Ternary Formulations Research Articles

Advanced Flexible Wearable Electronics from Hybrid Nanocomposites Based on Cellulose Nanofibers, PEDOT:PSS and Reduced Graphene Oxide

The need for responsible electronics is leading to great interest in the development of new bio-based devices that are environmentally friendly. This work presents a simple and efficient process for the creation of conductive nanocomposites using renewable materials such as cellulose nanofibers (CNF) from enzymatic pretreatment, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), and/or reduced graphene oxide (rGO). Different combinations of CNF, rGo, and PEDOT:PSS were considered to generate homogeneous binary and ternary nanocomposite formulations. These formulations were characterized through SEM, Raman spectroscopy, mechanical, electrical, and electrochemical analysis. The binary formulation containing 40 wt% of PEDOT:PSS resulted in nanocomposite formulations with tensile strength, Young’s modulus, and a conductivity of 70.39 MPa, 3.87 GPa, and 0.35 S/cm, respectively. The binary formulation with 15 wt% of rGO reached 86.19 MPa, 4.41 GPa, and 13.88 S/cm of the same respective properties. A synergy effect was observed for the ternary formulations between both conductive elements; these nanocomposite formulations reached 42.11 S/cm of conductivity and kept their strength as nanocomposites. The 3D design strategy provided a highly conductive network maintaining the structural integrity of CNF, which generated homogenous nanocomposites with rGO and PEDOT:PSS. These formulations can be considered as greatly promising for the next generation of low-cost, eco-friendly, and energy storage devices, such as batteries or electrochemical capacitors.

Complex viscosity and cohesive energy density of mixtures of sodium hyaluronate and hypromellose for medical devices

In the present study binary formulations of sodium hyaluronate (▪) and hypromellose (▪) were proposed as medical devices in the field of eye surgeries. Viscoelasticity is tested directly on binary solutions while the rheological behavior in the human eye is mimicked by monitoring the viscoelasticity of ternary mixtures ▪/▪/▪. Both binary and ternary formulations were rheologically characterized at 25∘C and 37∘C by means of measurements in the oscillatory regime. Amplitude sweep tests revealed that the range of linear viscoelasticity is strongly dependent on the concentration of ▪. For the proposed formulations, it was ascertained that the cohesive energy density at 37∘C decreases as ▪ concentration surges; in contrast, at 25∘C we detected an increase of cohesive energy were detected. At ▪ mass fraction of α1, the two obtained values were comparable. Frequency sweep tests revealed the pseudoplastic character of the binary formulations. In order to fit the complex viscosity modules, the Carreau-Yasuda model was modified. Numerical analysis of the results indicates that the best-fit to the model is obtained when the characteristic parameters take constant values, i.e. n=0 and m=1, regardless of the composition of the formulation. This implies that the modulus of complex viscosity decays hyperbolically. Frequency sweep tests on the ternary formulations were analyzed in terms of both the modulus of complex viscosity to confirm the previous scientific evidence together with an investigation of the phase shift angle between the viscous and elastic components. The results indicate that the addition of water has a different impact on the structure and the cohesion of the mixture at different temperatures. These results suggest that the ternary mixture structure can be sensitively modulated by temperature and the content of water.

The development of ternary and quaternary solid dispersion based hydrotropic blends of atorvastatin calcium

