Binary Mixtures Of Poly Research Articles

Study of molecular association in binary mixtures of poly(vinyl pyrrolidone) (PVP) with ethanol, 1-propanol and 1-butanol through thermo-acoustical, FT-IR, UV–Vis spectroscopy and DFT studies

Study of molecular association in binary mixtures of poly(vinyl pyrrolidone) (PVP) with ethanol, 1-propanol and 1-butanol through thermo-acoustical, FT-IR, UV–Vis spectroscopy and DFT studies

Adaptive Morphology of Surface‐Segregated Micelles Synthesized from Polymerization‐Induced Self‐Assembly Co‐Mediated by a Binary Mixture of Macro‐RAFT Agents

AbstractSurface‐segregated micelles (SSMs) have shown potential applications in drug delivery, bioimaging, and Pickering emulsions due to their adaptive characteristics. A diverse set of SSMs are prepared by reversible addition–fragmentation transfer (RAFT)‐mediated polymerization‐induced self‐assembly (PISA). However, the obtained self‐assembled structures are mostly limited to spherical forms, and SSMs with a hierarchical structure are not yet prepared. In this study, SSMs with various hierarchical structures are generated by the dispersion polymerization of benzyl methacrylate (BzMA) co‐mediated by a binary mixture of poly(2‐(dimethylamino)ethyl methacrylate) and polydimethylsiloxane as macromolecular chain‐transfer agents (macro‐CTAs). The obtained structures include cylinders, vesicles, large compound micelles, and bundles of hoops. The morphological evolution of these structures and vesicle size can be readily tuned by varying the composition of the binary mixture of macro‐CTAs. This study expands the scope of RAFT‐mediated PISA for synthesizing well‐defined polymer nano‐objects with higher‐order morphologies for various applications.

Enhancing the organic solar cell efficiency by combining plasmonic and Förster Resonance Energy Transfer (FRET) effects

Here, we combine two strategies i.e., Förster resonance energy transfer and plasmonic effect, to enhance the photovoltaic performance in organic solar cells by introducing gold nanoparticles and squaraine in a binary mixture of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester. In this configuration, the Förster resonance energy transfer between poly(3-hexylthiophene) and squaraine reduces the electrical loss arising from the exciton recombination in poly(3-hexylthiophene), while gold nanoparticles enable an efficient charge carrier generation in poly(3-hexylthiophene):squaraine mixture as optically confirmed by photoluminescence measurement and transient absorption spectroscopy. The multicomponent organic solar cells demonstrate an enhancement of ~36% in power conversion efficiency over the reference device.

Enhanced superoxide sensitivity in organic field-effect transistor sensors by introducing nanoclay-polyphenol-polymer hybrid sensing channels.

Here we report that nanoclay-polyphenol-polymer hybrid sensing channels can greatly enhance the sensitivity for hazardous reactive oxygen species (ROS) in organic field-effect transistor (OFET) sensors. The hybrid layers were prepared by introducing nanoclay into the binary mixtures of poly(3-hexylthiophene) (P3HT) and rutin (a polyphenol) at various weight ratios. The presence of nanoclay improved the P3HT crystallinity in the hybrid films, which contributed to the increased drain current and well-maintained hole mobility even at the reduced amount of charge-transporting P3HT part. At the best composition (P3HT:rutin:nanocaly = 10:1:2 by weight), the OFETs with the hybrid layers were able to sense even 1 nM superoxide (a ROS) and exhibited pronouncedly enhanced sensitivity compared to those without nanoclay. The morphology investigation disclosed that rutin-nanoclay complexes formed in the hybrid films might be responsible for the enhanced sensitivity, because they let more rutin molecules protrude on the surface of channel layers for reactions with superoxide.

Cooperativity during Melting and Molecular Exchange in Micelles with Crystalline Cores.

Molecular exchange processes are important equilibration and transport mechanisms in both synthetic and biological self-assembled systems such as micelles, vesicles, and membranes. Still, these processes are not entirely understood, in particular the effect of crystallinity and the interplay between cooperative melting processes and chain exchange. Here we focus on a set of simple polymer micelles formed by binary mixtures of poly(ethylene oxide)-mono-n-alkyl-ethers (C_{n}-PEO5) which allows the melting point to be tuned over a wide range. We show that the melting transition is cooperative in the confined 4-5nm micellar core, whereas the exchange process is widely decoupled and unimeric in nature. As confirmed by differential scanning calorimetry, the total activation energy for ejecting a molecule out of the micellar core below the melting point is the sum of the enthalpy of fusion and the corresponding activation energy in the melt state. This suggests that a "local, single-chain melting process" preludes the molecular diffusion out of the micelle during chain exchange.

