INUTEC SP1 Research Articles

DISSOLUTION ENHANCEMENT AND FORMULATION OF FILM COATED TABLETS OF LORNOXICAM BY PHASE TRANSITION METHOD: IN VITRO AND IN VIVO EVALUATION

Objective: This study aimed to enhance the oral solubility and dissolution of poorly soluble lornoxicam by anti-solvent precipitation, and the manufacture of oral tablets by the phase transition method. 
 Methods: The solvent was mixture of polyethylene glycol 400 and absolute ethanol. Three stabilizers Inutec SP1, Pluronic F127, Sucrose ester S1670 at two concentrations and two matrix formers Mannitol, and Avicel PH102 were used to obtain 12 formulae. The formulae were characterized regarding their infrared spectroscopy (IR), differential scanning calorimetry (DSC), particle size (PS) measurement, drug content and dissolution. Further characterizations were done for the optimum formula by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Four tablet formulae were manufactured by phase transition method. The optimum tablets (T3) were evaluated through hardness, drug content, disintegration, dissolution, IR, and stability studies. Finally, (T3) was compared to conventional tablets in New Zealand rabbits using crossover design.
 Results: The dissolution rate for the prepared formulae was enhanced, from 3.44 to 5.96 folds. Statistical significance was obtained using one and two way ANOVA among formulae. The optimum tablet formula (T3) had hardness 5.637±1.57 kg, drug content 90.424±1.19%, disintegration time 341.5±9.62 s and the drug dissolved 72.107±0.0025%. Stability, after one month storage of the selected tablets at (25 °c/60% relative humidity), was satisfactory. The absorption extent of lornoxicam from (T3) compared to the conventional tablets was higher.
 Conclusion: Taken together, the obtained results confirmed successfully the potential of the promising formula (T3), over the conventional tablets of lornoxicam.

The interfacial, emulsification and encapsulation properties of hydrophobically modified inulin

Octenyl- and dodecenyl succinic anhydride derivatives (OSA- and DDSA-) of inulin have been synthesised and their solution and interfacial properties have been determined and compared to a commercially available alkylated inulin, Inutec SP1. All samples formed micellar aggregates in solution above a critical concentration (critical aggregation concentration) and were able to ‘dissolve’ a hydrophobic dye. They were also able to form stable oil-in-water (O/W) emulsions as assessed by measurements of their droplet size as a function of time. DDSA-inulin with a high degree of substitution was found to be effective at encapsulating beta carotene using the solvent evaporation method which yielded a solid which dissolved readily in simulated gastric fluid. The results confirm the potential application of these materials in a number of areas including, drug delivery, pharmaceuticals, neutraceuticals, cosmetics and personal care.

Influence of non-ionic surfactant type on the salt sensitivity of oregano oil-in-water emulsions

During the last decade, there has been a growing interest for more “label-friendly” ingredients in food industry, as well as in pharmaceuticals, and cosmetics. Thus, a lot of research has been developed to the antimicrobial and/or antioxidant characteristics of essential oils. We, therefore, examined the influence of environmental stress conditions (i.e. salt addition and acidification) on the stability of oregano essential oil emulsions that were stabilized by either Tween 80 or Inutec SP1. Whereas Tween 80 is a non-ionic, food-grade ethoxylated sorbitan ester, Inutec SP1 is a biodegradable and renewable hydrophobically modified inulin. Whereas the emulsions prepared with Tween 80 exhibited phase separation (oiling off) at all salt concentrations studied, the emulsions stabilized with Inutec SP1 remained stable for several days; pH variation on the other hand exhibited no significant effect on the stability. Diffusion ordered spectroscopy measurements by nuclear magnetic resonance (DOSY NMR) as well as viscosity measurements suggested the dehydration of the polyoxyethylene (POE) head groups of Tween 80 upon NaCl addition. Measurements by a Quartz crystal microbalance with dissipation, on the other hand, presented no NaCl effect on the thickness of the adsorbed Tween 80 layer to a hydrophobic surface. Besides the effect of NaCl addition or pH variation, the influence of the ripening inhibitor concentration in the lipid phase and/or temperature variation on the Ostwald ripening levels were also investigated. Emulsions containing a 50:50 ratio of oregano essential oil to sunflower oil stored at 4°C exhibited a significant reduction in Ostwald ripening rate. This study has implications for the development of essential oil emulsions to be used as antimicrobial agent when exposed to environmental stress conditions.

