Total Solubility Parameter Research Articles

Modeling ionomer swelling dynamics of a sulfonated polyphenylene, pentablock copolymers, and nafion

ABSTRACTThe water swelling behavior of Nafion, sulfonated poly(phenylene) (sPP), and poly[t‐butyl styrene‐b‐hydrogenated isoprene‐b‐sulfonated styrene‐b‐hydrogenated isoprene‐b‐t‐butyl styrene) was studied in order to understand microscopic molecular interactions. Ionomer swelling was modeled using the Flory‐Rehner relationship to predict solvent‐ionomer interaction parameter (χ12) and effective number of elastically active chains (n). Water swollen PBC had a decreasing χ12 from 1.146 to 0.516 when its ion‐exchange capacity (IEC) increased from 1.0 to 2.0. Nafion 117 and sPP χ12 values were 0.93 and 0.807 at an IEC of 0.91 and 1.8. Polymer water uptake was inversely dependent upon n and IEC or sulfonic acid‐group concentration. The following trend was noted for ionomer type, n, and water uptake: PBC‐2.0 (159 wt % and 7.89e‐4 mol/cm3) > sPP (48.6 wt % and 1.40e‐3 mol/cm3) > Nafion 117 (23 wt % and 1.24e‐3 mol/cm3). The ionomer's Gibb's total free change (ΔGTot) due to water swelling for Nafion 117 was −15.3 J, sPP was −28.5 J, and PBC‐2.0 was −53.2 J. An empirical equation was created to estimate a material's total solubility parameter (δ); and dispersion (δd), dipolar (δp,), and hydrogen bonding (δh) forces. The δ values for Nafion 117, sPP, and PBC‐2.0 were 19.9 (J/cm3)1/2, 21.3 (J/cm3)1/2, and 21.0 (J/cm3)1/2. Idealized swelling within an ionomer due to solvent. Ion domains are comprised of fixed sulfonated acid groups (SO3H) along the polymer's backbone. These functional groups provide interaction sites for molecules to diffusion and swell chains. The total change in free energy ΔG is dominated by ΔGmix that is attributed to hydrogen bonding and the concentration of elastically active chains n, which directly impacts its chemical potential Δμ. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 435–443

Influence factors of determining optimal organic solvents for swelling cured brominated epoxy resins to delaminate waste printed circuit boards

In the previous study, organic solvent dimethyl sulfoxide (DMSO) could effectively delaminate waste printed circuit boards (WPCBs) by swelling cured brominated epoxy resins (CBER). To find more organic solvents which can swell CBER, the total and three-dimensional Hansen solubility parameters (3d-HSP) of CBER in WPCBs were calculated by a group contribution method and an equilibrium swelling degree method. During testing equilibrium swelling degree, seventeen industrial common organic solvents were used to swell CBER in WPCBs. The results were that the total solubility parameter of CBER (δt) was 24.6–26.4 (J/cm3)1/2, and 3d-HSP were that dispersion force (δd) was 20.9(J/cm3)1/2, intermolecular dipole interaction force (δp) was 11.1(J/cm3)1/2, and hydrogen-bonding force (δh) was 11.6 (J/cm3)1/2. Then, 3-cresol was chosen to swell CBER in WPCBs according to its total and 3d-HSP. Result indicated that the WPCBs were delaminated completely in 3-cresol solvent. Finally, experimental results and theoretical analysis showed that the glass transition temperature (Tg) and solubility parameter of CBER were two very important factors for choosing organic solvents to delaminate the WPCBs. In addition, interaction forces of molecular functional groups between CBER and organic solvents were also an influence factor.

Compatibility of Thermally Reduced Graphene with Polyesters

ABSTRACTThe compatibility of thermally reduced graphene (TRG) with multiblock copolyesters, composed of poly(butylene terephthalate) (PBT) segments and poly(tetramethylene ether) glycol segments, was examined in detail. The morphology observed by optical microscopy and scanning electron microscopy showed that the compatibility was enhanced with increasing content of the PBT segment in the polyester. This compatibility behavior was analyzed quantitatively, by using the percolation threshold of electrical conductivity, and then further analyzed by using the Hansen solubility parameters to provide a general quantitative guideline to predict the compatibility of TRG with various polymers. The results suggest that the total solubility parameter, δT, value of TRG is larger than 24.0 (MPa)½, and thus that the compatibility with polymer is enhanced as the δT value of a polymer increases toward 24.0 (MPa)½. However, this prediction does not fit well in the presence of a comonomer such as acrylic acid, which has a high tendency to hydrogen bond with itself.

