Binary Polymer Research Articles

Synthesis and characterization of a novel active polymer for enhanced oil recovery

AbstractA new type of quaternary ammonium surface‐active polymer for enhanced oil‐recovery application was synthesized through the free‐radical polymerization of a functional monomer (DMCA) with acrylic acid (AA) and acrylamide (AM) and denoted as AM/AMPS/DMCA. The optimum polymerization conditions of AM/AMPS/DMCA were explored, and its chemical structure was characterized by Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance, and environmental scanning electron microscopy. The molecular weight of AM/AMPS/DMCA was determined by gel‐permeation chromatography. Its thickening ability, oil–water interfacial tension, and emulsifying property were investigated. Results showed that AM/AMPS/DMCA had superior thickening ability and lower interfacial tension than the binary polymer AM/AMPS, as well as good emulsifying properties. AM/AMPS/DMCA also yielded 26.00% oil recovery, higher than the 20.57% of AM/AMPS, as determined using polymer‐flooding tests. The oil‐displacement mechanisms of this surface‐active polymer at pore level were also explored. Analysis of microscopic displacement characteristics through a visual micromodel revealed that AM/AMPS/DMCA solution improved sweep efficiency and reduced residual‐oil saturation due to its bulk viscosity and surface activation. All these findings indicated the excellent potential of AM/AMPS/DMCA in oil displacement.

Chains Stiffness Effect on the Vertical Segregation of Mixed Polymer Brushes in Selective Solvent.

The microstructure of the binary polymer brushes in the selective solvent was studied using the numerical lattice self-consisting field approach. The case was considered when the selectivity to the solvent (the Flory-Huggins parameter χ) was varied only for one type of chains (responsive chains) while the others (non-responsive chains) remained hydrophilic (χ = 0). In such a brush, with an increase in the hydrophobicity of the responsive chains, a transition occurs between two two-layer microstructures. In the initial state the ends of the longer responsive chains are located near the external surface of the brush and those of non-responsive chains are inside the brush. When the hydrophobicity of the responsive chains becomes high enough then the reversed two-layer microstructure is formed, when the ends of non-responsive chains are located near the brush surface and the responsive chains collapse on the brush bottom. In contrast to previous works, the stiffness parameter (Kuhn segment length p) for one or for both types of chains was varied and its effect on the mechanism and characteristics of the transition was studied. If the stiffness of only responsive chains increases, then the transition occurs with the formation of an intermediate three-layer microstructure, where a layer of responsive chains is located between layers formed by non-responsive ones. If both types of chains have the same p, then the transition occurs gradually without the formation of an intermediate three-layer microstructure. For both cases, the effect of p on the critical value of χ*, corresponding to the transition point and on the steepness of the transition was investigated.

Confinement-Induced Fractionation and Liquid-Liquid Phase Separation of Polymer Mixtures.

The formation of (bio)molecular condensates via liquid-liquid phase separation in cells has received increasing attention, as these aggregates play important functional and regulatory roles within biological systems. However, the majority of studies focused on the behavior of pure systems in bulk solutions, thus neglecting confinement effects and the interplay between the numerous molecules present in cells. To better understand the physical mechanisms driving condensation in cellular environments, we perform molecular simulations of binary polymer mixtures in spherical droplets, considering both monodisperse and polydisperse molecular weight distributions for the longer polymer species. We find that confinement induces a spatial separation of the polymers by length, with the longer ones moving to the droplet center. This partitioning causes a distinct increase in the local polymer concentration near the droplet center, which is more pronounced in polydisperse systems. Consequently, the confined systems exhibit liquid-liquid phase separation at average polymer concentrations where bulk systems are still in the one-phase regime.

Increases in Miscibility of a Binary Polymer Blend Confined within a Nanoparticle Packing

Despite various physical and chemical strategies that have been explored, compatibilization of polymer blends has proved elusive. Confinement of polymers has shown to induce substantial and at times unexpected changes in glass-transition temperature, dynamics, and morphology of these materials. Although confinement of blends to thin films have shown to influence phase separation structure and chain mobility, the impact of confinement on the miscibility of polymer mixtures is much less understood. Here, we present a computational study using field-theoretic simulations to understand the thermodynamics of polymer blends that are confined in the interstices of nanoparticle packings where both polymers have neutral interactions with the nanoparticle surfaces. We calculate their binodal phase envelopes and show that two polymers that would undergo macroscopic phase separation become miscible when they are subjected to extreme nanoconfinement. The strength of the repulsion required to induce phase separation increases significantly as confinement increases. We find that this enhanced miscibility is driven by both an increase in entropic penalty upon phase separation and a decrease in enthalpic repulsion with increasing confinement. We relate the change in enthalpy to a reduction in the number of polymer–polymer contacts near nanoparticle surfaces and the change in entropy to a reduction in conformational freedom due to the formation of a polymer–polymer interface near nanoparticle surfaces. Confinement-induced mixing of polymers in nanoparticle packings could enable precise tuning of mechanical and transport properties of nanocomposite films and membranes.

