Copolymer Surfactant Research Articles

Hydrophobic polyurethane polyHIPEs templated from mannitol within nonaqueous high internal phase emulsions for oil spill recovery

ABSTRACTAlthough amphiphilicity is an integral component for the applications of polyHIPEs (PHs), it is challenging to produce hydrophobic PHs from hydrophilic monomers. Herein, hydrophobic polyurethane (PU) PHs have been fabricated from a water‐soluble mannitol within block copolymer surfactant‐stabilized, nonaqueous high internal phase emulsions (HIPEs). These highly porous, interconnected, macroporous PU PHs were hydrophobic with water contact angles between 102° and 140°, demonstrating that water‐soluble monomers could be used for fabrication of hydrophobic PHs. The block copolymer surfactant acted not only as the HIPE stabilizer, but also as a monomer, enhancing hydrophobicity and overcoming some drawbacks imposed by conventional inert stabilizers. The solvents used for PU PH synthesis and purification were easily recovered and reused, showing that nonaqueous HIPE templating for PU PH preparation is an efficient and facile route. The PU PHs were investigated for oil spill reclamation and they were demonstrated to be an ideal candidate for such an application. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1315–1321

Micellar and rheological properties of some sodium deoxycholate-based poly(ester ether)urethane ionomer biomaterials in N,N-dimethylformamide solutions

In this work new sodium deoxycholate-based poly(ester ether)urethane ionomers are prepared. The micellar and rheological behaviour of these polyurethanes in N,N-dimethylformamide solutions are studied by means of transmission electron microscopy, dynamic light scattering, steady state fluorescence measurements and rheological oscillatory tests. For poly(ethylene oxide)- and poly(propylene oxide)-based polyurethanes spherical core-shell micellar morphology was obtained, whereas for pluronic-based polyurethanes micellar aggregate morphology was obtained. Increased values of critical micelle concentration were determined for the polyurethanes containing more solvophilic poly(ethylene oxide) segments as found for Pluronic block copolymer surfactants. It was found that the type of polyether macrodiol influences the micellar morphology and rheological behaviour. Viscosity of the polyurethane solutions is influenced by their concentration, micellar network, molecular weight and hard segment content of polyurethane. Shear thinning (pseudoplastic) behaviour of the polyurethane solutions was revealed. Gel-sol transitions and liquid-like behaviour were revealed by amplitude sweep tests. Gel-like behaviour and gel-sol transitions were revealed by frequency sweep tests.

Influence of poloxamine copolymeric surfactant on wetting behavior of tarballs in southwestern Caspian coast

Tarball pollution in the southwestern coasts of the Caspian Sea in Iran has raised a great environmental concern in the recent years. Hence, it seems crucial to develop an appropriate technique for rapid mitigation of tarball pollution. In this research work, utilizing various aliquots of poloxamine copolymeric surfactant to reduce tarballs adhesion and to easily remove tarballs from water and sand surfaces is investigated. As the first stage, the impact of tarballs on alteration of the surface wettability under different contact times (1–180 min) is studied through contact angle measurements. Then, the contact angle and interfacial tension (IFT) between water (sea and distilled water) and tarball are measured at 30 °C and 100 psi in the presence of poloxamine solution where the three-phase system includes water, tarball, and air. An increase in the contact angle between water drop and tarball contaminated glass surface from 31.48° to 125.21° implies that the tarball varies the surface wettability toward a hydrophobic state in the absence of poloxamine. According to the results, at the highest poloxamine concentration (0.3 g/ml), the contact angle decreases to 14.28°. In addition, IFT between the synthetic oil (extracted from tarballs) and water lowers from 5.57 mN/m to 0.97 mN/m for the sea water and from 13.38 mN/m to 1.17 mN/m for the distilled water at the maximum concentration of poloxamine. Thus, poloxamine can be employed to modify the surface wettability. It appears that poloxamine is an effective surfactant for elimination of sticky oily pollutants in the form of tarballs from the solid or sand surface as it modifies the surface wettability toward the water-wet condition. This study can assist researchers and engineers to find suitable chemicals in terms of technical, environmental, and economic aspects for efficient removal of oily contaminants from polluted beaches.

