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This paper provides a review of the literature on the use of Pluronic (R) triblock copolymers for drug encapsulation over the last 10 years. A special focus is given to the progress of drug delivery systems (e.g., micelles, liposomes, micro/nanoemulsions, hydrogels and nanogels, and polymersomes and niosomes); the beneficial aspects of Pluronic (R) triblock copolymers as biological response modifiers and as pharmaceutical additives, adjuvants, and stabilizers, are also discussed. The advantages and limitations encountered in developing site-specific targeting approaches based on Pluronic-based nanostructures in cancer treatment are highlighted, in addition to inno-vative examples for improving tumor cytotoxicity while reducing side effects. info:eu-repo/semantics/publishedVersion

International audience; Hydrogels are deployed widely in all areas of regenerative medicine, including bioprinting. The transport and mechanical properties exhibited by hydrogel assemblies are controlled by their organization and hierarchical assembly. This paper points out the role of the nanoscale size and ordering of hydrophobic cross-linked domains on the mechanical and degradation properties of three-dimensional (3D) printed amphiphilic hydrogels. A series of six poly(propylene fumarate)-block-poly(ethylene glycol)-block-poly(propylene fumarate) (PPF-b-PEG-b-PPF) ABA triblock copolymers were synthesized by varying both the water-soluble PEG block and the cross-linkable hydrophobic terminal PPF block lengths. Self-assembled hydrogels were formed by dissolving these amphiphilic PPF-b-PEG-b-PPF copolymers in water and covalently cross-linking the PPF units via digital light processing (DLP) additive manufacturing. Differential scanning calorimetry (DSC), in situ diffuse reflectance infrared spectroscopy (DRIFTS-IR) measurements, small-angle neutron scattering (SANS), and compressive measurements highlight how structural properties correlate with mechanical properties within this hydrogel system. Finally, swelling and in vitro degradation tests showed the influence of the nanoscale ordering on the degradation timescale.

Amphiphilic copolymers with poly (alkyl acrylate) as hydrophobic and poly (acrylic acid) (AA) as hydrophilic block have been synthesised. The alkyl chain was varied from butyl to dodecyl, thereby varying systematically the polarity of the hydrophobic block whose length was between 35 and 70, while the PAA block had ~ 100 units. Such relatively short amphiphiles should equilibrate quickly in aqueous solution, and their corresponding self-assembly properties were characterised by means of critical micelle concentration (cmc) determination. Detailed information regarding the aggregate structures was obtained by static light scattering (SLS) and small angle neutron scattering (SANS). This could be correlated with the molecular architecture of the copolymers and the degree of ionisation of the PAA block. Generally, it is found that the aggregation numbers become smaller upon fully charging the PAA head group and only for dodecyl acrylate really well-defined micellar aggregates are formed. This means that the extent of hydrophobicity of the alkyl acrylate block and its length determine in a clear fashion the propensity for micelle formation and the mass and aggregation number of the formed micelles.

Poly(dimethylsiloxane) (PDMS) elastomer coatings containing an amphiphilic hydrolyzable diblock copolymer additive were prepared and their potential as marine antifouling and antiadhesion materials was tested. The block copolymer additive consisted of a PDMS first block and a random poly(trialkylsilyl methacrylate (TRSiMA, R = butyl, isopropyl)-co-poly(ethyleneglycol) methacrylate (PEGMA) copolymer second block. PDMS-b-TRSiMA block copolymer additives without PEGMA units were also used as additives. The amphiphilic character of the coating surface was assessed in water using the captive air bubble technique for measurements of static and dynamic contact angles. The attachment of macro- and microorganisms on the coatings was evaluated by field tests and by performing adhesion tests to the barnacle Amphibalanus amphitrite and the green alga Ulva rigida. All the additive-based PDMS coatings showed better antiadhesion properties to A. amphitrite larvae than to U. rigida spores. Field tests provided meaningful information on the antifouling and fouling release activity of coatings over an immersion period of 23 months.