All-solid-state lithium-sulfur batteries enabled by single-ion conducting binary nanoparticle electrolytes.

We designed solid-state hybrid electrolytes with single-ion conducting properties by co-assembling binary core-shell polymer nanoparticles. By controlling the nanoparticle size and number, we created superlattices that optimized the Li+ concentration and transport. The electrolytes exhibited a remarkable ionic conductivity (10-4 S cm-1), lithium transference number (0.94), electrochemical stability (up to 6 V), and modulus (0.12 GPa) at 25 °C. The mechanical strength of these electrolytes depended minimally on temperature at 25-150 °C because of the robustness of the cores. When implemented in Li-S batteries with no liquids, they demonstrated an initial discharge capacity of 1090 mA h g-1 at 0.05C, a cycle life of over 200 cycles, and a rate capability with a discharge capacity of 627 mA h g-1 at 3C.

Single junction binary and ternary polymer solar cells-based D–A structured copolymer with low lying HOMO energy level and two nonfullerene acceptors

The power conversion efficiency of the ternary PSCs (16.32%) is higher than that for binary counterparts, i.e., 13.16% and 12.62% for P(DTB-BDD):DBTBT-IC and P(DTB-BDD):Y6, respectively.

Polymer Composites with Self-Regulating Temperature Behavior: Properties and Characterization.

A novel conductive composite material with homogeneous binary polymer matrix of HDPE (HD) and LLDPE (LLD), mixed with conductive filler consisting of carbon black (CB) and graphite (Gr), was tested against a HDPE composite with a similar conductive filler. Even the concentration of the conductive filler was deliberately lower for (CB + Gr)/(LLD + HD), and the properties of this composite are comparable or better to those of (CB + Gr)/HD. The kinetic parameters of the ρ-T curves and from the DSC curves indicate that the resistivity peak is obtained when the polymer matrix is fully melted. When subjected to repeated thermal cycles, the composite (CB + Gr)/(LLD + HD) presented a better electrical behavior than composite CB + Gr)/HD, with an increase in resistivity (ρmax) values with the number of cycles, as well as less intense NTC (Negative Temperature Coefficient) effects, both for the crosslinked and thermoplastic samples. Radiation crosslinking led to increased ρmax values, as well as to inhibition of NTC effects in both cases, thus having a clear beneficial effect. Limitation effects of surface temperature and current intensity through the sample were observed at different voltages, enabling the use of these materials as self-regulating heating elements at various temperatures below the melting temperature. The procedure based on physical mixing of the components appears more efficient in imparting lower resistivity in solid state and high PTC (Positive Temperature Coefficient) effects to the composites. This effect is probably due to the concentration of the conductive particles at the surface of the polymer domains, which would facilitate the formation of the conductive paths. Further work is still necessary to optimize both the procedure of composite preparation and the properties of such materials.

Efficient and Nonhalogenated Solvent-Processed Organic Solar Cells Enabled by Conjugated Donor–Acceptor Block Copolymers Containing the Same Benzodithiophene Unit

Organic solar cells (OSCs) based on conjugated block copolymers (CBCs) have gained considerable attention owing to their simple one-pot solution process. However, their power conversion efficiencies (PCEs) require significant improvement. Furthermore, the majority of efficient CBC-based OSCs are processed using environmentally toxic halogenated solvents. Herein, we develop a new CBC (PBDB-T-b-PY5BDT) and demonstrate efficient and stable OSCs achieved by a halogen-free solution process. We design a (D1-A1)-b-(D1-A2)-type CBC (PBDB-T-b-PY5BDT) that shares the same benzodithiophene (BDT) units in donor and acceptor blocks. This alleviates unfavorable molecular interactions between the blocks at their interfaces. The PBDB-T-b-PY5BDT-based devices exhibit a high PCE (10.55%), and they show good mechanical, thermal, and storage stabilities. Importantly, we discuss the potential of our OSCs by preparing two different control systems: one based on a binary polymer blend (PBDB-T:PY5BDT) and another based on a conjugated random copolymer (CRC, PBDB-T-r-PY5BDT). We demonstrate that the photovoltaic performance, device stability, and mechanical robustness of the CBC-based OSCs exceed those of the binary all-polymer solar cells and CRC-based OSCs.

