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A simple and inexpensive method for ultrafast and recyclable photoRDRP (in the absence of any conventional photoinitiators or dye sensitizers) in ionic liquid is developed, yielding low dispersity poly(glycidyl methacrylate) and well-defined amphiphilic poly(glycidyl methacrylate)-b-poly(poly(ethylene glycol)methacrylate) diblock copolymers thereof. The copolymer's stimuli response has been assessed against pH and temperature changes. The absence of polymerization in the absence of light enables temporal control and paves the way for potential application in the area where precise spatiotemporal “on/off” control and resolution are desirable. DFT calculations rationalize the underlying mechanism of the polymerization.

Magnetically separable and reusable Ni–Co alloy nanoparticles were employed to achieve ambient temperature reversible deactivation radical polymerization (RDRP) of methyl acrylate (MA), for the first time, yielding well-defined PMA (at least up to 124 500 g mol−1) with a low dispersity (Đ ≤ 1.20). The controlled polymerization character of RDRP of MA was confirmed from the linear semilogarithmic plot exhibiting pseudo first order kinetics, a linear increase of the molecular weight of the polymer with monomer conversion maintaining low Đ and the synthesis of PMAs of varying molecular weights from 2200 to 124 500 g mol−1 with low Đ. In addition, linear PMA-Br was used as a macroinitiator for the synthesis of several well-defined PMA-b-poly(M) block copolymers (where “M” stands for (2-dimethylamino)ethyl methacrylate (DMAEMA), tert-butyl methylacrylate (TBMA) and 2,2,3,3,4,4,5,5-octafluoropentyl acrylate (OFPA)), with acceptable Đs (≤ 1.24), demonstrating the high chain-end fidelity of the macroinitiator. The synthesized PMA-b-PDMAEMA demonstrated dual pH- and thermo-responsive properties. Upon hydrolysis, the synthesized PMA-b-PTBMA leads to the formation of unprecedented carboxylic acid-functionalized PMA derivatives. PMA-b-POFPA copolymers with varying OFPA mol% in the copolymer led to polymers with tunable surface hydrophobicity, as revealed by the water contact angle measurements.

Recyclable Ni–Co alloy nanoparticle catalyzed synthesis of well-defined poly(methyl methacrylate) (PMMA, up to 129 500 g mol−1) with low dispersity (Đ = 1.30) via a reversible deactivation radical polymerization technique is reported. The combined advantages of easier catalyst preparation and handling, predictability, simple recovery and reusability up to multiple cycles without a notable decrease in the control over the polymerization make the process an ideal methodology for the synthesis of tailored polymers.

A novel dual pH/thermoresponsive amphiphilic poly(histidine methacrylamide)-block-hydroxyl-terminated polybutadiene-block-poly(histidine methacrylamide) (PHisMAM-b-PB-b-PHisMAM) triblock copolymer biohybrid, composed of hydrophobic PB and ampholytic PHisMAM segments, is developed via direct switching from living anionic polymerization to recyclable nanoparticle catalyst-mediated reversible-deactivation radical polymerization (RDRP). The transformation involved in situ postpolymerization modification of living polybutadiene-based carbanionic species, end-capped with ethylene oxide, into dihydroxyl-terminated polybutadiene and a subsequent reaction with 2-bromo-2-methylpropionyl bromide resulting in a telechelic ATRP macroinitiator (Br-PB-Br). Br-PB-Br was used to mediate RDRP of an l-histidine-derived monomer, HisMAM, yielding a series of PHisMAM-b-PB-b-PHisMAM triblock copolymers. The copolymer's stimuli response was assessed against pH and temperature changes. The copolymer is capable of switching among its zwitterionic, anionic, and cationic forms and exhibited unique antifouling properties in its zwitterionic form. These novel triblock copolymers are expected to be show promising potential in biomedical applications.

A new multi-stimuli responsive tryptophan-based styryl homopolymer exhibiting dual upper critical solution temperature (UCST)- and lower critical solution temperature (LCST)-type thermosensitivities under different conditions is presented. The monomer 4-vinylbenzyl N-[(tert-butoxy)carbonyl]-L-tryptophan (Boc-TrpVBz) is prepared by a simple substitution reaction followed by its subsequent RAFT polymerization to produce the poly(Boc-TrpVBz) homopolymer. Poly(Boc-TrpVBz) is not soluble in water, but is soluble in different organic solvents (such as DMSO, DMF and MeOH). An interesting upper critical solution temperature (UCST)-type turbid-to-transparent phase transition is detected for poly(Boc-TrpVBz) in mixed solvents containing any of these three solvents and a minimum percentage of water. The UCST-type cloud point is found to increase upon increasing the percentage of added water and the molecular weight of poly(Boc-TrpVBz). Furthermore, poly(Boc-TrpVBz) is soluble in water at above pH 7.5 and exhibits a lower critical solution temperature (LCST)-type transparent-to-turbid transition upon addition of tetrabutylammonium halide salts with a large organic cation. The LCST-type cloud point is variable with respect to the salt concentration and the nature of the halide ion. The deprotection of the Boc moiety of poly(Boc-TrpVBz) produces zwitterionic poly(TrpVBz) containing –NH2 and –COOH groups, which exhibits dual pH- and thermo-responsiveness in aqueous solution below pH 2. In the cases of UCST- and LCST-type transitions, the turbidity is caused by the formation of spherical polymer aggregates as observed via TEM and FESEM.

A novel triple stimuli sensitive block copolymer is prepared by magnetically separable and reusable (up to multiple cycles) Ni-Co alloy nanoparticles mediated reversible deactivation radical polymerization (RDRP) at 25 °C, that responds to changes in temperature, pH, and light. Design of this block copolymer constitutes a temperature-sensitive N-isopropylacrylamide (NIPAM), an acid-sensitive lysine methacrylamide (LysMAM), and a light responsive umbelliferone (UMB) end group. The stimuli response, in response to one stimulus as well as combinations of stimuli, has been evaluated. Responsiveness to light allows the construction of self-healing materials. Density functional theory calculations rationalize the underlying mechanism of the polymerization.

