Spherical Micellar Aggregates Research Articles

Synthesis, Optimization and Molecular Self-Assembly Behavior of Alginate-g-Oleylamine Derivatives Based on Ugi Reaction for Hydrophobic Drug Delivery.

To achieve the optimal alginate-based oral formulation for delivery of hydrophobic drugs, on the basis of previous research, we further optimized the synthesis process parameters of alginate-g-oleylamine derivatives (Ugi-FOlT) and explored the effects of different degrees of substitution (DSs) on the molecular self-assembly properties of Ugi-FOlT, as well as the in vitro cytotoxicity and drug release behavior of Ugi-FOlT. The resultant Ugi-FOlT exhibited good amphiphilic properties with the critical micelle concentration (CMC) ranging from 0.043 mg/mL to 0.091 mg/mL, which decreased with the increase in the DS of Ugi-FOlT. Furthermore, Ugi-FOlT was able to self-assemble into spherical micellar aggregates in aqueous solution, whose sizes and zeta potentials with various DSs measured by dynamic light scattering (DLS) were in the range of 653 ± 25~710 ± 40 nm and -58.2 ± 1.92~-48.9 ± 2.86 mV, respectively. In addition, RAW 264.7 macrophages were used for MTT assay to evaluate the in vitro cytotoxicity of Ugi-FOlT in the range of 100~500 μg/mL, and the results indicated good cytocompatibility for Ugi-FOlT. Ugi-FOlT micellar aggregates with favorable stability also showed a certain sustained and pH-responsive release behavior for the hydrophobic drug ibuprofen (IBU). Meanwhile, it is feasible to control the drug release rate by regulating the DS of Ugi-FOlT. The influence of different DSs on the properties of Ugi-FOlT is helpful to fully understand the relationship between the micromolecular structure of Ugi-FOlT and its macroscopic properties.

Alkanediol–hexafluoroisopropanol amphiphilic supramolecular solvent: Fabrication, characterization, and application potential for doping control of hormones and metabolic modulators in human urine

A novel amphiphilic supramolecular solvent (SUPRAS) was developed by hexafluoroisopropanol (HFIP)-induced self-assembly of 1,2-hexanediol in an aqueous matrix. Its application potential in multiclass determination was assessed by extracting from urine 10 prohibited hormones and metabolic modulators (log P from 2.38 to 7.57) listed by the World Anti-Doping Agency (WADA). This SUPRAS is stably formed across a wide pH range (2–12) and is unaffected by salt concentrations (<10 % g mL−1 of NaCl), and it has a higher density than water. The dehydration and hydrogen bonding ability of HFIP, as well as hydrophobic interactions between alkanediols, dominates the formation of the SUPRAS. The nanostructure of the SUPRAS, composed of 1,2-hexanediol, HFIP, and a high content of water (>25 %, w/w), forms large spherical micellar aggregates (10–100 μm) that exhibit amphiphilic properties. A 1,2-hexanediol-HFIP SUPRAS-based liquid-phase microextraction (LPME) method for detection of selected prohibited drugs in urine coupled with liquid chromatography–tandem mass spectrometry (LC-MS/MS) was established, optimized, and validated. The method showed fast extraction time (30 s of vortex) and low solvent consumption (160 μL of organic solvent). Under the optimal conditions (7 % g mL−1 of 1,2-hexanediol, 10 % v/v of HFIP), the SUPRAS achieved high extraction efficiencies (>80 %) and an enrichment factor of 6.0, with minimal matrix effects for all analytes due to its high amphiphilicity and large surface area. The method demonstrated excellent linearity (R ≥0.9909), with method limits of detection ranging from 0.018 to 0.18 ng mL−1 and method limits of quantitation ranging from 0.060 to 0.60 ng mL−1, which are well below the minimum required performance levels set by authorities. Furthermore, the intra- and inter-day relative recoveries for spiked human urine samples varied in the ranges of 90.3–121 % and 88.1–119 %, respectively, with relative standard deviations less than 13 % and 19 %, respectively. This SUPRAS-based LPME method proves to be simple, highly efficient, and eco-friendly, and it has promising potential for multiclass determination in doping control.

