Cloud Point Measurements Research Articles

Investigation of the impacts of several diols on the phase behavior and physico-chemical quantities associated with the Triton X-100 and antidiabetic drug mixture

Drug-surfactant interaction phenomena have received popularity in the pharmaceutical industry and technological sectors from the view point of wider applications. Herein, we aimed to investigate the clouding behavior and various thermodynamic properties of Triton X-100 (TX-100) and metformin hydrochloride drug (MNH; an antidiabetic drug) mixture in the attendance of diols followed by the cloud point measurement technique. The dosage form of metformin hydrochloride drug controls the glucose level in the blood. The different types of diols, i.e., ethylene glycol (EG), 1,2-propylene glycol (1,2-PrG), 2,3-butanediol (2,3-BD), and 1,5-pentanediol (1,5-PD) were uniformly used in this inspection. The effect of diols, with the variation of their concentrations on the clouding behavior of TX-100 + MNH mixture having fixed content of TX-100 (92.7 mmol kg−1) and MNH drug (2 mmol kg−1), were examined. The most enhanced CP value was experienced in the aqueous 1,5-PD medium, whereas the lowest CP value was observed in the aqueous EG medium. The CP values were recorded for the working system under the effect of changing concentrations of diols, which were observed to follow the sequential order: CPH2O+1,5−PD>CPH2O+2,3−BD>CPH2O+1,2−PrG>CPH2O+EG. The clouding progression of the working system was realized to be nonspontaneous as concluded from the positive free energy change (ΔGco) values. The positive and negative values of enthalpy (ΔHco) and entropy (ΔSco) change were documented, respectively, at the low and high concentrations of diols. The hydrophobic interactions amongst different components are predominant at the low concentrations of diols, whereas the electrostatic interactions are leading factors at the high concentrations of diols. Enthalpy-entropy compensation parameters were computed and interpreted with proper perceptive. The outcomes of this observation may be effective and helpful in the various industrial sectors, especially in the drug carrier system in the pharmaceutical arena.

Experimental Evaluation of CO2-Soluble Nonionic Surfactants for Wettability Alteration to Intermediate CO2-Oil Wet during Immiscible Gas Injection

Summary The change in wettability of limestone reservoirs from oil-wet toward gas-wet can enhance crude oil production during immiscible CO2 injection. Therefore, in this research, we investigated the impact of wettability alteration to CO2-wet on oil recovery factor via dissolution of fluorine-free, CO2-philic, nonionic surfactants such as C4(PO)6 and C41H83O19 in CO2. Based on the cloudpoint measurements, the dissolution pressures of nonionic surfactants in supercritical CO2 ranged between 2,100 psi and 2,700 psi (below the reservoir pressure, i.e., 3,000 psi) at reservoir temperature, 65°C; these pressures are commensurate with CO2-enhanced oil recovery (EOR) pressures. Also, the C4(PO)6 and C41H83O19 can reduce the CO2-oil interfacial tension (IFT). Moreover, the CO2/C4(PO)6 and C41H83O19 solutions can change the limestone wettability from strongly oil-wet (Θ ~ 20o) to intermediate CO2/oil-wet (Θ = 95o and 110o) at reservoir conditions. The relative permeability curves also confirmed it by changing the curvature to the left and decreasing the residual oil saturation in both cases of CO2/C4(PO)6 and C41H83O19 solutions. The 20.8% and 13.1% additional oil recoveries were achieved during the 30,000 ppm CO2/C4(PO)6 and C41H83O19 solution scenarios, respectively, relative to the pure CO2 injection scenario. These nonionic surfactants are not able to make CO2-in-oil foam; therefore, wettability alteration and perhaps IFT reduction are the dominant mechanisms of EOR induced by the dissolution of nonionic surfactants in CO2, instead of CO2 mobility control. Consequently, the dissolution of fluorine-free, oxygenated, CO2-philic, nonionic surfactants (such as C4(PO)6 and C41H83O19) in CO2 at 30,000 ppm concentration can be a well-qualified candidate for altering the limestone wettability to intermediate CO2-oil-wet during the immiscible CO2 injection.

The Effects of Incorporating Nanoclay in NVCL-NIPAm Hydrogels on Swelling Behaviours and Mechanical Properties.

