FRAGMENTATION OF PRIMARY FLOCS IN EMULSIONS AND THE SUBSEQUENT REDUCTION OF COALESCENCE

In existing theories emulsion desiabilization is considered as the combined processes of irreversible flocculation and coalescence of dispersed droplets. This approach can be justified when the potential pit characterizing the energy of droplet interaction is sufficiently deep, i.e. excluding small droplet dimensions, strong electrosiatic repulsion and low electrolyte concentrations. For smaller droplet dimensions and stronger electrostatic repulsions the emulsion instability must be considered as a combined process of reversible flocculation and coalescence. In this paper a mathematical model that couples the kinetics of flocculation, coalescence and floe fragmentation is developed in order to quantify the kinetic instability of emulsions with charged submicron droplets. The characteristic limes for flocculation (Smoluchowski's time τ_c) for coalescence (coalescence time τ_c) and for disaggregation (doublet lifetimeτ_d) are considered model parameters. The mathematical model applies to the case when and τ_d<< τ_c, which corresponds to a situation with a small multiplet concentration compared to the concentration of doublets and a singlet-doublet quasi-equilibrium. It is established that at singlet-doublet quasi-equilibrium the rate of the decline in the total droplet concentration is described by second order kinetics in distinction to the exponential time dependence valid for coalescence at irreversible flocculation. The double disintegration reduces the entire coalescence rate, expressed as τ_sm/ τ_d. This reduction is very large at small values of Td. The mathematical model presented can hased on the spontaneous disintegration of doublets predict changes in emulsion stability for model systems and also for technologically important emulsions.     

Methylcellulose-induced stability changes in protein-based emulsions

The emulsifying and oil-in-water stabilizing properties of methylcellulose (MeC) were investigated in bovine serum albumin (BSA)-based emulsions. The creaming stability, flocculation, surface concentration of BSA and MeC and droplet size were determined. Results obtained showed modifications of creaming rates that were related to MeC concentrations in the continuous and dispersed phases. Viscosity effects on creaming and changes in average droplet size (d₄₃) relating to droplet coverage were identified and delineated. Studies performed on macroscopic oil–water and air–water interfaces were used to identify interfacial structuring and composition. A good agreement was found between droplet surface composition and the resistance to coalescence of emulsion droplets. Emulsions that demonstrated a more rigid-like adsorbed interfacial layer were more stable with respect to coalescence. This study involving model emulsion systems provides a new insight into the stability of industrial preparations containing mixtures of proteins and polysaccharides.     

Kinetics Model of Destabilization of Oil Droplets in Oily Wastewater Emulsions

In this article, a mathematical model that accounts for the kinetics of flocculation and coalescence of emulsion drops was developed to quantify the kinetics of emulsion stability. The model is similar to that developed by Borwankar et al. in 1992 with corrections in coalescence rate constant and collision efficiency factor. It includes a term to describe efficiency of collisions. Also, the coalescence rate constant was defined as a function of the total number of particles that were present in the system at the moment. The model has four adjustable parameters, and nonlinear least square optimization is used to obtain the adjustable parameters. The obtained adjustable parameters by the model served as parameters that can be used to quantitatively evaluate the effectiveness of a set of different demulsifiers by measuring total numbers of drops versus time and by determining the adjustable parameters and comparing them. The results of the presented model and the model of Borwankar et al. were compared with experimental data. The results of the new model were in good agreement with experimental data and showed the model's ability for dispalying the behavior of droplets during the destabilization processes of emulsions.     

Contribution of steric and electrostatic repulsion forces to the stability of styrene latices copolymerized with acrylic acid

Acrylic acid (AA) is used in many emulsion polymerization formulations to improve the colloidal stability of the latex product. The improved stability originates from electrostatic repulsion complemented with steric repulsion. The strength of the electrostatic and steric repulsion forces in a styrene (S)/AA copolymer latex was investigated at different pH values, electrolyte concentrations, and temperatures. A comparison was made with an S homopolymer latex. Transmission electron microscopic pictures, combined with visual inspections, provided understanding of the mechanisms leading to coagulation in polystyrene (PS)/AA copolymer latices. Colloidal stability of the unswollen sodium dodecyl sulfate stabilized PS latex is based on electrostatic repulsion. Destabilization by sodium chloride resulted in aggregation. The acidic PS/AA latex remained stable against aggregation at high electrolyte concentrations because of steric repulsion. The acidic PS/AA latex showed a strong tendency to flocculate at increasing electrolyte concentrations. Flocculation was not observed for high‐pH PS/AA latices at high electrolyte concentrations. Steric repulsion of the acid PS/AA latex was lost at temperatures higher than the critical coagulation temperature (35 °C), and flocculation was followed by aggregation and coalescence. The high‐pH PS/AA latex was stable even at high electrolyte concentrations and temperatures up to 80 °C because of strong electrosteric stabilization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2985–2995, 2003     