Solubility parameters of hypromellose acetate succinate and plasticization in dry coating procedures

Solubility parameters of HPMCAS have not yet been investigated intensively. On this account, total and three-dimensional solubility parameters of HPMCAS were determined by using different experimental as well as computational methods. In addition, solubility properties of HPMCAS in a huge number of solvents were tested and a Teas plot for HPMCAS was created. The total solubility parameter of about 24 MPa0.5 was confirmed by various procedures and compared with values of plasticizers. Twenty common pharmaceutical plasticizers were evaluated in terms of their suitability for supporting film formation of HPMCAS under dry coating conditions. Therefore, glass transition temperatures of mixtures of polymer and plasticizers were inspected and film formation of potential ones was further investigated in dry coating of pellets. Contact angles of plasticizers on HPMCAS were determined in order to give a hint of achievable coating efficiencies in dry coating, but none was found to spread on HPMCAS. A few common substances, e.g. dimethyl phthalate, glycerol monocaprylate, and polyethylene glycol 400, enabled plasticization of HPMCAS; however, only triethyl citrate and triacetin were found to be suitable for use in dry coating. Addition of acetylated monoglycerides to triacetin increased coating efficiency, which was likewise previously demonstrated for triethyl citrate.

Measurement and correlation of deferiprone solubility: Investigation of solubility parameter and application of van't Hoff equation and Jouyban–Acree model

The available solubility of deferiprone (DFP) in mono and mixed solvent systems is limited. The aim of this work is to find solvation of DFP with respect to the composition of the solvent mixture. Solubility of DFP in water, ethanol (EtOH) and N-methyl-2-pyrrolidone (NMP) was experimentally determined at 293.2, 298.2, 303.2, 308.2 and 313.2K. Its solubility in aqueous binary mixtures of EtOH and NMP was also investigated. Solubility of DFP in aqueous binary solvent mixtures of ethylene glycol (EG), propylene glycol (PG) and polyethylene glycol 400 (PEG 400) and non-aqueous binary solvent mixtures of EG+EtOH, EG+NMP, EG+PG and EG+PEG 400 is investigated and solubility profile shape of each system is explained in terms of solubility parameter. Total solubility parameter of DFP is calculated by Fedor's group contribution method and compared to solubility parameter of various solvent mixtures in order to estimate maximum solubility in specific co-solvent ratio.Based on the generated experimental solubility data, trained versions of the van't Hoff and Jouyban–Acree models were used to simulate DFP solubility in the binary mixture compositions. The applicability of the thermodynamic model to predict the solubility of DFP was studied. The experimental data was used to provide accurate estimations of solubility in the investigated solvent systems using van't Hoff and Jouyban–Acree equations.

Combined Atomistic Molecular Calculations and Experimental Investigations for the Architecture, Screening, Optimization, and Characterization of Pyrazinamide Containing Oral Film Formulations for Tuberculosis Management.