An overview on fluorinated olefin-based architectures prepared by reversible deactivation radical polymerization (RDRP) techniques and their applications is presented. Controlled syntheses of well-defined fluoropolymers are discussed as a route to prepare tailored macromolecules of various architectures, such as homopolymers, block copolymers (BCPs), graft copolymers, and star/miktoarms. Primary examples of different strategies of synthesis include (a) Iodine Transfer Polymerization (ITP), (b) Reversible Addition-Fragmentation Chain Transfer/Macromolecular Design via the Interchange of Xanthates (RAFT/MADIX) polymerization, (c) Atom Transfer Radical Polymerization (ATRP), (d) Nitroxide Mediated Polymerization (NMP), (e) Organometallic-Mediated Radical Polymerization (OMRP) and (f) Others systems (based on tellurium, cobalt and other complexes). Synthesis of BCPs and graft copolymers of vinylidene fluoride (VDF), chlorotrifluoroethylene (CTFE) and other fluorinated monomers are also discussed, as along with those synthesized via Copper(I)-catalyzed azide-alkyne cycloaddition (click chemistry). Phase behavior and self-assembly of the fluorinated block copolymers are also reported. Special attention is devoted to the applications of fluoropolymer architectures in producing thermoplastic elastomers, medical tactile sensors, fuel cells membranes, functional coatings, electroactive polymers (e.g. piezoelectric/ferroelectric/dielectric devices and actuators), high energy storage capacitors, surfactants and composites.

International audience

International audience; This article describes the synthesis and characterization of a series of well-defined block copolymers (BCPs) comprising a poly(vinyl acetate-alt-tert-butyl-2-trifluoromethacrylate) (poly(VAc-alt-MAF-TBE)) alternating copolymer segment and a homopolymer segment (PVAc, polystyrene, poly(meth)acrylate, polyacrylamide, or poly(N-vinylpyrrolidone)) using RAFT polymerization under mild conditions (at 40 °C). The abilities of four chain transfer agents (CTAs) to copolymerize VAc and MAF-TBE were compared. Recently reported as a universal RAFT CTA, cyanomethyl 3,5-dimethyl-1H-pyrazole-1-carbodithioate (CDPCD) afforded better-defined BCPs compared to O-ethyl-S-(1-methoxycarbonyl)ethyldithiocarbonate (CTA-XA), 2-cyano-2-propyl benzodithioate (CPDB), and 4-cyano-4-(2-phenylethanesulfanylthiocarbonyl)sulfanyl pentanoic acid (PETTC). While the chain extension of poly(VAc-alt-MAF-TBE)-DPCD with vinyl acetate (VAc), styrene (St), n-butyl acrylate (nBA), and dimethyl acrylamide (DMA) led to well-defined poly(VAc-alt-MAF-TBE)-b-poly(M) BCPs with acceptable dispersity values (Đ ≤ 1.36), high Đ values were observed when methyl methacrylate (MMA) and N-vinylpyrrolidone (NVP) were used to form the second block. An attempt to synthesize poly(M)-b-poly(VAc-alt-MAF-TBE) block copolymers using poly(M)-DPCD as the macroCTA led to copolymers with high Đ values (1.53–2.0).Graphical abstract: Syntheses of 2-(trifluoromethyl)acrylate-containing block copolymers via RAFT polymerization using a universal chain transfer agent

International audience; Vinylidene fluoride (VDF)-based copolymers bearing pendant trialkoxysilane groups for potential applications for coatings were synthesized via a free radical copolymerization of VDF with functional 2-trifluoromethyl acrylate cyclic carbonate monomer (MAF-cyCB), followed by introduction of silane pendant groups. MAF-cyCB was prepared from 2-trifluoromethacrylic acid with 70% overall yield. Radical copolymerization of VDF with MAF-cyCB initiated by tert-amyl peroxy-2-ethylhexanoate at varying [VDF]0/[MAF-cyCB]0 ratios led to several poly(VDF-co-MAF-cyCB) copolymers having different molar percentages of VDF (77−96%). The average molecular weights (Mns) reached up to 19 000 g mol−1 in fair to good yields (45−74%). Compositions and microstructures of all synthesized copolymers were achieved by 1H and 19F NMR spectroscopies. The resulting poly(VDF-co-MAF-cyCB) copolymers exhibited moderately high melting temperature (131−161 °C, with respect to the VDF content) while the degree of crystallinity, which reached up to 34%, decreased with increasing MAF-cyCB. Then, the pendant cyclic carbonate ester groups of the synthesized poly(VDF-co-MAF-cyCB) copolymers were quantitatively converted into novel triethoxysilane-functionalized PVDF, which could be further hydrolyzed under acidic conditions into trihydroxysilanefunctionalized PVDF. Finally, steel plates were coated with the silylated PVDF and displayed improved adhesion properties compared to those of pristine PVDF.

