Binary Polymer Systems Research Articles

Tailored binary polymer system PCL-PEO for advanced biomedical applications: Optimization, characterization and in vitro analysis

Combining a hydrophobic polymer such as polycaprolactone (PCL) with a hydrophilic polymer polyethylene oxide (PEO) in a binary polymer system can enable a range of novel applications in biomedical engineering by permitting exceptional therapeutic release, antimicrobial possibilities, and heterogeneous tissue engineering scaffolds. In this work, both PCL and PEO were dissolved in chloroform at 15 w/v % at six different ratios to prepare binary polymer solutions. The rheological properties of the singular and binary polymer solutions were measured, and fibers were spun using pressurized gyration. The fiber morphologies of the prepared materials were studied using scanning electron microscopy (SEM). By immersing samples in deionized water, binary polymeric fibers with varying swelling behaviors were developed and analyzed using optical microscopy. The results were used to identify an optimum PCL:PEO binary mixture in chloroform. Chemical compositions of singular/binary polymer composites loaded with ibuprofen (IBP) were characterized by Fourier-transform infrared spectroscopy (FTIR) and thermal analysis was examined using differential scanning calorimetry (DSC). In vitro studies on PEO–IBP exhibited an instant release rate of 90 % in 40 s, whereas PCL–IBP and PCL:PEO–IBP revealed a sustained release of 87–96 % in 72 h, respectively. The results were used to discuss the potential use of binary polymer systems in biomedical applications.

Facile Blending Strategy for Boosting the Conjugated Polymer Semiconductor Transistor's Mobility.

The optimization of field-effect mobility in polymer field-effect transistors (FETs) is a critical parameter for advancing organic electronics. Today, many challenges still persist in understanding the roles of the design and processing of semiconducting polymers toward electronic performance. To address this, a facile approach to solution processing using blends of PDPP-TVT and PTPA-3CN is developed, resulting in a 3.5-fold increase in hole mobility and retained stability in electrical performance over 3 cm2 V-1 s-1 after 20 weeks. The amorphous D-A conjugated structure and strong intramolecular polarity of PTPA-3CN are identified as major contributors to the observed improvements in mobility. Additionally, the composite analysis by X-ray photoelectron spectroscopy (XPS) and the flash differential scanning calorimetry (DSC) technique showed a uniform distribution and was well mixed in binary polymer systems. This mobility enhancement technique has also been successfully applied to other polymer semiconductor systems, offering a new design strategy for blending-type organic transistor systems. This blending methodology holds great promise for the practical applications of OFETs.

Extrusion foaming of multiphasic polyethylene/ethylene-vinyl acetate copolymer/carbon nanotube mixtures: Tailoring foam properties by selective localization of nanoparticles

Semi-conductive foams based on low-density polyethylene/ethylene-vinyl acetate copolymer (LDPE/EVA) blends in the presence of carbon nanotubes (CNTs) were prepared using a twin-screw extrusion process. The effects of CNTs content and localization state in the binary mixture on the physical and structural properties of LDPE/EVA/CNT foams were investigated. The results confirmed that the void fraction, cell density, bubble size and cell size distribution of foams are optimal against CNT loading. The lightest LDPE/EVA/CNT foam was obtained by the CNT localization in the LDPE matrix. This foam containing 2.5 phr of CNT had smaller cells and more uniform cell size comparing to the pure blend foam. The cell density of this foam was 1.598 × 106 cells/cm3, which is much larger than that for the blend foam, 8.64 × 105 cells/cm3. However, the CNT localization state in the dispersed EVA domains resulted in lower void fractions and cell densities comparing with the LDPE/EVA blend foam. The findings clarify the profound impact of the nanofiller localization state on the foam properties of the binary polymeric systems. Light semiconductive LDPE/EVA foams with small cells, uniform cell size and high cell densities were achieved by localizing and dispersing the CNT nanoparticles in the LDPE matrix phase.