Stabilisation of dispersions using a graft copolymer of hydrophobically modified polyfructose

This paper describes the use of a graft copolymer of hydrophobically modified inulin (polyfructose) (INUTEC SP1) for the stabilisation of dispersions. It starts with a section on the adsorption and conformation of the polymer at the interface. The results show a high affinity isotherm with irreversible adsorption. This is due to the multi-point attachment of the graft copolymer to the surface by several alkyl chains that are grafted to the polyyfructose backbone. The adsorbed layer thickness Δ of the graft copolymer on model polystyrene particles with radius R was determined using rheological measurements. The relative viscosity-core volume fraction π of the latex are compared with the theoretical value calculated using the Dougherty-Krieger equation allowing one to obtain the hydrodynamic thickness Δ. The latter was found to be 9.2nm indicating strong hydration of the polyfructose loops and tails by water molecules. Evidence for this strong hydration was obtained using cloud point measurements. The graft copolymer INUTEC SP1 was then used to prepare emulsions of paraffin oil or silicone oil-in-water emulsions. The latter remained stable with no coalescence for more than 1year both at room temperature and at 50°C and also in the presence of high electrolyte concentrations (2moldm−3 NaCl). This high stability of the emulsion is due to the multi-point attachment of the graft copolymer with several alkyl chains to the oil, leaving the strongly hydrated loops and tails of polyfructose dangling in solution, thus ensuring effective steric stabilisation. The high stability of the emulsion was confirmed using disjoining pressure measurements which indicated the presence of a Newton black film that showed no rupture up to a disjoining pressure of 4.5×104Pa. INUTEC SP1 was then used for the preparation of polystyrene (PS) and polymethylmethacrylate (PMMA) latex by emulsion polymerisation. The stability of the resulting latexes was determine by measuring the critical coagulation concentration (CCC) using CaCl2. By post addition of INUTEC SP1 to the latex dispersion, the CCC is significantly increased indicating effective steric stabilisation. The latter was confirmed using atomic force microscopy (AFM) whereby the interaction force between a hydrophobic glass sphere and glass plate, both coated with the graft copolymer, was measured both in water and in the presence of Na2SO4 (up to 1.5moldm−3). In all cases repulsive interaction was obtained indicating the effectiveness of INUTEC SP1 for latex stabilisation. INUTEC SP1 was also used for stabilisation of nano-dispersions (with diameters in the range 20–200nm). The high ratio of adsorbed layer thickness to particle or droplet size (d/R) results in a very shallow attractive minimum in the energy-distance curve. This indicates absence of any weak or strong flocculation. INUTEC SP1 could significantly reduce Ostwald ripening of nano-emulsions by strong adsorption at the oil/water interface and enhancement of the Gibbs elasticity.

Hydrophobically modified inulin as an amphiphilic carbohydrate polymer for micellar delivery of paclitaxel for intravenous route

Micellization offers several advantages for the delivery of water insoluble drugs including a nanoparticulate ‘core–shell’ delivery system for drug targeting. Recently, hydrophobically modified polysaccharides (HMPs) are gaining recognition as micelle forming polymers to encapsulate hydrophobic drugs. In this manuscript, for the first time, we have evaluated the self-assembling properties of a lauryl carbamate derivative of the poly-fructose natural polymer inulin (Inutec SP1® (INT)) to form paclitaxel (PTX) loaded micelles. INT self-assembled into well-defined micellar structures in aqueous environment with a low critical micellar concentration of 27.8μg/ml. INT micelles exhibited excellent hemocompatibility and low toxicity to cultured cells. PTX loaded INT micelles exhibited a mean size of 256.37±10.45nm with excellent drug encapsulation efficiency (95.66±2.25%) and loading (8.69±0.22%). PTX loaded micelles also displayed sustained release of PTX and enhanced anti-cancer efficacy in-vitro in mouse melanoma cells (B16F10) compared to Taxol formulation with Cremophor EL as solvent. In addition, PTX loaded INT micelles exhibited comparable in-vivo antitumor activity in B16F10 allograft mouse model at half the dose of Taxol. In conclusion, INT offers safe, inexpensive and natural alternative to widely used PEG-modified polymers for the formulation of micellar delivery systems for paclitaxel.

