Hydrogen-bonding Solubility Parameter Research Articles

Precise heteroatom doping determines aqueous solubility and self-assembly behaviors for polycyclic aromatic skeletons

Developing effective strategies to improve the hydrophilicity or aqueous solubility of hydrophobic molecular scaffolds is meaningful for both academic research and industrial applications. Herein, we demonstrate that stepwise and precise N/O heteroatoms doping on a polycyclic aromatic skeleton can gradually alter these structures from hydrophobic to hydrophilic, even resulting in excellent aqueous solubility. The Hansen solubility parameters (HSP) method shows that the three partial solubility parameters are closely related to N/O doping species, numbers and positions on the molecular panel. The hydrogen bonding solubility parameter indicates that the hydrogen bonding interactions between N/O doped molecules and water play a key role in enhancing hydrophilicity. Moreover, three optimized water-soluble molecules underwent a self-assembly process to form stable nanoparticles in water, thus facilitating better hydrogen bonding interactions disclosed by HSP calculations, NMR and single crystal X-ray analysis. These ensembles even show quasi-solid properties in water from NMR and luminescence perspectives.

Polyvinyl Butyral with Different Acetalization Degrees: Synthesis and Solubility Parameters

In the research described here polyvinyl butyral (PVB) samples with mass acetalization degrees of 84.4%, 70.4%, 58.8%, 40.3% and number-average molecular weights (M n) of 29300 ∼ 36100 g mol−1 were synthesized using p-toluenesulfonic acid as a catalyst. The PVB samples were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and differential thermogravimetric analysis (DTGA). Furthermore, the solubility parameters of the PVB with different acetalization degrees were determined by the Hansen Solubility Parameter in Practice (HSPiP) software, turbidimetric titration and group contribution methods. The results showed that the total solubility parameter (δ t) and two of the solubility parameter components (polar solubility parameter δ p and hydrogen bonding solubility parameter δ h) increased linearly with the decrease of the acetalization degree of the PVB, while the change of δ d (dispersion solubility parameter) was not obvious. The correlation between the solubility parameters and acetalization degree of PVB was established. The solubility parameters obtained in this paper can be used to predict the affinity of PVB with solvents or additives, which is convenient for solvent selection and formulation design.

Investigation on Three-Dimensional Solubility Parameters for Explanation and Prediction of Swelling Degree of Polydimethylsiloxane Pervaporation Membranes

Using polydimethylsiloxane (PDMS) as a basic matrix to prepare ethanol and butanol permselective pervaporation membranes is a vibrant field. Many studies have verified that the three-dimensional Hansen solubility parameters (HSP) theory offers a valid explanation for the swelling performance of ethanol and butanol in PDMS. Five parameters (δD, δP, δH, δt, and Ra) are defined in HSP theory which can be individually used to explain the interaction strength between a solvent and a polymer. However, for the above five parameters, which one is the most effective parameter for deciding the swelling degree still needs to be determined. In this study, a commonly used hydroxy-terminated PDMS precursor was adopted to prepare the PDMS network. The HSP of the chosen PDMS precursor was measured by an advanced “solubility-rating” method. The special software package HSPiP (4.1.03), purchased from the HSPiP team, was used to process the “solubility-rating” results. The equilibrium swelling degree (Q value) of the PDMS network in water, ethanol, butanol, and toluene was measured and the relationships between the five HSP parameters of the solvents and the logarithmic equilibrium swelling degree, log(Q), were discussed. It was found that the measured polar parameter, δP, of PDMS was 0.12 MPa0.5. The measured hydrogen bonding parameter, δH, was larger than δP, attaining a value of 8.6 MPa0.5, because the hydroxy groups directly contributed to the hydrogen bonding solubility parameter, δH. With respect to the relationships between log(Q) and δD, δP, δH, δt, and Ra, linear relationships existed after plotting log(Q) vs. δP and log(Q) vs. δH. The linear relation degree of the fitted lines was 0.995 and 0.989, respectively. Their standard deviations were 0.149 and 0.232, respectively. Therefore, a better linear relationship existed between log(Q) and δP than the other solubility parameters. This indicated that the polar interaction was the main effect for deciding the swelling degree of the PDMS network in water and alcohol systems.