Following the formulation development from a previous study utilising N-vinylcaprolactam (NVCL) and N-isopropylacrylamide (NIPAm) as monomers, poly(ethylene glycol) dimethacrylate (PEGDMA) as a chemical crosslinker, and Irgacure 2959 as photoinitiator, nanoclay (NC) is now incorporated into the selected formulation for enhanced mechanical performance and swelling ability. In this research, two types of NC, hydrophilic bentonite nanoclay (NCB) and surface-modified nanoclay (NCSM) of several percentages, were included in the formulation. The prepared mixtures were photopolymerised, and the fabricated gels were characterised through Fourier transform infrared spectroscopy (FTIR), cloud-point measurements, ultraviolet (UV) spectroscopy, pulsatile swelling, rheological analysis, and scanning electron microscopy (SEM). Furthermore, the effect of swelling temperature, NC types, and NC concentration on the hydrogels' swelling ratio was studied through a full-factorial design of experiment (DOE). The successful photopolymerised NC-incorporated NVCL-NIPAm hydrogels retained the same lower critical solution temperature (LCST) as previously. Rheological analysis and SEM described the improved mechanical strength and polymer orientation of gels with any NCB percentage and low NCSM percentage. Finally, the temperature displayed the most significant effect on the hydrogels' swelling ability, followed by the NC types and NC concentration. Introducing NC to hydrogels could potentially make them suitable for applications that require good mechanical performance.

Enhanced oil recovery via dissolution of low molecular weight PDMS in CO2 during immiscible gas injection in matrix-fracture system

Oil recovery in natural fracture reservoirs can be improved by reducing the capillary force during the gravity drainage process in matrix-fracture system. In the current study, a modified gas was generated via dissolution of low molecular weight poly(dimethyl siloxane) (PDMS, average Mw 3780 g/mol, 10000 – 50000 ppm) in CO2 to enhance oil recovery at 50 °C or 70 °C and 3000 psi. Cloud point measurements indicated that PDMS dissolved in CO2 at pressures less than 3000 psi, which was below the minimum miscibility pressure (MMP) of ∼3600 psi at 70 °C determined with the vanishing interfacial technique. The solution density increased from 669.6 kg/m3 for pure CO2 to 780.3 kg/m3 for CO2/PDMS (50000 ppm) at 70 °C and 3000 psi, thereby reducing the density difference between the CO2-rich fluid and crude oil (ρo=865.2 kg/m3) in matrix-fracture system. Also, CO2-oil interfacial tension (IFT) was reduced from 65 to 15 dyn/cm via the dissolution of 50000 ppm PDMS in CO2. Therefore, it led to the CO2 diffusion coefficient increased in both reservoir-fluid saturated porous media and bulk oil scenarios 3–4 fold and 4–7 fold respectively in comparison to pure CO2 injection. These PDMS-induced changes reduced the capillary effects in gas-invaded zone, which consequently led to an increase in oil recovery of 25% points (from 31% to 56%) compared to pure CO2 injection in the case of capillary continuity during gravity drainage tests. For the field-scale, because the PDMS can dissolve in CO2 at pressures and temperatures which are commensurate with CO2 EOR, it is a promising CO2-philic chemical for increasing CO2 density and improving CO2 diffusion coefficient in gas invaded zone compared to conventional CO2 injection.

A novel approach to mixed micelles formation: study the interactions between bis-quaternary ammonium salts and nonionic surfactant Triton X-100

Abstract This article focuses on the description of novel mixed system formulations of bis-quaternary ammonium salts (bis-QASs) and the nonionic surfactant Triton X-100 (TX-100). Measurements of surface tension (γ), foam stability, contact angle (CA) and cloud point (CP) were investigated at different ratios of the given compounds. The results indicated that changes in the structure of the bis-QASs amphiphilic cation, including the length of the alkyl spacer and the presence or absence of –OH groups, affected the adsorption and micellization. Furthermore, the elongation of the alkyl spacer in the bis-QASs structure affects the increase in the CP temperature. The research carried out shows the future potential of mixed combinations (bis-QASs and TX-100) to be used in industrial applications.