Novel approach for tuning micellar characteristics and rheology of a sulfate-free anionic surfactant sodium cocoyl glycinate

Amino acid based mild and sulfate-free anionic surfactant, sodium cocoyl glycinate (SCGLY) forms spherical micellar aggregates in water. The mixed micellar characteristics of SCGLY has been studied in the presence of nonionic surfactants like cocamide diethanolamine (CDEA) and lauryl glucoside (LG). The ternary aqueous system of SCGLY/CDEA/LG depicts higher surface activity and stronger aggregation ability compared to corresponding single or binary surfactant systems as revealed by tensiometry. The effect of pH (5.5–6.5) and total surfactant concentration (14–18 wt%) on thickening of SCGLY/CDEA/LG system is studied by rheology measurements. The presence of CDEA/LG amid charged SCGLY head group shrinks the electrostatic repulsion and induces sphere-to-rod micellar transition depicting low or moderate viscosity under as-prepared neutral pH. With alteration in pH, viscosity augmented to a maximum (at pH ~5.8) followed by a viscosity decrease. This is a novel finding for mild sulfate-free SCGLY surfactant solution which otherwise is very hard to thicken. Micellar size and charge is attained by dynamic light scattering, while micellar shapes and aggregation numbers are determined by small-angle neutron scattering (SANS) measurements. Moreover, foaming behavior (foamability and stability) and mildness property (zein solubility) of SCGLY can be optimized as per the necessity in the presence of CDEA and LG. This work might prove to be an innovative approach to tune the micellar characteristics and rheology of amino acid based surfactant formulation which could be extremely beneficial for cost-effective, thickener-free, sulfate-free surfactant systems used in cleansing composition with desired viscosity.

Structure and dynamics of an aqueous solution containing poly-(acrylic acid) and non-ionic surfactant octaethylene glycol n-decyl ether (C10E8) aggregates and their complexes investigated by molecular dynamics simulations.

A detailed molecular dynamics simulation study of the self-assembly, intermolecular structure and thermodynamic behavior of an aqueous solution of non-ionic surfactant octa ethylene glycol n-decyl ether (C10E8) in the presence of a non-ionic polar polymer poly(acrylic acid) PAA is presented. The aggregation number Nagg and concentration of surfactant Cs in the simulation systems were varied in the range 0.01-0.32 M and 5 < Nagg < 101 (dilute to concentrated) with a dilute polymer concentration (Cp = 0.01 M). Lamellar aggregates of non-ionic surfactant in bulk aqueous solution are shown by molecular level computations for the first time. Spherical micellar aggregates and lamellar aggregates are formed at low and high Nagg, respectively. The transition from the spherical micelle phase to the lamellar phase in a binary solution is captured for the first time. A conformational transition from coiled to extended PAA chains adsorbed on the surfactant aggregate occurs at a particular value of Nagg, commensurate with the transition from spherical micelle aggregates to anisotropic lamellar aggregates. Formation of the surfactant aggregate in binary and ternary solutions and the polymer-surfactant complex in a ternary solution is enthalpically favored. Adsorption of PAA on the surfactant aggregate surface is driven by hydrogen bonds (HBs) between carboxylic acid groups of PAA and ethylene oxide groups of C10E8. A significant number of HBs occur between polar oxygens of C10E8 and hydroxyl oxygens of PAA. The results are in agreement with the limited available experimental data on this system.

Poly(N-isopropylacrylamide)-b-Poly(L-lysine)-b-Poly(L-histidine) Triblock Amphiphilic Copolymer Nanomicelles for Dual-Responsive Anticancer Drug Delivery.

A series of ABC triblock poly(N-isopropylacrylamide)75-block-poly(L-lysine)35-block-poly(L-histidine)n (p(NIPAM)75-b-p(Lys)35-b-p(His)N) (N = 35,50,75,100) copolymer bio-conjugates were prepared by combining reversible addition-fragmentation chain transfer polymerization and fast ring-opening polymerization of N-carboxyanhydride a-amino acid using 1,3-dicyclohexylimidazolium hydrogen carbonate as a catalyst. All the resulting triblock copolymers self-assembled into spherical micellar aggregates in aqueous solution, irrespective of the chain length of the histidine block. The micellar aggregates encapsulated the anticancer drug doxorubicin (Dox) and exhibited high drug loading efficiency. Temperature and pH stimuli were applied to investigate the controlled release of Dox. The non-cytotoxic nature of the polymers was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cellular uptake of the Dox-loaded micelles revealed that the micelles successfully release Dox in cancer cells in response to pH- and temperature-induced morphological change. In-vitro studies further confirmed that the Dox-loaded triblock copolymer micelle is an excellent platform for drug delivery.