Background and objective: Atorvastatin calcium (ATV) has a solubility in aqueous solutions of greater than 0.1 mg/ml to less than 1 mg/ml, which is very slightly soluble. When developing dosage forms for these medications, formulation scientists still face challenges. This study's goal was to use various hydrotropic agents in the formation of solid dispersion-based hydrotropic blends to improve the solubility properties of atorvastatin calcium. Methods: In this study, twenty-two distinct binary, ternary, and quaternary formulations of ATV were prepared by employing five different hydrotropic agents and combining at least two hydrotropic agents in concentrations of 10% and 20% (w/v). Moreover, solid dispersion by the solvent evaporation method and physical mixture-based hydrotropic blends in the ratio of (1:2) have been formulated. The produced formulations were characterized using an FTIR analysis. Results: According to the findings, binary formulations containing 20% (w/v) concentrations of sodium benzoate (SB), sodium salicylate (SS), and resorcinol (R) enhanced the solubility ratio of ATV by 439.31, 689.57, and 106.21 folds, respectively. Furthermore, ternary formulations (FT14) and quaternary formulations (FQ18) resulted in the enhancement of ATV solubility by 938.45 and 995.12 folds, respectively. Ternary solid dispersion demonstrated the highest enhancement in solubility ratio by 87.68 folds and resulted in a higher dissolution rate of ATV than pure samples of the drug. Finally, FTIR analyses excluded any interactions between medications and excipients by showing no noticeable shift in the peaks. Conclusion: Solid dispersion based hydrotropic blends can provide the production of the dosage forms of practically insoluble drugs with a favorable enhancement ratio in solubility.

Evaluation of Suitable Polymeric Matrix/Carriers during Loading of Poorly Water Soluble Drugs onto Mesoporous Silica: Physical Stability and In Vitro Supersaturation.

The application of mesoporous carriers in formulations of amorphous solid dispersions (ASDs) has been suggested to enhance the stability of amorphous drugs. However, mesoporous carriers do not demonstrate satisfactory inhibitory effects on the precipitation of active pharmaceutical ingredients (APIs), and the inclusion of an appropriate polymer within ASDs becomes imperative to maintaining drug supersaturation. The aim of this study was to evaluate ternary olanzapine (OLN) ASDs with Syloid 244FP and to find an appropriate polymeric carrier. The polymer's selection criteria were based on the physical stability of the ASDs and the release rate of the drug from the systems. The polymers investigated were hydroxypropylmethyl cellulose (HPMC) and copovidone (coPVP). The formation of ASDs was achievable in all investigated cases, as demonstrated by the complete lack of crystallinity confirmed through both powder X-ray diffraction (pXRD) analysis and differential scanning calorimetry (DSC) for all developed formulations. The solvent shift method was employed to evaluate the ability of the studied carriers to inhibit the precipitation of supersaturated OLN. coPVP emerged as a more suitable precipitation inhibitor compared with HPMC and Syloid 244 FP. Subsequently, in vitro dissolution studies under non-sink conditions revealed a higher degree of supersaturation in ternary systems where coPVP was used as a polymeric carrier, as these systems exhibited, under the examined conditions, up to a 2-fold increase in the released OLN compared with the pure crystalline drug. Moreover, stability studies conducted utilizing pXRD demonstrated that ternary formulations incorporating coPVP and Syloid 244 FP maintained stability for an extended period of 8 months. In contrast, binary systems exhibited a comparatively shorter stability duration, indicating the synergistic effect of coPVP and Syloid 244 FP on the physical stability of the amorphous API. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) studies showed that the development of stronger molecular interactions can be provided as an explanation for this synergistic effect, as the formation of robust H-bonds may be considered responsible for inhibiting the precipitation of the supersaturated API. Therefore, the incorporation of coPVP into OLN ASDs with Syloid 244 FP is considered a highly promising technique for increasing the degree of OLN supersaturation in in vitro dissolution studies and improving the stability of systems.

Successful Formulation Window for the design of pharmaceutical tablets with required mechanical properties

Pharmaceutical tablet formulations combine the active ingredient with processing aids and functional components. This paper evaluates compressibility based predictive models for binary and ternary formulations to establish an acceptable range of tablet compression parameters that satisfy prescribed quality target criteria for tablets including minimum tablet strength and processing constraints such as maximum ejection stress and maximum compaction pressure. The concept of Successful Formulation Window (SFW) is introduced. A methodology is proposed to determine the SFW for a given formulation based on compaction simulator data collected for individual formulation components. The methodology is validated for binary and ternary mixtures and lubricated formulations. The SFW analysis was developed to support tablet formulation design to meet mechanical requirements.