Self-assembly of giant bottlebrush block copolymer surfactants from luminescent organic electronic materials.

Bottlebrush copolymers have shown promise as building blocks for self-assembled nanomaterials due to their reduced chain entanglement relative to linear polymers and their ability to self-assemble with remarkably low critical micelle concentrations (CMCs). Concurrently, the preparation of bottlebrush polymers from organic electronic materials has recently been described, allowing multiple optoelectronic functions to be incorporated along the length of single bottlebrush strands. Here we describe the self-assembly of bottlebrush surfactants containing soluble n-butyl acrylate blocks and carbazole-based organic semiconductors, which self-assemble in selective solvent to give spherical micelles with CMCs below 54 nM. These narrowly dispersed structures were stable in solution at high dilution over periods of months, and could further be functionalized with fluorescent dyes to give micelles with quantum yields of 100%. These results demonstrate that bottlebrush-based nanostructures can be formed from organic semiconductor building blocks, opening the door to the preparation of fluorescent or redox-active micelles from giant polymeric surfactants.

Hydration-Dependent Hierarchical Structures in Block Copolymer–Surfactant Complex Salts

Block copolymer–surfactant “complex salts” (BCPCS), containing one neutral water-soluble block and one polyion/surfactant-ion block, were prepared from poly(acrylamide)-block-poly(acrylic acid) block copolymers by neutralizing the acrylate charges with cationic dodecyl- or hexadecyltrimethylammonium surfactant counterions. The BCPCS were studied in hydrated samples containing 20–99 wt % water (and no additional ions) employing small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and visual inspection. Selected samples in D2O were also investigated. The results reveal for the first time, for hydrated samples, the formation of ordered hierarchical structures on both block copolymer and surfactant length scales, analogous to structures that have previously been reported for solvent-free block copolymer–surfactant complexes in the solid or melt. The BCPCS structures do not dissolve but display a finite swelling also in the presence of excess water. The structure on the BCP length scale (lamell...

Effect of triblock copolymer surfactant composition on flow-induced phase inversion emulsification in a tapered channel

HypothesisPhase inversion emulsification (PIE) is a process that inverts the dispersed and continuous phases of an emulsion and is useful for preparing emulsions that are challenging to produce using conventional techniques. A recent work has shown that PIE can be induced by flowing an emulsion through a tapered channel. Although prior studies have shown that flow-induced PIE (FIPIE) is influenced by the flow conditions and wetting properties of the channel surface, little is known about the effect of surfactant structure on FIPIE. We hypothesize that FIPIE is affected by the composition and structure of the surfactant used for emulsion stabilization. ExperimentsWe use Pluronics, a series of ABA triblock copolymers composed of hydrophilic poly(ethylene oxide) (PEO) and hydrophobic poly(propylene oxide) (PPO) with various lengths (A = PEO, B = PPO), as model surfactants to test this hypothesis. We observe that triblock copolymer surfactants with long PEO blocks suppress FIPIE. A scaling analysis based on a polymer brush model qualitatively agrees with the experimental observation. We also show that for small molecular weight Pluronics, FIPIE is significantly suppressed when Pluronics with large PPO blocks are used. FindingsOur results strongly indicate that the steric repulsion provided by the PEO blocks as well as the dilatational elasticity provided by the PPO blocks are key factors that control the FIPIE process.

Additive-Free Rice Starch-Assisted Synthesis of Spherical Nanostructured Hematite for Degradation of Dye Contaminant.

Nanostructured hematite materials for advanced applications are conventionally prepared with the presence of additives, tainting its purity with remnants of copolymer surfactants, active chelating molecules, stabilizing agents, or co-precipitating salts. Thus, preparing nanostructured hematite via additive-free and green synthesis methods remains a huge hurdle. This study presents an environmentally friendly and facile synthesis of spherical nanostructured hematite (Sp-HNP) using rice starch-assisted synthesis. The physicochemical properties of the Sp-HNP were investigated by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DR UV-Vis), and nitrogen adsorption–desorption analysis. The Sp-HNP showed a well-crystallized structure of pure rhombohedral phase, having a spherical-shaped morphology from 24 to 48 nm, and a surface area of 20.04 m2/g. Moreover, the Sp-HNP exhibited enhanced photocatalytic degradation of methylene blue dye, owing to the large surface-to-volume ratio. The current work has provided a sustainable synthesis route to produce spherical nanostructured hematite without the use of any hazardous agents or toxic additives, in agreement with the principles of green chemistry for the degradation of dye contaminant.