Equilibrium model for estimating micellar aggregation number from surface equation

The Aggregation Surface Equation (ASE) is attained by coupling the Gibbs adsorption equation and surface aggregation isotherm. The resulting equation can be used to study fluid-fluid interfaces in connection with the micelle formation process. This new equation contains two boundary conditions in the vicinity of the saturation region: (i) the critical micelle concentration (CMC), which corresponds to the onset of micelle formation; and (ii) the critical spherical micelle concentration (CSC) (i.e. the completion of spherical micellar aggregates). These boundary conditions, which appear within a narrow surfactant concentration range, provide the basis to calculate the average aggregation number under the assumption of constant average aggregation number and spherical micelles geometry. The resulting Surface Equation (SE) contains the maximum surface concentration of the surface monolayer, the critical micelle concentration and the micelle average aggregation number. The mass action law allows extending the ASE as a function of the free monomer, as opposed to the total or nominal surfactant concentration, which was recently performed in the STAND model (Langmuir, 32, (16), (2016), 3917-3925). This paper presents a simple and direct method to calculate the micellar average aggregation number from surface tension data and the proposed surface equation.

Preparation of Doxorubicin-Loaded Amphiphilic Poly(D,L-Lactide-Co-Glycolide)-b-Poly(N-Acryloylmorpholine) AB2 Miktoarm Star Block Copolymers for Anticancer Drug Delivery.

Owing to their unique topology and physical properties, micelles based on miktoarm amphiphilic star block copolymers play an important role in the biomedical field for drug delivery. Herein, we developed a series of AB2-type poly(D,L-lactide-co-glycolide)-b-poly(N-acryloyl morpholine) (PLGA-b-PNAM2) miktoarm star block copolymers by reversible addition–fragmentation chain–transfer polymerization and ring-opening copolymerization. The resulting miktoarm star polymers were investigated by 1H NMR spectroscopy and gel permeation chromatography. The critical micellar concentration value of the micelles increases with an increase in PNAM block length. As revealed by transmission electron microscopy and dynamic light scattering, the amphiphilic miktoarm star block copolymers can self-assemble to form spherical micellar aggregates in water. The anticancer drug doxorubicin (DOX) was encapsulated by polymeric micelles; the drug-loading efficiency and drug-loading content of the DOX-loaded micelles were 81.7% and 9.1%, respectively. Acidic environments triggered the dissociation of the polymeric micelles, which led to the more release of DOX in pH 6.4 than pH 7.4. The amphiphilic PLGA-b-PNAM2 miktoarm star block copolymers may have broad application as nanocarriers for controlled drug delivery.

Redox-Sensitive Polymer Micelles Based on CD44 and Folic Acid Receptor for Intracellular Drug Delivery and Drug Controlled Release in Cancer Therapy.

Redox-responsive ferrocene (Fc)-grafted supramolecular block copolymers functionalized with hyaluronic acid (HA-g-β-CD/Fc-polymers or HAP) or folic acid (FA-g-β-CD/Fc-polymers or FAP) were synthesized by host-guest interaction. The copolymer structures were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and gel permeation chromatography. The block copolymers self-assemble into spherical micellar aggregates in aqueous solution, and exhibit reversible redox characteristics in the presence of an oxidant and reductant. The tunable redox response was evaluated by transmission electron microscopy, ultraviolet-visible spectroscopy, cyclic voltammetry and dynamic light scattering. The micelles rapidly release DOX under oxidative and acidic condition in vitro. Furthermore, presence of HA and FA on the micelles enabled effective uptake by the CD44 and FA receptor-overexpressing cancer cells. Taken together, the redox responsive Fc-block copolymer micelles have good biocompatibility, biodegradability, low toxicity, and high selectivity, and are a highly promising drug delivery system for cancer therapy.

The effect of composition on the rheological behavior of commercial chocolates

A detailed rheological study was performed on four commercial chocolate samples containing similar solids particle sizes. Two dark chocolates with different cocoa content, a sugar free chocolate and a milk chocolate were studied. Samples were characterized by proximal composition, Differential Scanning Calorimetry, Scanning Electron Microscopy, continuous and oscillatory shear rheometry at different temperatures. The complex shear thinning behavior displayed by the samples was described by several rheological models. The Carreau model provided the best fits in the widest shear rate range. The cocoa content and total fat were the most important parameters of the sample formulation, since the degree of chocolate structuring is a function of the solids content and most rheological properties significantly depended on them. Milk chocolate samples showed a very small frequency dependency resembling the behavior of a strong gel. This type of strong gel character has not been previously reported for milk chocolate. We believe that milk proteins can act as surfactants and stabilizers, that are able to induce the formation of spherical micellar aggregates within the chocolate structure (as evidenced by SEM). At low frequencies, they play an important role in chocolate solid particle packing, helping the suspension structure to become more stable under oscillatory deformation.