Recrystallized agglomerated meloxicam: evaluation of anti-nociceptive effect

Meloxicam (Mel) is a non steroidal anti-inflammatory drug belonging to BCS class II category. Hence, its pharmacological effect is affected by its low water solubility. The aim of this study was to improve the solubility and dissolution rate of meloxicam. Mel was recrystallized into spherical agglomerates (SA) with or without different polymers (PEG 4000, Inutec SP1, PVP k30, Pluronic F127 and HPsCD) at three different concentrations (0.0125, 0. 025 and 0.05 % w/v) using quasi emulsion solvent diffusion (QESD) and neutralization techniques (NT). Mel SA containing low concentration level of polymer (0.0125 % w/v) showed highest solubility and dissolution rate enhancement compared to pure Mel. DSC and IR outcome showed no chemical alteration in the recrystallized drug. DSC and PXRD studies showed that crystallinity of Mel was retained in all of the prepared SA (although slightly reduced compared to pure Mel). The anti-nociceptive effect of F2 (QESD) and F29 (NT) (showing highest dissolution in simulated gastric fluid) was assessed in mice using acetic acid induced abdominal writhing in comparison to pure drug. The selected formulae showed significantly higher analgesic activity in comparison to the pure drug and the control.

Characterization of ternary solid dispersions of nimesulide with Inutec SP1 and β-cyclodextrin and evaluation of anti-inflammatory efficiency in rats

Objective The objective of this investigation is to enhance the physicochemical properties of nimesulide (NS) and the stability of NS solid dispersions in order to improve the anti-inflammatory activity of the drug. Background NS – a NSAID – is sparingly soluble in water and this low aqueous solubility in addition to its poor wettability leads to variability in the bioavailability of the drug. Materials and methods In the present study, ternary dispersions of NS were investigated using a new polymeric carrier, Inutec SP1 (Inutec), in combination with β cyclodextrin (β-CD). The ternary dispersions were prepared using different ratios of NS and β-CD (2 : 1; 1 : 1; 1 : 2), to which a fixed amount of Inutec (20% w/w of total formula) was added using different methods of incorporation of the drug. Physical mixtures of equivalent compositions were prepared by physically mixing the ingredients. The optimal formulation obtained with a full factorial experimental design was used for the evaluation of anti-inflammatory activity. Results In the ternary dispersions, the dissolution behavior improved in comparison with the physical mixtures and was found to be dependent on the technique of incorporation of the drug, the method of preparation, and the molar ratio of drug to β-CD. Physical characterization of the ternary dispersions by infrared spectroscopy (FTIR), differential scanning calorimetry, and X-ray powder diffraction indicated a decrease in crystallinity because of partial inclusion in β-CD and the effect of Inutec, which promoted the formation of microcrystals or partial amorphization of the drug during the processing of the dispersions by kneading. Differential scanning calorimetry and X-ray powder diffraction curves of the dispersions prepared by the solvent method indicated the presence of a polymorphic form of NS with a lower melting point. The optimized ternary dispersion predicted by the full factorial design showed good physical stability following an accelerated stability test. The ternary dispersion of NS, Inutec, and β-CD was found to show better anti-inflammatory efficiency in rats compared with a commercial tablet of NS. Conclusion It can be concluded that the dissolution properties and the anti-inflammatory efficacy of the ternary dispersions of NS with β-CD and Inutec were enhanced because of a secondary solubilization of the inclusion by the polymeric surfactant.

Use of polysaccharide based surfactants to stabilize organically modified clay particles aqueous dispersion

Pure as well as organically modified clay minerals are widely applied particles in different research areas. For the incorporation of hydrophobic organically modified clay particles into the hydrogel matrix, a stable aqueous dispersion must be prepared. In this article we report on the stabilization of aqueous dispersions of hydrophobic organically modified clay particles by using a non-ionic polysaccharide-based surfactant system-Inutec SP1 (based on chicory inulin). Different concentrations of surfactants were tested. Properties of the particulate surfactant-stabilized aqueous colloidal system were determined by electrophoretic mobility and dynamic light scattering measurements. Determination of contact angles gave us insight into the particles’ surface interaction ability with water and also some information regarding the conformation of adsorbed surfactant molecules on the particle surface. By using Inutec SP1, the wettability of clay particles was improved, particle size was reduced and consequently, enhancement of their dispersion ability in water-based systems was observed.