Temperature Transferable and Thermodynamically Consistent Coarse-Grained Model for Binary Polymer Systems

For the simulations of polymer systems, coarse-grained (CG) models are often developed to tackle the length and time scale limitations that are not feasible by all-atom molecular dynamic simulations. However, due to the necessary simplification or reduction in atomistic degrees of freedom, CG models usually have poor transferability over various temperatures, compositions, or thermodynamic states. In this work, the structure-based iterative Boltzmann inversion (IBI) method is further developed to obtain temperature transferable and thermodynamically consistent CG potentials for binary polymer systems. In particular, the conventional IBI procedure is first utilized to optimize single-component CG potentials from homopolymer systems while cross-interaction potentials from a random block copolymer system. Afterward, a thermodynamic integration method is applied to refine the cross-interaction potential between two constituent components in binary systems until the Flory–Huggins parameter (χ) between two components is matched with experimental value. We apply the above optimization procedure for the polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) as an example, which is widely studied experimentally, and the χ value can be easily obtained in the literature. To validate the transferability of the obtained CG potential, systems of both PS and PMMA homopolymers, random block copolymers, diblock copolymers, and PS/PMMA blends with various compositions are simulated. Many properties, including the mass density, radius distribution function, and bonded distribution functions, between CG beads generated from CG simulations match very well with those from atomistic simulations in the simulated temperature range, i.e., from 453 to 500 K. More importantly, phase morphologies of diblock copolymers and phase diagram of PS/PMMA binary blends over wide temperature and compositional ranges generated from CG simulations using our model are in good agreement with experimental results and predictions from self-consistent field theory.

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

Simulation of Binodal and Spinodal Curves of Phase State Diagrams for Binary Polymer Systems.

A new approach is proposed for simulating binodal and spinodal curves of phase diagrams for binary polymer systems. It is shown that the Flory–Huggins theory makes it possible to predict phase behavior in a wide range of temperatures and concentrations based on limited data on the components’ solubility. The approbation data of the technique are presented in the example of PS–PB and PS–PMMA systems, for which generalized phase diagrams are constructed.

Binary polymer systems for biomedical applications

ABSTRACT Binary polymer systems provide significant advantages in the preparation of materials used in biomedical applications. To highlight the importance and need of binary polymer systems in biomedical applications; utilisations of nano-carrier and fibre are discussed in detail in terms of their use as biomaterial, and their potential for further development with focus on dual and sequential drug delivery applications. On the other hand, in fibre technology, creation of binary polymer systems have been investigated using spinning processes such as electrospinning and even more recently innovated pressurised gyration. How these methods can be used to promote the mass production of binary polymer systems with various morphologies and characteristics are elucidated. The effects of different polymer materials, including solvents, mechanical properties, and the rate of degradation of polymers, are discussed. Current polymer blending systems and manufacturing processes are analysed, and technologies for biomaterials are carefully considered with up to date details.

Preparation and structural characteristics of composite alginate/casein emulsion gels: A microscopy and rheology study

Composite polysaccharide-protein emulsion gels are ubiquitous in real food systems, but the underlying formation mechanism has not been well understood. In this study, binary alginate/casein systems were selected as a template to prepare four types of composite gels, where the casein concentration was 8.0% (w/v) and the alginate (Alg) concentration varied (0.2, 0.4 & 0.75%, w/v). Based on the composite gel systems, the Alg/casein emulsion gels with 20% oil phase fraction (v/v) were further prepared by dispersing emulsified oil droplets into the binary polymer systems, followed by adding glucono-δ-lactone (GDL) to induce gelation. It was found that irrespective of the polymer types that were used to prepare and/or stabilize emulsions, the oil droplets were always located into the casein-dominant regions. At low Alg concentrations, the emulsion gels featured a casein-dominant network with small Alg-enriched liquid droplets entrapped inside; with increasing Alg addition, the emulsion gels tended to converse into a bicontinuous phase structure, as in the case of composite Alg/casein gel matrices (without oil droplets). Depending on emulsion preparation strategies, the incorporation of oil droplets also affected the phase separation rate and extent between the Alg and the caseins. Moreover, with increasing Alg concentration, the gelation time of the composite emulsion gels was shortened, possibly because a higher concentration of Alg exerted a more pronounced effect on promoting casein aggregation. Overall, our study is anticipated to not only give an insight into the formation of composite polysaccharide-protein emulsion gels, but also to offer a methodology for developing novel emulsion-gel related foods.