Characterization of chemical composition distribution of ethylene-propylene-diene terpolymers by room temperature liquid adsorption chromatography and comparison to statistical approach

The chromatographic analysis of ethylene-propylene-diene (EPDM) terpolymers has hitherto been carried out only at high temperature, 120–160 °C. However, EPDM terpolymers are amorphous which could potentially allow to study their chromatographic behavior at room temperature (RT). To verify this hypothesis, cloud point measurements were realized to determine prospective solvent candidates. The identified solvents enabled injecting EPDM and model ethylene propylene norbornene terpolymers at RT.The retention of EPDM terpolymers on porous graphitic carbon (PGC) is a function at least two adsorbing comonomer components, ethylene and diene, in all tested chromatographic systems. This makes it difficult to characterize the chemical composition distribution (CCD) of terpolymers, which is of immense technical interest. Therefore, a modified form of LAC (LACm) was employed for determining the CCD of EPDM terpolymers using the identified solvents. Finally, the CCD obtained using different experimental methods was compared to the CCD determined using Monte Carlo simulations.

Constructing and validating ternary phase diagrams as basis for polymer dissolution recycling

One of the recycling methods for polymer waste is the dissolution-precipitation process, which is based on dissolving the polymer in a suitable solvent followed by contaminant removal by, optionally filtration, and polymer precipitation through the addition of a nonsolvent. As showcased for poly(vinyl chloride) (PVC), a polymer used in the construction sector and for packaging, the current work makes clear that the less studied ternary phase diagrams are a very promising tool for the ideal solvent-nonsolvent selection. Such ternary phase diagrams provide compositional information concerning the phase separation process pushing forward the dissolution-precipitation recycling technology. It is demonstrated that these diagrams can be constructed by connecting the Flory-Huggins theory, Hansen solubility parameters and UNIQUAC activity coefficients. Model validation is performed via cloud point measurements for which one can utilize labour-intensive visual inspection or, as demonstrated in this work, one can also apply dynamic light scattering and turbidimetry, with the latter as the preferred method that is cheaper and faster. Ternary phase diagrams for multiple solvent-nonsolvent systems are theoretically constructed and experimentally validated, considering cyclohexanone-ethanol and THF-ethanol as solvent-nonsolvent pairs. It follows that PVC phase diagrams are inherently different compared to other, more commonly studied polymers, such as polyethersulfone (PES) and that for PVC the addition of a ternary interaction parameter might be required.

Effect of anionic and nonionic hydrotropes on the clouding behavior and thermodynamic properties of nonionic surfactant and ciprofloxacin hydrochloride drug mixture

In the present study, the cloudy development of nonionic triton X-100 (TX-100) and an antibiotic drug ciprofloxacin hydrochloride (CFH) mixture has been conducted by applying the cloud point (CP) measurements method. The CP of TX-100 + CFH mixture was examined in aqueous solutions of hydrotropes (HDTs) (sodium benzoate (NaBenz), sodium salicylate (NaSal), 4-amino benzoic (4-ABA), polyethylene glycol (PGE) and Caffeine (CAF)). The TX-100 and CFH concentration were conserved constant at 50 and 1 mmol kg−1 correspondingly throughout the investigation. The CP values of TX-100 + CFH solution were augmented in the existence of NaBenz, NaSal, CAF along with PEG but diminished in aq. 4-ABA solution; the effects were obtained to be augmented with the enhancing hydrotropes contents. The CP values for TX-100 + CFH mixture in aq. hydrotropes media follow the pattern: CP(aq.4-ABA)<CPaq.CAF≈CPaq.PEG<CPaq.NaBenz<CPaq.NaSal. Therefore, the solubility of TX-100 + CFH mixture is achieved to be decreased in aq. solutions of 4-ABA while the solubility experienced an enhancement in aq. NaSal, NaBenz, PEG and CAF solutions. Among hydrotropes used in the present study, NaSal is the most effective solubility enhancer. The free energy (ΔGc0) were achieved to be positive in all the solvent media used in the study which exposes that the cloudy development process isnot spontaneous. The enthalpy (ΔHc0) and the entropy (ΔSc0) of clouding were obtained to be positive in hydrotropes media. The ΔHc0 and ΔSc0 values imply that the main forces of the cloudy formation in TX-100 and CFH system are hydrophobic interaction, hydrogen bonding, and electrostatic interactions. The compensation temperature (Tc) along with the intrinsic enthalpy gain (ΔHc0,∗) were also calculated and discussed. It is probable that the knowledge gained from these types of studies will be quite helpful in both pharmaceutics formulations and drug delivery system.