All-Aqueous Bicontinuous Structured Liquid Crystal Emulsion through Intraphase Trapping of Cellulose Nanoparticles.

Here, we describe the all-aqueous bicontinuous emulsions with cholesteric liquid crystal domains through hierarchical colloidal self-assembly of nanoparticles. This is achieved by homogenization of a rod-like cellulose nanocrystal (CNC) with two immiscible, phase separating polyethylene glycol (PEG) and dextran polymer solutions. The dispersed CNCs exhibit unequal affinity for the binary polymer mixtures that depends on the balance of osmotic and chemical potential between the two phases. Once at the critical concentration, CNC particles are constrained within one component of the polymer phases and self-assemble into a cholesteric organization. The obtained liquid crystal emulsion demonstrates a confined three-dimensional percolating bicontinuous network with cholesteric self-assembly of CNC within the PEG phase; meanwhile, the nanoparticles in the dextran phase remain isotropic instead. Our results provide an alternative way to arrest bicontinuous structures through intraphase trapping and assembling of nanoparticles, which is a viable and flexible route to extend for a wide range of colloidal systems.

A QSPR study for predicting θ(LCST) and θ(UCST) in binary polymer solutions

Lower critical solution temperature (LCST) and upper critical solution temperature (UCST) are key thermodynamic properties of binary polymer solutions. In this work, quantitative structure property relationship (QSPR) modeling was employed to predict θ(LCST) and θ(UCST) (LCST and UCST at the limit of infinite molar mass). Based on a series of topological norm descriptors and quantum chemical norm descriptors derived exclusively from the chemical structures of polymers and solvents, four linear topological and spatial LCST-QSPR and UCST-QSPR models were developed. The accuracy, robustness, and predictability of the proposed models were evaluated in detail by various statistical parameters (e.g., R2, MAE, MRE, and RMSE) and validation approaches (e.g., leave-one-out cross validation and Y-randomized validation). Various validation techniques and statistical indicators reveal that the spatial LCST-QSPR and UCST-QSPR models established by adding quantum chemical norm descriptors show better performances. Desirable agreements (Rtraining2 = 0.9423) between calculated and experimental θ(LCST) of 118 training set polymer solutions can be found in the spatial LCST-QSPR model as demonstrated by MRE of 2.65 %. Meanwhile, the spatial UCST-QSPR model shows the performances with MRE of 8.03 % and Rtraining2 of 0.8826 of 87 training set polymer solutions. The comparative results with those of different models from literatures further confirm the advantages of the as-developed models. The presented QSPR models are expected for rapid and accurate prediction of the θ(LCST) and θ(UCST) values of various binary polymer solutions.

Highly conductive gel polymer electrolytes for sodium-ion batteries with hard carbon anodes

Sodium-ion batteries are emerging as an alternative to lithium-based chemistries, with several manufacturers anticipating commercial production in the short perspective. However, the use of sodium is not yet as well established as lithium and thus, requires further development to overcome the safety issues, incompatibility of sodium with many electrode materials, and limited specific energy. The presented study aims to introduce new sodium conductive gel polymer electrolytes with binary polymer matrix and binary plasticizer and discuss their compatibility with a hard carbon anode. In this study, the polymer matrix consists of polyacrylonitrile and poly(methyl methacrylate) in three mass ratios, 9:1, 7:3, and 5:5. The plasticizer is a mixture of sulfolane and imidazolium-based ionic liquid with BF4– or NTf2– anion. The measurements revealed that a small amount of PMMA improves the properties of gel electrolytes, including size stability at high temperatures, thermal properties, and transfer number of cations in the gel electrolytes. The electrochemical properties strongly depend on the anion of the ionic liquid. However, the kinetics of Na+ conduction in a hard carbon anode is favorable in the presence of an ionic liquid with NTf2– anion. Furthermore, systems with hard carbon anode and gel electrolyte with sulfolane/[EMIm][NTf2] plasticizer exhibit activation energy of charge transfer process similar to the lithium-based chemistries. This fact makes these electrolytes good candidates for use in a sodium-ion battery.