In this research, the development and investigation of novel nanoobjects based on biodegradable random polypeptides and synthetic non-degradable glycopolymer poly(2-deoxy-2-methacrylamido-d-glucose) were proposed as drug delivery systems. Two different approaches have been applied for preparation of such nanomaterials. The first one includes the synthesis of block-random copolymers consisting of polypeptide and glycopolymer and capable of self-assembly into polymer particles. The synthesis of copolymers was performed using sequential reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerization (ROP) techniques. Amphiphilic poly(2-deoxy-2-methacrylamido-d-glucose)-b-poly(l-lysine-co-l-phenylalanine) (PMAG-b-P(Lys-co-Phe)) copolymers were then used for preparation of self-assembled nanoparticles. Another approach for the formation of polypeptide-glycopolymer particles was based on the post-modification of preformed polypeptide particles with an oxidized glycopolymer. The conjugation of the polysaccharide on the surface of the particles was achieved by the interaction of the aldehyde groups of the oxidized glycopolymer with the amino groups of the polymer on particle surface, followed by the reduction of the formed Schiff base with sodium borohydride. A comparative study of polymer nanoparticles developed with its cationic analogues based on random P(Lys-co-d-Phe), as well as an anionic one—P(Lys-co-d-Phe) covered with heparin––was carried out. In vitro antitumor activity of novel paclitaxel-loaded PMAG-b-P(Lys-co-Phe)-based particles towards A549 (human lung carcinoma) and MCF-7 (human breast adenocarcinoma) cells was comparable to the commercially available Paclitaxel-LANS.

A series of anionic homopolymers, poly(sodium 2-(acrylamido)-2-methyl-1-propanesulfonate) (PAMPS) and amphiphilic copolymers of AMPS and sodium 11-(acrylamido)undecanoate (AaU), both block (PAMPS75-b-PAaUn), and random (P(AMPSm-co-AaUn)), were synthesized and their antiviral activity against Zika virus (ZIKV) was evaluated. Interestingly, while the homopolymers showed limited antiviral activity, the copolymers are very efficient antivirals. This observation was explained considering that under the conditions relevant to the biological experiments (pH 7.4 PBS buffer) the macromolecules of these copolymers exist as negatively charged (zeta potential about −25 mV) nanoparticles (4–12 nm) due to their self-organization. They inhibit the ZIKV replication cycle by binding to the cell surface and thereby blocking virus attachment to host cells. Considering good solubility in aqueous media, low toxicity, and high selectivity index (SI) of the PAMPS-b-PAaU copolymers, they can be considered promising agents against ZIKV infections.

A series of nanoparticles (NPs) with a hydrodynamic radius from 20 to 100 nm in PBS was developed over the solubilization of hydrophobic dye methyl pheophorbide a (chlorin e6 derivative) by amphiphilic copolymers of N-vinylpyrrolidone with (di)methacrylates. Photophysical properties and biological activity of the NPs aqueous solution were studied. It was found that the dye encapsulated in the copolymers is in an aggregated state. However, its aggregation degree decreases sharply, and singlet oxygen quantum yield and the fluorescence signal increase upon the interaction of these NPs with model biological membranes—liposomes or components of a tissue homogenate. The phototoxic effect of NPs in HeLa cells exceeds by 1.5–2 times that of the reference dye chlorin e6 trisodium salt—one of the most effective photosensitizers used in clinical practice. It could be explained by the effective release of the hydrophobic photosensitizer from the NPs into biological structures. The demonstrated approach can be used not only for the encapsulation of hydrophobic photosensitizers for PDT but also for other drugs, and N-vinylpyrrolidone amphiphilic copolymers show promising potential as a modern platform for the design of targeted delivery vehicles.