Formulation of sustained-release microspheres of granulocyte macrophage colony stimulating factor by freezing-induced phase separation with dextran and encapsulation with blended polymers

This study aimed to assess the potential merits of formulating sustained-release microspheres of recombinant human granulocyte macrophage colony stimulating factor (rhGM-CSF) via freezing-induced phase separation (FIPS) of the protein with dextran followed by encapsulation with binary mixture of poly(lactic-co-glycolic acid) (PLGA) 2A (MW∼12K) and 3A (MW∼47K) or of PLGA2A and polylactic acid (PLA; MW∼83K). The formulated dextran particles and microspheres were characterized in vitro for loading, aggregation, bioactivity and release behavior of the protein where appropriate. rhGM-CSF retained about 60% of bioactivity with no significant aggregation after each formulation step. Encapsulation of protein-loaded dextran particles attained only 80% with the PLGA2A and PLGA3A blend, but 100% with the PLGA2A and PLA mixture. The former formulation exhibited a triphasic in-vitro release profile typical of PLGA microspheres while the latter revealed a much lower initial burst followed by a steady and complete release of rhGM-CSF with preserved bioactivity over a 15-day period.

Experimental and computational study on viscosity and optical dielectric constant of solutions of poly (ethylene glycol) 200

To understand the intermolecular interactions in binary mixtures of poly (ethylene glycol) 200 with ethanolamine, m-cresol and aniline respectively, absolute viscosities and refractive indices have been measured at varying concentrations and temperatures. Optical dielectric constant, polarisability, interaction parameter, enthalpy and entropy of viscous flow have been calculated. The viscosity data have been fitted by third order polynomial equation. The experimental data has been used to evaluate molar refraction deviation, deviation in viscosity and excess Gibb's free energy of activation for viscous flow and the results have been fitted to Redlich–Kister polynomial equation. The results reflect the intermolecular interaction and hydrogen bonding to be stronger in the binary mixture of poly (ethylene glycol) 200 with ethanolamine than with m-cresol and least with aniline. Different mixing rules have been applied to predict the optical dielectric constant of the liquid mixtures and their relative performances have been analysed.

Exciplex dynamics in a blend ofπ-conjugated polymers with electron donating and accepting properties: MDMO-PPV and PCNEPV

The photophysical properties of a solution processed blend of two semiconducting polymers with electron donating and electron accepting properties, respectively, as used in polymer photovoltaic devices have been investigated. We show that in the binary mixture of poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and poly[oxa-1,4-phenylene-(1-cyano-1,2-vinylene)-(2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylene)-1,2-(2-cyanovinylene)-1,4-phenylene] (PCNEPV) photoexcitation of either one of the polymers results in formation of a luminescent exciplex at the interface of the two materials. Photoinduced absorption spectroscopy shows that this exciplex can decay to the lowest triplet state $({T}_{1})$ of MDMO-PPV. Application of an electric field results in dissociation of the marginally stable exciplex into charge carriers, which provides the basis for the photovoltaic effect of this combination of materials. Spin allowed recombination of the charge carriers to the MDMO-PPV ${T}_{1}$ state is invoked to explain the field-enhanced quantum yield for triplet formation observed by photoinduced reflection measurements on photovoltaic devices made from the composite films. The field enhanced triplet yield is identified as loss mechanism for the photovoltaic performance of this combination of materials.

Photovoltaic Properties of a Conjugated Polymer Blend of MDMO−PPV and PCNEPV

Photovoltaic properties of solution-processed semiconducting polymer blends have been studied. It is demonstrated that photoinduced charge transfer occurs in binary mixtures of poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO−PPV) and poly[oxa-1,4-phenylene-(1-cyano-1,2-vinylene)−(2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylene)-1,2-(2-cyanovinylene)-1,4-phenylene] (PCNEPV). Further, it is shown that the photovoltaic performance is improved by a thermal treatment which alters the morphology of the photoactive layer. The temperature necessary to achieve the enhanced performance is related to transition temperatures of the pure polymers. Device optimization yields solar cells with a power conversion efficiency of 0.75% under standard test conditions (AM 1.5, 1000 W/m2).

The influence of competitive interactions on multiple eutectic phase behavior in poly(ethylene oxide) molecular complexes

Binary mixtures of poly(ethylene oxide) and resorcinol exhibit two eutectic phase transitions at 40 and 80 °C, which are separated by a single-phase stoichiometric complex at ≈33 mol% resorcinol. These eutectic temperatures increase slightly at higher molecular weights of poly(ethylene oxide). The eutectics and the molecular complex are absent in ternary mixtures with either 25 or 40 wt% poly(2-vinylpyridine) because both polymers contain electron-pair donors which participate in hydrogen bonding interactions with the hydroxyl groups of the small-molecule aromatic. In contrast, 25 wt% polystyrene does not disrupt the bi-eutectic phase behavior of poly(ethylene oxide) and resorcinol because polystyrene is inert in these ternary mixtures. The lightest lanthanides with the largest ionic radii in the first-row of the f-block, like LaCl 3(H 2O) 6 and CeCl 3(H 2O) x , are more effective than neodymium, terbium and ytterbium trichloride hexahydrates from the viewpoint of (i) competing with resorcinol, (ii) interacting with poly(ethylene oxide), (iii) eliminating eutectic melting, and (iv) disrupting the 2:1 stoichiometric complex between poly(ethylene oxide) and resorcinol. High-resolution 13C solid state NMR spectroscopy identifies resorcinol in several different molecular environments. Multiple resonances are observed for chemically equivalent, but morphologically and crystallographically inequivalent, 13C sites in the solid state. The isotropic chemical shift of the phenolic 13C site in this small-molecule aromatic is very sensitive to the strength of intermolecular interactions in various phases. For example, self-association of resorcinol in pure crystalline phase γ yields a phenolic carbon chemical shift at 155 ppm. The formation of a 2:1 stoichiometric complex between poly(ethylene oxide) and resorcinol in co-crystallized phase β is identified by a phenolic carbon chemical shift at 158 ppm. When resorcinol and poly(2-vinylpyridine) interact in a homogeneous amorphous phase, the phenolic carbon resonance appears at a chemical shift of 160 ppm. A resorcinol-rich disordered crystalline phase in ternary mixtures with poly(ethylene oxide) and poly(2-vinylpyridine) yields a phenolic carbon resonance at 159 ppm. Temperature-composition projections of the binary and ternary phase diagrams, constructed via differential scanning calorimetry, allow one to interpret 13C NMR spectra of these strongly interacting blends and complexes in the solid state.

