Hansen Space Research Articles

Cellulose Fiber with Enhanced Mechanical Properties: The Role of Co-Solvents in Gel-like NMMO System.

Cellulose has garnered attention in the textile industry, but it exhibits limitations in applications that require high strength and modulus. In this study, regenerated cellulose fiber with enhanced mechanical properties was fabricated from a gel-like N-methylmorpholine N-oxide (NMMO)-cellulose solution by modulating the intermolecular interaction and conformation of the cellulose chains. To control the interaction, two types of co-solvents (dimethyl acetamide (DMAc) and dimethyl formamide (DMF)) were added to the cellulose solutions at varying concentrations (10, 20, and 30 wt%). Rheological analysis showed that the co-solvents reduced the solution viscosity by weakening intermolecular interactions. The calculated distance parameter (Ra) in Hansen space confirmed that the co-solvent disrupted intermolecular hydrogen bonding within cellulose chains. The solutions were spun into fiber via a simple wet spinning process and were characterized by X-ray diffraction (XRD) and universal testing machine (UTM). The addition of co-solvent led to an increased crystallinity index (C.I.) owing to the extended cellulose chains. The modulus of the resulting fiber was increased when the co-solvent concentration was 10 wt%, regardless of the co-solvent type. This study demonstrates the potential for enhancing the mechanical properties of cellulose-based products by modulating the conformation and interaction of cellulose chains through the addition of co-solvent.

Fabrication and Characterization of a Lead-Free Cesium Bismuth Iodide Perovskite through Antisolvent-Assisted Crystallization.

Cesium bismuth iodide perovskite material offers good stability toward ambient conditions and has potential optoelectronic characteristics. However, wide bandgap, absorber surface roughness, and poor surface coverage with pinholes are among the key impediments to its adoption as a photovoltaic absorber material. Herein, bandgap modification and the tailoring of surface morphology have been performed through molar ratio variation and antisolvent treatment, whereby type III antisolvent (toluene) based on Hansen space has been utilized. XRD and Raman spectroscopy analyses confirm the formation of a 0D/2D mixed dimensional structure with improved optoelectronic properties when the molar ratio of CsI/BiI3 was adjusted from 1.5:1 to 1:1.5. The absorption results and Tauc plot determination show that the fabricated film has a lower bandgap of 1.80 eV. TRPL analysis reveals that the film possesses a very low charge carrier lifetime of 0.94 ns, suggesting deep defects. Toluene improves the charge carrier lifetime to 1.89 ns. The average grain size also increases from 323.26 nm to 444.3 nm upon toluene addition. Additionally, the inclusion of toluene results in a modest improvement in PCE, from 0.23% to 0.33%.

Whiter and Greener RP-HPLC Method for Simultaneous Determination of Dorzolamide, Brinzolamide, and Timolol Using Isopropanol as a Sustainable Organic Solvent in the Mobile Phase

A sustainable reversed-phase chromatographic method has been developed and validated for the simultaneous determination of three active pharmaceutical ingredients, dorzolamide, brinzolamide, and timolol, used to treat glaucoma. The eco-friendly solvent isopropanol has been used as an organic mobile phase constituent. According to the Hansen space green solvent selection tool, isopropanol has a G score of 6.5, comparable to ethanol, which has a G score of 6.6. The mobile phase consists of isopropanol: aqueous sodium acetate buffer (0.1 M, pH 4.25) in the ratio of 10:90 (v/v). The flow rate was maintained at 1 mL/min. Dorzolamide and brinzolamide were detected at 254 nm, and timolol was detected at 295 nm. A high-purity silica with a polymeric C18 modification column (150 × 4.6 mm, 5 µm particle size) was used for this separation. The three compounds were eluted within 8 min. The method was validated according to ICH guidelines. The calibration curves were linear in the range of 20–70 µg/mL, 40–140 µg/mL, and 20–70 µg/mL for dorzolamide, brinzolamide, and timolol, respectively. The LODs were found to be 1.61 µg/mL, 1.60 µg/mL, and 3.16 µg/mL for dorzolamide, brinzolamide, and timolol, respectively. Good accuracy and precision were obtained for the three compounds. The greenness and whiteness of the method were indicated using the AGREE, ChlorTox, and RGB12 tools.