Formation and CO2/N2 Switchable Ability of a Novel Copolymer Poly(N,N-Diethylaminoethyl Methacrylate-co-Sodium Vinylsulfonate)

A novel copolymer surfactant has been prepared via a free radical copolymerization of CO2-switchable monomer N,N-diethylaminoethyl methacrylate and the hydrophilic monomer sodium vinyl-sulfonate and characterized. The results of conductivity, dynamic light scattering and cryogenic transmission electron microscopy study showed the change of the microstructure of copolymer in water by adding or removing of CO2. The copolymer aqueous solution was found to exhibit reversible switchability by the bubbling of CO2/N2.

Synthesis of mesoporous silica spheres utilizing in tandem with POSS-based block copolymer and anion surfactant as dual-template

In this work, novel mesoporous silica spheres were prepared by calcination of golf-shaped silica microspheres, which were fabricated via a typical sol-gel method by using synthetic amphiphilic block copolymer poly(acrylate isobutyl polyhedral oligomeric silsesquioxane)-b-poly(dimethylaminoethyl methacrylate co-styrene)) (PAPOSS-b-(PDMAEMA-co-PSt) and anionic surfactant sodium dodecyl sulfate (SDS) as dual-template. Firstly, three different POSS-based block copolymers were synthesized through subsequent homopolymerization of acrylate isobutyl POSS and chain extension of dimethylaminoethyl methacrylate (DMAEMA) and styrene with various feed ratios via reversible transfer radical polymerization (RAFT). These amphiphilic block polymers and SDS were utilized as cooperative template to golf-shaped silica microspheres. The electrostatic interaction between protonated PDMAEMA segments and anion surfactant as well as the strong interaction between PAPOSS segments and silicon source plays the dominant role in forming golf-shaped silica spheres. Moreover, the surface morphology of silica spheres can be tuned by varying molar ratio of PDMAEMA/PAPOSS. The resulting golf-shaped silica microspheres were further calcined to give mesoporous silica spheres which exhibited a BET surface area of 1031 m2 g−1, a total pore volume of 0.826 cm3 g−1, and a narrow pore size distribution centered at 3.20 nm.

Solvent Effects on Tuning Pore Structures in Polyimide Aerogels.

This work evaluates the effects of solvents and a block copolymer surfactant on pore structures in polyimide aerogels synthesized via sol-gel reaction process. Specifically, cross-linked polyimide gel networks are synthesized in single or mixed solvents from a combination of dimethylformamide, N-methylpyrrolidone, and dimethylacetamide and supercritically dried to obtain aerogels. The bulk density, pore size, and mechanical properties of aerogels are determined. The results show that gel times are strongly dependent on the electron acceptance ability of the solvent system and concentration of the surfactant. At longer gel times, the polyimide strands coarsen and the pores in aerogel shift from predominantly mesoporous to macroporous state with corresponding reduction in compressive modulus. The block copolymer surfactant also slows down gelation and coarsens the polyimide strands but only weakly affects the compressive modulus of the aerogels.

Synthesis of Novel Periodic Mesoporous Organosilicas Containing 1,4,5,8-Naphthalenediimides within the Pore Walls and Their Reduction To Generate Wall-Embedded Free Radicals.