Miscibility of Poly(methyl methacrylate)-/Poly(vinyl acetate) Blend in 2-Dimensional State at the Air/Water Interface

The miscibility in binary polymer systems in 2-dimensional state at the air/water interface was investigated by the relationship between the mean molecular area at a constant surface pressure and the mole fraction of one component in the binary mixtures of poly(methyl methacrylate)(PMMA) and poly(vinyl acetate)(PVAc). Compatibilization of the immiscible PMMA/PVAc blend at the air/water interface was achieved by introducing carboxyl acid to either of the two component polymers.

Microwave dielectric relaxation in binary mixtures of poly(ethylene glycols) in solution

Microwave dielectric relaxation in binary mixtures of poly(ethylene glycols) in solution

Thermal diffusivity in a binary mixture of poly(phenylene oxide) and polystyrene

The thermal diffusivity of a binary blend of poly(phenylene oxide) and polystyrene was investigated by the AC Joule heating technique in a practical temperature range including glassy state and melt state. The temperature dependence of the thermal diffusivity and the glass transition temperature ( T g) of the blends were clearly observed. The single T g, characteristic for this blend, increased with increasing the blend ratio of poly(phenylene oxide). The thermal diffusivity was also dependent on the blend composition.

Light-scattering studies on the dynamics of long-chain macromolecules in shear flow

By use of the Springer-Wölfle theophotometer, the shear-induced orientation of high-molar-mass polystyrene ( M w = 10.3 × 10 6 g mol −1) is investigated in dilute solution. It is known that the degree of molecular orientation in extremely good and poor solvents is significantly different and, furthermore, that its dependence on shear rate is a function of solvent power. For this reason, the present investigation deals with polystyrene in solvents of intermediate quality, represented by binary mixtures of poly(methylvinylether) (PMVE) and toluene. Owing to the variation of the PMVE fraction, which builds an isorefractive pair with toluene, a variation of both solvent quality and viscosity is realized. This investigation proves that the degree of orientation is induced not only by hydrodynamic interaction but also by thermodynamic interaction, and therefore describes a non-linear function of solvent power. The observed dependence of the rheo-optically detected molecular orientation on solution properties is interpreted and discussed in the light of various theoretical predictions.

ポリオキシメチレン／ノボラック樹脂混合系の高次構造と力学的性質

ポリオキシメチレン (POM) /ノボラック樹脂混合系の応力-ひずみ挙動を調べた. 延性高分子であるPOMに脆性材料であるノボラック樹脂を混合したにもかかわらず, 破断伸びを増大させうる組成が存在し, 破断伸びをPOM単体のそれの6倍にもさせうることがわかった. DSC, 偏光顕微鏡観察, 光散乱法, 小角X線散乱法などによる結晶高次構造に関する知見を破断面のSEM観察結果と併せて考えることにより, ノボラック樹脂の球晶間析出を抑制して球晶寸法を極力小さくすることによって, 上述の大きな破断伸びが得られることがわかった.

Glass Transition Temperature, Compatibility and Viscosity of Poly(methyl metacrylate) Blended with Homo-or Copolymers of Alkyl Metacrylates

Abstract Investigation of glass transition temperature and viscosity of binary mixtures of poly(methyl metacrylate) with statistic copolymers of methyl metacrylate and ethyl, butyl or octyl metacrylates as well as mixtures of poly(methyl metacrylate) with poly(ethyl, poly(butyl or poly(octyl metacrylates) has been carried out. The regions of one-and two-phase states of the above-mentioned mixtures were found from the glass transition temperature date. It has been shown that the mixtures of poly(methyl metacrylate) with copolymers of methyl metacrylate in combination with ethyl metacrylate are capable of forming one-phase systems throughout the whole range of the mixture compositions when extensively varying the copolymers compositions. The transition to copolymers of methyl metacrylate involving butyl and especially octyl metacrylates leads to a sharp narrowing of the range of the composition of their mixtures with poly(methyl metacrylate) in which they form one-phase-systems. We have established dependen...