Adherent Moving of Polymers in Spherical Confined Binary Semiflexible Ring Polymer Mixtures

Based on the coarse-grained model, we used molecular dynamics methods to calculate and simulate a semiflexible long ring–semiflexible short ring blended polymer system confined in a hard sphere. We systematically studied the distribution and motion characteristics of the long ring chain. The results show that when the short ring is short enough (Lshort < 20), the long ring (Llong = 50) is separated from the blend system and then distributed against the inner wall. As the length of the short ring increases (Lshort ≥ 20), the long ring can no longer be separated from the blending system. Moreover, we found that the long ring demonstrates a random direction of adherent walking behavior on the inner surface of the hard sphere. The velocity of the long ring decreases with the increase in the short ring length Lshort. Specifically for Lshort ≥ 20, the system does not undergo phase separation and the speed of the long ring decreases sharply along with the long ring distributed inside the confined bulk. This is related to the inner wall layer moving faster than the inside bulk of the restricted system. Our simulation results can help us to understand the distribution of macromolecules in biological systems in confined systems, including the restricted chromosome partitioning distribution and packing structure of circular DNA molecules.

Effect of Phase Heterogeneity on the Properties of Poly(vinyl alcohol)-Based Composite Pervaporation Membranes.

The structure, thermophysical characteristics, and pervaporation properties of composite membranes based on poly(vinyl alcohol) (PVA) are studied in dependence of the film preparation conditions. It is shown that the nature of the supramolecular organization of the composite polymer film determines which of the components of the separated mixtures of toluene and heptane predominantly penetrate through the corresponding pervaporation membrane. The observed structural effects can become more pronounced if the second component of a polymer mixture is purposefully selected (in this case, poly(N,N-dimethylaminoethyl methacrylate) instead of poly(acrylic acid)) or a nano-sized filler that can be well dispersed in the polymer matrix is introduced. Multi-wall carbon nanotubes are introduced into binary PVA-containing polymer blends. The influence of these fillers on the structure and transport properties of the obtained membranes is studied.

Induced Smectic E Phase in a Binary Blend of Side-Chain Liquid Crystalline Polymers.

Two liquid crystalline polymers containing an azobenzene or cyanobiphenyl mesogenic side chain that adopt smectic A phases are mechanically mixed at 1:1 mesogen molar ratio at an isotropic phase temperature and then cooled. The resultant binary polymer mixture behaves like a single component as revealed by polarized microscopy observation and differential scanning calorimetry, indicating that the binary mixture forms a fully compatible polymer blend. Moreover, the simple polymer blend unexpectedly leads to a higher-ordered smectic E phase where a herringbone structure is formed with restricted mesogen axis rotation. These results suggest a specific intermolecular interaction between the two mesogens, thereby inducing unusual compatibilized polymer blends and the most ordered liquid crystal (LC) phase.

Influence of Dopant Concentration and Annealing on Binary and Ternary Polymer Blends for Active Materials in OLEDs.

Obtaining white light from organic LEDs is a considerable challenge and, to realize white light emission, many studies have been conducted, primarily addressing two- or three-color blend systems as a promising strategy. In this work, pristine films, grown by spin coating, consisting of commercial blue Poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO), green Poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), and red spiro-copolymer (SPR) light-emitting materials, were studied as reference materials. Afterward, binary (SPR doped in host PFO) and ternary (SPR and F8BT doped in host PFO) thin films were successfully prepared with various ratios. The characterization of the as-grown and thermally-treated blend films was focused on their optical and photophysical properties. After, the fabrication of OLED devices on glass substrates was carried out for the evaluation of a blend's composition and annealing in terms of the devices' electrical characteristics and electro-emission properties in order to achieve white light emission. Their analysis provided insights into the energy transfer mechanisms between the constituent materials, which were correlated to host-guest interactions as well as to the structural changes originated by thermal treatment, leading to the crystallization of PFO. Finally, the OLEDs based on ternary blends approach the white light emission with (x, y) of (0.272, 0.346). These fabricated devices also exhibit turn-on voltages as low as 3 V, accompanied by remarkable luminance values above 3000 cd/m2.

Surface enrichment structures in a binary polymer system with different stiffnesses confined in slits

Surface enrichment structures in a binary polymer system with different stiffnesses confined in slits

Prediction of refractive indices and molecular radii of binary mixtures of Polyethylene glycol (PEG-200,400) and cyclic ethers: Insight into molecular interactions

Using five refractive index mixing rules: Lorentz–Lorenz, Gladstone–Dale, Weiner, Heller, and Arago –Biot; refractive indices of six binary polymer mixtures have been determined at 303.15 K, under atmospheric pressure. The binary mixtures investigated here are PEG-200 + 1,3-Dioxolane, PEG-200 + Oxolane, PEG-200 + Oxane, PEG-400 + 1,3-Dioxolane, PEG-400 + Oxolane, and PEG-400 + Oxane. A good agreement has been observed between the obtained results and respective literature data for all these mixtures. The relative merit of refractive index mixing rules is assessed. Deviation in refractive index and reduced free volume values are also calculated using the refractive index data taken from the literature. Furthermore, the molecular radius of these binary polymer mixtures is computed with the help of the refractive index and molar volume data. In addition, an ideal mixing method is also employed to calculate the molecular radius of these systems.The molecular radius of these binary mixtures is found to be additive with respect to the mole fraction of the pure components. Finally, the results are discussed in terms of the intermolecular interactions among the constituent molecules.

