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The objective of the present investigations was to assess the use of thermodynamic phase diagrams and the Gibbs free energy of mixing, ΔG mix , for the screening of the polymeric carriers by determining the ideal drug-loading for an amorphous solid dispersion formulation and optimum processing temperature for the hot-melt extrusion of a non-glass-forming drug. Mefenamic acid (MFA) was used as a model non-glass-forming drug and four chemically distinct polymers with close values of the solubility parameters, viz. Kollidon® VA64, Soluplus®, Pluronic® F68, and Eudragit® EPO, were used as carriers. The thermodynamic phase diagrams were constructed using the melting point depression data, Flory-Huggins theory, and Gordan-Taylor equation. The Gibbs free energy of mixing was estimated using the values of the drug-polymer interaction parameter, χ, and Flory-Huggins theory. The rank order miscibility of MFA in the four polymeric carriers estimated based on the difference in the values of their solubility parameters, Δδ, did not correlate well with the thermodynamic phase diagrams and Gibbs free energy plots. The study highlights the limitation of using the solubility parameter method in screening the polymeric carriers for poorly glass-forming drugs and reiterates the applicability of thermodynamic phase diagrams and Gibbs free energy plots in determining the ideal drug-loading and optimum processing temperature for hot-melt extrusion., (Copyright © 2021 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Pharmaceutical research, whether industrial or academic, has attempted to adopt approaches most efficient for the development of innovations. With the abundance of literature and growth of modern techniques available to minimize the number of trials, research is becoming more systematic by the day. Screening and selection of polymers for a pharmaceutical formulation can be challenging, considering the variety of polymers available and under development. Multiple considerations and experimentations are required to select a polymer to attain the target product profile. In this review, a stepwise discussion of techniques useful to screen and select polymers suitable for hot melt extrusion processing are explored and reported. First of all, selecting a range of polymers available for certain formulation types, for example, immediate release or modified release. Secondly, the screening of these selected polymers based on their physical and chemical properties as these properties should be in line with the active pharmaceutical ingredients (APIs) and the processing limitations of the equipment. Finally, selecting polymers using theoretical models such as solubility parameters and Flory Huggins modeling. Utilization of these three steps before proceeding to experimental methods will minimize the use of resources and provide a higher degree of accuracy towards the development of efficient, stable, and consistent products., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Amorphous drug-polymer systems or amorphous solid dispersions are commonly used in pharmaceutical industry to enhance the solubility of compounds with poor aqueous solubility. The degree of miscibility between drug and polymer is important both for solubility enhancement as well as for the formation of a physically stable amorphous system. Calculation of solubility parameters, Computational data mining, Tg measurements by DSC and Raman mapping are established traditional methods used to qualitatively detect the drug-polymer miscibility. Calculation of Flory-Huggins interaction parameter, computational analysis of X-Ray Diffraction (XRD) data, solid state Nuclear Magnetic Resonance (NMR) spectroscopy and Atomic Forced Microscopy (AFM) have been recently developed to quantitatively determine the miscibility in amorphous drug-polymer systems. This brief review introduces and compiles these qualitative and quantitative methods employed in the evaluation of drug-polymer miscibility. Combination of these techniques can provide deeper insights into the true miscibility of the drug-polymer systems., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Novel bio-based polyurethane (PU) nanocomposites composed of cellulose nanofiller extracted from the rachis of date palm tree and polycaprolactone (PCL) diol based PU were prepared by casting/evaporation. Two types of nanofiber were used: cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). The mechanical and thermal properties of the nanocomposite films were studied by DMA, DSC, and tensile tests and the morphology was investigated by SEM. Bionanocomposites presented good mechanical properties in comparison to neat PU. While comparing both nanofillers, the improvement in mechanical and thermal properties was more pronounced for the nanocomposites based on CNF which could be explained, not only by the higher aspect ratio of CNF, but also by their better dispersion in the PU matrix. Calculation of the solubility parameters of the nanofiller surface polymers and of the PU segments portend a better interfacial adhesion for CNF based nanocomposites compared to CNC., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Encapsulation of poorly soluble drugs in polymer nanoparticles is a common strategy to increase bioavailability of drugs. The miniemulsion‐solvent evaporation technique is widely used for encapsulating drugs in polymer nanoparticles because it is a versatile process, allowing many drug–polymer pair combinations. However, above a critical concentration of drug, which depends on the drug and polymer, nanoparticles tend to precipitate. Herein, the importance of drug solubility and miscibility in the polymer phase for selecting the optimal polymer matrix is investigated. Ibuprofen, naproxen methyl ester, and naproxen, as models for poorly soluble drugs, are encapsulated with various loadings in polycaprolactone nanoparticles by the miniemulsion‐solvent evaporation method. The miscibility between drug and polymer is estimated by calculating Flory–Huggins interaction parameters (χ) from differential scanning calorimetry measurements and calculating the difference in Hansen solubility parameter of drugs and polymer. Both values can be used for determining the feasibility of the drug encapsulation in polymer nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: The introduction of oligomeric polystyrene (PS) side chains into the conjugated backbone is proven to enhance the processability and electronic properties of semiconducting polymers. Here, two series of donor and acceptor polymers are prepared with different molar percentages of PS side chains to elucidate the effect of their substitution arrangement on the all‐polymer solar cell performance. The observed device performance is lower when the PS side chains are substituted on the donor polymer and higher when on the acceptor polymer, indicating a clear arrangement effect of the PS side chain. The incorporation of PS side chains to the acceptor polymer contributes to the decrease in phase separation domain size in the blend films. However, the reduced domain size was still an order of magnitude larger than the typical exciton diffusion length. A detailed morphological study together with the estimation of solubility parameter of the pristine PS, donor, and acceptor polymers reveals that the relative value of solubility parameter of each component dominantly contributes to the purity of the phase separated domain, which strongly impacts the amount of generated photocurrent and overall solar cell performance. This study provides an understanding of the design strategies to improve the all‐polymer solar cells. [ABSTRACT FROM AUTHOR]

