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Aluminum (Al) alloys, especially the 2xxx series due to high strength to weight ratio have found extensive use in aerospace, marine, and automobile industries. The present research trend is microalloying (wt.% < 0.1) these alloys with trace elements viz. Cd, Sn, Ag, In, etc. For these applications, welding becomes an inevitable technique, which is a tougher challenge for Al alloys, and Friction Stir Welding (FSW) is recently explored. In present work, 2219Al alloy and the same alloy microalloyed with 0.06 wt.% Cd were processed by casting route. They were then welded by FSW and mechanical properties and microstructure of the welded joints were studied. The hardness value increased while the impact toughness decreased due to trace addition of Cd. The microstructural study revealed three zones viz. weld nugget zone (WNZ), thermo mechanically affected zone (TMAZ) and heat affected zone (HAZ), identified by the formation of fine, columnar, and spherical grains, respectively.

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The mammalian target of rapamycin (mTOR) pathway, which plays a critical role in regulating cellular growth and metabolism, is aberrantly regulated in the pathogenesis of a variety of neoplasms. Here we demonstrate that dual mTORC1/mTORC2 inhibitors OSI-027 and PP242 cause catastrophic macropinocytosis in rhabdomyosarcoma (RMS) cells and cancers of the skin, breast, lung, and cervix, whereas the effects are much less pronounced in immortalized human keratinocytes. Using RMS as a model, we characterize in detail the mechanism of macropinocytosis induction. Macropinosomes are distinct from endocytic vesicles and autophagosomes in that they are single-membrane bound vacuoles formed by projection, ruffling, and contraction of plasma membranes. They are positive for EEA-1 and LAMP-1 and contain watery fluid but not organelles. The vacuoles then merge and rupture, killing the cells. We confirmed the inhibition of mTORC1/mTORC2 as the underpinning mechanism for macropinocytosis. Exposure to rapamycin, an mTORC1 inhibitor, or mTORC2 knockdown alone had little or reduced effect relative to the combination. We further demonstrate that macropinocytosis depends on MKK4 activated by elevated reactive oxygen species. In a murine xenograft model, OSI-027 reduced RMS tumor growth. Molecular characterization of the residual tumors was consistent with the induction of macropinocytosis. Furthermore, relative to the control xenograft tumors, the residual tumors manifested reduced expression of cell proliferation markers and proteins that drive the epithelial mesenchymal transition. These data indicate a role of mTORC2 in regulating tumor growth by macropinocytosis and suggest that dual inhibitors could help block refractory or recurrent RMS and perhaps other neoplasms and other cancer as well.

Mucosotropic human papillomaviruses (HPVs) cause prevalent anogenital infections, some of which can progress to cancers. It is imperative to identify efficacious drug candidates, as there are few therapeutic options. We have recapitulated a robust productive program of HPV-18 in organotypic raft cultures of primary human keratinocytes. The HPV E7 protein induces S phase reentry, along with DNA damage response (DDR) in differentiated cells to support viral DNA amplification. A number of small molecule inhibitors of DDR regulators are in clinical use or clinical trials to treat cancers. Here, we used our raft culture system to examine effects of inhibitors of ATR/Chk1 and ATM/Chk2 on HPV infection. The inhibitors impaired S-phase reentry and progression as well as HPV DNA amplification. The Chk1 inhibitor MK-8776 was most effective, reducing viral DNA amplification by 90&ndash, 99% and caused DNA damage and apoptosis, preferentially in HPV infected cells. We found that this sensitivity was imparted by the E7 protein and report that MK-8776 also caused extensive cell death of cervical cancer cell lines. Furthermore, it sensitized the cells to cisplatin, commonly used to treat advanced cervical cancer. Based on these observations, the Chk1 inhibitors could be potential effective agents to be re-purposed to treat the spectrum of HPV infections in single or combination therapy.