Nanosized systems of DOX with antitumor activity on the base of micelle-like particles of amphiphilic thermosensitive copolymers of N-vinylpyrrolidone (VP) with triethylene glycol dimethacrylate (TEGDM), and N-vinylpyrrolidone and methacrylic acid (MAA) with TEGDM were explored. They were investigated in aqueous solutions by electron absorption spectroscopy, dynamic light scattering and cyclic voltammetry. Experimental data and quantum-chemical modeling indicated the formation of a hydrogen bond between oxygen-containing groups of monomer units of the copolymers and H-atoms of OH and NH2 groups of DOX; the energies and H-bond lengths in the considered structures were calculated. A simulation of TDDFT spectra of DOX and its complexes with the VP and TEGDM units was carried out. Electrochemical studies in PBS have demonstrated that the oxidation of encapsulated DOX appeared to be easier than that of the free one, and its reduction was somewhat more difficult. The cytotoxicity of VP-TEGDM copolymer compositions containing 1, 5 and 15 wt% DOX was studied in vitro on HeLa cells, and the values of IC50 doses were determined at 24 and 72 h of exposure. The copolymer compositions containing 5 and 15 wt% DOX accumulated actively in cell nuclei and did not cause visual changes in cell morphology.

This paper deals with the development of polymeric nanocarriers based on amphiphilic copolymers of N-vinyl-2-pyrrolidone and acrylic acid of various molecular weights synthesized through the AIBN-initiated radical copolymerization of N-vinyl-2-pyrrolidone and acrylic acid in the presence of n-octadecyl mercaptan. The structure of the copolymers is characterized by 1Н NMR, 13С NMR, IR and MALDI-TOF MS spectroscopy. It is shown that the length of the hydrophilic block defines the size of the nanoaggregates while impacting the steric stabilization efficiency and the probability of the interchain hydrogen bond formation. The hydrogen bonds formation between the residues of N-vinyl-2-pyrrolidone and acrylic acid is in agreement with the reduction of the ζ-potential of the nanoaggregates and the critical aggregation concentrations upon increasing the molecular weight. The presence of acrylic acid residues in the amphiphilic macromolecules leads to a higher affinity for doxorubicin and slow partial release of doxorubicin bonded with the aggregates’ corona, which is helpful for reducing its cardiac toxicity. Nanoaggregates with a paclitaxel-loaded hydrophobic core are obtained, showing the possibility of dual loading. The amphiphilic copolymers of N-vinyl-2-pyrrolidone and acrylic acid containing an n-octadecyl thio end group are thus promising candidates for combination cancer therapy with immobilized anti-cancer drugs, paclitaxel, and doxorubicin.

This article presents the evaluation of diblock and triblock poly(ethylene glycol)-b-poly(1,3-trimethylene carbonate) amphiphilic copolymers (PEG-PTMCs) as excipients for the formulation of long-acting injectables (LAIs). Copolymers were successfully synthesised through bulk ring-opening polymerisation. The concomitant formation of PTMC homopolymer could not be avoided irrespective of the catalyst amount, but the by-product could easily be removed by gel chromatography. Pure PEG-PTMCs undergo faster erosion in vivo than their corresponding homopolymer. Furthermore, these copolymers show outstanding stability compared to their polyester analogues when formulated with amine-containing reactive drugs, which makes them particularly suitable as LAIs for the sustained release of drugs susceptible to acylation.

RESUMEN En años recientes hubo un auge del uso de terapias génicas para el tratamiento de enfermedades de gran incidencia, como el cáncer. Generalmente, estas se basan en la liberación de material genético como plásmidos, en el núcleo celular, con lo cual se corrige una función o se induce la producción de proteínas deficientes a nivel fisiológico. Para llevar a cabo la terapia génica se requiere de vectores capaces de encapsular el material genético y garantizar su entrega en el núcleo celular. Los polímeros catiónicos sintéticos han llamado la atención como vectores, debido a su capacidad de condensar ácidos nucleicos para formar partículas que los protegen de la degradación enzimática y facilitan su captación celular. La polietilenimina y el polimetacrilato de N, N-dimetilaminoetilo son los polímeros catiónicos más eficaces para la administración génica. Sin embargo, estos requieren modificaciones químicas específicas para eliminar o disminuir algunas limitaciones tales como su alta citotoxicidad y baja biodegradabilidad. En este artículo se analizan algunas de estas modificaciones, enfocándose en avances recientes en el desarrollo de copolímeros anfifílicos como precursores de nanopartículas usadas como vectores génicos. SUMMARY During recent years, the use of genetic therapies has taken relevance in the treatment of high-incidence diseases such as cancer. Usually, they are based on the release of genetic material, as plasmids, into the cell nucleus, which corrects a function or induces the production of a deficient protein at the physiological level. To carry out gene therapy, vectors capable of encapsulating the genetic material and guaranteeing its delivery in the target cell nucleus are required. Synthetic cationic polymers have attracted great attention as vectors due to their ability to condense nucleic acids to form particles that protect them from enzymatic degradation and facilitate their cellular uptake. Polyethylenimine and poly (N, N-dimethylaminoethyl methacrylate) are the most effective cationic polymers for gene delivery. However, these polymers require specific chemical modifications to either avoid or diminish their high cytotoxicity and low biodegradability. This review analyzes some of these modifications, focusing on recent advances in the development of amphiphilic copolymers as precursors of nanoparticles used as gene vectors.

