Triblock Micelles Research Articles

Precisely Prepared Hierarchical Micelles of Polyfluorene-block-Polythiophene-block-Poly(phenyl isocyanide) via Crystallization-Driven Self-Assembly.

The precise preparation of hierarchical micelles is a fundamental challenge in modern materials science and chemistry. Herein, poly(di-n-hexylfluorene)-block-poly(3-tetraethylene glycol thiophene) (poly(1m-b-2n)) diblock copolymers and polyfluorene-block-polythiophene-block-poly(phenyl isocyanide) triblock copolymers were synthesized using a one-pot process via the sequential addition of corresponding monomers using a Ni(II) complex as a single catalyst for living/controlled polymerization. The crystallization-driven self-assembly of amphiphilic conjugated poly(1m-b-2n) led to the formation of nanofibers with controlled lengths and narrow dispersity. The block copolymers exhibited white, yellow, and red emissions in different self-assembly states. By using uniform poly(1m-b-2n) nanofibers as seeds, introducing the polyfluorene-block-polythiophene-block-poly(phenyl isocyanide) triblock polymer as a unimer in the seed growth process, and adjusting the structure of the poly(phenyl isocyanide) block and the polarity of self-assembly solvent, A-B-A triblock micelles, multiarm branched micelles, and raft micelles were prepared.

Precisely Prepared Hierarchical Micelles of Polyfluorene‐block‐Polythiophene‐block‐Poly(phenyl isocyanide) via Crystallization‐Driven Self‐Assembly

The precise preparation of hierarchical micelles is a fundamental challenge in modern materials science and chemistry. Herein, poly(di‐n‐hexylfluorene)‐block‐poly(3‐tetraethylene glycol thiophene) (poly(1m‐b‐2n)) diblock copolymers and polyfluorene‐block‐polythiophene‐block‐poly(phenyl isocyanide) triblock copolymers were synthesized using a one‐pot process via the sequential addition of corresponding monomers using a Ni(II) complex as a single catalyst for living/controlled polymerization. The crystallization‐driven self‐assembly of amphiphilic conjugated poly(1m‐b‐2n) led to the formation of nanofibers with controlled lengths and narrow dispersity. The block copolymers exhibited white, yellow, and red emissions in different self‐assembly states. By using uniform poly(1m‐b‐2n) nanofibers as seeds, introducing the polyfluorene‐block‐polythiophene‐block‐poly(phenyl isocyanide) triblock polymer as a unimer in the seed growth process, and adjusting the structure of the poly(phenyl isocyanide) block and the polarity of self‐assembly solvent, A‐B‐A triblock micelles, multiarm branched micelles, and raft micelles were prepared.

Bacteria-responsive programmed self-activating antibacterial hydrogel to remodel regeneration microenvironment for infected wound healing.

There is still an urgent need to develop hydrogels with intelligent antibacterial ability to achieve on-demand treatment of infected wounds and accelerate wound healing by improving the regeneration microenvironment. We proposed a strategy of hydrogel wound dressing with bacteria-responsive self-activating antibacterial property and multiple nanozyme activities to remodel the regeneration microenvironment in order to significantly promote infected wound healing. Specifically, pH-responsive H2O2 self-supplying composite nanozyme (MSCO) and pH/enzyme-sensitive bacteria-responsive triblock micelles encapsulated with lactate oxidase (PPEL) were prepared and encapsulated in hydrogels composed of L-arginine-modified chitosan (CA) and phenylboronic acid-modified oxidized dextran (ODP) to form a cascade bacteria-responsive self-activating antibacterial composite hydrogel platform. The hydrogels respond to multifactorial changes of the bacterial metabolic microenvironment to achieve on-demand antibacterial and biofilm eradication through transformation of bacterial metabolites, and chemodynamic therapy enhanced by nanozyme activity in conjunction with self-driven nitric oxide (NO) release. The composite hydrogel showed 'self-diagnostic' treatment for changes in the wound microenvironment. Through self-activating antibacterial therapy in the infection stage to self-adaptive oxidative stress relief and angiogenesis in the post-infection stage, it promotes wound closure, accelerates wound collagen deposition and angiogenesis, and completely improves the microenvironment of infected wound regeneration, which provides a new method for the design of intelligent wound dressings.