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

The conventional radical homopolymerization of TrFE initiated by a ˙CF3 radical (generated in situ from perfluoro-3-ethyl-2,4-dimethyl-3-pentyl persistent radical, PPFR) is presented. Reactions were carried out at an increasing PPFR concentration (initial [TrFE]0 : [PPFR]0 molar ratios varying from 2.5 to 20.0 mol%) to influence the molar masses (Mn, ranging between 7700 and 38 100 g mol−1). PTrFE homopolymer yields were high (76–87%). The microstructures of such synthesized PTrFEs were characterized by 1H and 19F NMR spectroscopy. The generated PTrFE chains were exclusively terminated by CF3 end-groups, as revealed by MALDI-TOF spectroscopy and NMR analysis, indicating that the ˙CF3 radicals initiated the polymerization of TrFE. The addition of the ˙CF3 radicals onto TrFE was predominantly regioselective (66%) leading mainly to a CF3–CHF–CF2–PTrFE homopolymer. Furthermore, the CF3 end group could be used as an efficient label to determine the PTrFE molar masses by 19F NMR spectroscopy that also enabled us to assess the chain defects (14%). The thermal properties of these CF3–PTrFE–CF3 polymers revealed (i) a high thermal stability (their degradation under an oxidative atmosphere started from 362 °C and ranged even up to 428 °C for higher molar masses of PTrFEs) and (ii) a semi-crystalline behavior with a crystallinity rate averaging 36%.

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: In the past few years, 3D organoid cultures of patient-derived tumors or patient-derived xenografts have gained significant attention as faster and more economical ex vivo alternatives to animal models for the pre-clinical evaluation of therapeutics. We reported previously that raft cultures of ex vivo epithelial warts, normal human epithelia from various anatomic sites, as well as cancer cell lines (cervical and melanoma) grown at the liquid:air interface recapitulate parental tissue phenotypes. Here we describe adaptation of the above technique to develop Organoid Raft Culture (ORC) of tumors of various origin and validation as preclinical models for drug evaluation. Methods: A stromal equivalent (SE) consisting of buffered rat-tail collagen and J2 mouse fibroblasts was prepared in 24-well tissue culture plates. Freshly harvested tumors from patients or patient-derived xenografts of cervical cancers were minced to Citation Format: Nilam Sanjib Banerjee, Dianne W. Moore, Abhisek Gangrade, Donald J. Buchsbaum, Luise Burt Nabors, Thomas R. Broker, Louise T. Chow. Development of organoid raft cultures of cervical, breast and glioblastoma tumors as quick economical ex vivo human cancer models for pre-clinical drug evaluation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB250.

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.