A Procedure for Rational Probe Liquids Selection to Determine Hansen Solubility Parameters

AbstractHansen Solubility Parameters (HSP), viewed in the context of similarity whenever dispersion is focused, offer valuable insights into the surface characteristics of nanoparticles. However, existing methods for determining HSP via the sedimentation of nanoparticles require multiple probe liquids, resulting in time‐consuming, costly experiments with potential health risks. To address this, we developed a two‐step strategy that enables a systematic selection of liquids. The key element of the approach is to first identify the rough location of the Hansen sphere in the three‐dimensional Hansen space using a well‐chosen set of probe liquids of different polarities and chemical structures. Then, depending on the outcome of the first step, a particular choice of liquids is made for the final HSP determination. Taken together, the introduced procedure reduces the amount of required liquids for experiments from currently more than ten to a maximum of seven chosen based on a well‐defined, coherent methodology. Validation was performed on carbon black, non‐pigmentary nano‐scale titania, silicon/carbon composites, and lanthanum cobaltite particles, i. e., relevant materials that are commonly utilized in fuel cells, batteries, cyclohexene oxidation, catalytic combustion, photocatalysis, and heterogeneous Fenton reactions. The study showcases the potential to save time, costs, and efficiently determine HSP values in a comparable manner.

A Rule for Response Sensitivity of Structural-Color Photonic Colloids.

To mimic natural photonic crystals having color regulation capacities dynamically responsive to the surrounding environment, periodic assembly structures have been widely constructed with response materials. Beyond monocomponent materials with stimulus responses, binary and multiphase systems generally offer extended color space and complex functionality. Constructing a rule for predicting response sensitivity can provide great benefits for the tailored design of intelligently responsive photonic materials. Here, we elucidate mathematical relationships between the response sensitivity of dynamically structural-color changes and the location distances of photonic co-phases in three-dimensional Hansen space that can empirically express the strength of their interaction forces, including dispersion force, polarity force, and hydrogen bonding. Such an empirical rule is proven to be applicable for some typical alcohols, acetone, and acetic acid regardless of their molecular structures, as verified by angle resolution spectroscopy, in situ infrared spectroscopy, and molecular simulation. The theoretical method we demonstrate provides rational access to custom-designed responsive structural coloration.

MeSesamol, a bio-based and versatile polar aprotic solvent for organic synthesis and depolymerization

Applications of polar aprotic solvents are inevitable in the chemical industry, but few nonhazardous alternatives are available. Herein, we propose methyl sesamol (MeSesamol) as a promising new bio-based alternative for polar aprotic solvents and demonstrate its versatile applications. MeSesamol was derived from natural resources using environmentally friendly and facile procedures, such as methylation using dimethyl carbonate. MeSesamol has a distinctive smell and demonstrates excellent properties as a green solvent candidate: high boiling and open-cup flash points, immiscibility with water but miscibility with common organic solvents, high stability and resistance to several acids and bases. MeSesamol was an effective solvent in nine C–C coupling reactions, including the Suzuki and Sonogashira reactions and asymmetric Michael addition. MeSesamol lies close to dichloromethane (DCM) in Hansen space and achieves a similar or higher yield and enantiomeric excess (up to 97% and 99%, respectively) in the asymmetric Michael reactions compared to DCM. MeSesamol proved to be an excellent recyclable solvent in the depolymerizations of bisphenol-A polycarbonate (BPA–PC) and polyethylene terephthalate (PET). MeSesamol was recycled in five reaction cycles with excellent efficiency (92%–100%) and outstanding cumulative monomer yields (92% bisphenol-A from BPA–PC and 92% terephthalic acid from PET). To properly compare the depolymerization reactions, we propose two green metrics, namely, the corrected energy-economy factor (εcorr) and the corrected environmental energy impact (ξcorr).