Background: Chemotherapeutic approaches to the control of HPV infection suffer from a lack of specificity. For most existing HPV inhibitors, the weak antiviral effects observed in cellular assays suggest that further improvements in selecting targets, in drug potency, and in bioavailability and cell uptake are required. Objective: To synthesize novel 1,3-oxazole derivatives and define their antiviral activities against the human papillomavirus (HPV) in vitro. Methods: Determination of transient replication of an HPV-11 in transfected HEK293 cells, and HPV-18 DNA amplification in an organotypic squamous epithelial raft culture of primary human keratinocytes (PHKs), and cytotoxicity assays were used. Results: Bioassays showed that the synthesized compounds 2, 4, 5, and 9 exhibited potent antiviral activity against low-risk HPV-11 (IC50 = 1.7–9.6 μM) in a transient DNA replication assay and exhibited low cytotoxicity in HEK293 cells compared to cidofovir (CDV), antiviral agent in clinical use. Selectivity indices of compounds 4 and 5 were 20–40 times greater than that of CDV. However, compounds 4 and 9 did not exhibit a significant antiviral effect against high-risk HPV-18 infections in organotypic epithelial raft cultures. Although prophylactic HPV vaccines are now available to protect against primary infections by the seven genotypes most commonly found in cervical, penile, anal and oro-pharyngeal cancers (HPV16, 18, 31, 33, 45, 52, and 58) and two genotypes (HPV6 and 11) that cause benign anogenital warts and laryngeal papillomas, they do not protect against infections by other HPV types. Moreover, individuals already infected with HPV will not benefit from the vaccines. Thus, the need for antiviral agents to treat HPV-associated diseases remains great, but few options currently exist. Conclusions: We show that substituted 1,3-oxazole derivatives are a promising structure class of chemical compounds for the development of antiviral drugs against HPV lesions.

This report describes the design and synthesis of a zwitterionic [Boc-L-methionine-(2-methacryloylethyl)]sulfoniopropanesulfonate (METMASPS) monomer derived from methionine followed by its subsequent RAFT polymerization in water to produce a zwitterionic polymer (PMETMASPS). The aqueous METMASPS monomer solution exhibits transparent to turbid and turbid to transparent transitions near to its isoelectric point (5.75) upon switching the pH from anything below 4.8 to 4.8–6.8 and from 4.8–6.8 to above 6.8. Furthermore, in the pH range of 4.8–6.8, this turbid suspension transforms into a transparent solution showing a clear upper critical solution temperature (UCST)-type phase transition. However, the zwitterionic polymer is soluble in water at any pH value ranging from 1 to 12, but its transparent aqueous solution turns into a turbid solution exhibiting a soluble–insoluble phase transition upon addition of different kosmotropic anions such as SO42−, Ct3−, H2PO4− and Ac− of the Hofmeister series. This colloidal turbid suspension containing anion becomes transparent showing a distinct UCST-type phase transition upon heating. The cloud point (Tcp) is tunable with respect to the molecular weight of the polymer and the concentration of ions as well as solution pH. Finally, the antifouling property of the as-synthesized zwitterionic PMETMASPS is studied against resistance towards a model protein, bovine serum albumin (BSA) through the monitoring of anti-aggregating behaviour via DLS and is compared with that of poly(ethylene glycol) (PEG).

International audience; The synthesis of poly(fluoroacrylate)s with tunable wettability and improved adhesion for potential applicationas functional coatings was achieved via radical copolymerization of 2,2,2-trifluoroethylα-fluoroacrylate (FATRIFE) with 2-(trifluoromethyl)acrylic acid (MAF), an adhesion-promoting monomer.These copolymerizations, initiated by tert-butyl peroxypivalate at varying comonomer feed ([FATRIFE]0/[MAF]0) ratios led to a series of poly(FATRIFE-co-MAF) copolymers with different molar compositions infair to good conversions (32–87%) depending on the MAF feed content. The microstructures of the synthesizedpoly(FATRIFE-co-MAF) copolymers were determined by 19F NMR spectroscopy. Even at MAFfeed contents higher than 50%, MAF incorporation into the copolymers was lower than 50%, since MAFdoes not undergo any homopolymerization under radical polymerization conditions. The reactivity ratiosof the (FATRIFE; MAF) monomer pair were also determined (rFATRIFE = 1.65 ± 0.07 and rMAF = 0 at 56 °C)evidencing the formation of statistical copolymers. Initiation involving a highly branched perfluorinatedradical that released a •CF3 radical enabled the demonstration of the regioselective attack of the latterradical onto the CH2 of FATRIFE. The resulting poly(FATRIFE-co-MAF) copolymers exhibited various glasstransition temperatures (Tgs) depending on their compositions. Tg values increased with increasing MAFcontents in the copolymer. In addition, their thermal stability (the temperature for 10% weight loss in air,Td10%) increased with increasing FATRIFE content in the copolymer and reached 348 °C (for that containing93 mol% FATRIFE). Finally, a high copolymer MAF content led to both a good adhesion onto metalsubstrates and to improved hydrophilicity, as revealed by the decrease of the water contact angle from107° (for a reference PFATRIFE homopolymer) to 81° (for a copolymer containing 42 mol% MAF).

International audience; Unique alternating copolymers based on vinylacetate (VAc) and tert-butyl-2-trifluoromethacrylate (MAFTBE,a nonhomopolymerizable monomer under radicalconditions) have been synthesized by nitroxide-mediatedpolymerization (NMP) using a SG1-based BlocBuilderalkoxyamine (MAMA-SG1) at moderate temperature (at 40°C) in dimethyl sulfoxide. First-order kinetics and linearevolutions of the molecular weight (up to 17100 g mol−1),maintaining low dispersity values (Đ ≤ 1.33), confirmed thecontrolled nature of the copolymerization. Interestingly, noneof the starting monomers could undergo homopolymerizationunder the NMP condition initiated by MAMA-SG1. Theresulting alternating copolymers were characterized by 1H, 13C, 19F, and 31P NMR spectroscopies and size exclusionchromatography (SEC). The poly(VAc-alt-MAF-TBE) copolymer is amorphous and exhibited a single glass transitiontemperature of 59 °C. This is the first report of nitroxide-mediated (co)polymerization of VAc leading to well-definedcopolymers with satisfactory yields. The results presented in this study established a new route via NMP toward the synthesis ofstrictly 1:1 alternating fluorocopolymers that can display diverse functionalities.

Effective use of Diels–Alder chemistry led to the development of thermally amendable and self-healing polymeric materials based on a copolymer of cyclopenta-1,3-dien-1-ylmethyl 2-(trifluoromethyl)acrylate (MAF-Furan) and 2,2,2-trifluoroethyl α-fluoroacrylate (FATRIFE). The cross-linked copolymer demonstrated acceptable thermal stability. The temperature-induced self-healing capability of the polymer network was studied by using atomic force microscopy analysis.