Determination of solubility parameters of ionic liquids and ionic liquid/solvent mixtures from intrinsic viscosity.

The total and partial solubility parameters (dispersion, polar and hydrogen-bonding solubility parameters) of ten ionic liquids were determined. Intrinsic viscosity approaches were used that encompassed a one-dimensional method (1D-Method), and two different three-dimensional methods (3D-Method1 and 3D-Method2). The effect of solvent type, the dimethylacetamide (DMA) fraction in the ionic liquid, and dissolution temperature on solubility parameters were also investigated. For all types of effect, both the 1D-Method and 3D-Method2 present the same trend in the total solubility parameter. The partial solubility parameters are influenced by the cation and anion of the ionic liquid. Considering the effect on partial solubility parameters of the solvent type in the ionic liquid, it was observed that in both 3D methods, the dispersion and polar parameters of a 1-ethyl-3-methylimidazolium acetate/solvent (60:40 vol %) mixture tend to increase as the total solubility parameter of the solvent increases.

Crystallization of Piroxicam Solid Forms and the Effects of Additives

AbstractThe relative stabilities of the two anhydrous polymorphs and the monohydrate of piroxicam in ethanol/water mixtures and the crystallization behavior of the solid forms in the presence of 11 additives were studied. At 37 °C, form II is thermodynamically more stable than form I, while the relative stability of form II and the monohydrate depends on the water concentration in the solution. The total Hansen solubility parameter δT and the hydrogen bonding solubility parameter δH of the substances can partly explain the effects of the additives on the crystallization of the solid forms. The additives that selectively promoted the crystallization of form I are the ones with δT and δH parameters similar to those of piroxicam.

Assessment of the thermodynamic properties of poly(2,2,2-trifluoroethyl methacrylate) by inverse gas chromatography

The thermodynamic properties of poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA) were determined by the aid of the inverse gas chromatography technique (IGC), at infinite dilution. The interactions between the polymer and 15 solvents were examined in the temperature range of 120–150°C via the estimation of the thermodynamic sorption parameters, the parameters of mixing at infinite dilution, the weight fraction activity coefficients and the Flory–Huggins interaction parameters. Additionally, the total and the partial solubility parameters of PTFEMA were estimated. The findings of this work indicate that the type and strength of the intermolecular interactions between the polymer and the solvents are strongly depended on the functional groups of the polymer and the solvents. The proton acceptor character of the polymer is responsible for the preferential solubility of PTFEMA in chloroform which acts as a proton donor solvent. The results also reveal that the polymer is insoluble in alkanes and alcohols whereas it presents good miscibility with polar solvents, especially with 2-butanone, 2-pentanone and 1,4-dioxane. Furthermore, the total and dispersive solubility parameters appear diminishing upon temperature rise, whereas the opposite behavior is noticed for the polar and hydrogen bonding solubility parameters. The latter increase with temperature, probably, due to conformational changes of the polymer on the solid support. Finally, comparison of the solubilization profiles of fluorinated methacrylic polymers studied by IGC, leads to the conclusion that PTFEMA is more soluble compared to polymers with higher fluorine content.