Machine learning of organic solvents reveals an extraordinary axis in Hansen space as indicator of spherical precipitation of polymers

AbstractMachine learning is an emerging tool in the field of materials chemistry for uncovering a principle from large datasets. Here, we focus on the spherical precipitation behavior of polymers and computationally extract a hidden trend that is orthogonal to the availability bias in the chemical space. For constructing a dataset, four polymers were precipitated from 416 solvent/nonsolvent combinations, and the morphology of the resulting precipitates were collected. The dataset was subjected to computational investigations consisting of principal component analysis and machine learning based on random forest model and support vector machine. Thereby, we eliminated the effect of the availability bias and found a linear combination of Hansen parameters to be the most suitable variable for predicting precipitation behavior. The predicted appropriate solvents are those with low hydrogen bonding capability, low polarity, and small molecular volume. Furthermore, we found that the capability for spherical precipitation is orthogonal to the availability bias and forms an extraordinary axis in Hansen space, which is the origin of the conventional difficulty in identifying the trend. The extraordinary axis points toward a void region, indicating the potential value of synthesizing novel solvents located therein.

Dependency of polyacrylonitrile membrane structures on Hansen solubility parameters during non‐solvent induced phase separation

AbstractIn this study, non‐solvent induced phase separation (NIPS) is used to prepare polyacrylonitrile (PAN) based membranes. A thorough analysis on the correlations between coagulation conditions and membrane structures was carried out according to Hansen solubility parameters of coagulants and solvents. When coagulant is various, a larger Hansen solubility distance (Ra) between PAN and coagulant leads to a quicker phase separation and faster growth of finger‐like pores. By comparison, when PAN solvent is tuned by adding small amount of water, the Ra plays totally different roles for the formation of dense layer and the growth of finger‐like pores. The structural variations of PAN membranes have been mapped in Hansen space according to the Ra. Additionally, the low temperature induced sol–gel transition of PAN solution also affects the pore structures of the resultant membranes. These results would be helpful for better understanding the NIPS and fabricating PAN and other types of polymer membranes with desired structures and performances.

High-Throughput Screening of Blade-Coated Polymer:Polymer Solar Cells: Solvent Determines Achievable Performance.

Optimization of a new system for organic solar cells is a multiparametric analysis problem that requires substantial efforts in terms of time and resources. The strong microstructure‐dependent performance of polymer:polymer cells makes them particularly difficult to optimize, or to translate previous knowledge from spin coating into more scalable techniques. In this work, the photovoltaic performance of blade‐coated devices was studied based on the promising polymer:polymer system PBDB‐T and PF5‐Y5 as donor and acceptor, respectively. Using the recently developed high‐throughput methodology, the system was optimized for multiple variables, including solvent system, active layer composition, ratio, and thickness, among others, by fabricating more than 500 devices with less than 24 mg of each component. As a result, the power conversion efficiency of the blade‐coated devices varied from 0.08 to 6.43 % in the best device. The performed statistical analysis of the large experimental data obtained showed that solvent selection had the major impact on the final device performance due to its influence on the active layer microstructure. As a conclusion, the use of the plot of the device efficiency in the Hansen space was proposed as a powerful tool to guide solvent selection in organic photovoltaics.

Robot-Based High-Throughput Screening of Antisolvents for Lead Halide Perovskites

Summary Solution-based processing of photovoltaic materials has important advantages, including lower overall costs and easier upscaling of fabrication, where the solvents play an essential role. Antisolvent crystallization technique is often applied to achieve high-quality perovskite materials. However, the basic chemistry of the solvent-antisolvent crystallization is still not well understood. Besides, common antisolvents are toxic, and their number is limited. In this work, a novel robot-based method was used to screen the efficient antisolvents for different solvent-perovskite systems. 336 combinations of perovskite-solvent-antisolvent could be prepared and characterized by the integrated robotic platform in 2 days. In addition, we provided a detailed working mechanism of the solvent-antisolvent crystallization approach. Furthermore, hundreds of potential antisolvents were proposed based on high-throughput screening and simulation. Verification tests match well with theory, and all reported antisolvents used for photovoltaic device optimizations are within our predicted range of the Hansen space, indicating that the predictions are reliable.

Competitive Adsorption between a Polymer and Solvents onto Silica.