High-risk HPV infections lead to development of cervical cancer. This study identified the differential expression of 16 novel genes (LY6K, FAM83A, CELSR3, ASF1B, IQGAP3, SEMA3F, CLDN10, MSX1, CXCL5, ASRGL1, ELAVL2, GRB7, KHSRP, NOVA1, PTBP1, and RNASEH2A) in HPV-infected cervical tissue samples and keratinocytes. Eight of these genes (CDKN2A, ELAVL2, GRB7, HSPB1, KHSRP, NOVA1, PTBP1, and RNASEH2A) encode RNA-binding proteins. Further studies indicated that both HPV16 and HPV18 infections lead to the aberrant expression of selected RBP-encoding genes. We found that viral E6 and E7 decrease NOVA1 expression but that E7 increases RNASEH2A expression via E2F1. The altered expression of these genes may be utilized as biomarkers for high-risk (HR)-HPV carcinogenesis and progression., RNA-binding proteins (RBPs) control mRNA processing, stability, transport, editing, and translation. We recently conducted transcriptome analyses comparing normal (i.e., healthy) cervical tissue samples with human papillomavirus (HPV)-positive cervical cancer tissue samples and identified 614 differentially expressed protein-coding transcripts which are enriched in cancer-related pathways and consist of 95 known RBPs. We verified the altered expression of 26 genes with a cohort of 72 cervical samples, including 24 normal cervical samples, 25 cervical intraepithelial neoplasia grade 2 (CIN2) and CIN3 samples, and 23 cervical cancer tissue samples. LY6K (lymphocyte antigen 6 complex locus K), FAM83A (family member with sequence similarity 83), CELSR3, ASF1B, IQGAP3, SEMA3F, CLDN10, MSX1, CXCL5, ASRGL1, ELAVL2, GRB7, KHSRP, NOVA1, PTBP1, and RNASEH2A were identified as novel candidate genes associated with cervical lesion progression and carcinogenesis. HPV16 or HPV18 infection was found to alter the expression of 8 RBP genes (CDKN2A, ELAVL2, GRB7, HSPB1, KHSRP, NOVA1, PTBP1, and RNASEH2A) in human vaginal and foreskin keratinocytes. Both viral E6 and E7 decreased NOVA1 expression, but only E7 increased the expression of RNASEH2A in an E2F1-dependent manner. Proliferating cell nuclear antigen (PCNA) directs RNASEH2 activity with respect to DNA replication by removing the RNA primers to promote Okazaki fragment maturation, and two factors are closely associated with neoplasia progression. Therefore, we predict that the induction of expression of RNASEH2A via viral E7 and E2F1 may promote DNA replication and cancer cell proliferation.

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.

Podocalyxin-like protein (PODXL) is a member of CD34 family proteins. It is the protein that carries many post-translational epitopes responsible for various pluripotent surface markers including TRA-1-60, TRA-1-81, GCTM2, GP200, and mAb84. However, PODXL has not attracted the attention of stem cell biologists. Here, we report several features of PODXL mRNA and protein in pluripotent stem cells. Similar to the modification-dependent pluripotent epitopes, PODXL transcripts and carrier protein are also features of pluripotency. PODXL is highly expressed in early human embryos from oocytes up to four-cell stages. During reprogramming of human cells to pluripotency, in contrast to TRA-1-60 and TRA-1-81, PODXL is activated by KLF4 at a very early time of reprogramming. Although TRA-1-60 and TRA-1-81 are completely lost upon differentiation, a residual PODXL(+) population exists even after extended differentiation and they were identified by the universal human PODXL epitope 3D3. Unlike TRA-1-60 and TRA-1-81 epitopes that are unique to primate pluripotent stem cells (PSCs), PODXL carrier protein can be used as a murine surface marker. Most importantly, antibody to 3D3 epitope causes massive necrosis and apoptosis of human PSCs (hPSCs). We suggest that 3D3 antibody could be employed to eliminate the tumorigenic pluripotent cells in hPSC-derived cells for cell transplantation.

Herein we demonstrate the utility of polyisobutylene (PIB) as a fully printable self-healing sealant for protecting organic photovoltaic devices from degradation under ambient conditions. These sealants can be applied on flexible substrates using drop casting, spin coating or blade coating. PIB-based crosslinked sealants show excellent device stability, especially the low molecular weight PIB.

A series of hydroxyl-terminated polyisobutylene-b-polyethylene (PIB-b-PE-OH) copolymers were synthesized by combining living cationic polymerization and polyhomologation. Allyl-terminated PIBs, synthesized by living cationic polymerization, were hydroborated with BH3·THF to produce 3-arm boron-linked stars, PIB3B, which served as macroinitiators for the in situ polyhomologation of dimethylsulfoxonium methylide. The resulting 3-arm star block copolymers, (PIB-b-PE)3B, were oxidized/hydrolysed to afford PIB-b-PE-OH. Characterization of all intermediates and final products by high temperature gel permeation chromatography (HT-GPC) and proton nuclear magnetic resonance spectroscopy (1H NMR) revealed the well-defined character of the copolymers. The thermal properties of the copolymers were studied by differential scanning calorimetry (DSC).