Direct Measurement of Interaction Forces between Adsorbed Polymer Layers

Abstract The interaction forces between adsorbed layers of two graft copolymers were directly measured using surface force apparatus and atomic force microscopy. Two types of graft copolymers that were adsorbed on hydrophobic surfaces were used: (i) a graft copolymer consisting of poly(methyl methacrylate)/poly(methacrylic acid) backbone (the B chain) on which several poly(ethylene oxide) chains are grafted (to be referred to as PMMA/PEOn) and (ii) a graft copolymer consisting of inulin (linear polyfructose with degree of polymerization greater than 23) (the A chain) on which several C12 chains are grafted (INUTEC SP1). In the first case, adsorbed layers of the graft copolymer were obtained on mica sheets and the interaction forces were measured using the surface force apparatus. In the second case, the interaction forces were measured using atomic force microscopy (AFM). For this purpose, a hydrophobically modified glass sphere was attached to the tip of the cantilever of the AFM and the glass plate was also made hydrophobic. Both the sphere and the glass plate contained an adsorbed layer of INUTEC SP1. The curves of energy E(D) versus distance D for the graft copolymer of PMMA/PEOn between mica surfaces bearing the graft copolymer could be used to estimate the interaction energy between flat surfaces, by using Derjaguin approximation for cross cylinders. The results were compared with the theoretical calculations using de Gennes scaling theory. The agreement between experimental results and theoretical calculations was satisfactory. The same graft copolymer was used in latex dispersions, and the high frequency modulus G′∝ was measured as a function of the volume fraction φ of the dispersion. This high-frequency modulus could be related to the potential of mean force. In this way, one could compare the results obtained from rheology and those obtained from direct measurement of interaction forces. In the AFM method, the interaction forces are measured in the contact area between two surfaces, i.e., the surfaces of a spherical glass particle and a glass plate. The glass spheres and plates were hydrophobized using dichlorodimethylsilane. Results were obtained for adsorbed layers of INUTEC SP1 in water and in the presence of various concentrations of Na2SO4 (0.3, 0.8, 1.0, and 1.5 mol dm−3). All results showed a rapid increase in force with a decrease in the separation distance, and the forces were repulsive up to the highest Na2SO4 concentration. This explains the high stability of dispersions when using INUTEC SP1 as the stabilizer.

Formulation and Stability Testing of Itraconazole Crystalline Nanoparticles

Itraconazole (ITZ) crystalline nanoparticles were prepared using relatively simple, low-cost sonoprecipitation technique, in which both the solvent and antisolvent were organic in nature. The effect of stabilizer type (hydroxypropyl methylcellulose, hydroxypropyl cellulose, Inutec SP1®, and pluronic F127), drying method (oven and freeze drying) and matrix former used (Avicel PH101, and Aerosil®200) on the dissolution performance as a key characteristic of nanocrystals was evaluated. In 10 min, all of the prepared nanocrystals showed 3.77-8.59 times improvement in percent drug dissolved compared to pure ITZ. Concerning the effect of stabilizer type, the following rank order can be given: pluronic F127 ≥ hydroxypropyl cellulose ≥ hydroxypropyl methylcellulose (HPMC) > inutec SP1. Freeze-dried ITZ nanocrystals containing Avicel PH 101 showed better dissolution rate compared to other nanocrystals. The chemical structure of itraconazole nanocrystals was not changed as revealed by Fourier transform infrared. Stability study of selected nanocrystals (F5, F7, and F8) revealed physical and chemical stability of F7 and F8, while a decrease in dissolution rate of F5 was observed (although being chemically stable) when stored under high relative humidity conditions. Although inutec is less potent than pluronic F127 and HPMC regarding their effect on dissolution rate enhancement, it is equipotent to pluronic F127 in preserving the rapid drug dissolution.