In polymer nanocomposites, particle-polymer interactions play a key role both in the processing and in the final properties of the obtained materials. Specifically, for silica, because of the surface polarity, surface modification is commonly used to improve the compatibility with apolar polymer matrices in order to prevent agglomeration. In this work, a new way to investigate the polymer-silica affinity and determine dispersibility parameters (HDP) of silica particles in the 3D Hansen space using a solvent approach is proposed. These parameters are estimated from the assessment of the stability of suspensions in a set of organic solvents. Based on the respective locations of the solvent, polymer, and silica representative points in the 3D Hansen space, the adsorption of a given polymer in solution in a given solvent can be predicted. This is shown with the industrial precipitated silica Zeosil 1165MP in combination with polystyrene and polybutadiene. It is shown that silanization of the silica particles decreases the adsorption of polystyrene, even though because of this surface treatment, silica comes closer to polystyrene in the Hansen space. This counter-intuitive effect is rationalized based on the consideration of an adsorption parameter χS computed from the relative locations of the solvent, polymer, and particles in the 3D Hansen space. Basically, this parameter is related to the respective distances of the solvent and polymer representative points to that of the particle in the Hansen space.

Understanding and predicting the solubility of bio-crude oils

The solubility behavior of three renewable bio-liquids obtained from hydrothermal liquefaction, rapeseed oil, and two common refinery streams is investigated. 242 solubility tests are performed, which lay the foundation for testing three different solubility approaches, namely: Hildebrand, Wiehe, and Hansen solubility parameters, and gaining a better understanding of the blending capabilities of bio-liquids into refinery streams. Finally, a theoretical investigation of common bio-liquid model compounds is undertaken. Results show that the Hildebrand solubility parameter is inadequate in predicting the solubility behavior of bio-liquids and should not be pursued in trying to derive a method for predicting compatible matches of complex liquids. The two-dimensional Wiehe solubility parameters are accurate in predicting pure solvents and nonsolvents for such complex liquids. However, the Wiehe approach is incapable of predicting the mutual compatibillity of bio-liquids, too. The Hansen solubility parameters show a compatibility wall defined by a distance calculated in the Hansen space. Although an overlapping region exists, it is expected that further experiments can help defining a threshold value below which compatible matches can be found. A conservative estimate is that any binary mixture of complex liquids chemically comparable to those under investigation, having a mutual distance below 4.9 in the Hansen space, are compatible.

The use of solubility parameters and free energy theory for phase behaviour of polymer-modified bitumen: a review

Advances related to the use of solubility parameters and free energy theory for the phase behaviour study of polymer-modified bitumen (PMB) are reviewed in this paper. The origin and effects of PMB phase behaviour are criticised with a focus on PMB storage stability, morphology and swelling ratio. An overview of the solubility approach for studying PMB is given regarding the historical and future developments. Free energy expressions for PMB systems are analysed, including the free energy of mixing, elastic free energy and gradient energy. The kinetic aspects are discussed with respect to the diffusion and flow processes. It is indicated that the solubility bodies in the three-dimensional Hansen space and their degree of intersection can be useful for analysing the PMB thermodynamic equilibrium and thus storage stability. But they give no indication by themselves on the PMB morphology. With solubility parameters linked to the PMB free energy, however, an integrated thermodynamic approach can assist in understanding both PMB storage stability and morphology comprehensively. Due to the chemical complexity of bitumen and certain modifiers, the solubility body centres and radiuses should be both considered for a proper expression of the polymer-bitumen interaction in PMB. A hypothetical dilution process can simplify this process, but with limitations. The introduction of elastic free energy may lead to a new and more realistic expression of free energy for PMB system. With this overview, it is expected that a preliminary foundation is established towards a comprehensive and realistic thermodynamic framework for interpreting and predicting PMB phase behaviour.