Due to unique chelating and macrocyclic effects, crown ether compounds exhibit wide application prospects. They could be introduced into amphiphilic copolymers to provide new trigger mode for drug delivery. In this work, new amphiphilic random polymers of poly(lipoic acid-methacrylate-co-poly(ethylene glycol) methyl ether methacrylate-co-N-isopropylacrylamide-co-benzo-18-crown-6-methacrylamide (abbrev. PLENB) containing a crown ether ring and disulphide bond were synthesized via RAFT polymerization. Using the solvent evaporation method, the PLENB micelles were formed and then used to load substances, such as doxorubicin hydrochloride (DOX) and gold nanoparticles. The results showed that PLENB exhibited a variety of lowest critical solution temperature (LCST) in response to the presence of different ions, such as K+, Na+ and Mg2+. In particular, the addition of 150 mM K+ increased the LCST of PLENB from 31 to 37 °C and induced the release of DOX from the PLENB@DOX assemblies with a release rate of 99.84% within 12 h under 37 °C. However, Na+ and Mg2+ ions could not initiate the same response. Furthermore, K+ ions drove the disassembly of gold aggregates from the PLENB-SH@Au assemblies to achieve the transport of Au NPs, which is helpful to construct a K+-triggered carrier system.

Microbial biofilms are known to support a number of human infections, including those related to medical devices. This work is focused on the development of novel dual-function amphiphilic random copolymers to be employed as coatings for medical devices. Particularly, copolymers were obtained by polymerization of an antimicrobial cationic monomer (bearing tertiary amine) and an antioxidant and antimicrobial hydrophobic monomer (containing hydroxytyrosol, HTy). To obtain copolymers with various amphiphilic balance, different molar ratios of the two monomers were used. 1H NMR and DSC analyses evidenced that HTy aromatic rings are able to interact with each other leading to a supra-macromolecular re-arrangement and decrease the copolymer size in water. All copolymers showed good antioxidant activity and Fe2+ chelating ability. Cytotoxicity and hemolytic tests evidenced that the amphiphilic balance, cationic charge density and polymer size in solution are key determinants for polymer biocompatibility. As for the antimicrobial properties, the lowest minimal inhibitory concentration (MIC = 40 μg/mL) against Staphylococcus epidermidis was shown by the water-soluble copolymer having the highest HTy molar content (0.3). This copolymer layered onto catheter surfaces was also able to prevent staphylococcal adhesion. This approach permits not only prevention of biofilm infections but also reduction of the risk of emergence of drug-resistant bacteria. Indeed, the combination of two active compounds in the same polymer can provide a synergistic action against biofilms and suppress reactive species oxygen (ROS), known to promote the occurrence of antibiotic resistance. © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Background Polyglycerol is an attractive hydrophilic building block of amphiphilic copolymers for biomedical and pharmaceutical applications due to its biocompatibility, facile chemical modification, and anti-fouling activity. Herein we introduce theranostic nanoemulsions incorporating anti-cancer therapeutic and contrast agents using linear polyglycerol-poly(ε-caprolactone) diblock copolymers (PG-b-PCL). Lipiodol is used as a core oil that dissolves paclitaxel and serves as a contrast agent for computer tomography (CT). Methods PG-b-PCL is synthesized by three-step processes: polymerization of ethoxyethyl glycerol ether; ring-opening polymerization of ε-caprolactone; and deprotection of the PEEGE block. In vitro cytotoxicity of the polyglycerolated lipiodol nanoemulsions is demonstrated using HeLa ovarian cancer cells. The applicability of the prepared nanoemulsions as a contrast agent for CT imaging is also evaluated using micro-CT. Results Three compositions of PG-b-PCL with different block lengths are synthesized to prepare nanoemulsions. The polyglycerolated lipiodol nanoemulsions exhibit excellent anti-cancer activities, while placebo nanoemulsions have no significant cytotoxicity under the same condition. Micro-CT imaging of the nanoemulsions confirms the ability of nanoemulsions as a contrast agent. Conclusions This study suggests that PG-b-PCL is a promising polymeric emulsifier for effective stabilization and surface functionalization of drug delivery nanocarriers for therapeutic and imaging agents. Electronic supplementary material The online version of this article (10.1186/s40824-017-0108-4) contains supplementary material, which is available to authorized users.