Phase behavior of medium-length hydrophobically associating PEO-PPO multiblock copolymers in aqueous media

HypothesisThe micellization of block copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) is driven by the dehydration of PPO at elevated temperatures. At low concentrations, a viscous solution of isolated micelles is obtained, whereas at higher concentrations, crowding of micelles results in an elastic gel. Alternating PEO-PPO multiblock copolymers are expected to exhibit different phase behavior, with altered phase boundaries and thermodynamics, as compared to PEO-PPO-PEO triblock copolymers (Pluronics®) with equal hydrophobicity, thereby proving the pivotal role of copolymer architecture and molecular weight. ExperimentsMultiple characterization techniques were used to map the phase behavior as a function of temperature and concentration of PEO-PPO multiblock copolymers (ExpertGel®) in aqueous solution. These techniques include shear rheology, differential and adiabatic scanning calorimetry, isothermal titration calorimetry and light transmittance. The micellar size and topology were studied by dynamic light scattering. FindingsMultiblocks have lower transition temperatures and higher thermodynamic driving forces for micellization as compared to triblocks due to the presence of more than one PPO block per chain. With increasing concentration, the multiblock copolymers in solution gradually evolve into a viscoelastic network formed by soluble bridges in between micellar nodes, whereas hairy triblock micelles jam into liquid crystalline phases resembling an elastic colloidal crystal.

Synthesis of pH-Sensitive Macromolecular Micelles from Amphiphilic Star Copolymers for Drug Delivery

Stimuli-responsive copolymers are a significant class of smart materials extensively studied for drug delivery systems. Two novel amphiphilic four-arm star copolymers poly(ε-caprolactone)-b-poly(hydroxyethyl methacrylate) (4sPCL-b-PHMEA) and poly(ε-caprolactone)-b-poly(diethylaminoethyl methacrylate)-b-poly(hydroxyethyl methacrylate (4sPCL-b-PDEAM-b-PHEMA) with pH-responsive were designed and synthesized by a combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The structure of the copolymers and the particle size of macromolecular micelles were investigated by FT-IR and DLS, and the controlled release kinetics of two copolymer micelles was detected using adriamycin (DOX), a hydrophobic antitumor drug. The results showed that, the both micelles have appropriate particle size and can be used for DOX carrier, the DLC of 4sPCL-b-PHEMA and 4sPCL-b-PDEAM-b-PHEMA micelles were 21.30% and 27.25%, respectively. The release process showed that, comparing to the diblock star copolymer, triblock star copolymer had more significant pH-sensitivity. The cumulative release percentage of DOX in triblock micelles gradually increased with the decrease of pH. The cumulative release percentage of 14 h at pH 2.2 was about 80%, which had significant pH-sensitivity. A pH-sensitive four-arm star copolymer was synthesized, which can be used as drug delivery system for further research.

Synthesis, self-assembly, biodegradation and drug delivery of polyurethane copolymers from bio-based poly(1,3-propylene succinate)

A series of environmentally-friendly bio-based poly(1,3-propylene succinate) diols (bio-PPS) with different average molecular weights (Mn) were synthesized from bio-based 1,3-propanediol (bio-PDO) and bio-based succinic acid (bio-SA). With the employment of bio-PPS as a hydrophobic block and poly(ethylene glycol) (PEG) as a hydrophilic segment, the well-defined amphiphilic triblock and multi-block polyurethane (PU) copolymers with the urethane linkages between the blocks were synthesized and characterized. The chemical structures and molecular weights of these block PU copolymers were confirmed by proton nuclear magnetic resonance (1H NMR), Fourier transform infrared (FT-IR) spectrum, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). With the Mn of bio-PPS blocks increasing from 1.40 to 8.93 kg/mol, the degree of hydrogen bonding in the PUs reduced significantly, and the glass transition temperature increased from −42.8 to −35.4 °C and from −40.1 to −33.1 °C for triblock and multi-block copolymers, respectively. Transmission electron microscopy (TEM) images revealed that both triblock and multi-block PU copolymers could spontaneously self-assemble into near-spherical core-shell micelles in aqueous solution. With the increasing bio-PPS content in the copolymers, the sizes of triblock micelles from dynamic light scattering (DLS) measurement varied from 17 to 64 nm, and the critical micelle concentration (CMC) changed from 7.22 to 0.77 mg/L. For the multi-block series, the micelle sizes increased from 24 to 71 nm and the CMC values decreased from 2.85 to 1.79 mg/L. The enzymatic degradation of the micelles for 8 weeks under the physiological environment revealed that hydrophilic PEG segments could be detached from the main chain of triblock micelles, and the degradation mainly occurred at the ester group of bio-PPS blocks in the multi-block ones. Micelles with lower bio-PPS content and multi-block architecture degraded faster during the enzymatic degradation process. A controlled release profile was observed for the doxorubicin (DOX)-loaded micelles, more than 40% and 50% DOX were released after 75 h from triblock and multi-block micelles, respectively. Moreover, the addition of lipase could accelerate the DOX release from the micelles. Cytotoxicity test proved that the PU micelles were nontoxic, while the DOX loaded micelles showed concentration-dependent cytotoxicity to HeLa cells, suggesting its potential application in the drug delivery system.