Specific Features of the Structural Organization of Porphyrin-Containing Binary and Ternary Polymer Systems: X-Ray Diffraction and Atomic Force Microscopy Study

The structure of the samples of polymer porphyrin-containing photosensitizing systems with different contents of chlorin e6 trisodium salt (Ce6Na), sodium alginate, and polyvinylpyrrolidone was investigated by X-ray diffraction and atomic force microscopy (AFM). The samples were obtained in the form of films by evaporation of aqueous solutions containing these compounds in different proportions. X‑ray diffraction studies show that, in two-component films Ce6Na–sodium alginate, a separate phase of the first substance and the phase of the second substance with the same structure as in the one-component films of this polymer are formed. At the same time, in two-component films Ce6Na–polyvinylpyrrolidone and three-component films Ce6Na–sodium alginate–polyvinylpyrrolidone, as evidenced by X-ray diffraction, the main part of Ce6Na does not form a separate phase, but the structure of polyvinylpyrrolidone changes in comparison with the one-component films of this polymer. In addition, X-ray diffraction studies show that, in the films containing sodium alginate and polyvinylpyrrolidone, these polymers form two separate phases. This conclusion also follows from the AFM data, although no significant influence of Ce6Na on the surface structure of the films obtained using sodium alginate, polyvinylpyrrolidone, and their mixture is revealed by AFM.

Interaction between mucoadhesive cellulose derivatives and Pluronic F127: Investigation on the micelle structure and mucoadhesive performance

Systems composed of bioadhesive and thermoresponsive polymers can combine in situ gelation with bio/mucoadhesion, enhancing retention of topically applied drugs. The effect of bioadhesive sodium carboxymethylcellulose (NaCMC) and hydroxypropyl methylcellulose cellulose (HPMC) on the properties of thermoresponsive Pluronic® F127 (F127) was explored, including micellization and the mucoadhesion. A computational analysis between these polymers and their molecular interactions were also studied, rationalising the design of improved binary polymeric systems for pharmaceutical and biomedical applications. The morphological characterization of polymeric systems was conducted by SEM. DSC analysis was used to investigate the crystallization and micellization enthalpy of F127 and the mixed systems. Micelle size measurements and TEM micrographs allowed for investigation into the interference of cellulose derivatives on F127 micellization. Both cellulose derivatives reduced the critical micellar concentration and enthalpy of micellization of F127, altering hydrodynamic diameters of the aggregates. Mucoadhesion performance was useful to select the best systems for mucosal application. The systems composed of 17.5% (w/w) F127 and 3% (w/w) HPMC or 1% (w/w) NaCMC are promising as topical drug delivery systems, mainly on mucosal surfaces. They were biocompatible when tested against Artemia salina, and also able to release a model of hydrophilic drug in a controlled manner.

Diverse Particle Carriers Prepared by Co-Precipitation and Phase Separation: Formation and Applications.

Nanoparticles with diverse structures and unique properties have attracted increasing attention for their widespread applications. Co-precipitation under rapid mixing is an effective method to obtained biocompatible nanoparticles and diverse particle carriers are achieved by controlled phase separation via interfacial tensions. In this Minireview, we summarize the underlying mechanism of co-precipitation and show that rapid mixing is important to ensure co-precipitation. In the binary polymer system, the particles can form four different morphologies, including occluded particle, core-shell capsule, dimer particle, and heteroaggregate, and we demonstrate that the final morphology could be controlled by surface tensions through surfactant, polymer composition, molecular weight, and temperature. The applications of occluded particles, core-shell capsules and dimer particles prepared by co-precipitation or microfluidics upon the regulation of interfacial tensions are discussed in detail, and show great potential in the areas of functional materials, colloidal surfactants, drug delivery, nanomedicine, bio-imaging, displays, and cargo encapsulation.