Phase separation and aggregation phenomena of TX-100 and promethazine hydrochloride mixture: Influences of monohydroxy organic compounds

Clouding nature and thermodynamic characteristics of surfactant-drug systems are novel approaches to chemists, industrialists, and researchers due to the enormous applications of the such mixture in pharmaceutical as well as technological sectors. In this study, the phase separation, assembly formation, and thermodynamic properties of triton X-100 (TX-100) + promethazine hydrochloride (PMH) drug mixed system were investigated by means of cloud point (CP) measurement and UV–visible spectroscopic techniques. The influences of the monohydroxy alcohols (ethanol (EtOH), 1-propanol (1-PrOH), 2-propanol (2-PrOH), along with 2-methyl-1-propanol (iso-BuOH) on the clouding development of TX-100 + drug mixed system have also been demonstrated. At lower concentrations of aqueous alcoholic media, the variation of CP with the enhancement of concentrations of alcohol were observed and increased CP values follow the trend: CPH2O+2-PrOH>CPH2O+EtOH>CPH2O+iso-BuOH>CPH2O+1-PrOH. The critical micelle concentration (CMC) of TX-100 + PMH mixture was found to be experienced an augmentation with the boost of the temperature. The obtained free energy values revealed the non-spontaneity of clouding and spontaneous aggregation of TX-100 + PMH mixture. The non-spontaneity of clouding of TX-100 + PMH mixture reduces with enhancement of concentrations of alcohols. The ΔHc0 and ΔSc0 values were found to be positive in almost all cases except at higher concentration of aq. 2-PrOH and iso-BuOH which disclosed the existence of hydrophobic as well as electrostatic interactions. The micellization of TX-100 + PMH mixed system in an aqueous medium was also accompanied by the hydrophobic interaction. The entropy-enthalpy compensation parameters of the clouding and micellization phenomenon were also elucidated through appropriate explanations.

Electrostatic Interaction on Liquid–Liquid Phase Separation at Low Salt Fraction Revealed by Scattering Techniques

Past studies on salt-doped polymer blends indicate that the electrostatic effect is complicated due to the combined effects of translational entropy of dissociated ions, ion solvation, ion–ion correlation, and ion clustering, especially at high salt concentrations. It still remains a challenge to unveil the electrostatic interaction of dissociated ions on phase separation explicitly in experiments. To address this challenge, the key principle of this study is to have the salt at extremely low concentrations, while its effect on phase separation is significant enough to be detected by scattering techniques. This experimental design enables the solvation of dissociated ions as the dominating factor, carefully avoiding complications from other effects. We characterize concentration fluctuations at full length scales by small-angle laser light scattering, X-ray scattering, and neutron scattering. The measured cloud points, spinodal temperatures, correlation lengths, and effective interaction parameters exhibit significant increase with the salt fraction, indicating that the electrostatic interaction promotes phase separation. We further reveal the electrostatic interaction of cations and anions, respectively. The asymmetric deflection of the phase diagram is quantitatively explained by the composition-dependent solvation of dissociated ions. This fundamental research provides experimental support for the progress of recent theoretical work and is helpful to guide the structural control in polymer electrolytes.

Enhanced Intestinal Permeability of Cefixime by Self-Emulsifying Drug Delivery System: In-Vitro and Ex-Vivo Characterization.

Cefixime (CFX) belongs to a group of third-generation cephalosporin antibiotics with low water solubility and low intestinal permeability, which ultimately leads to significantly low bioavailability. This study aimed to increase solubility, improve drug release, and intestinal permeability of CFX by loading into SEDDS. Suitable excipients were selected based on drug solubility, percent transmittance, and emulsification efficiency. Pseudo-ternary phase diagram was fabricated for the identification of effective self-emulsification region. The best probably optimized formulations were further assessed for encumbered drug contents, emulsification time, cloud point measurement, robustness to dilution, mean droplet size, zeta potential, polydispersity index (PDI), and thermodynamic and chemical stability. Moreover, in vitro drug release studies and ex vivo permeation studies were carried out and apparent drug permeability Papp of different formulations was compared with the marketed brands of CFX. Amongst the four tested SEDDS formulations, F-2 formulation exhibited the highest drug loading of 96.32%, emulsification time of 40.37 ± 3 s, mean droplet size of 19.01 ± 1.12 nm, and demonstrated improved long-term thermodynamic and chemical stability when stored at 4 °C. Release studies revealed a drug release of 97.32 ± 4.82% within 60 min in simulated gastric fluid. Similarly, 97.12 ± 5.02% release of CFX was observed in simulated intestinal fluid within 120 min; however, 85.13 ± 3.23% release of CFX was observed from the marketed product. Ex vivo permeation studies displayed a 2.7-fold increase apparent permeability compared to the marketed product in 5 h. Owing to the significantly improved drug solubility, in vitro release and better antibacterial activity, it can be assumed that CFX-loaded SEDDS might lead to an increased bioavailability and antibacterial activity, possibly leading to improved therapeutic effectiveness.