Human papillomaviruses (HPVs) cause epithelial proliferative diseases. Persistent infection of the mucosal epithelia by the high-risk genotypes can progress to high-grade dysplasia and cancers. Viral transcription and protein activities are intimately linked to regulation by histone acetyltransferases and histone deacetylases (HDACs) that remodel chromatin and regulate gene expression. HDACs are also essential to remodel and repair replicating chromatin to enable the progression of replication forks. As such, Vorinostat (suberoylanilide hydroximic acid), and other pan-HDAC inhibitors, are used to treat lymphomas. Here, we investigated the effects of Vorinostat on productive infection of the high-risk HPV-18 in organotypic cultures of primary human keratinocytes. HPV DNA amplifies in the postmitotic, differentiated cells of squamous epithelia, in which the viral oncoproteins E7 and E6 establish a permissive milieu by destabilizing major tumor suppressors, the pRB family proteins and p53, respectively. We showed that Vorinostat significantly reduced these E6 and E7 activities, abrogated viral DNA amplification, and inhibited host DNA replication. The E7-induced DNA damage response, which is critical for both events, was also compromised. Consequently, Vorinostat exposure led to DNA damage and triggered apoptosis in HPV-infected, differentiated cells, whereas uninfected tissues were spared. Apoptosis was attributed to highly elevated proapoptotic Bim isoforms that are known to be repressed by EZH2 in a repressor complex containing HDACs. Two other HDAC inhibitors, Belinostat and Panobinostat, also inhibited viral DNA amplification and cause apoptosis. We suggest that HDAC inhibitors are promising therapeutic agents to treat benign HPV infections, abrogate progeny virus production, and hence interrupt transmission.

International audience; An original degradable fluorinated surfactant, 3-hydroxy-2-(trifluoromethyl)propanoic acid (MAF-OH), was applied for the emulsion polymerization of vinylidene fluoride (VDF) to yield a latex of PVDF, consisting of typically 100 nm particle diameters. This surfactant was shown to be easily decomposed in subcritical water, releasing fluoride anions. The % reversed head-to head (H–H) addition is greatly minimized (2.4%) in the PVDF, prepared in the presence of MAF-OH surfactant.

The kinetics and mechanism of the polymerization of isobutylene (IB) initiated by tert-butyl chloride and catalyzed by ethylaluminum dichloride (EADC)•bis(2-chloroethyl) ether (CEE) complex was studied in hexanes at 0 °C. The polymerization is first order in [IB] and in dry hexanes the slopes of the first order plots are independent of the [CEE]/[EADC] ratio in the range 1–1.5. From the slopes the steady state concentration of propagating cations [Mn+] = 1.8 × 10–11 M was calculated, which suggests an equilibrium between dormant and active species. The olefin distribution is independent of IB concentration and conversion. At low conversion, the number average molecular weight (Mn) is proportional to the starting IB concentration. In hexanes saturated with water, the polymerization rate is 5 times higher at [CEE]/[EADC] = 1 compared to that in dry hexanes. However, at [CEE]/[EADC] = 1.5, the rates in dry or wet hexanes are identical. To account for the low concentration of active centers determined from th...

The synthesis of l-serine-based zwitterionic polymers, poly(l-serinyl acrylate)s (PSAs), of controllable molecular weights and low polydispersities via reversible addition–fragmentation chain transfer (RAFT) polymerization in water at 70 °C is described. The obtained homopolymer PSA exhibits dual responsiveness toward pH and temperature in aqueous solution. The PSA exhibits an isoelectric point near pH 2.85 where the PSA molecules exist in its zwitterionic form. In the pH range of 2.3–3.5, the aqueous PSA solution appears as a two-phase system due to the formation of insoluble aggregates through the intra- and intermolecular electrostatic interaction between the pendent ammonium and carboxylate groups of the neighboring zwitterionic PSA molecules. Furthermore, in this pH range, the two-phase PSA solution becomes one-phase upon heating, exhibiting distinct reversible upper critical solution temperature (UCST)-type phase transition. The cloud point (Tp) is found to increase with increasing molecular weights...

This paper describes the designed synthesis of well-defined poly (methyl methacrylate)-block-polytyrosine (PMMA-b-Ptyr) copolymer conjugate from a dual initiator via combination of atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA), “Click chemistry” and ring-opening polymerization (ROP) of tyrosine-N-carboxyanhydride (NCA). The initial study of self-aggregation of PMMA-b-Ptyr conjugate in DMF reveals formation of hybrid micro/nanospheres as confirmed by field emission scanning electron microscopy (FESEM) and dynamic light scattering (DLS). It is observed that the sizes of the hybrid spheres increase with the increase of time of aggregation of PMMA-b-Ptyr conjugate in DMF. However, in depth study reveals that PMMA-b-Ptyr conjugate self-aggregates into different morphologies depending on the relative ratio of PMMA and Ptyr blocks in DMF as well as in alkaline water. We devised a simple solution-based approach to encapsulate an organic dye (Rhodamine-6G) into the aggregated hybrid micro/nanospheres as established by fluorescence microscopy and time-correlated single photon counting (TCSPC) techniques. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015

Polyisobutylene (PIB)-based polymer networks potentially useful as smart coatings for photovoltaic devices have been developed. Low molecular weight coumarin functional triarm star PIB was synthesized via a single step SN2 reaction of bromoallyl functional triarm star PIB with 4-methylumbelliferone or umbelliferone in the presence of sodium hydride. Quantitative end functionality was confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. UVA (λmax = 365 nm) induced reversible photodimerization of the coumarin moieties resulted in cross-linked elastomeric films exhibiting self-healing behavior. The extent of photodimerization/photoscission was monitored by UV-vis spectroscopy. The low oxygen (1.9 × 10(-16) mol m m(-2) s(-1) Pa(-1)) and moisture (46 × 10(-16) mol m m(-2) s(-1) Pa(-1)) permeability of the cross-linked polymer films suggest excellent barrier properties of the cross-linked polymer films. The self-healing process was studied by atomic force microscopy (AFM). For this, mechanical cuts were introduced in the cross-linked PIB films through micromachining with an AFM tip and the rate of healing induced by UV, sunlight, or both was followed by taking AFM images of the film at different time intervals during the repair process.