Fibroin-Alginate Scaffold for Design of Floating Microspheres Containing Felodipine

The objective of present work was to develop fibroin-sodium alginate floating microspheres of felodipine (FD) showing modified release. Binary polymer system of fibroin-sodium alginate was used to prepare microspheres by spray drying technique. Thus, FD loaded microspheres obtained were evaluated for % drug content, % entrapment efficacy, particle size, micromeritics, FT-IR, DSC, XRD, floatability profile, mucoadhesion, in vitro drug release, and accelerated stability studies. The drug content of FD-loaded microspheres (F1–F5) was in the range of 68.55 ± 1.20 to 78.21 ± 0.54 and entrapment efficacy 45.93 ± 0.41 to 61.60 ± 0.72%. The particle size varied from 60.33 ± 0.64 to 66.87 ± 0.85 μm. Acceptable Carr’s compressibility index and angle of repose demonstrated excellent flowability of microspheres (F1–F5). The FT-IR showed no chemical interactions between FD and polymers. The DSC and XRD indicated that FD was partially crystalline in microspheres. Floating parameters for optimized batch F2 were floating lag time10–15 s and floating time > 12 h. Floating buoyancy is 96.51 ± 0.66%. The in vitro drug dissolution kinetics of optimized F2 batch in 0.1NHCl and FSSGF demonstrated % drug release up to 80.42 ± 0.86% in 0.1NHCl and 84.64 ± 0.30% in FSSGF following Peppas model. Electrostatic repulsion between polymers successfully enabled the design of FD-loaded floating microspheres by spray drying. Excellent floating profile and extended release for 12 h, as per USFDA guidelines, have been demonstrated by the fibroin-sodium alginate binary composite system. In the future, fibroin-sodium alginate scaffold can be successfully used for tailor-made floating and release profiles of drugs belonging to different solubility classes.

Physicochemical stability of bioadhesive thermoresponsive platforms for methylene blue and hypericin delivery in photodynamic therapy

Hypericin (Hyp), a natural hydrophobic and photoactive pigment, and methylene blue (MB), a hydrophilic cationic dye, are utilized as photosensitizer (PS) for photodynamic therapy of cancer. Bioadhesive and thermoresponsive polymeric systems can improve the drug availability by increasing the contact time between the system and the mucosa and also controlling the drug release. In this work, an accelerated physicochemical stability study of binary polymeric systems composed of poloxamer 407 (Polox) and Carbopol 934 P (Carb) for MB or Hyp release was performed. Formulations were prepared containing Polox (20%, w/w), Carb (0.15%, w/w) and MB (0.25%, w/w) or Hyp (0.01%, W/W) and submitted to different stress conditions (5 ± 3 °C, 25 ± 2 °C and 40 ± 2 °C with relative humidity of 75 ± 5%) during 180 days. The samples were analyzed as macroscopic characteristics, photosensitizer content and mechanical properties by texture profile analysis. Both systems displayed decrease of photosensitizer content less than 5% during 180 days. MB-system showed an undefined reaction model, while Hyp-system displayed PS decay following a pseudo first-order reaction. Systems also displayed stable mechanical characteristics. The pharmaceutical analyses showed the good physicochemical stability of the bioadhesive platform for delivery Hyp and MB in photodynamic therapy.