Hyperbranched polylysine: Synthesis, mechanism and preparation for NIR-absorbing gold nanoparticles

The ring-opening polymerization (ROP) of N-(tetrafluoroboran ammonium)-l-lysine-N-carboxyanhydride (NH3BF4-Lys NCA) was initiated by triethylamine to prepare hyperbranched polylysine (HPlys) fluoroborate with narrow polydispersity at a low temperature. Both mass spectroscopy analysis and DFT computation evidenced that the resultant cyclic dimer mainly initiated ROP as a secondary species according to normal amine mechanism. The hyperbranched polylysine in aqueous solution existed in a unimolecular state at low concentrations, but transformed into spherical micellar aggregates at a high concentration of 5 mg/mL, as characterized by dynamic laser scattering and transmission electron microscopy. By utilizing multivalent coordination interactions between hyperbranched polylysine and gold, the plasmonic gold nanoparticles (HPlys@Au NPs) were successfully prepared in aqueous solution, which elevated the solution by 23.1 °C upon 5 min of NIR laser irradiation (808 nm, 2 W/cm2).

Cysteine-based amphiphilic peptide-polymer conjugates via thiol-mediated radical polymerization: Synthesis, self-assembly, RNA polyplexation and N-terminus fluorescent labeling for cell imaging

A water-soluble amphiphilic peptide-poly (1-vinylimidazole) [Boc-Cys (PVim)-Trp-OMe] bioconjugate is synthesized by ‘grafting from’ technique based on thiol-mediated radical polymerization. The attachment of fluorescein isothiocyanate (FITC) at the N-terminus of the peptide moiety of the bioconjugate results in the generation of fluorescent bioconjugate [FITC-Cys (PVim)-Trp-OMe]. MALDI-TOF-MS analysis confirms the attachment dipeptide moiety as well as FITC group. Owing to the amphiphilic nature, the [Boc-Cys (PVim)-Trp-OMe] bioconjugate undergoes spontaneous self-assembly into primary micelles and their subsequent secondary aggregation into spherical micellar aggregates (nanospheres) in water. The aqueous FITC-Cys (PVim)-Trp-OMe bioconjugate solution emits green light and exhibits a fluorescence emission with a maximum at 520 nm. The amphiphilicity of the fluorescent bioconjuagte molecules also triggers their self-assembly into micelles and micellar aggregates (nanospheres) with hydrophobic FITC-tagged dipeptide core and hydrophilic PVim cell in water. Further, the highly stable and non-toxic fluorescent bioconjugates are used for imaging of Chinese Hamster Ovary (CHO) cells. Finally, the polyplex formation between the untagged cationic Boc-Cys (PVim)-Trp-OMe bioconjugate and ribonucleic acid (RNA) at pH 5.5 is studied by fluorescence spectroscopy.

Self-assembly of Janus particles under shear.

We investigate the self-assembly of colloidal Janus particles under shear flow by employing hybrid molecular dynamics simulations that explicitly take into account hydrodynamic interactions. Under quiescent conditions, the amphiphilic colloids form spherical micellar aggregates of different sizes, where the solvophobic hemispheres are directed towards the core and the solvophilic caps are exposed to the solvent. When sufficiently strong shear is applied, the micelles disaggregate with a consequent decay of the average cluster size. Nonetheless, we find an intermediate shear rate regime where the balance between rearrangement and dissociation favors the growth of the aggregates. Additionally, our simulations show that clusters composed of either 6 or 13 particles are the most stable towards the shear flow due to their high geometric symmetry. Our findings open up a new range of applications for Janus particles, ranging from biotechnology to sensor systems.