Novel periodic mesoporous organosilicas (PMOs) containing 1,4,5,8-Naphthalenediimide (NDI) chromophores as an integral part of the pore walls were synthesized in acidic conditions, in the presence of inorganic tetraethyl orthosilicate, using triblock copolymer surfactant Pluronic P-123 as a template. The NDI precursor, the bridged silsesquioxane N, N'-bis(3-triethoxysilylpropyl)-1,4,5,8-naphthalenediimide, was synthesized by reaction of 1,4,5,8-naphthalenetetracarboxylic dianhydride with excess 3-aminopropyltriethoxysilane. A series of samples containing up to 19% (weight %) of NDI were prepared (the materials were labeled PMONDIs). 13C and 29Si solid-state nuclear magnetic resonance revealed that the NDI moiety was intact in the PMONDIs and efficiently grafted to the silica network. Samples with up to 16% NDI load presented an ordered two-dimensional-hexagonal mesoscopic structure, according to small-angle X-ray scattering, transmission electron microscopy, and nitrogen adsorption isotherms. Fluorescence spectra of the PMONDIs showed excimer formation upon excitation, suggesting high flexibility of the organic moieties. Reduction of PMONDIs with aqueous sodium dithionite led to the formation of wall-embedded NDI anion radicals, as observed by the appearance of new visible/near-infrared absorption bands. The PMONDIs were also shown to be efficient photocatalysts in the degradation of sulfadiazine, an antibiotic selected here as a model pollutant, which is usually present in water bodies and wastewater.

Quality by design approach to optimize the formulation variables influencing the characteristics of biodegradable intramuscular in-situ gel loaded with alendronate sodium for osteoporosis.

There are many challenges facing the use of alendronate sodium for the treatment of osteoporosis such as low bioavailability of 0.6% and oesophageal ulceration with bleeding. Due to the aforementioned limitation, the main objective of this research is to utilize a statistical experimental design in the formulation and optimization of alendronate in the form of controlled release biodegradable intramuscular in-situ gel. A Box–Behnken experimental design employing Statgraphics® software was used to develop an optimized in-situ gel formulation and to estimate the effects of Poly-DL-lactide-coglycolide as a primary polymer, the copolymer polycaprolactone, and lipid surfactant capryol 90. Every system was evaluated for gellation character, and in vitro release. As a novel technique for evaluation of the in-situ gel, in-vivo biodegradability rate was estimated in rats. Pharmacokinetic parameters were assessed in rabbits. The results indicated a significant effect of the copolymer and lipid surfactant on initial burst, and a significant effect of the primary and copolymer on drug percentage released. The optimum formulation showed a 5% initial burst, an in-vivo biodegradability rate estimated at 8% every seven days in rats, and the pharmacokinetic evaluation revealed that alendronate sodium mean residence time extended to 102 days in rabbits. In conclusion, the optimum biodegradable intramuscular in-situ gel formulations is a promising approach for providing higher bioavailability, extended release for more than three months, with elimination of esophageal side effects.

Mass transfer of molybdenum in L35 + sodium sulfate + H2O aqueous two-phase system with a packed column

Abstract The mass transfer characteristics of molybdenum in a packed extraction column using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer surfactant (L35) + sodium sulfate + H2O aqueous two-phase system was studied. The hold up of dispersed phase (eD) and the overall volumetric mass transfer coefficient of the dispersed phase (KDa) were measured with three kinds of packings, such as ceramic rasching rings, metal θ rings and glass springs under different conditions. The experimental results showed that the hold up of dispersed phase increases with increasing the flow rate of the dispersed phase, and decreases with the increase of the tie line length (TLL), and increases as increasing the void fraction of the packings. The mean residence time and the Peclet number of the dispersed phase decrease, showing that the axial diffusion extent of the dispersed phase become more serious with increasing the rate of dispersed phase and TLL, and increase with the increase of the void fraction of packing bed according to the sequence of ceramic raschig rings – glass springs – metal θ rings. The overall volumetric mass transfer coefficient of dispersed phase increases with the increase of the rate of dispersed phase and continuous phase and the specific area of three kinds of packings, and decreases with increasing TLL and operating temperature. The mass transfer resistance of two phases is not disregarded.

Expanded Kinetic Control for Persistent Micelle Templates with Solvent Selection

The precision control of nanoscale materials remains a challenge for the study of nanostructure-performance relationships. Persistent micelle templates (PMT) are a kinetic-controlled self-assembly approach that decouples pore and wall control. Here, block copolymer surfactants form persistent micelles that maintain constant template size as material precursors are added, despite the shifting equilibrium dimensions. Earlier PMT demonstrations were based upon solvent mixtures where kinetic rates were adjusted with the amount of water cosolvent. This approach is however limited because ever-higher water contents can lead to secondary porosity within the material walls. Herein, we report an improved method to regulate the PMT kinetics via the majority solvent. This enables a new avenue for the expansion of the PMT window to realize templated materials with a greater extent of tunability. In addition, we report a new small-angle X-ray scattering (SAXS)-based log-log analysis method to independently test the micelle-templated series for consistency with the expected lattice expansion with an increasing material:template ratio. The PMT window identified by the log-log analysis of the SAXS data agreed well with independent scanning electron microscopy measurements. The combination of improved micelle control with solvent selection along with SAXS validation will accelerate the development of a myriad of nanomaterial applications.