Effect of hydrophilic polymers on the solubility and dissolution enhancement of rivaroxaban/beta-cyclodextrin inclusion complexes

BCS class II drugs exhibit low aqueous solubility and high permeability. Such drugs often have an incomplete or erratic absorption profile. This study aimed to predict the effects of β-cyclodextrin (βCD) and different hydrophilic polymers (poloxamer 188 (PXM-188), polyvinyl pyrrolidone (PVP) and soluplus (SOLO)) on the saturated solubility and dissolution profile of hydrophobic model drug rivaroxaban (RIV). Binary inclusion complex with βCD were prepared by kneading and solvent evaporation method, at drug to cyclodextrin weight molar ratios of 1:1, 1:2, and 1:4. Saturated solubility of the hydrophobic model moiety was evaluated with βCD to explore the increment in saturated solubility. Dissolution test was carried out to assess the drug release from the produced binary inclusion complex in the aqueous medium. Solid state analysis was performed using Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Scanning electron microscopy (SEM) techniques. When compared to pure drug, the binary complex (Drug: βCD at molar ratio of 1:2 w/w) demonstrated the best performance in terms of enhanced solubility and drug release. Furthermore, ternary inclusion complex was prepared with hydrophilic polymers SOLO, PVP K-30 and PXM-188 at 0.5%,1%,2.5%,5% and 10% w/w to optimized binary formulation RIV:βCD (1:2) prepared by kneading (KN) and solvent evaporation (S.E) method. The findings demonstrated that among ternary formulations (1:2 Drug: βCD: SOLO 10% S.E) manifested greatest improvement in saturated solubility and dissolution rate. Results of solubility enhancement and improvement in dissolution profile of model drug by ternary inclusion complexation were also supported by FTIR, DSC, XRD, and SEM analysis. So, it can be concluded that the ternary inclusion systems were more effective compared to the binary combinations in improving solubility as well as dissolution of hydrophobic model drug rivaroxaban.

Elucidation of the using condition and working mechanism of tertiary lactose in dry powder formulations for inhalation

Tertiary lactose has been shown to improve aerosolization performance of carrier-based dry powder inhalation formulations. The working mechanism of the tertiary lactose, however, is still unclear, even the optimal working condition of the lactose fines. Two strategies to incorporate the tertiary lactose were proposed, the “tertiary lactose-carrier-API” and “tertiary lactose-API-carrier”, to decrease the adhesiveness of the drug-carrier by forming different powder aggregates. The effects of the tertiary lactose with different sizes and mass percentages on the aerosolization performance for the two types of formulations were systemically investigated. The results showed that the smaller-sized tertiary lactose is beneficial for powder dispersion and aerosolization, which could be further improved by optimizing its concentration. In terms of the aerosolization performance, the “tertiary lactose-carrier-API” type of ternary formulations obtained highly superior aerosolization performance and significantly enhanced detachment of fine drug particles from large particles in general.

Enhanced Solubility and Stability of Aripiprazole in Binary and Ternary Inclusion Complexes Using Hydroxy Propyl Beta Cyclodextrin (HPβCD) and L-Arginine.

