Structure, Diffusion, and Permeability of Protein-Stabilized Monodispersed Oil in Water Emulsions and Their Gels: A Self-Diffusion NMR Study

Romoscanu, Alexandre I.; Fenollosa, Annia; Acquistapace, Simone; Gunes, Deniz Z.; Deuchande, Teresa; Clausen, Pascal; Mezzenga, Raffaele; Nydén, Magnus; Zick, Klaus; Hughes, E. W.

doi:10.1021/la100774q

Cited by 18 publications

(12 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is directly related to different physical parameters such as the size and shape of the diffusing particle, the temperature, and the viscosity of the solution. It can be characterized by a diffusion tensor D, the trace of it being the diffusion coefficient D. It is a parameter characteristic of the nature and properties of liquids, solutions, and gels [63,64]. Thus it allows access to properties, such as molecular volume and/or weight, mobility and dynamic behavior, and chemical interactions with their environment.…”

Section: H Nmr Dosymentioning

confidence: 99%

Tetrapropylammonium Occlusion in Nanoaggregates of Precursor of Silicalite-1 Zeolite Studied by 1H and 13C NMR

et al. 2016

View full text Add to dashboard Cite

Abstract:The dynamic behavior of tetrapropylammonium (TPA) cations in the clear precursor sols for silicalite synthesis has been investigated by 1 H diffusion ordered spectroscopy (DOSY), T 1 , T 2 , and T 1ρ 1 H relaxation, as well as 1 HÑ 13 C cross polarization (CP) nuclear magnetic resonance. The DOSY NMR experiments showed the presence of strong solute-solvent interactions in concentrated sols, which are decreasing upon dilution. Similarities in dependence of diffusion coefficients with fractional power of the viscosity constant observed for nanoparticles, TPA cations and water led to the conclusion that they aggregate as anisotropic silicate-TPA particles. Relaxation studies as well as 1 HÑ 13 C CP experiments provide information on dynamic properties of ethanol, water and TPA cations, which are function of silicate aggregates. The general tendency showed that the presence of silicate as oligomers and particles decreases the relaxation times, in particular T 2 and T 1ρH , as a consequence of involvement of these latter in ion-pairing interactions with water-solvated TPA molecules slowing down their mobility. Furthermore, from the 1 HÑ 13 C CP dynamics curve profiles a change in the CP transfer regime was observed from fast (T CH << T 1ρH ) for solutions without silicates to moderate (T CH~T1ρH ) when silicates are interacting with the TPA cations that may reflect the occlusion of TPA into flexible silicate hydrate aggregates.

show abstract

Section: H Nmr Dosymentioning

confidence: 99%

Tetrapropylammonium Occlusion in Nanoaggregates of Precursor of Silicalite-1 Zeolite Studied by 1H and 13C NMR

et al. 2016

View full text Add to dashboard Cite

show abstract

“…While the first minimum is well modelled, the second minimum is not predicted. This has previously been observed when characterising monodisperse emulsions with radii from 12 to 20 µm [136], and is attributed to the model not accounting for diffusion of the molecules beyond the first shell of pores [135,136].…”

Section: Continuous Phase Diffusionmentioning

confidence: 64%

Structure and Rheology of Monodisperse and Bimodal Emulsions

Monahan¹

View full text Add to dashboard Cite

<p>Emulsions are the basis for many commercial products such as foodstuffs and paint due in part to their highly tunable flow properties. It is qualitatively understood that factors such as the dispersed phase droplet size and size distribution should affect how an emulsion flows because they influence how droplets can deform or pack. Since standard emulsification techniques such as blending and homogenization cannot produce emulsions with well-defined size distributions, little work has been done to, in particular, quantitatively determine the influence of droplet size distribution on emulsion flow properties. Consequently, in this investigation we have probed how the droplet size distribution affects emulsion flow properties by using model monodisperse emulsion systems with narrow, controllable droplet size distributions. Using a microfluidic flow focusing device, dodecane-in-water emulsions with diameters between 50 to 100 m with polydispersities less than 5% were produced, as characterized by pulsed field gradient nuclear magnetic resonance and optical microscopy. Due to the relatively large size of the droplets, it was only possible to examine the creamed phase of the emulsion. Samples of known polydispersity were made by mixing known quantities of two monodisperse emulsions. The monodisperse and bimodal emulsions were then subjected to rotational and oscillatory shear flow using a controlled stress rheometer to determine the effects of droplet size and size distribution on emulsion flow properties. Rotational and oscillatory rheological experiments showed that the monodisperse emulsions had two distinct behaviours: foam-like with appreciable thixotropy and yield stresses as well as emulsion-like with no evident thixotropy. The transition between these two behaviours appears to happen at a critical droplet radius between 33 and 37 micrometres. The rheological properties of the bimodal emulsions was split into three distinct behaviours. In samples that could be considered a matrix of large droplets perturbed by smaller droplets, the flow properties were similar to those of the constituent emulsion with the larger droplets. Increasing the number fraction of smaller droplets to a 1:1 ratio creates an entirely new phase with significantly reduced elastic properties. Surprisingly, when the emulsion primarily consists of small droplets, the flow properties are most similar to that of the large droplets. Additionally, despite the microstructural differences, all emulsions showed flow characteristics typical of soft glassy materials above the glass transition temperature. These results demonstrate the significant influence of microstructure on emulsion rheology, where altering the droplet size or polydispersity essentially creates a new phase with its own unique flow properties that is not simply a combination of the properties of the individual monodisperse components that make up the sample</p>

show abstract

“…Romoscanu et al [82] have fitted NMR data to this model for an oil-in-water emulsion with droplet size around 35 μm, and showed that this method has a high ability to predict the emulsion structure. This model was established for glassy spherical beads with rigid surfaces, hence the dynamics of the interface are not taken into account, resulting in deviation of the model at high q-value [77].…”