Process diagnosis of coalescence separation of oil-in-water emulsions-two case studies

Coalescence separation is a widely applied technology for oil/water emulsion separation. In this paper, we first review the existing coalescence theories regarding droplet capture, attachment and release. Two case studies are considered, dealing with the separation of oil-in-water emulsions using our recently developed coalescing filters. The first case (Case I) is associated with the separation of surfactant-stabilized hexadecane/water emulsions. The second case (Case II) addresses the separation of sulfonated kerosene/water emulsions in a continuous bench operation. In Case I, known wetting and collision theories were applied to understand the complex coalescence process occurring on the surface of the fibers. For this, the detrimental effect of surfactants on coalescence separation was taken into account. It was found that the best oil wetting coalescing material under water was not the most desired for coalescence, contradicting the existing theory. In addition, once the materials were pre-saturated with surfactant-containing emulsions, the oil wetting was enhanced significantly. However, the separation efficiency was maintained at the same level, unless the material adsorbed surfactant, resulting in minor reductions in the wetting angle. In Case II, based on the fiber properties and operation conditions, the droplet capture efficiency and released droplet size were calculated using the existing models. Fiber diameter and medium face velocity were found to affect not only the capture, but also drop release. Based on model predictions, the dominant capture mechanism was identified as interception followed by van der Waals forces. Overall, this work offers insights about the influencing parameters on oil/water emulsion separation for better designing coalescence systems.     

A microfluidic method to study demulsification kinetics

We present the results of experiments studying droplet coalescence in a dense layer of emulsion droplets using microfluidic circuits. The microfluidic structure allows direct observation of collisions and coalescence events between oil droplets dispersed in water. The coalescence rate of a flowing hexadecane-in-water emulsion was measured as a function of the droplet velocity and droplet concentration from image sequences measured with a high-speed camera. A trajectory analysis of colliding droplet pairs allows evaluation of the film drainage profile and coalescence time t(c.) The coalescence times obtained for thousands of droplet pairs enable us to calculate coalescence time distributions for each set of experimental parameters, which are the mean droplet approach velocity (v(0)), the mean dispersed phase fraction (φ) and the mean hydraulic diameter of a droplet pair (d(p)). The expected value E(t(c)) of the coalescence time distributions scales as E(t(c)) is proportional to (v(0))(-0.105±0.043)(d(p))(0.562±0.287), but is independent of φ. We discuss the potential of the procedure for the prediction of emulsion stability in industrial applications.     

Photolysis (193 nm) of aliphatic amino acids in aqueous solution

An investigation of the photochemical properties of glycine, aspartic acid, valine, leucine and methionine was carried out using nanosecond 193 nm laser irradiation and high performance liquid chromatography analysis. The quantum yields of formation of hydrated electrons (Φ_e−) and decomposition of the substrate (Φ_d) were determined for the five aliphatic amino acids in neutral aqueous solution at room temperature. From the dependences of Φ_e− on the laser intensity it follows that the mechanism of photo-ionization is monophotonic (single step). The Φ_d values under Ar and in the presence of oxygen or N₂O are interpreted on the basis of photo-ionization as the dominant process for decomposition of methionine and a significant contribution from photo-ionization in the other cases. A comparison was made between the Φ_d values (in the presence of oxygen) using irradiation at 193 nm and those from previous measurements at 213 nm.     

Oil-in-water Pickering emulsion destabilisation at low particle concentrations

Droplet evolution in unstable, dilute oil-in-water Pickering emulsions was characterised using a combination of light scattering, confocal microscopy and rheology. Emulsions were formed at concentrations of silanised fumed silica particles that are not sufficient to prevent destabilisation. The key result is that destabilisation initially occurs via a combination of droplet flocculation and permeation. Close contact between the drops enhances oil transfer from smaller drops to the larger ones. The large drops swell over time until the attached particle density is insufficient to protect the drops against coalescence. Examination of the emulsion microstructure revealed the relationship between drop stability and the structural characteristics of the aggregates formed due to coagulation of the silica particles in the emulsions. The implications of these results for controlling Pickering emulsion stability are discussed.     