The chemical homogeneity of telechelic polyisobutylene diol (PIB-diol), prepared by hydroboration-oxidation of allyl telechelic PIB obtained by reacting living PIB with allyltrimethylsilane, was investigated by liquid chromatography at critical conditions (LCCC) and HPLC coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). A normal phase gradient HPLC method was developed that was able to separate the as-synthesized PIB-diol into three components; PIB-diol, PIB-monool and PIB without any OH functionality. These were analyzed by MALDI-TOF MS, which suggested that the reaction of living PIB with allyltrimethylsilane was incomplete. LCCC using refractive index (RI) detector as a concentration detector allowed separation and quantification of PIB species according to their chemical heterogeneity (PIB-diol=95.3%, PIB-monool=3.3%, non-functional PIB=1.4%). The calculated number average functionality (Fn) of PIB-diol=1.94 suggests high quality of PIB-diol suitable for high molecular weight polyurethane synthesis.

When synthesis of highly reactive polyisobutylene (HR PIB) via cationic polymerization of isobutylene (IB) using ethylaluminum dichloride·bis(2-chloroethyl) ether (EADC·CEE) complex were carried out in metal reactors made of 316 stainless steel (SS), PIB olefin with up to 20% lower exo-olefin content were obtained compared to that obtained in glass reactors (up to 90%). In an effort to investigate this reduction in exo-olefin selectivity in SS reactors, we have studied the polymerization of IB using EADC·CEE complex in SS (minimum of 10.5% chromium content by mass), carbon steel (CS) (0% chromium content by mass), monel alloy 400 (M400) (0% chromium content by mass) and glass reactors. The latter was examined in the presence and absence of SS balls. Mechanistic studies using ATR-FTIR and 1H NMR spectroscopy suggest that this decrease in exo-olefin selectivity is due to a side reaction of EADC with Cr2O3 involving the loss of the ethyl group from EADC and decomplexation of the EADC·CEE complex which hinders the selective abstraction of the β-proton from the growing chain end. In the absence of chromium (CS and M400 reactors), the exo-olefin content is virtually identical to that obtained in glass reactors. Therefore, CS and M400 reactors are suitable to produce HR PIB with high exo-olefin content.

International audience; Unprecedented synthesis of multiblock poly(vinylidene fluoride) (PVDF, up to 16 300 g mol-1) with narrow-dispersity blocks (Ð=1.26) mediated by a fluorinated cyclic xanthate via reversible addition–fragmentation chain transfer (RAFT) polymerization is reported. Theas-synthesized multiblock PVDF was employed as a macroRAFT agent to prepare valuable multiblock copolymers with potentialapplications in emerging areas

International audience; Organometallic‐mediated radical polymerization (OMRP) has given access to well‐defined poly(vinyl acetate‐alt‐tert‐butyl‐2‐trifluoromethacrylate)‐b‐poly(vinyl acetate) and poly(VAc‐alt‐MAF‐TBE) copolymers composed of two electronically distinct monomers: vinyl acetate (VAc, donor, D) and tert‐butyl‐2‐trifluoromethacrylate (MAF‐TBE, acceptor, A), with low dispersity (≤1.24) and molar masses up to 57 000 g mol−1. These copolymers have a precise 1:1 alternating structure over a wide range of comonomer feed compositions. The reactivity ratios are determined as rVAc = 0.01 ± 0.01 and rMAF‐TBE = 0 at 40 °C. Remarkably, from a feed containing >50% molar VAc content, poly(VAc‐alt‐MAF‐TBE)‐b‐PVAc block copolymers are produced via a one‐pot synthesis. Such diblock copolymers exhibit two glass transition temperatures attributed to the alternating and homopolymer sequences. The OMRP of this fluorine‐containing alternating monomer system may provide access to a wide range of new polymer materials.

International audience; Vinylidene fluoride (VDF)-based copolymersbearing pendant phosphonic acid function for potentialapplication as anticorrosion coatings were synthesized viafree radical copolymerization of VDF with a new phosphorusco n t a i n i n g 2 - t r i fl u o r o m e t h a c r y l a t e monomer,(dimethoxyphosphoryl)methyl 2-(trifluoromethyl)acrylate(MAF-DMP). MAF-DMP was prepared from 2-trifluoromethacrylicacid in 60% overall yield. Radical copolymerizationsof VDF with MAF-DMP initiated by tert-amyl peroxy-2-ethylhexanoate at varying ([VDF]0/[MAF-DMP]0) feed ratiosled to several poly(VDF-co-MAF-DMP) copolymers havingdifferent molar percentages of VDF (79−96%) and number-average molecular weights (Mn’s) up to ca. 10 000 g mol−1 in fairyields (47−53%). Determination of the composition and microstructure of all the synthesized copolymers was done by 1H and19F NMR spectroscopies. The monomer reactivity ratios of this new VDF/MAF-DMP pair were also determined (rVDF = 0.76 ±0.34 and rMAF‑DMP = 0 at 74 °C). The resulting poly(VDF-co-MAF-DMP) copolymers exhibited high melting temperature (162−171 °C, with respect to the VDF content), and the degree of crystallinity reached up to 51%. Finally, the pendant dimethylphosphonate ester groups of the synthesized poly(VDF-co-MAF-DMP) copolymer were quantitatively hydrolyzed, giving rise tonovel phosphonic acid-functionalized PVDF (PVDF-PA). In comparison to hydrophobic poly(VDF-co-MAF-DMP) copolymers(the water contact angle, WCA, was 98°), the hydrophilic character of the PVDF-PA was found to be surprisingly ratherpronounced, exhibiting low WCA (15°). Finally, steel plates coated with PVDF-PA displayed satisfactory anticorrosionproperties under simulated seawater environment.