To date, effective treatment, prophylaxis, and control of tuberculosis (TB) infection is mainly dependent on the use of drugs. However, patient noncompliance with prescribed anti-TB treatment schemes remains a major problem confronting successful pharmacotherapeutic outcomes. Thus, the development of alternative delivery systems that can improve adherence for the existing anti-TB bioactives has been intensified in recent times. The aim of this investigation was to engineer an optimal, thermodynamically stable oral film (OF) formulation containing a key anti-TB agent, pyrazinamide (PYZ), employing molecular modeling and experimental tools. Four PYZ-loaded film variants (OF 1, OF 2, OF 3, OF 4) were constructed in silico and then prepared in vitro using the Accelrys Materials Studio software and solvent casting method, respectively. Screening and selection of the optimal OF was based on the computation of the total interaction energy (ET), kinetic energy (EK), solubility parameter (S), and cohesive energy density (CED) as well as determining mass, thickness, dissolution and disintegration times, dissolution pH, drug loading capacity, and surface morphology in vitro. OF 2 was selected as the optimal formulation as it displayed the lowest ET (-8006.28 kcal/mol), dissolution time (9.96 min), disintegration time (56.49 s), and weight (39.33 mg); moderate EK (1052.98 kcal/mol); highest S (44.55 (J/cm(3))(0.5)) and CED (1.99 × 10(9) J/m(3)), slim dimension (166 μm), good and unvarying drug loading capacity (98.04%), acceptable dissolution pH (6.70), and well-layered surface topography. The drug release behavior of the optimal OF 2 was best elucidated with the zero order (R(2) = 0.97) and Korsmeyer-Peppas (R(2) = 0.99) models. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) analyses showed that OF 2 was made of physically mixed multiple component polymeric and nonpolymeric compounds. OF 2 was semicrystalline in nature and displayed a dual phased ex vivo mucosal permeation pattern. In silico and in vitro physicomechanical quantities revealed OF 2's flexibility, robustness, and compressibility. OF 2 was most stable under controlled environmental humidity, pressure, and temperature conditions in silico and in vitro. OF 2 was potentially non-cytotoxic and biocompatible. Succinctly, this work demonstrated the applicability of a combination of atomistic molecular mechanics and dynamics calculations as well as experimental analyses to the fabrication, screening, optimization, and characterization of drug formulations. Lastly, the fabricated OF 2 formulation can function as a potential alternative for the effective loading and delivery of PYZ.

Determination of Solubility Parameters of Ibuprofen and Ibuprofen Lysinate.

In recent years there has been a growing interest in formulating solid dispersions, which purposes mainly include solubility enhancement, sustained drug release and taste masking. The most notable problem by these dispersions is drug-carrier (in)solubility. Here we focus on solubility parameters as a tool for predicting the solubility of a drug in certain carriers. Solubility parameters were determined in two different ways: solely by using calculation methods, and by experimental approaches. Six different calculation methods were applied in order to calculate the solubility parameters of the drug ibuprofen and several excipients. However, we were not able to do so in the case of ibuprofen lysinate, as calculation models for salts are still not defined. Therefore, the extended Hansen’s approach and inverse gas chromatography (IGC) were used for evaluating of solubility parameters for ibuprofen lysinate. The obtained values of the total solubility parameter did not differ much between the two methods: by the extended Hansen’s approach it was δt = 31.15 MPa0.5 and with IGC it was δt = 35.17 MPa0.5. However, the values of partial solubility parameters, i.e., δd, δp and δh, did differ from each other, what might be due to the complex behaviour of a salt in the presence of various solvents.

Physical stability of solid dispersions with respect to thermodynamic solubility of tadalafil in PVP-VA

The aim of this paper was to evaluate physical stability of solid dispersions in respect to the drug, tadalafil (Td), in vinylpyrrolidone and vinyl acetate block copolymer (PVP-VA). Nine solid dispersions of Td in PVP-VA (Td/PVP-VA) varied in terms of quantitative composition (1:9–9:1, w/w) were successfully produced by spray-drying. Their amorphous nature, supersaturated character and molecular level of mixing (a solid solution structure) were subsequently confirmed using DSC, PXRD, SEM and calculation of Hansen total solubility parameters. Due to thermal degradation of both components before the melting point of Td (302.3°C), an approach based on the drug crystallization from the supersaturated solid dispersion was selected to calculate the solubility of Td in the polymer. Annealing of the Td/PVP-VA solid dispersion (1:1, w/w) at selected temperatures above its Tg resulted in different stable solid dispersions. According to the Gordon–Taylor equation their new Tgs gave the information about the quantitative composition which corresponded to the thermodynamic solubility of Td in PVP-VA at given temperatures of annealing. The obtained relationship was fitted to the exponential function, with the calculated solubility of Td of 20.5% at 25°C. This value was in accordance with the results of hot stage polarizing light microscopy as well as stability tests carried out at 80°C and 0% RH, in which Td solid dispersions containing 10–20% of the drug were the only systems that did not crystallize within two months. A thermal analysis protocol utilizing a fast heating rate was shown to generate Td solubility data complementing the solid dispersion method. The Flory–Huggins model applied for the Td/PVP-VA system yielded the solubility value of 0.1% at 25°C, showing the lack of applicability in this case.

