegradable poly(lactic acid)/poly(propylene carbonate) blends

Binary blends of poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) were found to display a peculiar crystallization kinetics. The two biodegradable polymers were blended by melt mixing, to obtain binary blends at various compositions. Temperature‐modulated calorimetry and dynamic‐mechanical analysis indicated that the blend components are partially miscible, and display two separate glass transitions, at temperatures intermediate to those of the plain polymers. Electron microscopy analysis disclosed the morphology of PLA/PPC blends, made of PPC‐rich particles finely dispersed within the PLA‐rich matrix. The possible establishment of interactions between the functional groups of the two polymers upon melt mixing has been hypothesized as the reason for partial miscibility and compatibility of the two biodegradable polymers. The PLA/PPC blends display good mechanical properties, with enhanced performance at rupture compared with plain PLA. Most importantly, the addition of PPC affects also the crystallization kinetics of PLA, since the more mobile PPC chains favor diffusion of the stiffer PLA chain segments towards the growing crystals, which fastens the spherulite growth rate of PLA. Such positive influence of an amorphous polymer on crystal growth rate has been demonstrated here for the first time in blends that display phase‐separation in the melt. POLYM. ENG. SCI., 55:2698–2705, 2015. © 2015 Society of Plastics Engineers

Poly(Lactic Acid)-Based Blends With Tailored Physicochemical Properties for Tissue Engineering Applications: A Case Study

Binary blends of poly(L-lactic) acid (PLLA: 201790 Da) and poly(lactide-co-glycolide) (PLGA) (LA:GA = 50:50 mol:mol; 32030 Da) with various compositions were prepared. Physicochemical properties of PLLA/PLGA blends were analyzed. Blends showed a biphasic morphology, with distinct glass transition temperatures, which only slightly approximated compared to pure polymers. Analysis of tensile mechanical properties through the Kerner-Uemura-Takayanagi model showed compatibility for PLLA/PLGA 75/25 blend. Rapid degradation of PLGA phase (2–8 weeks) in PLLA/PLGA 75/25 blend led to porous samples, which appear promising for drug delivery and tissue engineering. A limited inflammatory reaction resulted from subcutaneous implantation of PLLA/PLGA 75/25 in Balb-c mice.

Stabilizing poly(vinyl chloride) using its blends with poly(methyl methacarylate): Pyrolysis GC/MS studies

Binary blends of poly(vinyl chloride) (PVC) with poly(methyl methacarylate) (PMMA) of various compositions were prepared through solution blending. Thermogravimetric and pyrolysis studies of these blends were carried out and the volatile products were separated and quantitatively analyzed by GC/MS. Harmful pyrolysis products from PVC like HCl and different aromatic hydrocarbons are significantly suppressed in presence of a small amount of PMMA. The stabilization effect on PVC was found to be the most significant with 10wt.%. PMMA contents in the matrix. Mechanism of the stabilization has been explained by the interaction of micro- and macro-radicals resulting from PMMA with PVC, which stabilize the unzipping of polymer chains by a reversible blocking mechanism and increase the amount of cross-linked residue retained above 500°C.

Crystallization of double crystalline block copolymer/crystalline homopolymer blends: 1. Crystalline morphology

The crystalline morphology formed in binary blends of poly(ε-caprolactone)- block-polyethylene (PCL-b-PE) copolymers and PCL homopolymers has been examined using synchrotron small-angle X-ray scattering (SR-SAXS) and differential scanning calorimetry (DSC) as a function of the homopolymer fraction in the blend. The PE block crystallized first on quenching from a lamellar microdomain structure to set a hard lamellar morphology (PE lamellar morphology) in the blend, followed by the crystallization of PCL chains (i.e., PCL homopolymers + PCL blocks). Two binary blends were studied by considering the miscible state of PCL homopolymers in the microdomain structure: when the PCL homopolymers were uniformly mixed with PCL blocks, they formed a mixed crystal. When the PCL homopolymers were localized between PCL blocks in the microdomain structure, DSC results suggested the possible formation of separate PCL crystals in the PE lamellar morphology. The effect of the advance crystallization of PE blocks on the subsequent crystallization of PCL chains was discussed as compared with the crystalline morphology formed in PCL-block-polybutadiene copolymer/PCL homopolymer blends, where the crystallization of PCL chains started directly from a microdomain structure without forming the hard lamellar morphology.