Emulsification using micro porous glass (MPG): surface behaviour of milk proteins

To investigate the emulsifying properties and adsorption behaviour of high molecular amphiphilic substances such as proteins, it is important to maintain the native status of the used samples. The new method of micro porous glass (MPG) emulsification could offer an opportunity to do this because of the low shear forces. The oil-in-water emulsions were produced by dispersing the hydrophobic phase (liquid butter fat or sunflower oil) through the MPG of different average pore diameters (d_p=0.2 or 0.5 μm) into the flowing continuous phase containing the milk proteins (from reconstituted skim milk and buttermilk). The emulsions were characterised by particle size distribution, creaming behaviour and protein adsorption at the hydrophobic phase. The particle size distribution of protein-stabilised MPG emulsions is determined by the pore size of MPG, the velocity of continuous phase (or wall shear stress σ_w) and the transmembrane pressure. A high velocity of =2 m s⁻¹ (σ_w=13.4 Pa) and low pressure (pressure of disperse phase slightly exceeded the critical pressure Δp_TM=4.5 bar of 0.2 μm-MPG) led to the smallest droplet diameter. As a consequence of average droplet diameters of d₄₃>3.5 μm creaming was observed without centrifugation in all MPG emulsions after 24 h, but no coalescence of the oil droplets occurred. The study of protein adsorption showed that the MPG emulsification at low shear forces resulted in lower protein load values (2.5±0.5 mg m⁻²) than pressure emulsification (11.5±1.0 mg m⁻²). In addition, the various emulsification conditions (MPG or pressure homogenization) led to differences in the relative proportions of casein fractions, whey proteins and milk fat globule membranes (MFGM) at the fat globule surfaces.     

Flocculation and Coalescence of Oil-in-Water Poly(dimethylsiloxane) Emulsions

The stability of poly(dimethylsiloxane) (PDMS) oil-in-water emulsions has been investigated in the presence of added NaCl as well as in the presence of added surfactant. The emulsions were prepared using a combination of nonionic (C(x)E(y), x and y represent the number of methylene (C) and ethylene oxide (E) groups, respectively) and cationic (quarternary alkylammonium) surfactants. The droplets were observed to exhibit weak flocculation in the presence of high NaCl concentration (1 M). Phase separation and optical microscopic observations revealed that the principal mechanism for emulsion destabilization at high salt concentration was coalescence, which was accelerated at elevated temperature (50 degrees C). The effective coalescence rate for diluted emulsions was investigated using photon correlation spectroscopy. The small effective Hamaker constant for PDMS is the primary reason for the slow rate of coalescence observed for the emulsions at neutral pH in the presence of NaCl. The stability of PDMS emulsions to flocculation is qualitatively similar to that reported for low Hamaker constant dispersions (e.g., microgel particles). Addition of cationic surfactants (cetyltrimethylammonium chloride and dodecyl dimethylbenzylammonium chloride) to the negatively charged droplets after preparation was shown to decrease the emulsion stability once the surfactant concentration exceeded the CMC. Electrophoretic mobility measurements showed that added cationic surfactant changed the sign of the droplet charge from negative to positive at concentrations well below the CMC. Charged micelles of the same sign as the droplets are electrostatically excluded from close approach to the droplet surface within a distance (varepsilon) which results in depletion flocculation. Copyright 2000 Academic Press.     

Ethanol-in-oil emulsion (E/O) stabilized by polyglycerol polyricinoleate: A potential delivery system for ethanolic extract

This study evaluated how variations in polyglycerol polyricinoleate (PGPR) concentration and ethanol dispersed phase content affect the stability of ethanol-in-oil (E/O) emulsions. Results indicate that the stable 10?wt% E/O emulsions can be produced using 2?wt% PGPR. Increasing the ethanol dispersed phased content at constant PGPR concentration caused instability in emulsion. These emulsions remained stable to droplet flocculation and coalescence in the presence of Centella asiatica ethanol extract. PGPR does not greatly decrease the interfacial tension of the ethanol–oil interface. However, it adsorbed at the interface and stabilized the ethanol droplets in the emulsion via steric mechanism.     