The organometallic-mediated radical polymerization (OMRP) of vinyl acetate (VAc) and its OMR copolymerization (OMRcoP) with tert-butyl 2-trifluoromethylacrylate (MAF-TBE) mediated by Co(SAL)2 (SAL = 2-formylphenolato or deprotonated salicylaldehyde) produced relatively well-defined PVAc and poly(VAc-alt-MAF-TBE) copolymers at moderate temperature (

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.

A convenient and water-based approach is described for the synthesis of an l-lysine-based zwitterionic polymer, poly(e-l-lysinyl acrylamide) (PLAM), without using protecting group chemistry, chromatographic purifications, and organic solvents as the reaction media. PLAM contains both amine and carboxylic acid groups in each repeating unit, which can either be protonated or deprotonated just by altering the pH of the solution to obtain overall positive or negative charge. PLAM is tested for its applicability as a zwitterionic polymeric buffer in water. Cu(II) ion-induced aggregation of PLAM as a function of solution pH is studied. Spherical nanogel aggregates are formed at pH 9.5 due to aggregation of PLAM through its complexation with Cu(II) ion. Spherical aggregates appear to dissociate via breaking of the complexation at a pH < 5.5 resulting in molecular dissolution of PLAM. This aggregation process is pH reversible. The Cu(II)-PLAM aggregates are used as a template for fabrication of CuO and CuS nanoparticles.

Purpose To report the achievement rate of bare Descemet membrane (DM) dissection with the help of microbubble incision technique in eyes with failed big bubble formation and to investigate the mechanism of the microbubble rescue technique through ex vivo imaging of human cadaver corneas. Methods This retrospective clinical study included 80 eyes of 80 patients that underwent deep anterior lamellar keratoplasty (DALK). In 22/80 (27.5%) cases, big bubble dissection failed. After puncturing the microbubbles, viscodissection helped to achieve separation of DM from the remaining stroma. In addition, an ex vivo study with human cadaver cornea specimens, gross photography, and anterior segment optical coherence tomography imaging was accomplished ex vivo to explore the mechanism of this method. Results Microbubble dissection technique led to successful DALK in 19 of 22 cases of failed big bubble. Microperforation occurred in 3 eyes. Deep anterior lamellar keratoplasty was completed without any complications in 2 out of the 3 eyes with microperforation. In 1 eye, conversion to penetrating keratoplasty was required. Microbubble-guided viscodissection achieved 95.4% (21/22) success in exposing bare DM in failed big-bubble cases of DALK. Anterior segment optical coherence tomography imaging results of cadaver eyes showed where these microbubbles were concentrated and their related size. Conclusions Microbubble-guided DALK should be considered an effective rescue technique in achieving bare DM in eyes with failed big bubble. Our ex vivo experiment illustrated the possible alterations in cornea anatomy during this technique.

Wound healing involves a number of factors that results in the production of a "closed" wound. Studies have shown, in animal models, acceleration of wound healing with the addition of adipose-derived stromal cells (ADSC). The cause for the positive effect which these cells have on wound healing has not been elucidated. We have previously shown that addition of ADSC to the dermal equivalent in 3-dimensional skin cultures accelerates reepithelialization. We now demonstrate that conditioned media (CM) from cultured ADSC produced a similar rate of healing. This result suggests that a feedback from the 3-dimensional epithelial cultures to ADSC was not necessary to effect the accelerated reepithelialization. Mass spectrometry of CM from ADSC and primary human fibroblasts revealed differences in secretomes, some of which might have roles in the accelerating wound healing. Thus, the use of CM has provided some preliminary information on a possible mode of action.

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.