Synthesis of NVCL-NIPAM Hydrogels Using PEGDMA as a Chemical Crosslinker for Controlled Swelling Behaviours in Potential Shapeshifting Applications.

Stimuli-responsive hydrogels have recently gained interest within shapeshifting applications due to their capabilities to expand in water and their altering swelling properties when triggered by stimuli, such as pH and heat. While conventional hydrogels lose their mechanical strength during swelling, most shapeshifting applications require materials to have mechanical strength within a satisfactory range to perform specified tasks. Thus, stronger hydrogels are needed for shapeshifting applications. Poly (N-isopropylacrylamide) (PNIPAm) and poly (N-vinyl caprolactam) (PNVCL) are the most popular thermosensitive hydrogels studied. Their close-to-physiological lower critical solution temperature (LCST) makes them superior candidates in biomedicine. In this study, copolymers made of NVCL and NIPAm and chemically crosslinked using poly (ethylene glycol) dimethacrylate (PEGDMA) were fabricated. Successful polymerisation was proven via Fourier transform infrared spectroscopy (FTIR). The effects of incorporating comonomer and crosslinker on the LCST were found minimal using cloud-point measurements, ultraviolet (UV) spectroscopy, and differential scanning calorimetry (DSC). Formulations that completed three cycles of thermo-reversing pulsatile swelling are demonstrated. Lastly, rheological analysis validated the mechanical strength of PNVCL, which was improved due to the incorporation of NIPAm and PEGDMA. This study showcases potential smart thermosensitive NVCL-based copolymers that can be applied in the biomedical shapeshifting area.

Physicochemical approaches reveal the impact of electrolytes and hydrotropic salt on micellization and phase separation behavior of polymer polyvinyl alcohol and surfactant mixture

The polymer-surfactant mixture has usages in numerous industries mainly in the production of daily used materials. Herein, the micellization and phase separation nature of the sodium dodecyl sulfate (SDS) and TX-100 along with a synthetic water-soluble polymer-polyvinyl alcohol (PVA) have been conducted using conductivity and cloud point (CP) measurement tools. In the case of micellization study of SDS + PVA mixture by conductivity method, the CMC values were obtained to be dependent on the categories and extent of additives as well as temperature variation. Both categories of studies were performed in aq. solutions of sodium chloride (NaCl), sodium acetate (NaOAc), and sodium benzoate (NaBenz) media. The CP values of TX 100 + PVA were decreased and enhanced in simple electrolytes and sodium benzoate media respectively. In all cases, the free energy changes of micellization (∆Gm0) and clouding (∆Gc0) were obtained as negative and positive respectively. The enthalpy (∆Hm0) and entropy (∆Sm0) changes for SDS + PVA system micellization was negative and positive respectively in aq. NaCl and NaBenz media, and in aq. NaOAc medium the ∆Hm0 values were found negative while ∆Sm0 were found negative except at the highest studied temperature (323.15 K). The enthalpy-entropy compensation of both processes was also assessed and described clearly.

Structure and Phase Behavior of Bottlebrush Diblock Copolymer-Linear Homopolymer Ternary Blends

In this work, we systematically investigated the structure and phase behavior of ternary mixtures containing an AB bottlebrush diblock copolymer and A and B linear homopolymers, where A is polystyrene and B is poly(ethylene oxide), using a combination of small-angle X-ray scattering and cloud point measurements. We found that the overall phase behavior of such mixtures closely resembles the linear counterparts, with lamellae occurring in the copolymer-rich region, macrophase separation in the homopolymer-rich region, and a bicontinuous microemulsion in between. However, the increase in lamellar and microemulsion domain spacing with increasing homopolymer content is significantly weaker than that found with ternary mixtures containing linear diblock copolymers and depends on the relative size of the homopolymers and bottlebrush side chains. We attribute this behavior to an unconventional spatial distribution of the homopolymer within the bottlebrush architecture of the diblock copolymer. These ternary mixtures offer a promising platform for the design of cocontinuous materials with an expanded parameter space made possible by the application of bottlebrush polymers.