Self-stratifying coatings are promising coating systems based on incompatible polymer blends which can produce polymer/polymer laminate. A complex multi-layer or gradient coating structure is formed from one single coat, providing an undercoat and finishing coating. The preferential distribution of concentration through the film thickness greatly eliminates the interfacial adhesion failure without compromising the advantages of a multi-layer system, and thus favors an industrial eco-efficient process. Powder, waterborne and solventborne coating systems are able to stratify: the most well-known and effective systems are described in this review. Finally, this concept constitutes a great possible versatile process for a broad range of applications and could thus favor the development of new products, taking into account the reduction of solvent and labor cost [ABSTRACT FROM AUTHOR]

Abstract: The solubility parameters of hydroxypropylcellulose (HPC) were measured with the viscosity method and estimated from proposing a group contribution approach for the prediction of δ based on the separation of the solubility parameter into three components (dispersion, polarity, and hydrogen bonding contributions). Hansen’s three dimensional solubility parameters were calculated approximately through the contributions of the structural groups. The compatibility of the HPC and polyacrylonitrile (PAN) blend system was studied with theoretical calculations as well as experimental measurements. Viscometric methods, polarized optical microscopy (POM), scanning electron microscopy (SEM), infrared spectrophotometric and thermogravimetry analysis (TGA) were employed for this investigation. The viscometric methods and polarized optical microscopy results were obtained from the blended solution in the range of 0–1.0 weight fraction of PAN, and the scanning electron microscopy, infrared spectrophotometric and thermogravimetry analysis results were obtained from the transparent films cast from the blended solutions that contained 0.2, 0.5 and 0.8 weight fractions of PAN, respectively. The results showed an excellent compatibility existed in the blends system, which may due to the strong hydrogen-bonding interaction between the hydroxyl group of HPC and the nitrile group of PAN. [Copyright &y& Elsevier]

Self-etching primers and adhesives contain very hydrophilic methacrylate monomers that result in high water sorptions by their polymers. Water sorption plasticizes the polymers and lowers their mechanical properties. The purpose of this work was to rank the hydrophilicity of a series of acidic primers by their Hoy's solubility parameters ( δ) to determine if there was a significant relationship between the δ of polymers and their mechanical properties. A series of six acidic primer blends containing a fixed concentration of phenyl-P but variable amounts of 2-hydroxyethyl methacrylate (HEMA), 2,2 bi[4-(2-hydroxy-3-methacryloyloxy)propane (BisGMA), and triethylene-glycol dimethacrylate (TEGDMA) was formulated and their Hoy's solubility parameters calculated. The polymers were cast into small ‘I’ beams and light-cured. The modulus of elasticity (E) and ultimate tensile strength (UTS) were measured in dry polymers and after immersion in water for 24 h. The results showed significant correlations between E and UTS under dry or wet conditions. Both E and UTS fell significantly when the specimens were immersed in water. After water immersion, the E and UTS showed significant correlations with Hoy's δp values. Both E and UTS correlated significantly with the BisGMA concentration of the polymers, either wet or dry. The percentage changes in E or UTS were significantly correlated with the water sorption of the polymers. [ABSTRACT FROM AUTHOR]