Effects of various liquid organic solvents on solvent‐induced crystallization of amorphous poly(lactic acid) film

AbstractThe effects of 60 organic solvent on poly(lactic acid) (PLA) were systematically investigated using the Hansen solubility parameter (HSP). The hydrogen bonding solubility parameter accurately reflects the solubility of PLA films using HSP but it depends on hydrogen bonding, as well as dispersion and polar parameters. The PLA films immersed in organic solvent became cloudy and showed no changes in chemical structure. However, solvent‐induced crystallization of the PLA films was observed. Crystalline structures do not dependent on the organic solvent but on the degree of swelling. The organic solvent‐induced crystallization formed a crystallized mixture of a‐ and β‐forms. The density of the crystalline PLA films was lower than that of amorphous PLA films. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Thermodynamic characterization of poly(1,1,1,3,3,3-hexafluoroisopropyl methacrylate) by inverse gas chromatography

The thermodynamic characterization of a fluorinated methacrylic homopolymer was conducted by means of inverse gas chromatography (IGC) at infinite dilution. The polymer under study, poly(1,1,1,3,3,3-hexafluoroisopropyl methacrylate) (PHFIMA) was synthesized via a free radical polymerization reaction and was properly characterized prior to IGC measurements. The IGC characterization encompassed the calculation of the thermodynamic sorption parameters, the parameters of mixing at infinite dilution, the weight fraction activity coefficients and the Flory–Huggins interaction parameters of 15 probes. Moreover, the total and partial solubility parameters of the polymer were determined. The impact of the temperature and the chemical nature of the probes on the aforementioned thermodynamic parameters are discussed. Results demonstrate that PHFIMA is insoluble in almost every tested solvent, with the exception of chloroform, due to its proton donor character which is favorable for the formation of hydrogen bonds with the fluorine groups and the oxygen atoms of the carbonyl groups (proton acceptors) of the polymer. Furthermore, the total and dispersive solubility parameters descend in a linear manner with the increase of temperature, whereas the polar and hydrogen bonding solubility parameters increase when temperature rises, probably due to the conformational changes of the polymer on the solid support.

Viscoelastic Behavior of Cellulose Acetate in a Mixed Solvent System

The effect of increasing water composition on the rheological and microstructural behavior of a ternary cellulose acetate (CA)/N,N-dimethylacetamide (DMA)/water system is examined. Addition of water to the CA/DMA system results in enhanced steady shear viscosity and dynamic viscoelastic properties and ultimately to phase-separated gel formation. The changes in dynamic rheological behavior of the system during gelation correlate well with the combined solubility parameter (delta) and, in particular, the Hansen hydrogen-bonding solubility parameter index (delta(h)) of the solvent system, suggesting hydrogen-bonding interactions may be the major route initiating the sol-gel process. For all gels studied, the elastic modulus and the critical stress to yield shifts to higher values with increasing CA concentration and/or water content. In addition, the elastic modulus exhibits a power-law behavior with water content, with the same power-law exponent observed for gels containing different CA concentrations. Addition of water leads to formation of a denser gel network, as evidenced from direct visualization of the gel microstructure through confocal microscopy.

An electron spin resonance probe method for the understanding of petroleum asphaltene macrostructure

Molecularly, petroleum asphaltenes are induced dipoles, which agglomerate into nanometer-sized colloids of different aggregation states. The electron spin resonance (ESR) vanadyl probe method is used to investigate the asphaltene macrostructures under different temperatures and microwave powers. Oxovanadium complexes native to an asphaltene isolated from Boscan crude oil, Venezuela, function as tracers to examine the behavior of micelle agglomerates when subjected to a microwave field. Both mobile and bounded oxovanadium compounds in colloidal asphaltene solution are in a state of equilibrium. It is noted that a greater amount of mobile vanadyl complexes can be stabilized in a dispersing medium (single-aromatic ring solvent series) with a higher-valued Hansen hydrogen bonding solubility parameter. We found that conversion of ESR vanadyl hyperfine lines occurs from anisotropic to isotropic as the temperature of a 4% Boscan asphaltene solution in o-xylene increased from 25°C to 100°C. Free tumbling of total vanadyl complexes in organic solvent signifies dissociation of micelles at packing imperfections prior to their release from aromatic hosts. Coupling of petroleum asphaltenes with microwave power can overcome charge transfer and charge balance interactions within micelle agglomerates. The relative content of mobile to bounded vanadyl complexes in 4% Boscan asphaltene solution of o-xylene was found to increase with microwave power at 45°C. Microwave energy will enable effective dispersion of colloidal asphaltene in heavy oil refining and upgrading.