Studies of Kinetics of Coalescence of Water‐in‐Furrial Crude Oil Emulsions by Confocal Microscopy

The kinetic of coalescence of water in Furrial crude oil emulsions (W/O) during the initial stage of demulsification process is showed through of high‐resolution image micrographics by using a confocal microscope. Furrial crude oil from Monagas state is a crude oil extra heavy with severe flocculation/aggregation problems. The kinetic of the initial stage in the coalescence process is critical and of great importance in the definition of the foreword behavior. This information allowed us to characterize the demulsification rate process in a Furrial crude oil. Total W/O emulsion separation was achieved about of 2 hours at 80ºC. The initial fast coalescence is characterized by a short binary coalescence time, which is followed by a large binary coalescence time. Our results demonstrate that the initial coalescence rate determinate the time necessary to achieve a total separation.     

Coalescence coupling with flocculation in dilute emulsions within the primary and/or secondary minimum

The simplest singlet–doublet emulsions (SDE) exhibit singlet–doublet quasi-equilibrium (s.d.e.) and slow coalescence between doublets. Orthokinetic coagulation and creaming may be eliminated using low-density contrast emulsions. The investigation of the evolution in time of the total number of droplet in such emulsions at SDE was recommended as a standard method to determine the characteristic times of the elementary acts of coalescence (τ_c) and doublet fragmentation (τ_d) [J. Disp. Sci. Technol. 19 (1998) 311]. Further improvement of this method and its automation requires discrimination between singlets and doublets in the bulk, which is possible for droplets of approximately 5 μm in size. Simultaneously, the droplet dimension must not be too large as the fragmentation time increases rapidly with the droplet dimension, while it has to be very small in compare to the Smoluchowski time (τ_sm) to preserve the condition for SDE. It is shown here that this controversy in the demand to the droplet size can be satisfied by a simultaneous decrease in electrolyte concentration, increase in surface potential and decrease in droplet volume fraction. The calculation of the fragmentation time in a wide range of electrolyte concentration, surface potential and particle radius shows that τ_d may be very small in compare to τ_sm (increases at small volume fractions) at such large mini-emulsion droplet dimension as it is necessary for a singlet and doublet discrimination. The second experimental difficulty is the discrimination between doublets in the primary (PD) and secondary minimum (SD) using video microscopy, while there is a huge difference in their kinetic behavior in respect to fragmentation and coalescence. The analysis of the domains for PD only, for SD only, and for a coexistence of SD and PD shows that the characterization of mini-emulsions has to be accomplished using experimental conditions corresponding to the domain of SD only.     

Stability of Emulsions Containing Both Sodium Caseinate and Tween 20

The creaming and rheology of oil-in-water emulsions (30 vol% n-tetradecane, pH 6.8) stabilized by a mixture of commercial sodium caseinate and the non-ionic emulsifier polyoxyethylene sorbitan monolaurate (Tween 20) has been investigated at 21 degrees C. The presence of sufficient Tween 20 to displace most of the protein from the emulsion droplet surface leads to greatly enhanced emulsion creaming (and strongly non-Newtonian rheology) which is indicative of depletion flocculation by nonadsorbed surface-active material (protein and emulsifier). In emulsions containing a constant amount of surface-active material, the replacement of a very small fraction of Tween 20 by caseinate in a stable pure Tween 20 emulsion leads to enhanced creaming for a small fraction of the droplets, and this fraction increases with increasing replacement of emulsifier by protein. This behavior is probably due to depletion flocculation, although an alternative bridging mechanism is also a possibility. The overall stability of these sets of emulsions can be represented in terms of a global stability diagram containing regions of bridging flocculation and coalescence (low content of surface-active material), stability (intermediate content), and depletion flocculation (high content). Copyright 1999 Academic Press.     