The low water solubility of an active pharmaceutical ingredient (aripiprazole) is one of the most critical challenges in pharmaceutical research and development. This antipsychotic drug has an inadequate therapeutic impact because of its minimal and idiosyncratic oral bioavailability to treat schizophrenia. The main objective of this study was to improve the solubility and stability of the antipsychotic drug aripiprazole (ARP) via forming binary as well as ternary inclusion complexes with hydroxypropyl-β-cyclodextrin (HPβCD) and L-Arginine (LA) as solubility enhancers. Physical mixing and lyophilization were used in different molar ratios. The developed formulations were analyzed by saturation solubility analysis, and dissolution studies were performed using the pedal method. The formulations were characterized by FTIR, XRD, DSC, SEM, and TGA. The results showcased that the addition of HPβCD and LA inclusion complexes enhanced the stability, in contrast to the binary formulations and ternary formulations prepared by physical mixing and solvent evaporation. Ternary formulation HLY47 improved dissolution rates by six times in simulated gastric fluid (SGF). However, the effect of LA on the solubility enhancement was concentration-dependent and showed optimal enhancement at the ratio of 1:1:0.27. FTIR spectra showed the bond shifting, which confirmed the formation of new complexes. The surface morphology of complexes in SEM studies showed the rough surface of lyophilization and solvent evaporation products, while physical mixing revealed a comparatively crystalline surface. The exothermic peaks in DSC diffractograms showed diminished peaks previously observed in the diffractogram of pure drug and LA. Lyophilized ternary complexes displayed significantly enhanced thermal stability, as observed from the thermograms of TGA. In conclusion, it was observed that the preparation method and a specific drug-to-polymer and amino acid ratio are critical for achieving high drug solubility and stability. These complexes seem to be promising candidates for novel drug delivery systems development.

Evaluation of in-vitro antifungal activity against Fusarium incarnatum of binary and ternary combinations of lemongrass, garlic and mustard oil-encapsulated lipid nanoemulsions

Summary Encapsulated lipid nanoemulsions (EO-LNs) from garlic oil, lemongrass oil and mustard oil were prepared by a combined method of homogenization and sonication with the aim to generate highly effective formulations against Fusarium incarnatum (laboratory bioassays). Their combined binary and ternary formulations (preparations by mixing an equal volume ratio of each EO-LNs) were also tested. The synergistic/additive/antagonistic antifungal effect of the EOs (under nanoform) in their combined formulations was determined using the SynergyFinder software with the Bliss independence model. Results revealed the synergistic effect of the combined binary and ternary formulations of garlic oil-encapsulated LNs (NaG), lemongrass oil-encapsulated LNs (NaL) and mustard oil-encapsulated LNs (NaM). Furthermore, the ternary combination, at the same concentration of each constituent EO, had higher antifungal activity than the binary combinations. Nonetheless, at 600 times dilution the NaLG (binary combination) inhibited 96% the mycelial growth of F. incarnatum, which was significantly higher than the efficacy of NaMLG (ternary combination) in the same dilution. This could be possibly attributed to the 1.5-time higher concentration of each constituent EO in the binary combination compared to that in the ternary formulation. In addition, NaLG, even at the high EO concentration of 0.4 g/L, did not show any phytotoxicity symptoms on lettuce plants.

Ball milling and hot-melt extrusion of indomethacin–l-arginine–vinylpyrrolidone-vinyl acetate copolymer: Solid-state properties and dissolution performance

Commonly applied approaches to enhance the dissolution properties of low water-soluble crystalline active pharmaceutical ingredients (APIs) include their amorphization by incorporation into a polymeric matrix and the formation of amorphous solid dispersions, or blending APIs with low-molecular-weight excipients and the formation of a co-amorphous system. This study focused on the preparation and characterization of binary (consisting of indomethacin (IND) and polymer – copovidone (PVP VA 64), as a carrier, or amino acid – L-arginine (ARG), as a co-former) and ternary (comprising the same API, polymer, and amino acid) formulations. Formulations were produced by ball milling (BM) and/or hot-melt extrusion (HME), and extensive physicochemical characterization was performed. Specifically, the physicochemical and solid-state properties of a model IND–ARG system incorporated into a polymeric matrix of PVP VA 64 by HME and BM as well as by combined BM/HME method together with the impact of the preparation strategy on the dissolution profiles and long-term physical stability were investigated. Ball-milled binary and ternary formulations were found to be amorphous. The residual crystals corresponding to IND–ARG salt were identified in the ternary formulations produced via HME. Despite the presence of a crystalline phase, dissolution tests showed that ternary systems prepared by HME exhibited improved IND solubility when compared to pure crystalline IND and their corresponding physical mixture. None of the binary and ternary formulations that were initially fully amorphous did undergo recrystallization during the entire period of preservation (minimum of 12 months) in dry conditions at 25 °C.