Swollen mixed Pluronic surfactant micelles as templates for mesoporous nanotubes with diverse bridged-organosilica frameworks

Bridged-organosilica nanotubes with a variety of bridging groups (methylene, ethylene, ethenylene, phenylene and p-xylylene) were synthesized using swollen mixtures of Pluronic triblock copolymer surfactants as micellar templates. The mixtures consisted of Pluronic F127 surfactant (EO106PO70EO106) with long poly(ethylene oxide), PEO, blocks, which help prevent the formation of consolidated structures, and another Pluronic with shorter PEO blocks and higher poly(propylene oxide) content, which promote swelling and the cylindrical micelle morphology. In the presence of toluene as a swelling agent, the use of Pluronic P123 (EO20PO70EO20) in the mixture allowed us to readily generate organosilica nanotubes, but the products were often contaminated, sometimes substantially, with large nanospheres and other impurities. On the other hand, the use of Pluronic P104 (EO27PO61EO27) instead of Pluronic P123 typically afforded nanotube products of significant purity. The nanotube morphology was well preserved upon the surfactant removal via extraction or calcination, even though the resulting nanotubes were often more clustered. The nanotubes exhibited high surface areas and uniform inner diameters in the range from ∼12 to 21 nm, depending on the composition and synthesis conditions. Our results indicate that the swollen mixed Pluronic surfactant templates provide an unprecedented access to mesoporous bridged-organosilica nanotubes.

Copolymer surfactant catalyzed membrane sealing linked to reduction in interfacial tension

Copolymer surfactant catalyzed membrane sealing linked to reduction in interfacial tension

Evolution of tar ball aggregates in Caspian Sea: Implications of connectionist tools linked with image analysis

Intensive petroleum activities in the Caspian Sea lead to a considerable oil pollution in the various parts of this region. Tar balls stranded on the south coast of the Caspian Sea evidently cause (and accelerate) this serious environmental threat. In this study, a poloxamine copolymeric surfactant is used to agglomerate tar balls in a system containing the solvent, antisolvent, and Caspian Sea tar balls. This research work is conducted to determine the cumulative size distribution of tar balls in the presence of a poloxamine copolymer. The evolution of tar ball aggregates is experimentally and theoretically investigated and the steady‐state size distribution of the tar balls is estimated by Back Propagation Artificial Neural Network (ANN‐BP) and a new evolutionary algorithm, called Imperialist Competitive Algorithm (ICA). The average size of tar ball aggregates increases with time and reaches a maximum value. It then declines and eventually approaches a steady‐state condition so that an almost constant size for the particles is attained. The statistical analysis shows a good agreement between the predicted values (obtained by the neural network combined with ICA, known as ANN‐ICA) and the real data for the steady‐state size distribution of the aggregates. This research study can considerably help to further understand evolution of tar balls (that hit the beaches) and consequently to find effective and economical ways for tar balls removal from the beaches. © 2018 American Institute of Chemical Engineers Environ Prog, 37: 1901–1907, 2018

Surfactant Copolymer Annealing of Chemically Permeabilized Cell Membranes.

Structural breakdown of the cell membrane is a primary mediator in trauma induced tissue necrosis. When membrane disruption exceeds intrinsic membrane sealing processes, biocompatible multi-block amphiphilic copolymer surfactants such as Poloxamer 188 (P188) have been found to be effective in catalyze or augment sealing. Although in living cells copolymer induced sealing of membrane defects has been detected by changes in membrane transport properties, it has not been directly imaged. In this project we used Atomic force microscopy (AFM) to directly image saponin permeabilized and poloxamer sealed plasma membranes of monolayer cultured MDCK and 3T3 fibroblasts. AFM image analysis resulted in the density and diameter ranges for membrane indentations per 5×5 μm area. For control, saponin lysed, and P188 treatment of saponin lysed membranes, the supra-threshold indentation density was 3.6 ± 2.8, 13.8 ± 6.7, and 4.9 ± 3.3/cell, respectively. These results indicated that P188 catalyzed reduction in size of AFM indentations which correlated with increase cell survival. This evidence confirm that biocompatible surfactant P188 augment natural cell membrane sealing capability when intrinsic processes are incapable alone.