Single-walled carbon nanotube-mediated physical gelation of binary polymer blends: An efficient route to versatile porous carbon electrode materials

A non-covalent approach to prepare nanotube-containing gels was developed based on the physical gelation of two polymers, polyvinyl alcohol (PVA) and polyacrylonitrile (PAN), with different microphase behaviors in water/dimethyl sulfoxide (DMSO) mixture. Single-walled carbon nanotubes (SWNTs) were incorporated into the binary-polymer/binary-solvent system to alter the physical gelation behavior and, in turn, to achieve unique physicochemical characteristics of the resulting gels. SWNTs were wrapped with PVA, which extended the binary polymer system to a ternary polymer system consisting of PVA bound to SWNTs, free PVA, and PAN. It was observed that the SWNT/PVA/PAN ensembles gelled with appropriate amounts of water in DMSO and the gelation behavior was reversible. The amounts of water and SWNT were determined to be key parameters affecting the formation of the gels. The SWNT/PVA/PAN gels were successfully converted to carbonaceous gels via heat treatment in an inert atmosphere, which can be extended to several applications such as electrode materials. The macroporous carbonaceous gels were further functionalized via manganese deposition followed by potassium hydroxide activation, which yielded excellent cell performance in a neutral electrolyte with the energy density of 9.6–24.8 Wh kg−1 and power density of 8.0–0.1 kW kg−1.

Specific Spatial Localization of Actin and DNA in a Water/Water Microdroplet: Self-Emergence of a Cell-Like Structure.

The effect of binary hydrophilic polymers on a pair of representative bio‐macromolecules in a living cell has been examined. The results showed that these bio‐macromolecules exhibited specific localization in cell‐sized droplets that were spontaneously formed through water/water microphase segregation under crowding conditions with coexisting polymers. In these experiments, a simple binary polymer system with poly(ethylene glycol) (PEG) and dextran (DEX) was used. Under the conditions of microphase segregation, DNA was entrapped within cell‐sized droplets rich in DEX. Similarly, F‐actin, linearly polymerized actin, was entrapped specifically within microdroplets rich in DEX, whereas G‐actin, a monomeric actin, was distributed evenly inside and outside these droplets. This study has been extended to a system with both F‐actin and DNA, and it was found that DNA molecules were localized separately from aligned F‐actin proteins to create microdomains inside microdroplets, reflecting the self‐emergence of a cellular morphology similar to a stage of cell division.

Assessing Mucoadhesion in Polymer Gels: The Effect of Method Type and Instrument Variables.

The process of mucoadhesion has been widely studied using a wide variety of methods, which are influenced by instrumental variables and experiment design, making the comparison between the results of different studies difficult. The aim of this work was to standardize the conditions of the detachment test and the rheological methods of mucoadhesion assessment for semisolids, and introduce a texture profile analysis (TPA) method. A factorial design was developed to suggest standard conditions for performing the detachment force method. To evaluate the method, binary polymeric systems were prepared containing poloxamer 407 and Carbopol 971P®, Carbopol 974P®, or Noveon® Polycarbophil. The mucoadhesion of systems was evaluated, and the reproducibility of these measurements investigated. This detachment force method was demonstrated to be reproduceable, and gave different adhesion when mucin disk or ex vivo oral mucosa was used. The factorial design demonstrated that all evaluated parameters had an effect on measurements of mucoadhesive force, but the same was not observed for the work of adhesion. It was suggested that the work of adhesion is a more appropriate metric for evaluating mucoadhesion. Oscillatory rheology was more capable of investigating adhesive interactions than flow rheology. TPA method was demonstrated to be reproducible and can evaluate the adhesiveness interaction parameter. This investigation demonstrates the need for standardized methods to evaluate mucoadhesion and makes suggestions for a standard study design.

Reaction-mediated entropic effect on phase separation in a binary polymer system

We present a computer simulation to study the phase separation behavior induced by polymerization in a binary system comprising polymer chains and reactive monomers. We examined the influence of interaction parameter between components and monomer concentration on the reaction-induced phase separation. The simulation results demonstrate that increasing interaction parameter (enthalpic effect) would accelerate phase separation, while entropic effect plays a key role in the process of phase separation. Furthermore, scanning electron microscopy observations illustrate identical morphologies as found in theoretical simulation. This study may enrich our comprehension of phase separation in polymer mixture.