Highly insulating thermoplastic blends comprising a styrenic copolymer for direct‐current power cable insulation

The impact of the composition of blends comprising low-density polyethylene (LDPE), isotactic polypropylene (PP) and a styrenic copolymer additive on the thermomechanical properties as well as the direct-current (DC) electrical and thermal conductivity is investigated. The presence of 5 weight percent (wt%) of the styrenic copolymer strongly reduces the amount of PP that is needed to enhance the storage modulus above the melting temperature of LDPE from 40 to 24 wt%. At the same time, the copolymer improves the consistency of the thermomechanical properties of the resulting ternary blends. While both the DC electrical and thermal conductivity strongly decrease with PP content, the addition of the styrenic copolymer appears to have little influence on either property. Evidently, PP in combination with small amounts of a styrenic copolymer not only allows to reinforce LDPE at elevated temperatures but also functions as an electrical conductivity-reducing additive, which makes such thermoplastic ternary formulations possible candidates for the insulation of high-voltage power cables.

In silico formulation prediction of drug/cyclodextrin/polymer ternary complexes by machine learning and molecular modeling techniques

Ternary cyclodextrin (CD) complexes (drug/CD/polymer) can effectively improve the solubility of water-insoluble drugs with large size than binary CD formulations. However, ternary formulations are screened by a trial-and-error approach, which is laborious and material-wasting. Current research aims to develop a prediction model for ternary CD formulations by combined machine learning and molecular modeling. 596 ternary formulations data were collected to build a prediction model by machine learning. The random forest model achieved good performance with R2 = 0.887 in ST prediction and R2 = 0.815 in ST/SB prediction. Two ternary formulations (Hydrocortisone/β-CD/HPMC and dovitinib/γ-CD/CMC) were used to validate the prediction model. Molecular modeling results showed that HPMC not only warped around hydrocortisone but also prevented CD molecules from self-aggregation to increase solubility. In conclusion, a prediction model for the ternary CD formulations was successfully developed, which will significantly accelerate the formulation screening process to benefit the formulation development of water-insoluble drugs.

A Rapid HPLC Method for the Concurrent Determination of Several Antihypertensive Drugs from Binary and Ternary Formulations

A rapid, synchronized liquid chromatographic method was established for the estimation of hydrochlorothiazide (HCZ), amlodipine (AMD), olmesartan (OLM), telmisartan (TEL), and irbesartan (IRB) in binary and ternary coformulations using the same chromatographic conditions. Five analytes were separated on a Zorbax C18 column using isocratic elution with a mobile phase consisting of acetonitrile, methanol, and 20 mM phosphate buffer (pH 3.5) in a ratio of 45:20:35% v/v. The analytes were detected at a wavelength of 230 nm at ambient temperature. Furthermore, the proposed liquid chromatographic procedure was validated for linearity, precision, accuracy, stability, and robustness using an experimental design. Analytes were separated with good resolution within 3.5 min. Analytes showed good linearity in a concentration satisfactory to analyze the different ratios of these analytes in the formulations. Pareto charts showed that the flow rate and mobile phase composition have a significant effect on the peak area of analytes and hence need to be carefully controlled, however, the method is robust. Finally, the different formulations consisting of HCZ, AMD, OLM, TEL, and IRB in different ratios were analyzed with high accuracy using an optimized HPLC method and compared with reported methods. Furthermore, the reported HPLC procedure is simple, rapid, and accurate and therefore can used for regular quality control of binary and ternary formulations using the same stationary and mobile phase.