Supercritical Fluid Extraction of Direct Coal Liquefaction Residue Basing on Hansen Solubility Parameters

The supercritical fluid extraction( SFE) of direct coal liquefaction residue using acetone,isopropanol and benzene as solvents was investigated. The Hansen solubility parameters were used to clarify the variations of both solvent and the solute in SFE process. An empirical equation in terms of the extended Hansen approach was proposed to correlate the extraction capacity with the Hansen solubility parameters of solvents. The results show that the extraction yield using supercritical benzene,of which the dispersive component is the major in total solubility parameters,obtained the highest extraction yield. The ideal solubility on organic components in direct coal liquefaction residue improved with the extraction temperature increasing. The empirical equation shows high consistency with experimental results. As a consequence,the theory of Hansen solubility parameter and extended Hansen approach are applicable to the study on supercritical fluid extraction of direct coal liquefaction residue.

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.

A new way to determine the three-dimensional solubility parameters of hydrogenated nitrile rubber and the predictive power

In order to understand the swelling behavior of hydrogenated nitrile rubber (HNBR) more fully, the total solubility parameters (δt) of HNBR (Therban 2568) were determined by equilibrium swelling tests. Then, the swelling responses were analysed by a computer program to determine the Hansen three-dimensional solubility parameter (HSP). The HSP values – determined from lightly cured rubber samples – were estimated as δd = 18.4 (J/cm3)1/2, δp = 6.0 (J/cm3)1/2, δh = 4.5 (J/cm3)1/2 and δt = 19.9 (J/cm3)1/2. The energy difference (Ra) between HNBR and solvents or solvent mixtures have been calculated by their HSP values and proven to be useful for predicting the swelling behaviour of HNBR. The swelling volume decreases with increasing Ra values. Using blended solvents, a clear correlation between Ra values and the rubber swelling response was established. Thus, it may be possible to use the Hansen three-dimensional solubility parameters to predict swelling phenomena of cured rubber articles in mixed fluids such as bio-fuels or lubricants. Also, the HSP values may be used to predict the response of rubber seals or gaskets when replacing toxic or expensive fluids with more favorable environmentally friendly or inexpensive ones.

Total and partial solubility parameters prediction: Lornoxicam in individual solvents

BackgroundThe solubility behavior of lornoxicam was used to predict its solubility parameter in untested solvents of several chemical classes varying from nonpolar to highly polar in nature. MethodsSupersaturated solution of lornoxicam was shaken in a water bath for 72 h at 25 °C. The drug content was determined after attaining the equilibrium. The extended Hansen's method was applied for analyzing the solubility datum and partial solubility parameters were obtained for knowing the solute–solvent interaction. The method applied regression analysis of logarithm of the experimental mole fraction solubility of the drug against the partial solubility parameters of the solvent. ResultsA correlation was up to 90% using Flory–Huggins size correction term B, in the prediction of lornoxicam solubility. The four parameter approach involving proton-donor and proton-acceptor parameters was used in fitting the solubility data (R2 = 84%). Further, the ‘B’ term coupled with four-parameter approach was result in 2% improved in the correlation. The total solubility parameter obtained by this method was 11.10 H, which was closer to the value obtained by Van Krevelan method (11.69 H). ConclusionThe ensuing partial solubility parameters obtained are δ2d = 9.03 H; δ2P = 5.40 H; δ2a = 3.27 H; δ2b = 1.93 H gives insights into the interaction capabilities of the drug. As δ2a > δ2b, proves lornoxicam is a Lewis acid i.e. a better proton donor which are in favor with its chemical structure. By various methods of datum analysis, the solubility parameter of lornoxicam was consigned at 11.10 H.