Miscibility and properties of poly(l-lactic acid)/poly(butylene terephthalate) blends

Binary blends of poly(l-lactide) (PLLA) and poly(butylene terephthalate) (PBT) containing PLLA as major component were prepared by melt mixing. The two polymers are immiscible, but display compatibility, probably due to the establishment of interactions between the functional groups of the two polyesters upon melt mixing. Electron microscopy analysis revealed that in the blends containing up to 20% of poly(butylene terephthalate), PBT particles are finely dispersed within the PLLA matrix, with a good adhesion between the phases. The PLLA/PBT 60/40 blend presents a co-continuous multi-level morphology, where PLLA domains, containing dispersed PBT units, are embedded in a PBT matrix. The varied morphology affects the mechanical properties of the material, as the 60/40 blend displays a largely enhanced resistance to elongation, compared to the blends with lower PBT content.

폴리(m-메틸렌 2,6-나프탈레이트)들의 고분자쌍 블렌드에 대한 상용성 지도

Binary blends of poly(m-methylene 2,6-naphthalate) (PmN, m=2-8) were prepared by the solution-blending method and their miscibility was investigated with glass transition, crystallization, and melting behaviors, which were obtained from differential scanning calorimetry. It was determined that all the blends in which the difference in the number of methylene units between two component polymers was one were miscible. The blends in which the difference in the number of methylene units was two show divergent miscibility: two miscible, two partially miscible, and one immiscible systems. Among the blends in which the difference in the number of methylene units was three, two systems were partially miscible and the other two were immiscible. All the blends in which the difference in the number of methylene units was four or more were immiscible. It was thus found that the difference in the number of methylene units between two component polymers in the blend is the primary structural factor affecting the miscibility of a binary blend of PmN. The border between miscible blends and immiscible ones was found to be at differences in methylene-unit numbers of two or three.

Blends of poly(vinyl chloride) with α‐methylstyrene‐acrylonitrile‐butadiene‐styrene copolymer: Thermal properties, mechanical properties, and morphology

Binary blends of poly(vinyl chloride) (PVC) with α‐methylstyrene‐acrylonitrile‐butadiene‐styrene copolymer (AMS‐ABS) were prepared via melt blending. A single glass transition temperature (Tg) was observed by differential scanning calorimetry, thus indicating that PVC is miscible with the α‐methylstyrene‐acrylonitrile‐styrene in AMS‐ABS. The results from attenuated total reflection Fourier transform infrared spectra indicated that specific strong interactions were not available in the blends. With increasing amounts of AMS‐ABS, both heat distortion temperature and thermal stability were increased considerably. With regard to mechanical properties, flexural and tensile properties decreased with increasing AMS‐ABS content. A synergism was observed in impact strength. The morphology of both impact‐fractured and tensile‐fractured surfaces, observed by scanning electron microscopy, correlated well with the mechanical properties. It is suggested that there was a transition of fracture mechanisms with the changing composition of the binary blends—from shear yielding for blends rich in PVC to cavitation for blends rich in AMS‐ABS. J. VINYL ADDIT. TECHNOL., 19:1–10, 2013. © 2013 Society of Plastics Engineers