Hansen Solubility Parameters as a Tool in the Quest for New Edible Oleogels

AbstractBy identifying the Hansen space of nonfood‐grade gelators, which are capable of gelling oil, insights into the molecular characteristics required for gelation of edible oil become apparent. In examining the 34 reported oleogelators, molecules that gel oil tend to have a dispersive Hansen solubility parameter (HSP) between 16.0 < δd > 17.5 MPa1/2, a polar HSP between 7.0 < δp > 11.0 MPa1/2, and a hydrogen‐bonding HSP between 7.0 < δh > 9.0 MPa1/2. Although this does not define the complete Hansen space of these gelators, it provides insight into what types of molecules may be capable of forming oleogels in vegetable oils to allow new discovery without relying solely on serendipity.

Prediction the concentration of graphite direct exfoliation by liquid solution with solubility parameters map

This study is to discuss solvent selection with graphene dispersion concentration of directly exfoliation graphite. That limiting boundaries of fractional cohesion parameters will be draw on the triangular diagram to prediction and estimate. It is based on the literature of data and check with experimental or other literature results, include organic solution, aqueous solution and ionic liquid. In this work, we found that estimated the graphene dispersion concentration by distance (Ra) of Hansen solubility parameters (HSP) between graphene and solvent, the lower Ra; the higher concentration, some case the lower Ra; the lower dispersion concentration (such as acetone). It is compatible with the graphene dispersion concentration on the Hansen space or Triangular fractional cohesion parameters dispersion diagram. From Triangular fractional cohesion parameters dispersion diagram, 2D maps are more convenient for researchers than 3D maps of Hansen space and quickly to find the appropriate combination of solvents for different application.

Molecular Nuances Governing the Self-Assembly of 1,3:2,4-Dibenzylidene-d-sorbitol.

1,3:2,4-Dibenzylidene-d-sorbitol (DBS) is the gold-standard for low-molecular-weight organogelators (LMOGs). DBS gels a wide array of solvents, as illustrated by the large Hansen sphere representing gels (2δd = 33.5 MPa1/2, δp = 7.5 MPa1/2, and δh = 8.7 MPa1/2; radius = 11.2 MPa1/2). Derivatives of DBS have been synthesized to isolate and determine molecular features essential for organogelation. In this work, π-π stacking and hydrogen bonding are the major noncovalent interactions examined. The importance of π-π stacking was studied using 1,3:2,4 dicyclohexanecarboxylidene-d-sorbitol (DCHS), which eliminates possible π-π stacking while still conserving the other structural aspects of DBS. The replacement of the benzyl groups with cyclohexyl groups led to a very a poor gelator; only one of the several solvents examined, carbon tetrachloride, formed a gel. 1,3:2,4-Diethylidene-d-sorbitol (DES), another DBS analogue incapable of π-π stacking but with very different polarity, gelated a large Hansen space (2δd = 34.0 MPa1/2, δp = 10.9 MPa1/2, and δh = 10.8 MPa1/2; radius = 9.2 MPa1/2). DES gels solvents with higher δp and δh values than DBS. To assess the role of hydrogen bonding, DBS was acetalated (A-DBS), and it was found that the Hansen space gelated by A-DBS shifted to less polar solvents with higher hydrogen-bonding Hansen solubility parameters (HSPs) (2δd = 33.8 MPa1/2, δp = 6.3 MPa1/2, and δh = 9.6 MPa1/2; radius = 11.1 MPa1/2) than for DBS. These systematic structural modifications are the first step in exploring how specific intermolecular features alter aspects of Hansen space corresponding to positive gelation outcomes.

Kinetics of 12-Hydroxyoctadecanoic Acid SAFiN Crystallization Rationalized Using Hansen Solubility Parameters.

Changes in solvent chemistry influenced kinetics of both nucleation and crystallization of 12-hydroxyoctadecenoic, as determined using differential scanning calorimetry and applying a modified Avrami model to the calorimetric data. Altering solvent properties influenced solvent-gelator compatibility, which in turn altered the chemical potential of the system at the onset of crystallization, the kinetics of gelation, and the resulting 12HOA crystal fiber length. The chemical potential at the onset of crystallization was linearly correlated to both the hydrogen-bonding Hansen solubility parameter and the solvent-gelator vectorial distance in Hansen space, Ra. Our work suggests that solvent properties can be modulated to affect the solubility of 12HOA, which in turn influences the kinetics of crystallization and the self-assembly of this organogelator into supramolecular crystalline structures. Therefore, modulation of solvent properties during organogelation can be used to control fiber length and thus engineer the physical properties of the gel.