Use of Hydrophobically Modified Inulin for the Preparation of Polymethyl Methacrylate/Polybutyl Acrylate Latex Particles Using a Semicontinuous Reactor

The seeded semicontinuous emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BuA) stabilized with a graft polymeric surfactant based on inulin, INUTEC SP1, as well as its mixture with sodium lauryl sulfate (SLS) is described. The mixture of SLS and Brij58 (alcohol ethoxylated) and the mixture of SLS and Pluronic P85 (block copolymer PEO-PPO-PEO) are also used as surfactant systems. The addition of methacrylic acid (MAA) or acrylic acid (AA) as comonomers is also studied. Previous results proved this inulin-derivative surfactant, INUTEC SP1, to be very effective on synthesizing latexes using a very low surfactant concentration. The kinetic features of the emulsion polymerization (instantaneous conversion and total conversion) were gravimetrically determined along the reactions. Latex dispersions were characterized by photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) to obtain the average particle size, the particle size distributions (PSDs) as well as the polydispersity index (PdI). The stability was determined by turbidimetry measurements and expressed in terms of critical coagulation concentration. The results showed that the use of the graft polymeric surfactant allowed obtaining highly stable nanoparticles, at low surfactant concentrations and high solid contents (up to 37 wt %). This is an improvement with respect to previous works, in which a mixture of the graft polymeric surfactant with another surfactant was required to obtain stable nanoparticles with low polydispersity, at high solid content. In the present work, low polydispersity was achieved using INUTEC as the only emulsifier, which was related to the absence of secondary nucleations. When a mixture of INUTEC SP1 and SLS is used, a wider PSD is obtained due to secondary nucleations. Replacing INUTEC SP1 by other nonionic surfactants such as Brij58 or Pluronic P85 leads to an increase of average particle size and wider PSD.

Stability of O/W Emulsion Films from Mixed Aqueous Solutions of Inulin-Based Polymeric and Polyethylene Glycol Surfactants

Oil-in-water (O/W) emulsion films stabilized by mixtures of an inulin-based polymeric surfactant INUTEC SP1 and a hexa(ethyleneglycol) mono n-dodecyl ether (C12(EO)6) surfactant were investigated to obtain disjoining pressure isotherms at various NaCl concentrations. A comparison with results on emulsion films stabilized by the individual components was made. At a constant INUTEC SP1 concentration, mixtures with different components' molar ratios were prepared by varying the C12(EO)6 concentration, C S . Below a certain value of C S in the mixtures, Newton black films were obtained, which remained stable to rupture with pressure increase and their stability significantly decreased with further increase in C S .

Emulsion and Wetting Films Stabilized by Hydrophobically Modified Inulin Polymeric Surfactant

Emulsion films of hydrophobically modified inulin (INUTEC SP1) polymeric surfactant, both in aqueous solution and in the presence of different electrolyte (NaCl, Na2SO4, MgSO4) concentrations have been studied. At constant disjoining pressure of 36 Pa the film thickness h w decreased with increase in electrolyte concentration until a critical value, C el,cr, was reached above which h w remained constant. This reduction in film thickness below C el,cr could be accounted for by the compression of the double layer. At a critical pressure that depends on the electrolyte type, the film jumped to a Newton Black Film (NBF) that remained very stable up to very high disjoining pressure at all electrolyte concentrations and electrolyte types studied. The polyfructose loops and tails in this NBF remain strongly hydrated and these results explain the high stability against coalescence of such INUTEC SP1 emulsions. Wetting films from INUTEC SP1 aqueous solutions on a hydrophilic quartz substrate were also studied. The results showed a dependence of film thickness on INUTEC SP1 concentration which could be accounted for by the adsorption and orientation of the polymer molecules at the solid-liquid interface. At low INUTEC SP1 concentration, the molecule adsorbs with the hydrophilic loops and tails leaving the alkylchains in solution. However at higher concentration a bilayer of INUTEC SP1 molecules could be produced by hydrophobic interaction between the alkyl chains on the backbone of the polymer and this resulted in an increase of the film thickness at high concentration. The film thickness decreased with increasing electrolyte concentration at constant INUTEC SP1 concentration till a critical value was reached above which h w remained virtually constant. The reduction of h w could be accounted for by compression of the electrical double layer in accordance with the DLVO-theory.