Compositions of Anticancer Drug with Micellar Nanocarriers and Their Cytotoxicity

Asymmetric diblock (DBC) and triblock (TBC) copolymers contained biocompatible chemically complementary polyacrylamide and poly(ethylene oxide) (PAAm-b-PEO-b-PAAm) or its monomethyl ether (MEPEO-b-PAAm), and also partially hydrolyzed triblock copolymer derivative (TBChydr) were used to create micelles of a special type. The micelles obtained are characterized by small CMCs and large values of the Gibbs micellization energy, thus indicating a high stability of DBC, TBC and TBChydr micelles in aqueous solutions and the capabilities of their use to encapsulate and deliver poorly soluble and/or toxic drugs in living organism. Morphological features and size of DBC and TBC micelles were determined by TEM. The electron images demonstrated spherical micelles of a polymolecular type, monomolecular type and separate micelle aggregates. TBC and TBChydr micelles were used to examine in vitro anticancer activity of their compositions with doxorubicin (Dox). The created micelle systems showed the enhanced cytotoxicity as compared to individual Dox against murine leukemia cells of L1210 line, murine transformed fibroblasts of L929 line and human T-leukemia cells of Jurkat line and allow to achieve a high efficacy at low Dox concentrations (0,1÷3 µg·cm-3) that opens the great prospects for essential decrease in drug dose at chemotherapy.

PLGA-PEG-PLGA triblock copolymeric micelles as oral drug delivery system: In vitro drug release and in vivo pharmacokinetics assessment

Poly (d,l-lactide-co-glycolide)-poly (ethylene glycol)-poly (d,l-lactide-co-glycolide) triblock copolymers (PLGA-PEG-PLGA) has been proven to be desirable for anti-cancer drug delivery by intravenous administration. But till now there is no report of developing this micelle as a sustained oral formulation for cancer therapy. 3β-acetoxy-urs-12-en-28-oic acid hexamethylenediamine (US597), a derivative of natural product ursolic acid has been developed as a novel cancer metastasis chemopreventive agent by us. Herein, we developed a new oral dosage formulation of PLGA-PEG-PLGA tri-block micelles loaded with US597 (US597@micelles). US597@micelles was prepared by a double emulsion solvent evaporation method, and characterized in regards to mean diameter (<100nm), drug loading (25.9–28.5%), zeta potential (5.76–10.65mV) and encapsulation efficiency (55.7–74.3%), respectively. In vitro, US597@micelles could ameliorate sustained drug release, inhibit cell proliferation by inducing apoptosis (46.6% of late apoptosis), and influence the integrity of nuclei and mitochondrial on HepG2. Moreover, in vivo pharmacokinetic study by UPLC/MS/MS method demonstrated better absorption, metabolism and elimination characters of US597@micelles as an oral dosage form (Cmax=53±49ng/mL, t1/2=8.716±7.033h) over free US597 (Cmax=14±11ng/mL, t1/2=16.433±8.821h). In conclusion, PLGA-PEG-PLGA micelles as a promising oral drug delivery system are able to improve the bioavailability and efficacy of US597 in cancer therapy.