The new polymeric systems for delivery in cosmetology applications were prepared using self-assembling amphiphilic graft copolymers. The synthesis based on &ldquo, click&rdquo, chemistry reaction included grafting of azide-functionalized polyethylene glycol (PEG-N3) onto multifunctional polymethacrylates containing alkyne units. The latter ones were obtained via atom transfer radical polymerization (ATRP) of alkyne-functionalized monomers, e.g., ester of hexynoic acid and 2-hydroxyethyl methacrylate (AlHEMA) with methyl methacrylate (MMA), using bromoester-modified retinol (RETBr) as the initiator. Varying the content of alkyne moieties adjusted by initial monomer ratios of AlHEMA/MMA was advantageous for the achievement of a well-defined grafting degree. The designed amphiphilic graft copolymers P((HEMA-graft-PEG)-co-MMA), showing tendency to micellization in aqueous solution at room temperature, were encapsulated with arbutin (ARB) or vitamin C (VitC) with high efficiencies (&gt, 50%). In vitro experiments carried out in the phosphate-buffered saline solution (PBS) at pH 7.4 indicated the maximum release of ARB after at least 20 min and VitC within 10 min. The fast release of the selected antioxidants and skin-lightening agents by these micellar systems is satisfactory for applications in cosmetology, where they can be used as the components of masks, creams, and wraps.

Novel amphiphilic copolymers have been synthesized based on a biocompatible poly(hydroxyethylaspartamide) (PHEA) backbone, bearing both anchoring groups for gold nanoparticles, such as thiols and disulfide, and conjugable moieties, such as amino groups, the latter as points suitable for appending further functional agents. The strategy was to functionalize α,β-poly[(N-2- hydroxyethyl)-d,l-aspartamide] (PHEA) with PEG2000-NH2 and with ethylenediamine (EDA) obtaining a partially pegylated copolymer with a large number of pendant primary amino groups. A fraction of the latter was conjugated with molecules bearing terminal thiol moieties such as 12-mercaptododecanoic acid (MDA) and disulfide groups such as lipoic acid (LA), obtaining the two amphiphilic derivatives PHEA-PEG2000-EDA-MDA (PPE-MDA) and PHEA-PEG2000-EDA-LA (PPE-LA), which also proved intrinsically able to self-assemble in polymeric micelles. The two copolymers efficiently coated gold nanostars (GNSs, size ∼40 nm), wrapping around the surface increasing only slightly the hydrodynamic diameter (reaching ∼45 nm), imparting them stability and a pH-switchable surface charge, due to the unreacted amino groups. Remarkably, the poor solvation and the huge steric hindrance experienced by the amino groups lowers the observed logarithmic protonation constants to 5.6-5.7. In vitro experiments demonstrated that PPE-MDA and PPE-LA copolymers have an intrinsic excellent biocompatibility in both the human brain neuroblastoma (SH-SY5Y) and human bronchial epithelial (16-HBE) cell lines. Interaction of the same cell lines with "nude" GNS and GNS coated with PPE-LA was also studied, disclosing a completely satisfactory biocompatibility of the latter. © 2013 American Chemical Society.