Unravelling the solvent flux behaviour of ceramic nanofiltration and ultrafiltration membranes

In order to increase the understanding of the underlying processes in organic solvent nanofiltration (OSN), a study has been undertaken aimed at clarifying the solvent flux behaviour of ceramic nanofiltration and ultrafiltration membranes. Ceramic membranes were chosen for their non-swelling character. Pure water and a variation of 11 different organic solvents were measured on a series of different ceramic membranes with pore-size diameters ranging from 0.9nm up to 100nm. To avoid any historical effects, each flux measurement was carried out on a new membrane.The flux results were analysed in a phenomenological way, and a common very simple linear relationship was observed between the product of flux and viscosity of the solvent, and the total Hansen solubility parameter of the solvent. The linear relationship was found for all membranes, independent of the membrane pore size and the membrane material. The slope of the linear relationship was found to depend exponentially on the pore-size diameter and on the polarity of the membrane surface. This result emphasizes the importance of viscosity in the solvent transport, but also of the polarity difference between membrane surface and solvent. The very simple flux model deduced, allows a straightforward prediction of the flux of any solvent or solvent mixture, once the water flux of the membrane is known. At the high pore-size end, the phenomenological model naturally transforms into the viscous-flow or pore-flow behaviour as required. A tentative physical explanation of the model takes into account the presence and extension of a water layer adsorbed to the total pore surface of these membranes.This work also shows that the water flux of a hydrophilic membrane gives a good indication of its molecular weight cut-off (MWCO), and therefore of its separation performance in water.

Mechanochemical activation of vincamine mediated by linear polymers: Assessment of some “critical” steps

The aim of the research was to investigate three “critical steps” that deserve particular attention during the mechanochemical activation of vincamine. The first step consisted in the selection of the best polymeric carrier/most affine stabiliser between linear PVP and NaCMC by using the GRID and the GRID based AutoDock software packages which permit to calculate their surface features and interactions. Moreover, the calculation of the partial and total solubility parameters supported the results obtained by GRID and AutoDock software.Then, after the selection of linear PVP-K30 as the suitable carrier, the influence of process and formulation variables on the amorphisation degree and solubility enhancement was studied, to select the most suitable process conditions and formulation parameters. Subsequently, the best performing samples were widely characterised using XRPD, TEM and SSNMR (including the proton relaxation (1H T1 NMR) time) techniques. These studies highlighted that all the coground samples were nanocrystalline solid dispersions indicating a dramatic difference between the amorphisation capacities of linear PVP-K30 and cross-linked PVP, used in previous analogous experiences. In particular, 13C, 15N and 1H T1 NMR data point to a description of the system as a dispersion of nanocrystals in the polymer. In these dispersions vincamine is in a disordered crystalline state due to extensive interactions and contacts with PVP-K30 but the main hydrogen bonding motif characterising its packing remains. Again, differently from cross-linked PVP, dissolution studies revealed that linear PVP-K30 was able to promote a complete in vitro solubilisation of vincamine in some coground samples. What is more important, by using a linear polymer, drug-to-polymer and milling time variables appeared less influent on the solid state and in vitro properties of the composites. Finally, stability studies conducted for a period of 1year highlighted the high physical stability of the selected samples.

Prediction of solubility parameter from intrinsic viscosity

Polymer for coating such as epoxy and alkyd resin use additives for enhancing physical properties, hardening acceleration, and decreasing viscosity. Therefore, diluent selection is important for blending of additives in the resin. The choice of these solvents is determined by comparing the solubility parameters. In this study, it is a measure of the intrinsic viscosity of epoxy resin by Ubbelohde viscometer and epoxy resin is calculated solubility parameter through intrinsic viscosity. The epoxy and alkyd resins’ solubility parameters were calculated from their intrinsic viscosities to be epoxy resin (δ2d=16.55, δ2p=5.98, δ2h=6.53) and alkyd resin (δ2d=19.11, δ2p=3.96, δ2h=4.86), respectively. Their total solubility parameters were calculated to be epoxy resin (δ2t=18.77) and alkyd resin (δ2t=20.11), respectively.

Characterization of the Solvent Properties of Glycerol Using Inverse Gas Chromatography and Solubility Parameters