A fluorescent amphiphilic poly(ethylene glycol)-peptide-fluorophore-peptide-poly(ethylene glycol) (PEG-Pep-F-Pep-PEG) triblock conjugate with a hydrophobic fluorophore moiety at the centre of the chain is synthesized by "grafting to" technique based on Schiff-base coupling chemistry. The conjugate is characterized by nuclear magnetic resonance (NMR), circular dichroism (CD), and fluorescence spectroscopy techniques. The aqueous solution of the triblock conjugate emits blue light and exhibits a fluorescence emission band at 430 nm. The amphiphilic conjugate molecules undergo self-assembly into micelles (D ≈ 15-20 nm) in aqueous solution as confirmed from transmission electron microscopy (TEM) and dynamic light scattering (DLS). The critical aggregation concentration is determined by pyrene fluorescence assay and is found to be 0.051 mg mL(-1) . The highly stable and low toxic fluorescent PEG-Pep-F-Pep-PEG conjugate micelles are used for imaging of HeLa cells.

A simple and convenient strategy is described for the in situ synthesis of ultra-small platinum nanoparticles (Pt NPs) at room temperature using poly(4-vinyl phenol) (PVPh) as both the reducing as well as the stabilizing agent in aqueous alkaline solution. This strategy excludes the use of any additional stabilizing agent in addition to use of a reducing agent. Transmission electron microscopic analysis confirms the formation of ultra-small spherical Pt NPs from 1.6 ± 0.2 to 2.2 ± 0.2 nm in diameter with a high degree of monodispersity depending on the ratio of PVPh to platinum salt concentrations used in a single reaction. The as-synthesized ultra-small Pt NPs exhibit extremely high catalytic activity towards the borohydride reduction of p-nitrophenol with very low activation energy (Ea = 24.6 kJ mol−1). Furthermore, the ultra-small PVPh-capped Pt NPs are successfully used as an excellent catalyst for hydrogenation of styrene and nitrobenzene in methanol with very high yield. The PVPh-capped Pt NPs are reusable for up to four cycles of catalysis reaction, although there is a substantial loss of its original activity after the first cycle.

International audience; The synthesis of functional poly(VDF-co-1234yf) copolymers bearing –OH end groups was achieved via iodine transfer copolymerizations of vinylidene fluoride (VDF) with 2,3,3,3-tetrafluoro-1-propene (1234yf) followed by selective post-functionalization. First, free radical copolymerization (FRP) (in absence of any chain transfer agent, CTA) of VDF with 1234yf was investigated in different experimental conditions: varying the comonomer feed ([VDF]0/[1234yf]0) ratio led to several poly(VDF-co-1234yf) copolymers with molecular weights (Mns) ranging between 4600 and 12400 g·mol-1 and dispersities (Ð) of ca. 2.05, and fair to good conversions (45-77%). Thermoplastic crystalline powders were obtained when mol % VDF in the copolymers was higher than 85 %, while amorphous copolymers contained a lower mol % VDF. This study also reports for the first time the determination of reactivity ratios (rVDF= 0.76 ± 0.34 and r1234yf = 1.23 ± 0.17 at 74 °C). Subsequently, iodine transfer polymerization (ITP) of VDF and 1234yf in the presence of 1-iodoperfluorohexane as the CTA in 1,1,1,3,3-pentafluorobutane and even in water using potassium persulfate as the initiator without any surfactant led to satisfactory yields (ca. 80%), Mn up to 4100 g·mol-1 and narrow Ð (ca. 1.35). Detailed kinetics study of ITP enabled to assess the chain transfer constant of C6F13I, CTr = 7.4 at 74 °C. The compositions and microstructures of all the obtained copolymers were determined by 1H and 19F NMR spectroscopies. Finally, chemical modification of the iodide end functionality of the poly(VDF-co-1234yf)-I copolymer into a primary hydroxyl end group was achieved by radical addition of these iodinated poly(VDF-co-1234yf) copolymers onto allyl alcohol, followed by selective reduction of iodine atoms.

International audience; The synthesis of ω-iodo and telechelic diiodovinylidene fluoride (VDF)-based (co)polymers by iodinetransfer polymerization (ITP) of VDF initiated by a trifluoromethylradical (generated by perfluoro-3-ethyl-2,4-dimethyl-3-pentyl persistent radical, PPFR) is presented. Reactions werecarried out in the presence of different chain transfer agents(CTAs, such as trifluoroiodomethane, 1,4-diiodoperfluorobutane,and molecular iodine) with/without tert-butyl 2-trifluoromethacrylate(MAF-TBE). Experimental conditions (natureof the solvents and CTAs, time, temperature, and initial[VDF]0:[CTA]0:[initiator]0 molar ratios) were varied toinfluence the yield of the reaction (up to 86%), the molar masses (Mn), dispersity values (Đ), chain end functionalities, andmicrostructures of the obtained polymers. Detailed kinetics study enabled to confirm the well-controlled polymerization: (i)synthesis of iodinated polymers with different molar masses (Mn,SEC = 1110−5800 g mol−1) and low Đ values (≤1.30), justsimply by varying the [VDF]0:[CTA]0 initial molar ratio; (ii) linear increase of Mn versus conversion, maintaining low Đ values(≤1.28); (ii) the presence of favored -CH2CF2-I end functionality up to 80% monomer conversion. The compositions andmicrostructures of all the obtained copolymers were characterized by 1H and 19F NMR spectroscopies. Deeper mechanisticinvestigation of the ITP of VDF initiated by •CF3 radical from PPFR was carried out. In the presence of CF3I as the CTA, thecompetitive presence of CF3 end group in CF3-PVDF-I was evidenced to arise from the CTA and showed a negligible amount ofCF3-PVDF oligomer dead chains initiated from •CF3 radical from PPFR. Very low chain defects (due to reversed -CH2CF2-CF2CH2- and -CF2CH2-CH2CF2- in VDF-VDF dyads, even the absence of such a later one) led to high melting points(161−173 °C) of the resulting polymers, as revealed by differential scanning calorimetry. The thermal stability of the polymersincreased with higher Mn values reaching 270 °C under air, while for copolymers containing MAF-TBE, the degradation occurredfrom 170 °C attributed to the release of isobutene from the tert-butyl side groups.