Recently, significant advances have been achieved for the synthesis of high performance polymers via living cationic polymerization. In this article, we review and highlight recent studies and developments in the field of living cationic polymerization for the production of well defined polymers with a brief overview of the fundamentals of cationic polymerization. Some exciting very recent examples of macromolecular architectures prepared by living cationic polymerization for designed applications are also presented. We conclude with an outline of the future directions in the applications of living cationic polymerization towards the synthesis of advanced polymer materials for many high-value future applications, including applications in biomedical fields.

High-temperature deformation behaviors of Al-5.9 pct Cu-0.5 pct Mg alloy and Al-5.9 pct Cu-0.5 pct Mg alloy containing 0.06 wt pct Sn were studied by hot compression tests conducted at different temperatures and strain rates. Trace content of Sn resulted in a significant increase of flow stress at various processing conditions. Artificial neural network (ANN) modeling was carried out providing excellent prediction of flow stress at different combinations of strain, strain rate, and temperature. It was possible to predict 100 and 89 pct of the flow stress values of the respective alloys within an error less than ±10 pct. The generated flow stress data were used to develop processing maps to delineate the process domains for safe metal working. The power dissipation efficiency maps revealed a maximum efficiency of 60 and 40 pct, respectively, for the base alloy and the microalloyed material. The instability maps generated for the Sn containing alloy revealed only one instability regime. The safe processing zone of the investigated alloys primarily lies at lower regimes of strain rate, which is extended up to higher deformation temperatures, with trace addition of Sn. Optical microscopy characterized these stable regions as dynamic recrystallization (DRX), which resulted in considerable flow softening observed at a low strain rate of 0.001 s−1. Instability was observed mainly due to shear band formation or intercrystalline cracking.

A facile approach for the preparation of mesoporous polymer nanospheres (MPN) and mesoporous carbon nanospheres (MCN) with complete shape retention based on surface-confined atom transfer radical polymerization of various methacrylate monomers from in situ generated initiator-modified hard silica nanospheres template is developed. This approach yields mesoporous silica-polymer hybrid nanospheres (MSPN) with mesopores that are uniformly filled with covalently attached well-defined poly(methacrylate)s. The silica frameworks are subsequently etched, resulting in MPN. Pyrolysis of MSPN and subsequent removal of silica template resulted in the production of MCN. They retain the size, shape, and mesoporous ordering of the silica template nanospheres. Gel permeation chromatography analysis of the silica free polymers reveals that they have controlled molecular weights and low polydispersities (PDIs). Kinetics studies reveal that the molecular weight of the grafted polymer increases linearly with time, maintaining low PDIs, indicating the living nature of the polymerization. The mesoporous polymer material is found to have low dielectric constant, which paves the way for their use as low-dielectric constant materials in microelectronics. This approach allows fabrication of functional MPN using functional comonomers, which are successfully used for the synthesis of “clickable” mesoporous polymer nanospheres, removal of ionic contaminates through anion exchange, and glucose sensing.

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

High temperature deformation behavior of Al–5.9%Cu–0.5%Mg alloy and Al–5.9%Cu–0.5%Mg alloy containing 0.06 wt.% of Sn was studied by hot compression tests at various temperatures and strain rates. Addition of trace amounts of Sn into the Al–Cu–Mg alloy system resulted in a significant increase of flow stress for all conditions of temperature and strain rate. 100% and 89% of the flow stress values during hot deformation could be predicted within ± 10% deviation values for the aluminum alloys with and without Sn content, respectively, by artificial neural network (ANN) modeling. From the deformation mechanism maps and microstructural investigation, the safe process regimes for hot working of the base alloy was identified to be at (i) very low strain rate (< 0.003 s−1) at temperature < 450 °C, and (ii) high temperature (> 400 °C) with strain rate > 0.02 s−1. For the micro-alloyed alloy, it was at low strain rates (< 0.01 s-1) for the entire temperature range studied. Flow softening for both alloys was observed to be at low strain rates and was identified to be due to dynamic recrystallization (DRX). The metallurgical instability during deformation was identified due to shear band formation and/or inter-crystalline cracking.