Copolymers of itaconic acid and methyl methacrylate as positive electron beam resists

The copolymers of itaconic acid with methyl methacrylate P(MMA–ItA), are expected to perform as highly sensitive electron beam resists based on their high e-beam chain scission efficiencies (Gs). The Gs for P(MMA–20% ItA) was 2.5 times that of PMMA, and the Gs for P(MMA–35% ItA) was nearly 5 times that of PMMA. The copolymers have exhibited improved thermal stability over PMMA, as indicated by a decomposition temperature for P(MMA–20% ItA) that is 30 °C higher than that of PMMA. Infrared analyses of the copolymers showed that anhydride formed during the prebake step of the lithographic evaluation. The anhydride was predominantly a five-membered intramolecular anhydride ring which formed within single monomeric itaconic acid units. Some intermolecular anhydride was suspected because of the reduced solubility of the baked copolymers. The copolymer resists were synthesized to contain 20 and 35 mole% itaconic acid. Copolymers of each composition were evaluated with varying prebake conditions to provide varying amounts of anhydride formation. These resists were then evaluated on the basis of sensitivity, contrast, and resolution. Appropriate solvent systems for developing the lithographic patterns were chosen using a three-dimensional solubility mapping technique based on polar, nonpolar, and hydrogen bonding solubility parameters. P(MMA–20% ItA), with a 160 °C prebake, exposed at 7.5×10−6 C/cm2 with an accelerating voltage of 20 kV, was developed using a mixture of ethyl acetate and MIBK without thinning of the unexposed resist. P(MMA–35% ItA) baked at 120 °C produced 1 μm wide images at 5 to 8 μC/cm2 with a contrast (γ) of 2.5 to 3.5. 10% thinning was observed when developing areas exposed at 8 μC/cm2. Vertical walls were obtained at about 10 μC/cm2, and undercutting was observed with higher doses.

Polymer miscibility in mixed organic liquids having acid‐base interaction—a modified two‐dimensional approach

AbstractA mixture of two organic liquids, each of which is a solvent for a given polymer, may become a nonsolvent mixture, if there is strong acid‐base interaction between the two solvents. Experimental results of such cases are presented for five polymers. These results are then correlated with the proposed modified form of the two‐dimensional approach. In the modification, an additional term for taking into account the acid‐base interaction is added to the expression for the hydrogen‐bonding solubility parameter of the liquid mixture; the dispersion forces and polar interactions are assumed to be undisturbed by the occurrence of the acid‐base interaction.

Polymer miscibility in mixed organic liquids. An extension of the two-dimensional approach

Previous work on the two-dimensional approach to polymer miscibility in organic liquids is extended to polymer–mixed liquid system. From thermodynamic considerations methods for calculating δh of the mixed liquid and χH of the polymer–mixed liquid system from properties of pure components are proposed, where δh is the hydrogen-bonding solubility parameter of the liquid, and χH is a term which takes account of the dispersion and polar interactions between the liquid and the polymer and of effects due to temperature and molecular size of the liquid. Using these two calculated parameters, the solvent power of the mixed liquid can be determined from its location on the χ plane.

Polymer miscibility in organic solvents and in plasticizers—a two‐dimensional approach

AbstractFrom thermodynamic considerations based on associated solution models and from the Hansen's three‐dimensional solubility parameter concept, it is found that the solvent power of an organic liquid for a given polymer can be characterized by two parameters, δh and χH, where δh is the hydrogen‐bonding solubility parameter of the liquid, and χH is a term which takes account of the dispersion and polar interactions between the liquid and the polymer and of the effects due to temperature and molecular size of the liquid. It is also found that Hansen's solubility sphere for the polymer can be represented as a solubility circle in the proposed χH−δh plane. The proposed approach is applied successfully to polymer–plasticizer systems.