A novel bifunctional bis(hemiacetal ester) chain transfer agent (CTA), 1,2-bis[1-(4-cyano-4-methyl-1-oxo-4-(phenylcarbonothioylthio)butanoxy)ethoxy] ethane (CMPTBEE), appropriate for the reversible addition-fragmentation chain transfer (RAFT) polymerization of methacrylate monomers, was successfully synthesized and used for the preparation of a family of 10 hydrolyzable end-linked polymer (co)networks. The family comprised three methyl methacrylate (MMA) homopolymer networks with different degrees of polymerization, 100, 150, and 200, and seven end-linked amphiphilic polymer conetworks of MMA and 2-(dimethylamino)ethyl methacrylate (DMAEMA) with a constant overall degree of polymerization equal to 200 but various compositions and architectures. The agreement of the experimentally measured molecular weights with the theoretically expected ones and the low molecular weight dispersities of the linear precursors to the (co)networks indicated successful control of the polymerization. All (co)networks were characterized in terms of their sol fraction and in terms of their degree of swelling in THF. The value of the former was found in the range between 4 and 50%, whereas that of the latter was around 13%. The presence of the hemiacetal ester groups allowed the hydrolysis of the most hydrophilic, DMAEMA-rich conetworks. The resistance to hydrolysis of the other (co)networks could be attributed to the large hydrophobic blocks surrounding and protecting from hydrolysis the hemiacetal ester groups of the CTA residue in the conetworks. © 2012 American Chemical Society. 45 19 7890 7899 Cited By :22

Soft nanogels are submicron-sized hydrophilic structures engineered from biocompatible polymers possessing the characteristics of nanoparticles as well as hydrogels, with a wide array of potential applications in biotechnology and biomedicine, namely, drug and protein delivery. In this work, nanogels were obtained using the physical self-assembly technique or ‘layer-by-layer’ which is based on electrostatic interactions. Liposomal vesicles were coated with alternating layers of hyaluronic acid and chitosan yielding a more viscous hydrogel formulation that previously reported core-shell nanoparticulate suspension, via simply modifying the physico-chemical characteristics of the system. Structural features, size, surface charge, stability and swelling characteristics of the nanogel were studied using scanning electron microscopy and dynamic light scattering. With a specific cranio-maxillofacial application in mind, the hydrogel was loaded with recombinant human (rh) bone morphogenetic protein-7, also known as osteogenic protein-1 or rhOP-1 and release was monitored over an extended period of 60 days. This preliminary study reports promising results on the formulation of a novel core-shell polymeric nanogel.

We described the fabrication of functional and microstructured surfaces from polymer blends by spray deposition. This simple technique offers the possibility to simultaneously finely tune the microstructure as well as the surface chemical composition. Whereas at lower polymer concentration, randomly distributed surface micropatterns were observed, an increase of the concentration leads to significant changes on these structures. On the one hand, using pure homopolystyrene fiber-like structures were observed when the polymer concentration exceeded 30 mg/mL. Interestingly, the incorporation of 2,3,4,5,6-pentafluorostyrene changed the morphology, and, instead of fibers, micrometer size particles were identified at the surface. These fluorinated microparticles provide superhydrophobic properties leading to surfaces with contact angles above 165°. Equally, in addition to the microstructures provided by the spray deposition, the use of thermoresponsive polymers to fabricate interfaces with responsive properties is also described. Contact angle measurements revealed variations on the surface wettability upon heating when blends of polystyrene and polystyrene-b-poly(dimethylaminoethyl methacrylate) are employed. Finally, the use of spraying techniques to fabricate gradient surfaces is proposed. Maintaining a constant orientation, the surface topography and thus the contact angle varies gradually from the center to the edge of the film depending on the spray angle., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)., The authors gratefully acknowledge support from the Consejo Superior de Investigaciones Científicas (CSIC). This work was equally financially supported by the Ministerio de Economía y Competitividad (MINECO) through MAT2013-47902-C2-1-R (JRH). Nelson Vargas Alfredo thanks the support for postdoctoral research from the CONACYT (CN: 251394).