Polythiophene–perylene diimide heterojunction field-effect transistors

Thin film field-effect transistors based on binary blends of poly(3-hexylthiophene) (P3HT) and two perylene diimide (PDI) derivatives with different alkyl substituents have been investigated in terms of device performance, microstructure and molecular organization on the surface. For the same blend ratios the PDIs phase separate differently due to solubility variation. Blends with a horizontal phase separation between the donor and acceptor show ambipolar behavior due to well defined homogenous pathways for both charge carriers. In this layer arrangement the polymer is located near the dielectric interface, while the PDI molecules crystallize on top of the film. Interestingly, the electron mobility is improved by a few orders of magnitude in comparison to the pure acceptor. This increase is attributed to the altered microstructure of PDI in the blends. Layers in which the PDI crystals are embedded within the polymer matrix and are not interconnected with each other lead only to hole transport in the transistor. For one blend ratio, the hole mobility improves by one order of magnitude compared to pure P3HT as a result of the reorganization of the polymer in the blend layer. This study provides new insights into the role of microstructure and molecular organization in the charge carrier transport in heterojunction field-effect transistors for the development of high-performance future devices.

Thermomechanical Behaviour of Poly(methyl methacrylate)/Copoly(ether-ester) Blends

Binary blends of poly(methyl methacrylate) (PMMA)/copoly(ether-ester) (COPE) elastomer were prepared under four different compositions by melt mixing technique using twin-screw extruder. The effects of COPE content on thermal and dynamic mechanical properties were investigated using various techniques such as thermogravimetric analysis (TGA), differential scanning calorimetric analysis (DSC), and dynamic mechanical analysis (DMA) for all PMMA/COPE blends. The properties of all the blends were evaluated in comparison with neat PMMA and COPE. All the blends show higher thermal stability than individual component. DSC analysis results reveal that all the blends show two glass transition temperature (Tg) values and the Tg value of PMMA has been shifted to lower side due to the presence of COPE content. The two step reduction in storage modulus corresponding to their Tg value reveal that the blends are immiscible in nature.

Improvement of the Thermal, Photo and Mechanical Properties of Poly (Vinyl Chloride) in Presence of Poly (Glycidyl Methacrylate)

Problem statement: Poly (vinyl chloride) suffers from poor heat stability. The thermal degradation of the polymer leads to the evolution of hydrogen chloride gas, extensive discoloration of the polymer and lowering of physical and mechanical properties. Approach: Binary blends of Poly (Vinyl Chloride) (PVC) and Poly (Glycidyl Methacrylate) (PGMA) have been prepared by solution blending aimed at the improvement of thermal and mechanical properties. Results and Conclusion: Thermal properties of the blends were studied using Scanning Calorimetry (DSC), Thermogravimetry (TGA) and potentiometric rate of dehydrochlorination. The increase of the PGMA content in the blend leads to thermal stability of the blend as shown from the thermogravimetry and the rate of dehydrochlorination results. All blends exhibited one major glass transition temperature (Tg) whose position on the temperature scale was lowered with increased level of PGMA. The miscibility of blends was also confirmed by the use of Scanning Electron Microscope (SEM). The improvement of the mechanical properties of various blends of the two polymers was also obtained.

Tacticity effects on glass transition and phase behavior in binary blends of poly(methyl methacrylate)s of three different configurations

Using optical and scanning electron microscopies, dynamic mechanical analysis, and differential scanning calorimetry, this study investigated effects of tacticity in PMMAs on the phase behavior in three pairs of binary blends comprising any two of isotactic-, syndiotactic-, and atactic-PMMAs. Miscibility was confirmed for all three binary blends (i.e., aPMMA/iPMMA, aPMMA/sPMMA, and iPMMA/sPMMA); however, the Tgvs. composition relationships for the aPMMA/iPMMA blend differ significantly. Configurational tacticity may lead to subtle differences in molecular interactions in the tactic polymers; and in turn such difference in the interactions causes variation in the glass transition and phase behavior in these three blends. This study also points out that the miscibility nature in iPMMA/sPMMA may constitute a prerequisite condition (necessary but not sufficient) for its tendency in forming complexes.