Control of Self-Assembled Structure through Architecturally and Compositionally Complex Block Copolymer Surfactant Mixtures

The self-assembly of binary mixtures of architecturally and compositionally diverse surfactant-like polystyrene–poly(2-vinylpyridine) (PS–PVP) block copolymers (BCPs) in solution and in thin films has been systematically studied. PS–PVP BCPs of different molecular architecture synthesized by living anionic polymerization, including linear diblocks, triblocks, and branched star-like copolymers all having different block sizes, styrene to 2-vinylpyridine ratios, and variations in numbers of arms, were employed as constituent building blocks for the construction of advanced copolymeric ensembles. While ensembles formed from monomodal PS–PVP BCPs exhibit simple spherical aggregate structures in the PS-selective solvent toluene, aggregates created by mixing PS–PVP BCPs of different architecture display structures that include spherical, worm-like and large compound micellar aggregates. This result is attributed to the complex, architecture-induced diversity of microphase segregation in the mixed systems, where...

ATRP를 이용한 Lysine 말단기를 가진 펩타이드-고분자 하이브리드 합성

Recently, the peptide(or protein)-polymer hybrid materials (PPs) were sought in many research areas as potential building blocks for assembling nanostructures in selective solvents. In PPs, the facile routes of preparing well-defined peptide-polymer bio-conjugates and their specific activities in various applications are important issues. Our strategy to prepare the peptide-polymer hybrid materials was to combine atom transfer radical polymerization (ATRP) method with solid phase peptide synthesis. The standard solid phase peptide synthesis method was employed to prepare the PYGK (proline-tyrosine-glycine-lysine) peptide. PYGK is an analogue peptide, PFGK (proline-phenylalanine-glycine-lysine), which interacted with plasminogen in fibrinolysis. The peptide and the peptide-initiator were characterized with MALDITOF mass spectrometry and H NMR spectrometer. The peptide-polymer, pSt-PYGK was characterized by GPC, IR, H NMR spectrometer and TLC. Spherical micellar aggregates were determined by TEM and SEM. Current synthesis methodology suggested opportunities to create the well-defined peptide-polymer hybrid materials with specific binding activity.

Multicompartment micelles from silicone-based triphilic block copolymers

An amphiphilic linear ternary block copolymer was synthesised in three consecutive steps via reversible addition–fragmentation chain transfer polymerisation. Oligo(ethylene glycol) monomethyl ether acrylate was engaged as a hydrophilic building block, while benzyl acrylate and 3-tris(trimethylsiloxy)silyl propyl acrylate served as hydrophobic building blocks. The resulting “triphilic” copolymer consists thus of a hydrophilic (A) and two mutually incompatible “soft” hydrophobic blocks, namely, a lipophilic (B) and a silicone-based (C) block, with all blocks having glass transition temperatures well below 0 °C. The triphilic copolymer self-assembles into spherical multicompartment micellar aggregates in aqueous solution, where the two hydrophobic blocks undergo local phase separation into various ultrastructures as evidenced by cryogenic transmission electron microscopy. Thus, a silicone-based polymer block can replace the hitherto typically employed fluorocarbon-based hydrophobic blocks in triphilic block copolymers for inducing multicompartmentalisation.

Unprecedented Relationship Between the Size of Spherical Chiral Micellar Aggregates and Their Specific Optical Rotations

Transmission electron microscopy (TEM) images and fluorescence quenching methods indicated that lauryl ester of L-phenylalanine (LEP) and lauryl ester of L-tyrosine (LET) form spherical chiral micelles in the 50-200 mM range and their size increases with concentration. The number of molecules present in these spherical chiral aggregates varied from 80 to 160 for LEP and 80-100 for LET. The specific optical rotation, representing circular birefringence, for LEP at 405 nm and 32 °C is found to increase linearly from 37 deg cc g(-1) dm(-1) for an isolated molecule to 56 deg cc g(-1) dm(-1) for ∼200 nm size aggregate. A similar trend was found for temperatures up to 70 °C and at other visible wavelengths. A linear relation between specific optical rotation and the size of aggregate is also observed for LET. Circular dichroism, as measured in both the visible and infrared wavelength regions, however did not reveal any concentration dependent changes. The unique sensitivity uncovered for specific optical rotation as a function of the size of spherical chiral aggregates is unprecedented and opens new areas of enquiry for physical chemists.