Fat retention at the tongue and the role of saliva: adhesion and spreading of 'protein-poor' versus 'protein-rich' emulsions

Fat perception of food emulsions has been found to relate to in-mouth friction. Previously, we have shown that friction under mouth-like conditions strongly depends on the sensitivity of protein-stabilized emulsion droplets to coalescence. Here, we investigated whether this also implies that oral fat retention depends in a similar manner on the stability of the emulsion droplets against coalescence. We investigate the separate contributions of droplet adhesion and droplet spreading to fat retention at the tongue, as well as the role of saliva. We perform ex vivo (Confocal Raman Spectroscopy; Confocal Scanning Laser Microscopy) experiments using pig's tongue surfaces in combination with human in vivo experiments. These reveal that protein-poor (unstable) emulsions are retained more at the tongue than protein-rich (stable) emulsions. Furthermore, the layer formed by adhering protein-poor droplets is more stable against rinsing. Saliva is found to be very efficient in removing fat and emulsion droplets from the oral surface but its role in fat retention needs further research. We relate our results to the colloidal forces governing droplet adhesion and spreading.     

Stabilisation of emulsions using hydrophobically modified inulin (polyfructose)

Oil-in-water (O/W) emulsions were prepared using a hydrophobically modified inulin surfactant, INUTEC^®SP1. The quality of the emulsions was evaluated using optical microscopy. Emulsions, prepared using INUTEC^®SP1 alone had large droplets, but this could be significantly reduced by addition of a cosurfactant to the oil phase, namely Span 20. The stability of the emulsions was investigated in water, in 0.5, 1.0 and 2 mol dm⁻³ NaCl as well as 0.5, 1.0, 1.5 and 2 mol dm⁻³ MgSO₄. All emulsions containing NaCl did not show any strong flocculation or coalescence up to 50 °C for almost 1 year storage. With MgSO₄ they were stable up to 50 °C and 1 mol dm⁻³. The stability of the emulsions against strong flocculation and coalescence could be attributed to the conformation of the polymeric surfactant at the O/W interface (multipoint attachment with several loops) and the strong hydration of the polyfructose chain in such high electrolyte concentrations. This was confirmed using cloud point measurements, which showed absence of any cloudiness up to 100 °C and at NaCl concentrations reaching 4 mol dm⁻³ and MgSO₄ reaching 1 mol dm⁻³. These high cloud points in electrolyte solutions could not be reached with polyethylene glycol. This clearly demonstrated the superiority of INUTEC^®SP1 surfactant as an emulsion stabiliser when compared with surfactants based on polyethylene glycol. Viscoelastic measurements showed a gradual increase in the storage modulus G′ with storage time both at room temperature and 50 °C. This was indicative of weak flocculation and absence of coalescence. The weak flocculation of the emulsions could be attributed to the presence of an energy minimum, G_min, in the energy–distance curve.     

Calculation of flocculation and coalescence rates for concentrated dispersions using emulsion stability simulations

A simple procedure for the quantification of flocculation (k(f)) and coalescence (k(c)) rates from emulsion stability simulations (ESS) of concentrated systems is presented. It is based on a simple analytical equation, which results from the sum of well-known formulas for the separate processes of flocculation and coalescence. The expression contains k(f) and k(c) as fitting parameters and is found to reproduce the behavior predicted by ESS spanning a wide range of volume fractions (1 < phi < 30%) and surfactant concentrations (1.2 x10(-5) < C < 1.2 x 10(-4) M). This procedure allows interpretation of ESS data in terms of the referred kinetic rates. Furthermore, it could also provide an additional mean for the direct comparison of the simulation data with experimental results.     

Stability and rheology of emulsions containing sodium caseinate: combined effects of ionic calcium and alcohol

We have investigated the combined effect of ionic calcium and ethanol on the visual creaming behavior and rheology of sodium caseinate-stabilized emulsions (4 wt% protein, 30 vol% oil, pH 6.8, mean droplet diameter 0.4 microm). A range of ionic calcium concentrations, expressed as a calcium/caseinate molar ratio R, was adjusted prior to homogenization and varying concentrations of ethanol were added shortly after homogenization. A stability map was produced on the basis of visual creaming behavior over a minimum period of 8 h for different calcium/caseinate/ethanol emulsion compositions. A single narrow stable (noncreaming) region was identified, indicating limited cooperation between calcium ions and ethanol. The shear-thinning behavior of the caseinate-stabilized emulsions is typical of systems undergoing depletion flocculation. Addition of calcium ions and/or ethanol was found to lead to a pronounced reduction in viscosity and the onset of Newtonian flow. The state of aggregation was correlated with emulsion microstructure from confocal laser scanning microscopy. Time-dependent rheology (18 h) with a density-matched oil phase (1-bromohexadecane) revealed that the visually stable emulsions were time-independent low-viscosity fluids. Surface coverage data showed that increasing amounts of caseinate were associated with the oil-water interface with increasing R and ethanol content. A decrease in free calcium ions in the aqueous phase with moderate increases in R and ethanol content was observed, which is consistent with greater calcium-caseinate binding (aggregation). Ostwald ripening occurred at the high-ethanol emulsion compositions that were stable to depletion flocculation. While the coarsening rate was low, this can account for the cream plug formation observed during gravity creaming experiments. The caseinate emulsion with no ionic calcium or ethanol exhibits depletion flocculation from excess nonadsorbed caseinate submicelles. Addition of calcium ions reduces the submicelle number density via specific calcium-binding in the aqueous phase (fewer, larger calcium-caseinate aggregates) and at the droplet surface (increased surface coverage). Nonspecific ethanol-induced (calcium-dependent) caseinate submicelle aggregation in the bulk phase and on the droplet surface (increased surface coverage) culminates in a reduction in the number density of caseinate submicelles. A narrow window of inhibition of depletion flocculation occurs in systems containing both calcium ions and ethanol, both species combining to aggregate the protein and so reduce the density of free submicelles.     