Four families of hyperbranched amphiphilic block copolymers of styrene (Sty, less polar monomer) and 2-vinylpyridine (2VPy, one of the two more polar monomers) or 4-vinylpyridine (4VPy, the other polar monomer) were prepared via self-condensing vinyl reversible addition-fragmentation chain transfer polymerization (SCVP-RAFT). Two families contained 4VPy as the more polar monomer, one of which possessing a Sty-b-4VPy architecture, and the other possessing the reverse block architecture. The other two families bore 2VPy as the more polar monomer and had either a 2VPy-b-Sty or a Sty-b-2VPy architecture. Characterization of the hyperbranched block copolymers in terms of their molecular weights and compositions indicated better control when the VPy monomers were polymerized first. Control over the molecular weights of the hyperbranched copolymers was also confirmed with the aminolysis of the dithioester moiety at the branching points to produce linear polymers with number-average molecular weights slightly greater than the theoretically expected ones, due to recombination of the resulting thiol-terminated linear polymers. The amphiphilicity of the hyperbranched copolymers led to their self-assembly in selective solvents, which was probed using atomic force microscopy and dynamic light scattering, which indicated the formation of large spherical micelles of uniform diameter. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1310–1319

In this study we present our efforts to homo- and co-polymerize, using group transfer polymerization (GTP), a dialkyl diester of itaconic acid, a naturally-derived unsaturated dicarboxylic acid. The monomer employed, di(n-butyl) itaconate (DBI), did not seem to polymerize by GTP to high conversion, but it displayed the remarkable ability to contribute to the polymer 1-2 units, suggesting that it would make a good end-functionalizing reagent for GTP. This was demonstrated by preparing by GTP hydrophilic homopolymers, and in situ adding to them DBI which is hydrophobic. The thus-obtained amphiphilic end-functionalized copolymers formed in water small micelles, whose aggregation numbers and radii of gyration were characterized using small-angle neutron scattering. © 2010 Elsevier Ltd. All rights reserved. 47 4 816 822 Cited By :9

14 pages; International audience; We consider a symmetrical poly(styrene-stat-(acrylic acid))-block-poly(acrylic acid), i.e., PSAA-b-PAA, dibloc copolymer, with a molar fraction AA ) 0.42 of acrylic acid, in the more hydrophobic PSAA statistical first block. We investigate its structural behavior at constant concentration in water using small-angle neutron scattering (SANS) by varying (i) the ionization of its acrylic acid motives via the pH by adding NaOH and (ii) the ionic strength of the solution by increasing the NaCl salt concentration cS. We present the resulting morphological phase diagram {pH, cS}, in which we identified two different lamellar phases presenting a smectic long-range order at small-to-intermediate ionizations and a spherical phase with a liquidlike shortrange order at larger ionization. In the low-ionization regime, the first lamellar phase comprises a water-free PSAA lamellar core surrounded by a dense poly(acrylic acid) brush swollen with water. Its mostly hydrophobic core still being glassy, this phase is unable to reorganize and is frozen in. A detailed analysis of the SANS data shows the osmotic nature of the polyelectrolyte brush, in which the Na+ counterions are confined so that local electroneutrality is satisfied. Above the pH at which the PSAA statistical block starts ionizing, the PSAA lamellar core melts. The second lamellar phase identified then comprises a PSAA core thinner than that of the frozen-in previous phase, implying a significant increase of the core/water interface and a decrease of the brush surface density. The transition from the first lamellar phase to the second one can be quantitatively shown to result from the balance between the two contributions: (i) the extra interfacial cost between the thinner core and water and (ii) the associated gain in entropy of mixing for the counterions confined inside the brush. At even higher ionization, the diblocks finally form spherical objects with a very small, pHdependent aggregation number and reach an apparent onset of self-association. When the highest ionization investigated is reached, the cores of these final spherical core-shell objects are found to contain a significant amount of water. We thereby demonstrate that at constant concentration, pH, and ionic strength both trigger a transition from frozen to molten hydrophobic phases as well as unexpected morphological transitions.