Protective behaviour of two phosphonate-based inhibitor systems containing lactobionic acid in corrosion control of carbon steel

Results of gravimetric measurements and polarization studies of corrosion control of carbon steel in aqueous medium containing chloride ions are presented. The selected inhibitors are ternary formulations containing phosphonic acids namely 1-Hydroxyethane-1,1-diphosphonic acid (HEDP) and Nitrilotris(methylenephosphonic acid) (NTMP), Zn(II) as a synergist and lactobionic acid (LBA) as the second synergist. In presence of lactobionic acid, the required quantities of both phosphonic acid and Zn(II) are reduced, making the ternary formulations extremely low toxic. Further, the dosages of the components for retention of protective behaviour are still lower. They are effective at pH from 5 to 8. The two new ternary systems are found to work efficiently for prolonged immersion times and also when the corrosive medium is non-static. The results of potentiodynamic polarization studies indicated that both the formulations function as mixed type inhibitors. The synergism of the inhibitor formulations is evident from the study.

Insights into the ameliorating ability of mesoporous silica in modulating drug release in ternary amorphous solid dispersion prepared by hot melt extrusion

In this work, the application of various mesoporous silica grades in the preparation of stabilized ternary amorphous solid dispersions of Felodipine using hot melt extrusion was explored. We have demonstrated the effectiveness of mesoporous silica in these dispersions without the need for any organic solvents i.e., no pre-loading or immersion steps required. The physical and chemical properties, release profiles of the prepared formulations and the surface concentrations of the various molecular species were investigated in detail. Formulations containing 25 wt% and 50 wt% of Felodipine demonstrated enhanced stability and solubility of the drug substance compared to its crystalline counterpart. Based on the Higuchi model, ternary formulations exhibited a 2-step or 3-step release pattern which can be ascribed to the release of drug molecules from the organic polymer matrix and the external silica surface, followed by a release from the silica pore structure. According to the Korsmeyer-Peppas model, the release rate and release mechanism are governed by a complex quasi-Fickian release mechanism, in which multiple release mechanisms are occurring concurrently and consequently. Stability studies indicated that after 6 months storage of all formulation at 30% RH and 20 °C, Felodipine in all formulations remained stable in its amorphous state except for the formulation comprised of 40 wt% Syloid AL-1FP with a 50 wt% drug load.

Design Parameters for Ionic Liquid–Molecular Solvent Blend Electrolytes to Enable Stable Li Metal Cycling Within Li–O2 Batteries

AbstractEffective utilization of Li‐metal electrodes is vital for maximizing the specific energy of lithium–oxygen (Li–O2) batteries. Many conventional electrolytes that support Li–O2 cathode processes (e.g., dimethyl sulfoxide, DMSO) are incompatible with Li‐metal. Here, a wide range of ternary solutions based on solvent, salt, and ionic liquid (IL) are explored to understand how formulations may be tailored to enhance stability and performance of DMSO at Li‐metal electrodes. The optimized formulations therein facilitate stable Li plating/stripping performances, Columbic efficiencies >94%, and improved performance in Li–O2 full cells. Characterization of Li surfaces reveals the suppression of dendritic deposition and corrosion and the modulation of decomposition reactions at the interface within optimized formulations. These observations are correlated with spectroscopic characterization and simulation of local solvation environments, indicating the persistent importance of DMSO–Li+‐cation interactions. Therein, stabilization remains dependent on important molar ratios in solution and the 4:1 solvent‐salt ratio, corresponding to ideal coordination spheres in these systems, is revealed as critical for these ternary formulations. Importantly, introducing this stable, non‐volatile IL has negligible disrupting effects on the critical stabilizing interactions between Li+ and DMSO and, thus, may be carefully introduced to tailor other key electrolyte properties for Li–O2 cells.

The role of fine excipient particles in adhesive mixtures for inhalation

AbstractDespite the fact that adding fines improve the drug dispersion performance during inhalation, the scarcity of mechanistic insight into the formulation process, independent of the aerosolization, has kept the dispute on the underlying improvement mechanism open. We therefore simulate ternary formulations (carrier, drug, fines) in a vibrational cell to explore the mixing mechanism and the effect of particle size and loading ratio of fines on formulation performance. Results suggest that the buffer theory is a critical contributory mechanism since it curtails the carrier's collision rate and, therefore, decreases agglomerate breakage. Consequently, relatively larger drug aggregates are formed over the carrier, which eventually experiences greater detachment forces. A simple dispersion test is performed to evaluate drug detachment rate at wall‐collision. An excess of cohesive fines, or using larger fines, diminishes the rotational kinetic energy of coarse particles by lumping them together. This reduces drug agglomerate breakage and leads to poor mixing.