Section: -1-1-2 Size Probing: Pore Hopping Analysismentioning

confidence: 99%

“…This model was established for glassy spherical beads with rigid surfaces, hence the dynamics of the interface are not taken into account, resulting in deviation of the model at high q-value [77]. Romoscanu et al [82] claimed that the oil droplet size and structure information can be extracted from the extrema of the model.…”

Section: -1-1-2 Size Probing: Pore Hopping Analysismentioning

confidence: 99%

“…Consider the following rheological models: The Einstein relationship for surfactant micellar solutions, microemulsions and diluted normal emulsions [82] and the Pal relationship for concentrated and coarse emulsions [90], respectively. The first relationship is an example of a simple analytical rheological model that expresses the viscosity of a dilute dispersion and is the basis of lots of emulsion models and the second one is a practical model built based on the analytical model (the factor of 2.5 is seen in the both formulas).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Effect of Length Scale on Flow Properties of Micro, Nano and Macro-Emulsions

Ghahraee¹

View full text Add to dashboard Cite

<p>Flow properties of a complex fluid depend on not only the characterizations of the components that make up the system but also the interactions between the phases. One of the most significant factors that affect these interactions is the length scale of the dispersed phase. According to Stokes law, the root of complex fluid rheological models, the velocity of a moving particle in a fluid is a function of the viscosity of the fluid and also the size of the moving droplet. The main aim of this research is to understand the crucial elements that define and control the rheological behaviour of complex fluids and thereby provide evidence for proposed modifications of the available rheological models to include parameters that capture the deduced crucial elements. In particular, by adjusting different aspects of Stokes law. The modified models can then be applied to a wider range of complex fluid systems, including emulsions, regardless of the chemicals that form the system. The complex fluids used in this research to develop the above are emulsions with droplets ranging over four orders of magnitude, 10 nm to 100 µm. Within a single base chemical system microemulsions, nanoemulsions and macroemulsions could be formed. The length scale and flow properties of each group were examined and the effect of length scale on rheological properties was investigated. Critical elements there were identified include: • Use of the appropriate viscosity value for the fluid through which the dispersed phase diffuses. It is often assumed that the viscosity of the pure continuous phase fluid can be used as the reference viscosity in the Stokes equation. In a real system the viscosity of the continuous phase can be strongly affected, and thereby defined by, the presence of the dispersed phase itself and the interfacial layer. Hence it is paramount that the appropriate reference viscosity is used. It is noted that the standard assumption is often applicable for highly diluted suspensions that are composed of rigid spheres. However, the research undertaken here demonstrates that this assumption must be reconsidered for more concentrated systems and particularly for emulsions. We recommend that for such systems the viscosity of the pure continuous phase is replaced by the constant viscosity of the sample at a zero shear rate. • Consideration of structural factors that also affect the viscosity. In particular it is often assumed that: 1- the droplets/particles are spherical and non-deformable; and 2- the dispersed phase presents as a single length scale, i.e. the system is a monodisperse system. The inclusion of these assumptions limits dramatically the applicability of the available models to fit and describe the real flow behaviour and thereby does not allow for predictability of behaviours. Typically models have been modified by adding experimental factors rather than explicitly incorporating the above factors into the development of a model. In this work the deviation from these rheological models are explained and correlated to the deviation from spherical structure and monodispersity. • Defining the relative viscosity as the ratio between the sample viscosity and the reference viscosity is common practice in the application of most rheological models. The viscosity of water tends to be taken as the reference viscosity. This leads to no agreement between the well-known rheological models and the experimental data, especially when applied to analysis of microemulsion rheology. In this work, we show that by taking the viscosity of the relevant ternary surfactant solution as the reference viscosity, the existing models can be applicable to microemulsions. This work sheds light on the relationship between the non-Newtonian behaviour of nanoemulsions and their underlying thermodynamic instability. In these systems the Newtonian behaviour is not evident till a shear rate of 100/s is reached. On the other hand the Newtonian viscosity is observed in thermodynamically stable systems, e.g. surfactant solutions and microemulsions, beyond a shear rate of 5/s or less. The Newtonian region also was observed in normal emulsions with narrow size distributions, dilute monodisperse coarse emulsions or dilute normal emulsions prepared in a Warring blender while a short chain alcohol is added to the system. By adding the short chain alcohol to the system not only the densities of the two phases are made similar and the emulsification is eased but also the polydispersity of the final emulsion is decreased. Finally a single model to be applicable to different types of emulsions with droplet sizes over five orders of magnitude was proposed. However the relationship is applicable to the systems with a low degree of polydispersity and once polydispersity is introduced the flow behaviour becomes complicated and the proposed model is not applicable.</p>

show abstract

Structure, Diffusion, and Permeability of Protein-Stabilized Monodispersed Oil in Water Emulsions and Their Gels: A Self-Diffusion NMR Study

Cited by 18 publications

References 41 publications

Tetrapropylammonium Occlusion in Nanoaggregates of Precursor of Silicalite-1 Zeolite Studied by 1H and 13C NMR

Tetrapropylammonium Occlusion in Nanoaggregates of Precursor of Silicalite-1 Zeolite Studied by 1H and 13C NMR

Structure and Rheology of Monodisperse and Bimodal Emulsions

The Effect of Length Scale on Flow Properties of Micro, Nano and Macro-Emulsions

Contact Info

Product

Resources

About