Comparison of Gel Relaxation Times and End-Block Pullout Times in ABA Triblock Copolymer Networks

The gel relaxation times of two different poly[styrene-b-(ethylene-alt-propylene)-b-styrene] (SEPS) ABA triblock copolymers in squalane at various concentrations has been measured by rheology. These relaxation times were compared with the results of previous time-resolved small-angle neutron scattering (TR-SANS) experiments, which measured chain exchange kinetics in SEP diblock and SEPS triblock micelles in squalane. The gels relaxed up to four orders of magnitude faster than expected based on the chain exchange measurements of equivalent diblock polymers. By accounting for two factors—a bias toward shorter end-block lengths in the gel relaxation, and a reduction in the energy barrier to chain pullout caused by the triblock architecture—a model is constructed that reconciles the surprisingly short gel relaxation times with the chain exchange times measured via TR-SANS.

Bioreducible poly(2-ethyl-2-oxazoline)–PLA–PEI-SS triblock copolymer micelles for co-delivery of DNA minicircles and Doxorubicin

The co-delivery of minicircle DNA (mcDNA) and small anti-cancer drugs via stimuli-sensitive nanocarriers is a promising approach for combinatorial cancer therapy. However, the simultaneous loading of drugs and DNA in nanosized delivery systems is remarkably challenging. In this study we describe the synthesis of triblock copolymer micelles based on poly(2-ethyl-2-oxazoline)–poly(L-lactide) grafted with bioreducible polyethylenimine (PEOz–PLA-g–PEI-SS) for co-delivery of supercoiled (sc) mcDNA vectors and Doxorubicin (Dox). These amphiphilic carriers take advantage of non-fouling oxazolines to confer biological stability, of PLA to provide a hydrophobic core for drug encapsulation and of bioreducible PEI-SS to provide mcDNA complexation and an on-demand stimuli-responsive release. The obtained results show that mcDNA-loaded micelleplexes penetrate into in vitro tumor spheroid models with specific kinetics and exhibit a higher gene expression when compared to non-bioreducible nanocarriers. Moreover, in vivo bioluminescence imaging showed that gene expression is detected up to 8days following mcDNA-micelles intratumoral administration. Furthermore, drug–gene co-delivery in PEOz–PLA-g–PEI-SS carriers was verified by successful encapsulation of both Dox and mcDNA with high efficacy. Moreover, dual-loaded micelleplexes presented significant uptake and a cytotoxic effect in 2D cultures of cancer cells. The co-delivery of mcDNA-Dox to B16F10-Luciferase tumor bearing mice resulted in a reduction in tumor volume and cancer cells viability. Overall, such findings indicate that bioreducible triblock micelles are efficient for focal delivery in vivo and have potential for future application in combinatorial DNA-drug therapy.

Cationic triblock copolymer micelles enhance antioxidant activity, intracellular uptake and cytotoxicity of curcumin

The aim of the present study was to develop curcumin loaded cationic polymeric micelles and to evaluate their loading, preservation of curcumin antioxidant activity and intracellular uptake ability. The micelles were prepared from a triblock copolymer consisting of poly(ϵ-caprolactone) and very short poly(2-(dimethylamino) ethyl methacrylate) segments (PDMAEMA9–PCL70–PDMAEMA9). The micelles showed monomodal size distribution, mean diameter of 145nm, positive charge (+72mV), critical micellar concentration around 0.05g/l and encapsulation efficiency of 87%. The ability of the micellar curcumin to scavenge the ABTS radical and hypochlorite ions was higher than that of the free curcumin. Confocal microscopy revealed that the uptake of curcumin by chronic myeloid leukemia derived K-562 cells and human multiple myeloma cells U-266 was more intensive when curcumin was loaded into the micelles. These results correlated with the higher cytotoxicity of the micellar curcumin compared to free curcumin. Intraperitoneal treatment of Wistar rats indicated that PDMAEMA–PCL–PDMAEMA copolymer, comprising very short cationic chains, did not change the levels of malondialdehyde and glutathione in livers indicating an absence of oxidative stress. Thus, PDMAEMA–PCL–PDMAEMA triblock micelles could be considered efficient and safe platform for curcumin delivery.