Making Heterometallic Metal–Metal Bonds in Keggin-Type Polyoxometalates by a Six-Electron Reduction Process

Polyoxometalates (POMs) represent a promising class of molecular electron reservoirs. However, their multielectron reduction gives rise to intricate physical-chemical phenomena that must be fully understood for their future use in energy-storage devices. Herein, we show that bulk electrolysis of the archetypal Keggin-type POM [Si(WVI2MoVIO10)(WVI3O10)3]4- in aqueous solution leads to the six-electron-reduced derivative [Si(WIV2MoIVO7(H2O)3)(WVI3O10)3]4- (notated SiW11Mo-VI') in which the mixed-metal triad acts as a storage unit for six electrons and six protons. X-ray diffraction analysis and multinuclear NMR (183W and 95Mo) studies reveal that this electron-rich species represents the first example of POMs containing heterometallic metal-metal bonds between addenda centers. This electron-rich POM can be further reduced through multielectronic events, while its full oxidation restores the structure of the oxidized parent ion. Remarkably, the formation of SiW11Mo-VI' results from a fast clustering process compared to that observed for the entirely W-based analogue, revealing that the formation of metal-metal bonds in the mixed-metal Mo/W POM is facilitated because the reaction rate is not limited by a slow disproportionation step. Last, we evaluate the supramolecular properties of SiW11Mo-VI' using a method based on the cloud-point measurement of a nonionic surfactant. This investigation demonstrates that the clustering process has dramatic consequences on the solution behavior of the POM, canceling its superchaotropic character due to a local structuring effect of the hydration shell. These fundamental results pave the way for applications using the massive electron-storage properties of mixed-metal POMs.

Phase separation and dynamical arrest of protein solutions dominated by short-range attractions.

The interplay of liquid-liquid phase separation (LLPS) and dynamical arrest can lead to the formation of gels and glasses, which is relevant for such diverse fields as condensed matter physics, materials science, food engineering, and the pharmaceutical industry. In this context, protein solutions exhibit remarkable equilibrium and non-equilibrium behaviors. In the regime where attractive and repulsive forces compete, it has been demonstrated, for example, that the location of the dynamical arrest line seems to be independent of ionic strength, so that the arrest lines at different ionic screening lengths overlap, in contrast to the LLPS coexistence curves, which strongly depend on the salt concentration. In this work, we show that the same phenomenology can also be observed when the electrostatic repulsions are largely screened, and the range and strength of the attractions are varied. In particular, using lysozyme in brine as a model system, the metastable gas-liquid binodal and the dynamical arrest line as well as the second virial coefficient have been determined for various solution conditions by cloud-point measurements, optical microscopy, centrifugation experiments, and light scattering. With the aim of understanding this new experimental phenomenology, we apply the non-equilibrium self-consistent generalized Langevin equation theory to a simple model system with only excluded volume plus short-range attractions, to study the dependence of the predicted arrest lines on the range of the attractive interaction. The theoretical predictions find a good qualitative agreement with experiments when the range of the attraction is not too small compared with the size of the protein.

New fluorinated cyclophosphazenes: synthesis, properties, applications

The work presents the synthesis and characterization of fluorinated cyclophosphazenes, which are readily soluble in supercritical CO2 and can be used as textile finishing chemicals in a supercritical CO2 deposition process. The reaction of hexachlorocyclophosphazene with sodium alcoholate of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol was performed. The reaction product analysis suggested that all parent hexachlorocyclophosphazene molecules participated in the reaction, 4- and 5-substituted fluorinated cyclophosphazene molecules comprised most of the reaction product. Cloud point measurements confirmed that the product is soluble in supercritical CO2 at moderate conditions. Fluorinated cyclophosphazene coating was deposited from solutions in supercritical CO2 onto cotton textile. Scanning electron microscopy revealed that the coating is deposited uniformly. The textile after treatment was hydrophobic with an initial contact angle of 106 ± 8 degrees. The obtained fluorinated cyclophosphazenes can be considered as building blocks for the further development of phosphazenes that are soluble in sc CO2 and can be used as hydrophobic finishing chemicals with improved properties.