International audience; Synthesis of poly(vinylidene fluoride)-based functional polymers with tunable wettability was achieved viaradical copolymerizations of vinylidene fluoride (VDF) with tert-butyl 2-trifluoromethacrylate (MAF-TBE)followed by hydrolysis of the tert-butyl ester groups. Radical copolymerizations of VDF with 2-trifluoromethylacrylic acid (MAF) and MAF-TBE were investigated under various experimental conditions:initiators, temperatures, and solvents. The polymerizations using peroxide initiators led to good yield(≥57%), while azo initiators did not lead to any polymerization. The compositions and microstructures ofall the obtained copolymers were determined by 1H and 19F NMR spectroscopies. The very low yield(23%) achieved in radical copolymerization of VDF with MAF in water was attributed to the regioselectivenucleophilic addition of water onto MAF, yielding a potential fluorosurfactant, 3-hydroxy-2-(trifluoromethyl)propanoic acid in good yield (85%). In contrast, no reaction was observed between MAF-TBE andwater, even in the presence of ammonium perfluorooctanoate as a (fluorinated) surfactant. Thepoly(VDF-co-MAF-TBE) copolymer was shown to be easily hydrolyzed under mild conditions to prepare–COOH-functionalized PVDF copolymers, without any dehydrofluorination of VDF units. The wettabilitiesof these copolymers were studied by water contact angle (WCA) measurement. Compared to thepoly(VDF-co-MAFTBE) copolymers (WCA = 102°), the –COOH functionalized PVDF copolymer exhibits alower WCA (57°). This work paves the way for the synthesis of PVDF-based functional copolymers withtunable wettability for potential applications in the preparation of membranes for water purification, coatingsor oil recovery systems.

Well-defined peptide-poly(e-caprolactone) (Pep-PCL) biohybrids were successfully synthesized by grafting-from ring-opening polymerization (ROP) of e-caprolactone (CL) using designed amine-terminated sequence-defined peptides as macroinitiators. MALDI-TOF-MS and 1H NMR analyses confirmed the successful attachment of peptide to the PCL chain. The gel permeation chromatography (GPC) measurement showed that the Pep-PCL biohybrids with controllable molecular weights and low polydispersities (PDI

Peptide−polymer hybrid bioconjugates containing poly(methyl methacrylate) chains attached with oligopeptide molecules were prepared by atom transfer radical polymerization (ATRP) using designed peptide-initiators. These initiators were synthesized from newly designed peptides with 2-bromoisobutyric acid via a standard coupling reaction. ATRP of methyl methacrylate was conducted using Br-terminated peptide as macroinitiator and copper(I) chloride/N,N,N′,N′′,N′′-pentamethyldiethylenetriamine as the catalyst system in dimethyl sulfoxide (DMSO) at an elevated temperature (90 °C). The peptide−polymer bioconjugates with controllable molecular weights and low polydispersities (PDI < 1.35) were obtained. We devised a simple solution approach in assembling the peptide−polymer bioconjugate molecules into hybrid micro/nanospheres in different organic solvents as confirmed from transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and dynamic light scattering (DLS) results. The ...

Living cationic polymerization of styrene was achieved with a series of initiating systems consisting of a HX-styrenic monomer adduct (X = Br, Cl) and ferric chloride (FeCl 3 ) in conjunction with added salts such as tetrabutylammonium halides ( n Bu 4 N + Y − ; Y − = Br − , Cl − , I − ) or tetraalkylphosphonium bromides [ n R′ 4 PBr; R′ = CH 3 CH 2 –, CH 3 (CH 2 ) 2 CH 2 –, CH 3 (CH 2 ) 6 CH 2 –] or tetraphenylphosphonium bromide [(C 6 H 5 ) 4 PBr] in dichloromethane (CH 2 Cl 2 ) and in toluene. Comparison of the molecular weight distributions (MWDs) of the polystyrenes prepared at different temperatures (e.g., −25 °C, 0 °C and 25 °C) showed that the polymerization is better controlled at ambient temperature (25 °C). The polymerization was almost instantaneous (completed within 1 min) and quantitative (yield ∼100%) in CH 2 Cl 2 . In CH 2 Cl 2 , polystyrenes with moderately narrow ( M w / M n ∼ 1.33–1.40) and broad ( M w / M n ∼ 1.5–2.4) MWDs were obtained respectively with and without n Bu 4 N + Y − . However, in toluene, the MWDs of the polystyrenes obtained respectively with and without n Bu 4 N + Y − / n R′ 4 P + Br − were moderately narrow ( M w / M n = 1.33–1.5) and extremely narrow ( M w / M n = 1.05–1.17). Livingness of this polymerization in CH 2 Cl 2 was confirmed via monomer-addition experiment as well as from the study of molecular weights of obtained polystyrenes prepared simply by varying monomer to initiator ratio. A possible mechanistic pathway for this polymerization was suggested based on the results of the 1 H NMR spectroscopic analysis of the model reactions as well as the end group analysis of the obtained polymer.