Poly(2-ethyl-2-oxazoline)–PLA-g–PEI amphiphilic triblock micelles for co-delivery of minicircle DNA and chemotherapeutics

The design of nanocarriers for the delivery of drugs and nucleic-acids remains a very challenging goal due to their physicochemical differences. In addition, the reported accelerated clearance and immune response of pegylated nanomedicines highlight the necessity to develop carriers using new materials. Herein, we describe the synthesis of amphiphilic triblock poly(2-ethyl-2-oxazoline)–PLA-g–PEI (PEOz–PLA-g–PEI) micelles for the delivery of minicircle DNA (mcDNA) vectors. In this copolymer the generally used PEG moieties are replaced by the biocompatible PEOz polymer backbone that assembles the hydrophilic shell. The obtained results show that amphiphilic micelles have low critical micellar concentration, are hemocompatible and exhibit stability upon incubation in serum. The uptake in MCF-7 cells was efficient and the nanocarriers achieved 2.7 fold higher expression than control particles. Moreover, mcDNA-loaded micelleplexes penetrated into 3D multicellular spheroids and promoted widespread gene expression. Additionally, to prove the concept of co-delivery, mcDNA and doxorubicin (Dox) were simultaneously encapsulated in PEOz–PLA-g–PEI carriers, with high efficiency. Dox–mcDNA micelleplexes exhibited extensive cellular uptake and demonstrated anti-tumoral activity. These findings led us to conclude that this system has a potential not only for the delivery of novel mcDNA vectors, but also for the co-delivery of drug–mcDNA combinations without PEG functionalization.

Synthesis of dual thermoresponsive ABA triblock copolymers by both living cationic vinyl polymerization and RAFT polymerization using a dicarboxylic RAFT agent

To elucidate a difference of micelles formed from AB di- and ABA tri-block copolymers, PMOVE–PNIPAM–PMOVE triblock copolymers were synthesized by both living cationic polymerization of MOVE and RAFT polymerization of NIPAM using a dicarboxylic RAFT agent, where MOVE is 2-methoxyethyl vinyl ether, NIPAM is N-isopropylacrylamide. The ABA triblock copolymers consist of cationically polymerizable monomer (A), MOVE, and radically polymerizable monomer (B), NIPAM. The key to success in the triblock copolymerization is to utilize a dicarboxylic RAFT agent/SnBr4 initiation system for living cationic polymerization. The cationic polymerization was simultaneously initiated from two protons per one dicarboxylic RAFT agent. After the cationic polymerization, the polymerization was quenched and then the RAFT carboxylate counter anion was concurrently recovered at ca. 86% efficiency, followed by the RAFT polymerization. The resulting PMOVE–PNIPAM–PMOVE triblock copolymers contain two thermoresponsive blocks. The resulting block copolymers reversibly formed or deformed micellar assemblies in water. When the chain length of the core-forming block, PNIPAM, is increased, larger micelles were invariably obtained. The triblock micellar size was larger than that of the corresponding diblock micelle. The micelles at the concentrated solution formed physical gel, and the minimum gelation concentration of the triblock micelles was lower than that of the corresponding diblock micelles.

Solubilization of Aromatic Hydrocarbons in Ethylene Oxide‐Propylene Oxide Triblock Micelles: Location of Solubilizate and its Effect on Micelle Size from 2D NMR and Scattering Techniques

AbstractThe solubilization of benzene and toluene in micellar solutions and the effects on the micellization and micelle size of ethylene oxide‐propylene oxide triblock copolymers were investigated by dynamic light scattering (DLS), small angle neutron scattering (SANS), and 2D NMR spectroscopy. The copolymeric surfactants have the same size as the middle hydrophobic polypropylene oxide block (Mol. Wt. 3250) and varying polyethylene oxide end blocks (30, 40 and 50%). The solubilization and the properties of the micelles in the presence of the solubilizates were investigated; the results reveal that the more hydrophobic copolymer showed better solubilization. The cloud points of the copolymers decreased in the presence of oils; the depression in the cloud point is due to the formation of an electron donor–acceptor complex. DLS shows that the effect of benzene is dominated at high oil concentration. SANS data show that the micelles remain spherical in shape and that the micellar core size does not change with higher benzene concentration; observed changes in the low scattering vector region could be because of some small amount of benzene clusters formed at higher benzene concentration. Finally, the locus of solubilization of the oils in the copolymer micelles was determined via 2D NMR experiments. In all cases, significant nuclear Overhauser effect spectroscopy (NOESY) cross peaks were observed that appeared to correlate well with the expected loci of these solubilizates in micelles. Hence, the noninvasive NOESY technique provides important information on the location of the aromatic solubilizates in these copolymer micelles that depends on the structure of the oils.