Influence of shellac on the improvement of solubility and supersaturation of loratadine amorphous solid dispersion using a new grade of HPMC

The use of ternary amorphous solid dispersions (ASDs) comprised of surfactants and synthetic polymers to improve the solubility of low water soluble active pharmaceutical ingredients (APIs) have been widely investigated as an emerging concept. Shellac is used as complex resin for coating purposes, but to the best of our knowledge, the use of shellac as natural excipient in ASDs has not been reported. The current study has sought to prepare binary and ternary ASDs of shellac, alone or in combination with HPMC, with the model API loratadine (LOR) via spray drying and hot melt extrusion to achieve solubility improvement and supersaturation maintenance. The ASDs were characterized and tested for their in-vitro dissolution performance. Among various shellac fractions within the ternary ASDs, the 10% weight fraction was found to increase the solubility 30 folds and maintain the supersaturation for 3 h compared to other binary and ternary formulations. This superiority was due to specific and stronger API matrix interactions detected via ATR-IR, which was further studied in terms of stability. It was found that there exists a correlation between the amount of the dissolved API and the API crystallinity, which dictates the level of supersaturation. While the crystallinity is set by the LOR concentration at the end of the test, the dissolution rate depended on the origin of the crystals.

The Influence of Co-Surfactants on Lamellar Liquid Crystal Structures Formed in Creams.

It is well-established that oil-in-water creams can be stabilised through the formation of lamellar liquid crystal structures in the continuous phase, achieved by adding (emulsifier) mixtures comprising surfactant(s) combined (of necessity) with one or more co-surfactants. There is little molecular-level understanding, however, of how the microstructure of a cream is modulated by changes in co-surfactant and of the ramifications of such changes on cream properties. We investigate here the molecular architectures of oil-free, ternary formulations of water and emulsifiers comprising sodium dodecyl sulfate and one or both of the co-surfactants hexadecanol and octadecanol, using microscopy, small-angle and wide-angle X-ray scattering and small-angle neutron scattering. We then deploy these techniques to determine how the structures of the systems change when liquid paraffin oil is added to convert them to creams, and establish how the structure, rheology, and stability of the creams is modified by changing the co-surfactant. The ternary systems and their corresponding creams are shown to contain co-surfactant lamellae that are subtly different and exhibit different thermotropic behaviours. The lamellae within the creams and the layers surrounding their oil droplets are shown to vary with co-surfactant chain length. Those containing a single fatty alcohol co-surfactant are found to contain crystallites, and by comparison with the cream containing both alcohols suffer adverse changes in their rheology and stability.

Curing kinetics of acrylate-based and 3D printable IPNs

In this work, the kinetics of curing of a new family of interpenetrating polymer networks (IPNs) obtained by co-formulation of a photocurable acrylic resin with a thermocurable epoxy/anhydride mixture is studied. The first curing stage is an acrylate free-radical photopolymerization at ambient temperature, and the second curing stage is an epoxy-anhydride copolymerization initiated with a nucleophilic tertiary amine at higher temperatures. The presence of a diperoxyketal thermal radical initiator added to the liquid formulation facilitates uniform and complete acrylate conversion during thermal second curing stage and opens the possibility of curing the same materials by thermal curing only. The thermal curing kinetics was studied by integral isoconversional and model fitting procedures, whereas photocuring kinetics was satisfactorily fitted to a first order expression. Thermal curing and storage stability at room temperature were successfully simulated by using the isoconversional kinetic parameters. These ternary formulations have potential as 3D printable thermosets.