The discovery of ultrasound-induced in-situ formation of coordination organogels using various isobutyric acids (such as isobutyric acid or 2-methylisobutyric acid or 2-bromoisobutyric acid) and zinc oxide nanoparticles was described. FTIR and XRD results suggest that ultrasound irradiation triggers the quick dissolution of zinc oxide nanoparticles by isobutyric acids, resulting in the in-situ formation of zinc isobutyrate complexes that undergoes fast sonocrystallization into gel fibers. FESEM results clearly demonstrate the formation of well-defined networks of fibers with several micrometers in length, but the average diameter of the fiber ranges from 30 to 65 nm, depending upon the nature of the isobutyric acids used. A combination of single-crystal structure analysis and powder XRD result was used to envisage the molecular packing present in the gel state. This is probably a very rare case of ultrasound-induced organogelation where metal oxide NPs are used as the precursor.

Effects of counterions of side chain amino acid based polyelectrolytes (PEs) on the solubility in aqueous medium, pH responsiveness, thermal properties, and ionic conductivities have been appraised. Deprotection of the tert-butyl carbamate (Boc) group from poly(Boc-l-leucine methacryloyloxyethyl ester) [P(Boc-l-Leu-HEMA)] was carried out to produce PE with trifluoroacetate as an associative counteranion (1a). PEs with bis(trifluoromethylsulfonyl)imide and hexafluorophosphate counteranion were prepared through anion exchange reactions of 1a. Protonation of the neutralized polymer (2) obtained from 1a, followed by anion exchange, leads to the production of miscellaneous PEs bearing different counteranions, such as tetrafluoroborate, trifluoromethanesulfonate, chloride, and nitrate. Differential scanning calorimetry traces of the PEs reveal that the comparatively larger and weakly coordinated counteranions require less thermal energy to dissociate, and thus, the glass transition temperature (Tg) of the PEs fall off with an increase in the size of the counteranion. A remarkable conductivity of 2.1 mS/cm was obtained in deionized water when Cl(-) acted as the counteranion. Steric and electronic factors of the counteranion induce a change of transition pH in different PEs, although the chiroptical nature was retained, as confirmed by circular dichroism spectroscopy.

5-Methyl cytosine (m5C) was detected in genomic DNA of the enteric pathogen Vibrio cholerae by HPLC analysis and immunoblotting with m5C-specific antibody. Although cleavage with the restriction endonuclease EcoRII revealed the absence of a Dcm homologue in V. cholerae, analysis of the genome sequence indicated the presence of a gene, designated in this study as vchM, which encodes a DNA (cytosine-5-)-methyltransferase (m5C-MTase) designated M.Vch. M.Vch is not associated with a restriction endonuclease or a mismatch very short patch repair (Vsr)-like endonuclease and is hence an ‘orphan’ or solitary MTase, although analysis of a phylogenetic tree indicated that related cytosine MTases are all components of restriction-modification systems. M.Vch recognizes and methylates the first 5′ C in the degenerate sequence 5′-RCCGGY-3′. RT-PCR analysis suggested that vchM gene expression is increased during the stationary phase of growth. During stationary phase, the spontaneous mutation frequency in the V. cholerae wild-type strain was significantly higher than in the corresponding vchM mutant strain, suggesting that the presence of M.Vch and the absence of a very short patch (VSP) repair-like system imposes upon V. cholerae a mutator phenotype.

The effects of human papillomavirus type 18 (HPV-18) E6 and E7 proteins on global patterns of host gene expression in primary human keratinocytes grown in organotypic raft culture system were assessed. Primary human keratinocytes were infected with retroviruses that express the wild-type HPV-18 E6 and E7 genes from the native differentiation-dependent HPV enhancer-promoter. Total RNA was isolated from raft cultures and used to generate probes for querying Affymetrix U95A microarrays, which contain >12,500 human gene sequences. Quadruplicate arrays of each E6/E7-transduced and empty vector-transduced samples were analyzed by 16 pairwise comparisons. Transcripts altered in ≥12 comparisons were selected for further analysis. With this approach, HPV-18 E6/E7 expression significantly altered the expression of 1,381 genes. A large increase in transcripts associated with DNA and RNA metabolism was observed, with major increases noted for transcription factors, splicing factors, and DNA replication elements, among others. Multiple genes associated with protein translation were downregulated. In addition, major alterations were found in transcripts associated with the cell cycle and cell differentiation. Our study provides a systematic description of transcript changes brought about by HPV-18 E6/E7 in a physiologically relevant model and should furnish a solid source of information to guide future studies.

We report the synthesis and catalytic activities of a mesoporous silica nanosphere supported palladiumII 2-aminopyridine complex (Pd-AMP-MSN). First, chloroalkyl functionalized mesoporous silica nanospheres (Cl-MSN) is prepared by an in situ co-condensation reaction of tetraethyl orthosilicate (TEOS) with ((chloromethyl)phenylethyl)trimethoxysilane (CMPE-TMS) using cetyltrimethylammonium bromide (CTAB) as the structure directing agent. The reaction of Cl-MSN with 2-aminopyridine followed by complexation with palladium acetate produces the catalyst Pd-AMP-MSN. FTIR spectroscopic analysis confirms the presence of 2-aminopyridine functionality inside the mesopores of the Pd-AMP-MSN. Nitrogen adsorption–desorption and X-ray diffraction analyses reveal mesoporous structures of the Pd-AMP-MSN catalyst with a specific surface area of 372 m2 g−1, a pore volume of 0.172 cm3 g−1 and a narrow pore size distribution (D ∼ 1.92 nm). FESEM and HRTEM results indeed show the formation of nanospheres with mesoporous structures. This catalytic system exhibits excellent activity in Suzuki–Miyaura cross-coupling reactions of aryl iodides, aryl bromides and also aryl chlorides with phenylboronic acids in water medium with high yields. This Pd-AMP-MSN catalyst could be quantitatively recovered by simple filtration and is found to be highly active without any significant loss of its catalytic activity in eight consecutive runs.