Role of Surface Tension in Gas Nanobubble Stability Under Ultrasound.

Shell-stabilized gas nanobubbles have recently captured the interest of the research community for their potential application as ultrasound contrast agents for molecular imaging and therapy of cancer. However, the very existence of submicron gas bubbles (especially uncoated bubbles) has been a subject of controversy in part due to their predicted Laplace overpressure reaching several atmospheres, making them supposedly thermodynamically unstable. In addition, the backscatter resulting from ultrasound interactions with nanoparticles is not predicted to be readily detectable at clinically relevant frequencies. Despite this, a number of recent reports have successfully investigated the presence and applications of nanobubbles for ultrasound imaging. The mechanism behind these observations remains unclear but is thought to be, in part, influenced heavily by the biophysical properties of the bubble-stabilizing shell. In this study, we investigated the effects of incorporating the triblock copolymer surfactant, Pluronic, into the lipid monolayer of nanobubbles. The impact of shell composition on membrane equilibrium surface tension was investigated using optical tensiometry, using both pendant drop and rising drop principles. However, these techniques proved to be insufficient in explaining the observed behavior and stability of nanobubbles under ultrasound. Additionally, we sought to investigate changes in membrane surface tension (surface pressure) at different degrees of compression (analogous to the bubble oscillations in the ultrasound field) via Langmuir-Blodgett experiments. Results from this study show a significant decrease ( p < 0.0001) in the nanobubble equilibrium surface tension through the incorporation of Pluronic L10, especially at a ratio of 0.2, where this value decreased by 28%. However, this reduction in surface pressure was seen only for specific compositions and varied with monolayer structure (crystalline phase or liquid-crystalline packing). These results indicate a potential for optimization wherein surface pressure can be maximized for both contraction and expansion phases with the proper lipid to Pluronic balance and microstructure.

Effects of nonionic surfactant and salts on the interactions between oppositely charged star-shaped copolymer and ionic surfactant in aqueous solutions

The interaction between star-shaped copolymer poly(2-(dimethylamino)ethyl methacrylate-b-2-(2-methoxyethoxy)ethyl methacrylate) (CDPDPM) and anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solutions are investigated by using fluorescence and dynamic light scattering (DLS) techniques. The effects of nonionic surfactant dodecyl β-D-maltopyranoside (C12G2) and salts including inorganic salt ammonium bromide (NH4Br) and organic salt tetra-n-butylammonium bromide (Bu4NBr) on the interaction between CDPDPM and SDS have been explored systematically. The results have suggested that SDS molecules can bind on CDPDPM by electrostatic interaction between the positively charged CDPDPM and negatively charged SDS and thus weaken the binding ability of CDPDPM to water molecules. CDPDPM exhibits temperature-responsive aggregation behavior in aqueous solution gradually with the increase of SDS concentration and the lower critical solution temperature (LCST) decreases correspondingly. The introduction of nonionic surfactant C12G2 changes the interaction between CDPDPM and SDS significantly by participate the formation of complexes and the stability of the CDPDPM/SDS complexes declines leading to the chance of forming larger complexes is deprived at higher temperature. The addition of NH4Br to the CDPDPM/SDS system can retard the binding of SDS on the polymer chains because of electrostatic shielding. Correspondingly, LCST is higher and the formed aggregates are smaller. For CDPDPM/Bu4NBr/SDS system, the phenomenon is similar to that of the CDPDPM/C12G2/SDS system. This should be attributed to the nature of Bu4N+, possesses not only positive charges but also certain hydrophobicity, and thus Bu4N+ has the ability to participate and facilitate the formation of SDS micelles. Obviously, the LCST of the mixed system can be tailored by adjusting the system composition on purpose.