AbstractThe production of glycerol from the synthesis of biodiesel has led to a market surplus of this polyhydric alcohol and additional research to find new applications for this versatile chemical. This study involves the use of inverse gas chromatography (IGC) to characterize the solute–solvent interactions between glycerol and a homologous series of aliphatic alcohols, in which the latter components are at infinite dilution in the glycerol, which is the stationary phase contained in a packed GC column. The IGC experiments were conducted between 51.5 and 111 °C for the n‐alcohols ranging from methanol to n‐butanol. All of the n‐alcohol homologs exhibited positive deviations from Raoult's law as based on mole fraction activity coefficients values ranging from 1.86 to 14.4. The measured mole fraction activity coefficients of the alcoholic solutes in glycerol showed good agreement with literature values, and in some cases with those predicted using existing theoretical models. The mole fraction activity coefficients increased going from methanol to n‐butanol, reflecting the change in the alcohol's cohesive energy densities relative to that for glycerol. The total solubility parameter of glycerol calculated from IGC data was found to be 34.8 MPa1/2 which is in good agreement with that obtained using Hansen solubility parameter approach (31.6 MPa1/2). This data can be used to characterize the solvent properties of glycerol as well as to provide thermodynamic data for the removal of the alcoholic solutes from glycerol.

Hansen Solubility Parameters in the Analysis of Solvent–Solvent Interactions by Inverse Gas Chromatography

The Flory–Huggins interaction parameters, for a solute with pure nonvolatile solvents and with binary mixtures of nonvolatile solvents were evaluated using Inverse Gas Chromatography (IGC) data at 403.15 K. The five solvents used have similar structure and nearly the same molar volume and their mixtures form regular solutions. The values were used to evaluate the Hansen solubility parameters (HSP) for the pure solvents and mixed solvent systems. The HSP are plotted as a function of composition of the polar solvent. The dispersion component, , and the polar component, , exhibited negative deviation whereas the hydrogen bonding component, , showed positive deviation in the four mixtures. However, the total solubility parameter was found to be almost linear with composition in the four binary systems. Further the total solubility parameter, , was used to calculate the molar excess heat of vaporization for the solvents (C78 + POH, C78 + PCN, C78 + TTF, and C78 + TMO) that was found to be negative for C78 (19,24-dioctadecyldotetracontane) + POH(18,23-dioctadecylhentetracontan-1-ol) and C78 + PCN(1-cyano-18,23-dioctadecylhentetracontane) systems and positive for C78 + TTF [19,24-bis(18,18,18-trifluorooctadecyl)-1,1,1,42,42,42-hexafluorodotetracontane), and C78 + TMO(17,22-bis-(16-methoxyhexadecyl)-1,38-dimethoxyoctatriacontane] and the other systems.

The effect of membrane formation parameters on performance of polyimide membranes for organic solvent nanofiltration (OSN): Part A. Effect of polymer/solvent/non-solvent system choice

Integrally skinned asymmetric crosslinked polyimide (PI) nanofiltration membranes suitable for organic solvent nanofiltration (OSN) were formed via the phase inversion method. A better understanding of how membrane formation parameters (such as composition of the dope solution, the evaporation step, and chemical properties of the polymer) affect membrane performance (flux and rejection) was sought. The findings were reported in three parts. In this paper, Part A of the study, the importance of the choice of polyimide and solvent system was studied. Membranes prepared from Ultem 1000 and Matrimid 5218 were much more open as compared to membranes prepared from P84 and HT P84. Increasing share of 1,4-dioxane used as a co-solvent did not improve rejection of membranes prepared from Ultem 1000 and Matrimid 5218. An introduction of a simple tool based on mutual solubility parameters allowed to qualitatively predict the effect of polyimide choice and solvent composition used in the dope solution on membrane performance. Lower value of the introduced total solubility parameter was very well correlated with lower rejection.

Dependence of the surface roughness of MAPLE-deposited films on the solvent parameters

Matrix-assisted pulsed laser evaporation (MAPLE) was used to deposit layers of poly(9,9-dioctylfluorene) (PFO) to study the relation between the solvent properties (laser light absorption, boiling temperature and solubility parameters) and the morphology of the deposited films. To this end, the polymer was diluted (0.5 wt%) in tetrahydrofuran—THF, toluene and toluene/hexane mixtures. The thickness of the films was equal to 70±20 nm. The morphology and uniformity of the films was investigated by Atomic Force Microscopy and by the photoluminescence emission properties of the polymer films, respectively. It is shown that, although the solubility parameters of the solvents are important in controlling the film roughness and morphology, the optical absorption properties and boiling temperature play a very important role, too. In fact, for matrices characterized by the same total solubility parameter, lower roughness values are obtained for films prepared using solvents with lower penetration depth of the laser radiation and higher boiling temperatures.