Wetting films from aqueous solutions of polymeric surfactants on hydrophobic solid surface

Wetting films from aqueous solutions of three different polymeric surfactants (hydrophobically modified inulin with two degrees of substitution, INUTEC SP1 and HMI-B, and hydrophobically modified polyacrylate, EFKA) were obtained on hydrophobic glass surfaces with different degrees of hydrophobicity. The equilibrium film thickness h was measured as a function of polymeric surfactant concentration C. For surfaces with low degree of hydrophobicity h increased, whereas for surfaces with high hydropobicity h decreased, with increase of C SP1. For HMI-B with higher degree of substitution h remained virtually constant for surfaces with low degree of hydrophobicity, while for high degree of hydrophobicity h increased with increase of C HMI-B . With EFKA h decreased with increase of polymeric surfactant concentration. The addition of 0.05 M NaCl caused a significant reduction in film thickness. A tentative explanation of the differences between the three polymeric surfactants was given in terms of the electrostatic interaction contribution. Two main features have been established: (i) stable films exist at high polymeric surfactant concentration and low degree of hydrophobicity of the solid surface; (ii) unstable films that rupture at low polymeric surfactant concentration and high degree of hydrophobicity of the solid surface.

Production and characterization of Hesperetin nanosuspensions for dermal delivery

Nanosuspensions of Hesperetin were produced using four different stabilizers, Poloxamer 188, Inutec SP1, Tween 80 and Plantacare 2000, possessing different mechanisms of stabilisation. The nanosuspensions were characterized with regard to size (photon correlation spectroscopy (PCS), laser diffractometry (LD)) and charge (zeta potential measurements). A nanocrystal PCS size of about 300 nm was obtained after 30 homogenization cycles at 1500 bar with the stabilizers Poloxamer, Inutec and Plantacare. Tween was slightly less efficient to preserve the nanocrystal size directly after production (347 nm). The short-term stability was assessed by storage of the nanosuspensions at 4 °C, room temperature and 40 °C. As predicted from the zeta potential measurements, Inutec and Plantacare stabilized nanosuspensions were stable with no change in PCS diameter and LD diameter 99%. Slight increases in size were found for the Poloxamer and the Tween stabilized nanosuspensions, which is not considered to impair their use in dermal formulations.

Comparison of oil-in-water emulsion films produced using ABA or AB n copolymers

Film thickness and disjoining pressure in emulsion films formed between two oil droplets in aqueous solutions of two ABA poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymers of the Pluronic series, F108 and P104, were investigated at different NaCl concentrations. The microinterferometric thin film pressure balance experimental technique was used. The results obtained were compared with those previously reported for an AB n graft copolymer of hydrophobically modified inulin, namely INUTEC SP1. It was noted that there are marked differences in the behavior of the emulsion films stabilized with Pluronics ABA copolymers and those based on the AB n graft copolymer INUTEC SP1. This difference in behavior was used to throw some light on the difference in stability of practical emulsions when using these two types of polymeric surfactants. It is concluded that emulsions using INUTEC SP1 should be more stable than those using Pluronics ABA copolymers in particular at high electrolyte concentrations.

Evaluation of the formulation of solid dispersions by co-spray drying itraconazole with Inutec SP1, a polymeric surfactant, in combination with PVPVA 64

In order to improve the in vitro performance and stability of co-spray-dried itraconazole/Inutec SP1 systems, the influence of adding PVPVA 64, a polymer that is compatible with itraconazole, was evaluated. Dissolution tests were carried out on several itraconazole/PVPVA 64/Inutec SP1 compositions and spray-dried itraconazole/PVPVA 64 powders were used as references. The physicochemical properties of the samples were assessed with modulated temperature differential scanning calorimetry (MDSC), X-ray powder diffraction (XRD) and environmental scanning electron microscopy (ESEM). Physicochemical analysis revealed that there is no interaction between itraconazole and Inutec SP1 and that sufficient amount of PVPVA 64 is required to keep the drug molecularly dispersed. The improvement of the ternary solid dispersions over the binary solid dispersions was composition dependent. On one hand the increased drug/PVPVA 64 ratio in the ternary systems slowed dissolution down, on the other hand this was compensated by the solubilizing power of Inutec SP1.