Formation mechanism and morphology of mesoporous SBA-16 type silica particles prepared with the triblock copolymer surfactant PEO 140PPO 39PEO 140

SEM micrographs of mesoporous SBA-16 type silica spheroidal microparticles prepared with the triblock copolymer surfactant PEO 140PPO 39PEO 140 between 80 and 125 °C and under different acid concentrations (HCl 0.2, 0.4 and 0.8 M), indicate that they are formed of coalesced nanoparticles. The coalescence degree is shown to increase with the temperature and with the presence of the co-surfactant cetyltrimethylammonium bromide (CTMABr), whereas the reverse trend is observed at high acidity. The nanoparticles formation from the initial triblock micelles and the silica source (TEOS) was followed in solution by dynamic light scattering (DLS) before the flocculation step (phase separation corresponding to the formation of micron-sized liquid particles by aggregation and fusion of the silica coated micelles). The variation of the scattered intensity and of the hydrodynamic diameter could be related to the TEOS hydrolysis degree leading to the formation of polycondensed siliceous species in the hydrophilic corona of the nanoparticles (composite colloids). Depending on the synthesis conditions, four types of nanoparticles could be defined according to the “hardness” of the siliceous species, which is related to their polycondensation degree and their distribution inside the corona of the nanoparticles. The morphology and texture of the resulting materials will depend on the type of nanoparticles and on the temperature at the phase separation (flocculation). In the absence of CTMABr, three kinds of materials are obtained: gel-like materials (low siliceous species hardness and low temperature), microparticles of mesoporous silica (medium hardness and medium temperature), blocks of aggregated nanoparticles (high hardness and high temperature). In the presence of CTMABr which acts like a buffer for the siliceous species hardness, well coalesced microparticles of mesoporous silica are obtained independently on the temperature and acidity conditions.

Characterization and comparison of diblock and triblock amphiphilic copolymers of poly(δ-valerolactone)

Three types of pegylated amphiphilic copolymers of poly(δ-valerolactone) (PVL) were copolymerized with methoxy poly(ethylene glycol) (MePEG) and poly(ethylene glycol) (PEG4000 and PEG10,000), respectively. Pegylation of PVL allowed copolymers possessing amphiphilic property and efficiently self-assembled to form micelles with a low critical micelle concentration (CMC) in the range of 10−7–10−8M. The average molecular weight of copolymers was in the range of 10,000–20,000 Da, and the polydispersity of copolymers was about 1.7–1.8. Higher mobility of low molecular weight PEG (i.e., MePEG and PEG4000) than high molecular weight PEG10,000 allowed valerolactone ring opening more efficient in terms of PVL/MePEG and PVL/PEG4000 copolymers possessing longer chain length in hydrophobic domain. Pegylated PVL with low CMC and triblock structure was preferred to encapsulate drug during micelle formation. Although all of these amphiphilic copolymers exhibited controlled release character, the micelles formed by triblock copolymer possessed a more stable core-shell conformation than that by diblock copolymer, and resulted in the release of drug from triblock micelles slower than that from diblock micelles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1836–1841, 2006

Association Characteristics of Copolymer Micelles in a Solvent Selective for the Middle Block

A combination of static and dynamic light-scattering studies provides a clear picture concerning the temperature-dependent association behavior of a long chain triblock copolymer-(t-Bs) 385 S 770 (t-Bs) 385 (S and t-BS represent styrene and tert-butylstyrene, respectively) in N,N-dimethylacetamide, a selective solvent for the middle block. The so-called anomalous micellization has been consistently observed between the unimer and micelle regions, which can be ascribed to the copolymer composition heterogeneity. The self-assembly process is enthalpy-driven, yielding closed association structures in the form of flower-like micelles, but only at or below room temperatures. A much lower critical micelle temperature or a much higher critical micelle concentration as well as the reduced association number is characteristic of the triblock micelles as compared with the diblock copolymer micelles of the same composition. The entropy penalty associated with the loop formation largely reduces the micellization ability.