A partition function and a complete thermodynamic description for pure polymer fluids have been investigated based on a self-avoid-walk lattice model. Caused by the introduction of Gibbs distribution into the Flory-Huggins theory, the partition function and the thermodynamic description depicted their dependence on temperature well. In the present study, we applied the theory to calculate polymer solubility parameters. The polymer solubility parameters predicted by our theory are well consistent with the experiment values. [ABSTRACT FROM AUTHOR]

Self-etching primers and adhesives contain very hydrophilic acidic monomers that result in high water sorption/solubilities of their polymers. However, the chemical composition of these products varies widely. The purpose of this work was to vary the chemical composition of experimental self-etching primers and adhesives to determine if the water sorption/solubility of the polymers were affected in a predictable manner. The Hoy's solubility parameters of these mixtures were calculated to permit ranking of the degree of hydrophilicity of the polymers. Water sorption/solubility was measured according to ISO 4049. The results showed highly significant ( R2 = 0.86, P < 0.001) correlations between water sorption and Hoy's solubility parameter for polar forces ( δp) of the polymers. Similar correlations were obtained between polymer solubility and δp. When these results were compared with previously published results obtained with more hydrophobic resins, excellent correlations were obtained, indicating that Hoy's δp values may be used to predict the water sorption behavior of methylmethacrylate polymers. [ABSTRACT FROM AUTHOR]

The solid and liquid additives used in polymers can be characterized by Hansen solubility parameters (HSP). Compatibility is found when these parameters for the polymer and the additive are close enough to each other. Mismatches lead to phase separation, or in the case of solid surfaces, to poorer adhesion than that otherwise attainable. Where the additives have distinctly different segments, such as surface-active agents, the respective segments seek regions of similar energy (HSP). Some additional information is included in . [Copyright &y& Elsevier]

The solubility parameter concept offers a method for quantifying the miscibility or compatibility of two or more liquids. The concept can also be applied to polymer systems, and in the textile area the disperse dyeing of polyester may be treated from the viewpoint of a solution of dye in the fiber. Some of the perhaps puzzling observations of the effects of dyeing auxiliaries on the exhaust dyeing process may be at least qualitatively understood by reference to the solubility parameters of fiber, dye and auxiliary. Although solubility parameter alone is not a sufficient basis for the explanation of all polyester dyeing phenomena, it can serve as a medium for the removal of some aspects of dyeing from the realm of necromancy. [ABSTRACT FROM AUTHOR]

Performing reactions in the presence of self-assembled hierarchical structures of amphiphilic macromolecules can accelerate reactions while using water as the bulk solvent due to the hydrophobic effect. We leveraged non-covalent interactions to self-assemble filled-polymer micelle nanoreactors (NR) incorporating gold nanoparticle catalysts into various amphiphilic polymer nanostructures with comparable hydrodynamic nanoreactor size and gold concentration in the nanoreactor dispersion. We systematically studied the effect of the hydrophobic co-precipitant on self-assembly and catalytic performance. We observed that co-precipitants that interact with gold are beneficial for improving incorporation efficiency of the gold nanoparticles into the nanocomposite nanoreactor during self-assembly but decrease catalytic performance. Hierarchical assemblies with co-precipitants that leverage noncovalent interactions could enhance catalytic performance. For the co-precipitants that do not interact strongly with gold, the catalytic performance was strongly affected by the hydrophobic microenvironment of the co-precipitant. Specifically, the apparent reaction rate per surface area using castor oil (CO) was over 8-fold greater than polystyrene (750 g/mol, PS 750); the turnover frequency was higher than previously reported self-assembled polymer systems. The increase in apparent catalytic performance could be attributed to differences in reactant solubility rather than differences in mass transfer or intrinsic kinetics; higher reactant solubility enhances apparent reaction rates. Full conversion of 4-nitrophenol was achieved within three minutes for at least 10 sequential reactions demonstrating that the nanoreactors could be used for multiple reactions. [ABSTRACT FROM AUTHOR]