Emulsion polymerization of styrene using mixtures of hydrophobically modified inulin (polyfructose) polymeric surfactant and nonionic surfactants

Polystyrene latex dispersions were pre- pared by emulsion polymerization, using a mixture of hy- drophobically modified Inulin (INUTEC 1 SP1) and various nonionic surfactants (cosurfactants). Two series of nonionic surfactants were used, namely Synperonic A (C13-15 alkyl chain with 7, 11, and 20 moles of ethylene oxide, EO) and Synperonic NP (nonylphenol with 10 and 15 moles of EO). For 5 wt % latex, the INUTEC SP1 concentration was kept constant at 0.0165 wt % and the initiator concentration was also kept constant at 0.0125 wt %, whereas the cosurfactant concentration was varied between 0.1 and 0.5 wt %. With the exception of Synperonic A20, all other cosurfactants showed an initial increase in particle diameter followed by a decreased reaching a value comparable with that obtained using INUTEC SP1 alone. However, A20 pro- duced a continuous reduction in particle diameter with increase of surfactant concentration, reaching a value of 100 nm at 0.5 wt % which is lower than the value obtained using INUTEC SP1 alone (188 nm). In all cases, addition of a cosurfactant enhanced the stability of latexes by co- adsorption at the solid-liquid interface. The enhanced sta- bility produced by the addition of cosurfactants to INU- TEC SP1 could be illustrated by using the mixture of INU- TEC SP1 and Synperonic A7 at 40 wt % of styrene latex concentration. In this case, the mixture produced lower particle size, much lower polydispersity index and much higher stability. These results are of significant value for industrial applications. 2008 Wiley Periodicals, Inc. J Appl Polym Sci 108: 811-815, 2008

Interaction Forces in Thin Liquid Films Stabilized by Hydrophobically Modified Inulin Polymeric Surfactant. 3. Influence of Electrolyte Type on Emulsion Films

The interaction forces in emulsion films stabilized using hydrophobically modified inulin (INUTEC SP1) were investigated as a function of concentrations of electrolytes of different types (NaCl, Na2SO4, and MgSO4). At a constant disjoining pressure of 36 kPa, a constant temperature of 22 degrees C, and a film radius of 100 microm, the film thickness, hw, decreased with an increase in electrolyte concentration until a critical value, Cel,cr, was reached above which hw remained constant. Cel,cr decreased with an increase in electrolyte valency (Cel,cr = 5 x 10(-2) mol.dm(-3) for NaCl and 1 x 10(-2) mol.dm(-3) for Na2SO4 and MgSO4). The reduction in film thickness below Cel,cr could be accounted for by the compression of the electrical double layer. The Pi-hw isotherms below Cel,cr could be fitted using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory (constant charge and constant potential cases were considered). At a certain pressure, the film jumped to a Newton black film. The pressure at the jump decreased with an increase in electrolyte valency as a result of the reduction of the electrostatic barrier. At electrolyte (NaCl, Na2SO4, or MgSO4) concentrations higher than Cel,cr, the jump occurred at a low pressure that was independent of the electrolyte type. The thickness of the Newton black film was independent of both the concentration and nature of the electrolytes studied. The results show clearly that the polyfructose loops and tails remain strongly hydrated both in water and in high concentrations of electrolytes of different types, and these results explain the high INUTEC SP1 emulsion stability against coalescence of emulsions prepared under such conditions.

Interaction forces between particles stabilized by a hydrophobically modified inulin surfactant

The adsorption isotherm of a hydrophobically modified inulin (INUTEC SP1) on polystyrene (PS) and poly(methyl methacrylate) (PMMA) particles was determined. The results show a high affinity isotherm for both particles as expected for a polymeric surfactant adsorption. The interactions forces between two layers of the hydrophobically modified inulin surfactant adsorbed onto a glass sphere and plate was determined using a modified atomic force microscope (AFM) apparatus. In the absence of any polymer, the interaction was attractive although the energy of interaction was lower than predicted by the van der Waals forces. The results between two layers of the adsorbed polymer confirms the adsorption isotherms results and provides an explanation to the high stability of the particles covered by INUTEC SP1 at high electrolyte concentration. Stability of dispersions against strong flocculation could be attributed to the conformation of the polymeric surfactant at the solid/liquid interface (multipoint attachment with several loops) which remains efficient at Na 2SO 4 concentration reaching 1.5 mol dm −3. The thickness of the adsorbed polymer layer in water determined both by AFM and rheology measurements, was found to be about 9 nm.