Do Molecular Gelators Cluster in Hansen Space?

Hansen solubility parameters (HSP) aid in the a priori prediction of which low molecular weight molecules have the potential to act as low molecular weight organogelators (LMOGs) and can immobilize certain liquids. The hydrogen-bonding HSP parameter individually has some predictive capacity on whether a molecule will form a gel, solution, or precipitate in a known liquid; in the case of benzene, gelators with δh > 5 MPa0.5 form gels, while molecules with δh < 10 MPa0.5 gel ethanol. Small molecules, which gel or remain in a solution state tend to cluster in specific regions of Hansen space. Excellent confinement of solutions was observed within a solubility sphere of benzene, ethanol, and acetonitrile. On the basis of the LMOGs selected, both the magnitude and directionality of the vector in Hansen space are important in predicting the gelation capacity (i.e., a gelator tends to gel toluene Δδp < −4 MPa0.5 when combining the role of Δ2δd and Δδp and ignoring Δδh).

Comparing and correlating solubility parameters governing the self-assembly of molecular gels using 1,3:2,4-dibenzylidene sorbitol as the gelator.

Solvent properties play a central role in mediating the aggregation and self-assembly of molecular gelators and their growth into fibers. Numerous attempts have been made to correlate the solubility parameters of solvents and gelation abilities of molecular gelators, but a comprehensive comparison of the most important parameters has yet to appear. Here, the degree to which partition coefficients (log P), Henry’s law constants (HLC), dipole moments, static relative permittivities (εr), solvatochromic ET(30) parameters, Kamlet–Taft parameters (β, α, and π), Catalan’s solvatochromic parameters (SPP, SB, and SA), Hildebrand solubility parameters (δi), and Hansen solubility parameters (δp, δd, δh) and the associated Hansen distance (Rij) of 62 solvents (covering a wide range of properties) can be correlated with the self-assembly and gelation of 1,3:2,4-dibenzylidene sorbitol (DBS) gelation, a classic molecular gelator, is assessed systematically. The approach presented describes the basis for each of the parameters and how it can be applied. As such, it is an instructional blueprint for how to assess the appropriate type of solvent parameter for use with other molecular gelators as well as with molecules forming other types of self-assembled materials. The results also reveal several important insights into the factors favoring the gelation of solvents by DBS. The ability of a solvent to accept or donate a hydrogen bond is much more important than solvent polarity in determining whether mixtures with DBS become solutions, clear gels, or opaque gels. Thermodynamically derived parameters could not be correlated to the physical properties of the molecular gels unless they were dissected into their individual HSPs. The DBS solvent phases tend to cluster in regions of Hansen space and are highly influenced by the hydrogen-bonding HSP, δh. It is also found that the fate of this molecular gelator, unlike that of polymers, is influenced not only by the magnitude of the distance between the HSPs for DBS and the HSPs of the solvent, Rij, but also by the directionality of Rij: if the solvent has a larger hydrogen-bonding HSP (indicating stronger H-bonding) than that of the DBS, then clear gels are formed; opaque gels form when the solvent has a lower δh than does DBS.

Research Progress in the Correlation between Gelation Properties and Solvent Parameters

To enable the effective development of functional gels, much effort has been dedicated to elucidating the mechanism of gelation. However, most existing studies have considered only the influence of the chemical structure of the gelators and/or external environmental factors; the contribution of the solvent in the gelation procedure is not yet understood. In this review, to reveal the solvent effects, the relationship between the gelation properties (such as the gel-sol phase transition temperature (Tgel), the critical gelation concentration (CGC), and the gelation behaviors) and the solvent parameters (e, ET(30), χ, δ, δd, δp, δh) is systematically discussed, based on recent research progress. Moreover, some experimental models for predicting the solvent effects (such as the one-dimensional model, Teas plot model, and Hansen space models) are introduced and discussed; these models could provide a guide for the development of new supramolecular gel systems.