The phase separation, interaction forces and thermodynamics of sodium alginate and TX-100 mixture in the manifestation of alcohols: UV–visible and cloud point measurement studies

Triton X-100 (TX-100 (a nonionic surfactant)) is widely applied to separate proteins from cell membranes while sodium alginate (SA; a biopolymer) has the usages as an ingredient in foods, fertilizers, textiles, pharmaceuticals items, etc. The clouding behaviors of the TX-100 + SA mixture have been investigated in the presence of different alcohols media. For the TX-100 + SA mixture in aq. alcohols environment, the observed cloud point (CP) values were found to enhance with the raising in concentration of alcohols and follow the order: CP2-PrOH > CP1-PrOH. > CPEtOH > CP2-BuOH. The standard free energy (ΔGc0), enthalpy (ΔHc0), and entropy (ΔSc0) of the clouding behavior of the employed TX-100 + SA mixture have been measured. The Gibbs free energy (ΔGc0) values were positive and reduced as the concentration of alcohols increased. Hence, the cloudy development of TX-100 + SA was non-spontaneous in nature. The magnitudes of enthalpy (ΔHc0) along with entropy (ΔSc0) were achieved positive in most of the systems while those were negative at the higher ethanol and butanol concentrations. The relevant transfer energies along with enthalpy–entropy compensation variables of clouding phenomena have been calculated and discussed in detail. The binding of TX-100 with SA in aq. EtOH/1-PrOH media was studied by means of a UV–visible spectroscopic tool while the binding constant (Kb) was determined using Benesi-Hildebrand plot. The Kb values are dependent on the study temperature and composition of the solvents. The hydrophobic, hydrogen bonding, and electrostatic interactions are recommended as the significant binding forces between TX-100 and SA.

How does soy 7S globulin influence the thermo-responsive fibration process of methylcellulose chains in aqueous solutions?

In the past decade, there is a number of studies focusing on the interactions between methylcellulose and ions/surfactants, whereas in real food and material systems, methylcellulose is widely co-existing with natural macromolecules such as polysaccharides and proteins, but their interplay has been scarcely studied so far. In this work, by selecting soy 7S globulin as a model protein, we have investigated the interplay between methylcellulose and soy 7S globulin in aqueous solutions, and its influence on the thermo-responsive behavior of methylcellulose chains. By combining particle sizing, isothermal titration calorimetry and cloud point measurements, it is observed that the addition of 7S globulin induces the formation of 7S globulin-methylcellulose aggregates, mainly driven by the weak hydrophobic force (∼ 0.03 kJ/mol) at T = 25 °C, and facilitated the formation of 7S globulin-methylcellulose fibrils aggregates at T = 50 – 70 °C, which shows thermo-responsive behavior. Atomic force microscopy and rheology results signify that the 7S globulin probably acted as multi-site centers to bridge fibrils together and eventually formed large spherical aggregates covered with reticular fibrous structures, along with the decrease in the modulus of 7S globulin-methylcellulose gel network, which is due to the heterogeneous distribution of aggregates and poor continuity of network. This study not only reveals the influence of 7S globulin on the thermo-responsive behavior of methylcellulose but also lays a foundation for further optimizing the performance of the 7S globulin-methylcellulose system in real food and material systems.

Lower Critical Solution Temperature Tuning and Swelling Behaviours of NVCL-Based Hydrogels for Potential 4D Printing Applications.

The phase transitions of poly (N-vinyl caprolactam) (PNVCL) hydrogels are currently under investigation as possible materials for biomedical applications thanks to their thermosensitive properties. This study aims to use the photopolymerisation process to simulate the 4D printing process. NVCL-based polymers with different thermal properties and swellability were prepared to explore the possibility of synthetic hydrogels being used for 4D printing. In this contribution, the thermal behaviours of novel photopolymerised NVCL-based hydrogels were analysed. The lower critical solution temperature (LCST) of the physically crosslinked gels was detected using differential scanning calorimetry (DSC), ultraviolet (UV) spectroscopy, and cloud point measurement. The chemical structure of the xerogels was characterised by means of Fourier transform infrared spectroscopy (FTIR). Pulsatile swelling studies indicated that the hydrogels had thermo-reversible properties. As a result, the effect of varying the macromolecular monomer concentration was apparent. The phase transition temperature is increased when different concentrations of hydrophilic monomers are incorporated. The transition temperature of the hydrogels may allow for excellent flexibility in tailoring transition for specific applications, while the swelling and deswelling behaviour of the gels is strongly temperature- and monomer feed ratio-dependent.