The Use of Binary Polymeric Networks in Stabilizing Polyethylene Oxide Solid Dispersions

The objective of this study was to determine if a high Tg polymer (Eudragit® S100) could be used to stabilize amorphous domains of polyethylene oxide (PEO) and hence improve the stability of binary polymer systems containing celecoxib (CX). We propose a novel method of stabilizing the amorphous PEO solid dispersion through inclusion of a miscible, high Tg polymer, namely, that can form strong inter-polymer interactions. The effects of inter-polymer interactions and miscibility between PEO and Eudragit S100 are considered. Polymer blends were first manufactured via hot-melt extrusion at different PEO/S100 ratios (70/30, 50/50, and 30/70 wt/wt). Differential scanning calorimetry and dynamic mechanical thermal analysis data suggested a good miscibility between PEO and S100 polymer blends, particularly at the 50/50 ratio. To further evaluate the system, CX/PEO/S100 ternary mixtures were extruded. Immediately after hot-melt extrusion, a single Tg that increased with increasing S100 content (anti-plasticization) was observed in all ternary systems. The absence of powder X-ray diffractometry crystalline Bragg’s peaks also suggested amorphization of CX. Upon storage (40°C/75% relative humidity), the formulation containing PEO/S100 at a ratio of 50:50 was shown to be most stable. Fourier transform infrared studies confirmed the presence of hydrogen bonding between Eudragit S100 and PEO suggesting this was the principle reason for stabilization of the amorphous CX/PEO solid dispersion system.

Design of binary polymeric platforms containing ɩ-carrageenan and hydroxypropylcellulose for use in cataract surgery

This study describes the design and characterisation of the rheological and mechanical properties of binary polymeric systems composed of 2-Hydroxypropylcellulose and ɩ-carrageenan, designed as ophthalmic viscoelastic devices (OVDs). Platforms were characterised using dilute solution, flow and oscillatory rheometry and texture profile analysis. Rheological synergy between the two polymers was observed both in the dilute and gel states. All platforms exhibited pseudoplastic flow. Increasing polymer concentrations significantly decreased the loss tangent and rate index yet increased the storage and loss moduli, consistency, gel hardness, compressibility and adhesiveness, the latter being related to the in-vivo retention properties of the platforms. Binary polymeric platforms exhibited unique physicochemical properties, properties that could not be engineered using mono-polymeric platforms. Using characterisation methods that provide information relevant to their clinical performance, low-cost binary platforms (3% hydroxypropylcellulose and either 1% or 2% ɩ-carrageenan) were identified that exhibited rheological, textural and viscoelastic properties advantageous for use as OVDs.

Evaluation of the methylene blue addition in binary polymeric systems composed by poloxamer 407 and Carbopol 934P using quality by design: rheological, textural, and mucoadhesive analysis

This study describes the investigation about the physicochemical behavior of methylene blue (Mb) addition to systems containing poloxamer 407 (Polox), Carbopol 934P (Carb), intended to be locally used by photodynamic therapy. A factorial design 23 (plus center point) was used to analyze the rheological, mucoadhesive and textural properties of the preparations. Systems containing the lower concentrations of Polox (15 and 17.5%, w/w) exhibited pseudoplastic flow and low degrees of rheopexy. On the other hand, at higher Polox concentration (20%, w/w) the systems display plastic flow and thixotropy. Carb and Mb exhibited a negative influence for the consistency and flow behavior index, due to the interaction between them. For most of the formulations, the increase of Polox and Mb content significantly increased storage modulus, loss modulus and dynamic viscosity. The systems display a sol–gel transition temperature, existing as a liquid at room temperature and gel at 29–37 °C. Increasing the temperature and the polymer concentration, the compressional properties of systems significantly increased. The mucoadhesion was noted to all formulations, except to systems composed by 15% (w/w) of Polox. The analyses enabled to understand and predict the performance of formulations and the polymer–Mb interactions, tailoring to the suit systems (Polox/Carb/Mb): 17.5/0.50/0.20 and 20/0.15/0.25.