Side-chain selenium-containing amphiphilic block copolymers: redox-controlled self-assembly and disassembly

In this paper we report the synthesis and study of a series of side-chain selenium-containing amphiphilic poly(ethylene oxide-b-acrylic acid) block copolymers PEO-b-PAA-Se. These block copolymers can self-assemble in aqueous solution and form spherical micellar aggregates. The selenide group of PEO-b-PAA-Se can change into hydrophilic selenoxide under mild oxidation of 0.1% hydrogen peroxide, leading to the disassembly of the spherical micellar aggregates. Small compounds like Nile Red can be encapsulated into the micellar aggregates and show fast release upon the addition of 0.1% hydrogen peroxide. More interestingly, the oxidation state of selenoxide can be reversed to selenide under reduction of Vitamin C, thus recovering the spherical aggregates. The reversible oxidation and reduction process shows good reversibility and can be repeated at least 7 times. It is hoped that this reversible redox controlled system may function as nanocontainers for potential application in the areas such as responsive drug delivery and anti-oxidation studies.

Photoresponsive soft materials: Synthesis and photophysical studies of a stilbene‐based diblock copolymer

AbstractAn amphiphilic diblock copolymer composed of a photoresponsive dialkoxycyanostilbene polymethacrylate and poly(ethylene oxide) (PDACS‐b‐PEO) was synthesized and its photophysical and aggregation properties were investigated. The amphiphilic nature of the polymer caused it to self‐assemble in water, and dynamic light scattering studies indicated formation of spherical aggregates with an average size of 160 nm. Atomic force microscopy images of dried films cast from solutions containing the polymer aggregates revealed supramolecular aggregates with a spherical morphology. Photoisomerization of the stilbene chromophore in PDACS‐b‐PEO on UV irradiation resulted in the destruction of the self‐assembled superstructures which could be attributed both to change in shape of the chromophore from the linear trans isomer to the bent cis isomer which would hinder self‐aggregation of the molecules and the higher dipole moment of the cis isomer leading to a reduction of the hydrophobic nature of the stilbene containing block of PDACS‐b‐PEO. It was observed that hydrophobic dyes such as curcumin could be encapsulated within the hydrophobic interior of the spherical micellar aggregates from which the encapsulated dye could be released on UV irradiation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

CdS-containing nano-assemblies of double hydrophilic block copolymers in water

Two samples of poly(sodium(sulfamate-carboxylate)isoprene)-block-poly(ethylene oxide) copolymer (SCIEO-1 and SCIEO-2) differing in molecular weight and relative length of polyelectrolyte blocks have been used as templates for the synthesis of cadmium sulfide (CdS) nanoparticles in aqueous media. The double-hydrophilic copolymer SCIEO has very high 1D charge density, and its polymer chain structure mimics that of polysaccharide heparin. It is soluble in aqueous media, but the addition of cadmium acetate (Cd(Ac)2) to its aqueous solution causes the formation of micellar aggregates with Cd2+containing insoluble cores above the threshold Cd2+ concentration. The trapped Cd2+ ions can be chemically transformed to CdS nanoparticles. The stability of hybrid SCIEO/CdS micelles depends on the ratio of PEO-to-SCI lengths: it was found that the SCIEO-2 copolymer with sufficiently long PEO block behaves as an effective stabilizer for the synthesis of CdS nanoparticles embedded in micelles, while SCIEO-1 does not. The morphology of aggregates varies with the Cd-to-SCI ratios and ranges from spherical to mixture of spherical and necklace-like micellar aggregates. A number of experimental techniques including static and dynamic light scattering, fluorescence correlation spectroscopy, atomic force and transmission electron microscopy, UV-vis, and fluorescence spectroscopy were employed for the characterization of both CdS containing hybrid micelles and embedded CdS nanoparticles.

Self-Assembly into Multicompartment Micelles and Selective Solubilization by Hydrophilic−Lipophilic−Fluorophilic Block Copolymers

Amphiphilic linear ternary block copolymers (ABC) were synthesized in three consecutive steps by the reversible addition−fragmentation chain transfer (RAFT) method. Using oligo(ethylene oxide) monomethyl ether acrylate, benzyl acrylate, and 1H,1H-perfluorobutyl acrylate monomers, the triblock copolymers consist of a hydrophilic (A), a lipophilic (B), and a fluorophilic (C) block. The block sequence of the triphilic copolymers was varied systematically to provide all possible variations: ABC, ACB, and BAC. All blocks have glass transition temperatures below 0 °C. Self-assembly into spherical micellar aggregates was observed in aqueous solution, where hydrophobic cores undergo local phase separation into various ultrastructures as shown by cryogenic transmission electron microscopy (cryo-TEM). Selective solubilization of substantial quantities of hydrocarbon and fluorocarbon low molar mass compounds by the lipophilic and fluorophilic block, respectively, is demonstrated.