Surface Coassembly of Binary Mixed Polymer Brushes and Linear Block Copolymer Chains.

Binary mixed polymer brushes (BMPBs) are two different homopolymer chains that are covalently anchored to the solid surfaces at high grafting densities. One feature of the BMPBs is the unique ability to make surface phase separation under external stimuli. In this research, we demonstrate that different surface nanostructures can be fabricated by surface coassembly of BMPBs and free block copolymer (BCP) chains. Polystyrene/poly(2-(dimethylamino)ethyl methacrylate) (PS/PDMAEMA) BMPBs on silica particles (PS-PDMAEMA-SiO2) are synthesized by a two-step "grafting to" approach. PDMAEMA-b-PS block copolymer (BCP) chains and PS-PDMAEMA-SiO2 make surface self-assembly and a variety of surface nanostructures are formed in methanol. The grafting densities of PS and PDMAEMA brushes, solvent, and the BCP structures all exert significant influences on the surface morphology. With an increase in PDMAEMA grafting density, the surface structures change from perforated layers, to rods, and to spherical surface micelles (s-micelles). The PS grafting density also exerts an effect on the formation of the surface nanostructures. At low PS grafting density, sparsely distributed s-micelles are produced, and at high density, densely distributed s-micelles are observed. Based on transmission electron microscopy and scanning electron microscopy results, a surface phase diagram is constructed, which provides a guide to the surface morphology control.

Influence of PCL and PHBV on PLLA Thermal and Mechanical Properties in Binary and Ternary Polymer Blends.

PLLA, PCL and PHBV are aliphatic polyesters which have been researched and used in a wide range of medical devices, and all three have advantages and disadvantages for specific applications. Blending of these materials is an attractive way to make a material which overcomes the limitations of the individual polymers. Both PCL and PHBV have been evaluated in polymer blends with PLLA in order to provide enhanced properties for specific applications. This paper explores the use of PCL and PHBV together with PLLA in ternary blends with assessment of the thermal, mechanical and processing properties of the resultant polymer blends, with the aim of producing new biomaterials for orthopaedic applications. DSC characterisation is used to demonstrate that the materials can be effectively blended. Blending PCL and PHBV in concentrations of 5-10% with PLLA produces materials with average modulus improved by up to 25%, average strength improved by up to 50% and average elongation at break improved by 4000%, depending on the concentrations of each polymer used. PHBV impacts most on the modulus and strength of the blends, whilst PCL has a greater impact on creep behaviour and viscosity. Blending PCL and PHBV with PLLA offers an effective approach to the development of new polyester-based biomaterials with combinations of mechanical properties which cannot be provided by any of the materials individually.

Enhancement of viscoelastic property of MABS processed by melt compounding and injection molding

AbstractThis work is focused on developing a new type of polymer blend to improve the viscoelastic property of methyl methacrylate acrylonitrile butadiene styrene (MABS). A multi‐phase binary polymer blend was prepared by melt mixing in a twin screw extruder with three different weight ratios (10, 20, and 30 wt%) with a dynamically vulcanized alloy consisting mostly of fully cured ethylene propylene diene rubber (EPDM) particles encapsulated in a polypropylene (PP) matrix trade name Santoprene and an engineered styrene based thermoplastic elastomer trade name VDT to enhance the viscoelastic property of the blends. The compatibility and performance of the binary blend were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Fourier transform infrared (FT‐IR) spectroscopy, nuclear magnetic resonance (NMR), laser microscopy, scanning transmission electron microscopy (STEM) and tensile analysis. The DMA analysis of the samples revealed that the damping performance was significantly increased with the incorporation of the elastomeric phase into the MABS matrix. In addition, the morphological analysis revealed that VDT is more compatible with MABS compared to Santoprene. The NMR and FT‐IR analysis further supported the reason for higher compatibility of VDT and MABS blend. The improvement of the damping properties has been observed with the increased wt % of the VDT and Santoprene in the blends.