The influence of interparticle surface forces on the coagulation of weakly magnetic mineral ultrafines in a magnetic field

In this paper, it is shown that the coagulation of dispersions of weakly magnetic mineral ultrafines (such as hematite and chromite) in an external magnetic field can be described theoretically by invoking interparticle forces. Essentially, coagulation occurs when the short-range London—van der Waals interactions and the long-range magnetic forces outweigh the stabilizing electric double layer repulsion. From classical colloid chemistry theory, we have calculated the various components of the potential energy for different-sized particles at a series of ionic strengths and magnetic field intensifies. Principles governing the stability of the suspensions were derived and the computations lead to the establishment of criteria which can be used to predict the stability of the suspensions of weakly magnetic oxide mineral ultrafines in a “wet magnetic separation process”.

Experimentally, the magnetic-field induced coagulation of ultrafines of natural hematite and chromite in aqueous suspensions at moderate ionic strength was investigated using a laboratory-scale electromagnetic solenoid. The experimental results relate the coagulation process (as determined by magnetosedimentation analysis) to particle size, slurry pH and the external magnetic field. In the magnetic fields, maximum coagulation occurred near the pH of the point of zero charge (pH_PZC) of the minerals (where the electrostatic double layer repulsion was reduced to a minimum) enabling the particles to enter the “primary minimum” energy sink. In contrast, in cases where the electrostatic repulsion was not suppressed, the long-range magnetic forces enabled coagulation to occur in the “secondary minimum”. This caused the formation of chains which appeared to be relatively stable at enhanced rates of settling. The experimental results could be interpreted from a theoretical analysis of the interparticle forces controlling the process.     

Impact of diblock copolymers on droplet coalescence, emulsification, and aggregation in immiscible homopolymer blends

Using rheo-optical techniques, we investigated the impact of interfacial wetting of symmetric diblock copolymers (BCPs) on the coalescence and aggregation of polydimethylsiloxane (PDMS) droplets in immiscible polyethylene-propylene (PEP) homopolymers. Anionic polymerization was used to synthesize well-defined matrix homopolymers and symmetric 16 kg/mol-to-16 kg/mol PDMS-b-PEP diblock copolymers with low polydispersity (PDI ≈ 1.02) as characterized with size exclusion chromatography and nuclear magnetic resonance spectroscopy. Blends were formulated to match the viscosities between the droplets and the matrix. Moreover, molecular weights of these components were varied to ensure that the inner block of the copolymer inside the droplet was collapsed and dry, whereas the outer block of the copolymer outside of the droplet was stretched and wet. Droplet breakup and coalescence as well as interfacial tensions were measured using rheo-optical experiments with Linkam shearing stage and an optical microscope. Subsequent to droplet breakup at high shear rates, we found that the BCPs mitigated shear-induced coalescence at lower shear rates. Based on surface tension measurements, the stretching of the BCP increased in lower molecular weight matrices, causing the droplet surface to saturate at lower coverage in line with theoretical predictions. Droplet aggregation was detected with further reductions in shear rate, which was attributed to the dewetting or the expulsion of the matrix from a saturated brush. Ultimately, the regions of droplet coalescence and aggregation were scaled by balancing the forces of shear with those due to the attraction between BCP-coated droplets.