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Polymer Chemistry

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https://www.readbyqxmd.com/read/29725358/self-assembly-of-random-co-polymers-for-selective-binding-and-detection-of-peptides
#1
Bo Zhao, Mahalia A C Serrano, Jingjing Gao, Jiaming Zhuang, Richard W Vachet, S Thayumanavan
Amphiphilic random co-polymers, which form stable reverse micelle-type assemblies, have been designed and synthesized. We demonstrate that the reverse micelles, formed by these co-polymers are capable of selectively binding peptides through electrostatic interactions, indicating that these random polymers can self-organize into functionally selective materials. Moreover, these random co-polymers also enable the ordered co-crystallization of matrix and extracted guest molecules, giving rise to substantial signal enhancements during MALDI-MS detection...
March 7, 2018: Polymer Chemistry
https://www.readbyqxmd.com/read/29276541/fully-recoverable-rigid-shape-memory-foam-based-on-copper-catalyzed-azide-alkyne-cycloaddition-cuaac-using-a-salt-leaching-technique
#2
Abeer A Alzahrani, Mohand Saed, Christopher M Yakacki, Han Byul Song, Nancy Sowan, Joshua J Walston, Parag K Shah, Matthew K McBride, Jeffrey W Stansbury, Christopher N Bowman
This study is the first to employ the use of the copper-catalyzed azide-alkyne cycloaddition (CuAAC) polymerization to form a tough and stiff, porous material from a well-defined network possessing a high glass transition temperature. The effect of the network linkages formed as a product of the CuAAC reaction, i.e., the triazoles, on the mechanical behavior at high strain was evaluated by comparing the CuAAC foam to an epoxy-amine-based foam, which consisted of monomers with similar backbone structures and mechanical properties (i...
January 7, 2018: Polymer Chemistry
https://www.readbyqxmd.com/read/29628993/synthesis-of-star-polymers-using-organocatalyzed-atom-transfer-radical-polymerization-through-a-core-first-approach
#3
Bonnie L Buss, Logan R Beck, Garret M Miyake
Synthetic routes to higher ordered polymeric architectures are important tools for advanced materials design and realization. In this study, organocatalyzed atom transfer radical polymerization is employed for the synthesis of star polymers through a core-first approach using a visible-light absorbing photocatalyst, 3,7-di(4-biphenyl)-1-naphthalene-10-phenoxazine. Structurally similar multifunctional initiators possessing 2, 3, 4, 6, or 8 initiating sites were used in this study for the synthesis of linear telechelic polymers and star polymers typically possessing dispersities lower than 1...
2018: Polymer Chemistry
https://www.readbyqxmd.com/read/29422955/mechanism-of-supplemental-activator-and-reducing-agent-atom-transfer-radical-polymerization-mediated-by-inorganic-sulfites-experimental-measurements-and-kinetic-simulations
#4
Pawel Krys, Marco Fantin, Patrícia V Mendonça, Carlos M R Abreu, Tamaz Guliashvili, Jaquelino Rosa, Lino O Santos, Arménio C Serra, Krzysztof Matyjaszewski, Jorge F J Coelho
The mechanism of atom transfer radical polymerization (ATRP) mediated by sodium dithionite (Na2 S2 O4 ), with CuII Br2 /Me6 TREN as catalyst (Me6 TREN: tris[2-(dimethylamino)ethyl]amine)) in ethanol/water mixtures, was investigated experimentally and by kinetic simulations. A kinetic model was proposed and the rate coefficients of the relevant reactions were measured. The kinetic model was validated by the agreement between experimental and simulated results. The results indicated that the polymerization followed the SARA ATRP mechanism, with a SO2 •- radical anion derived from Na2 S2 O4 , acting as both supplemental activator (SA) of alkyl halides and reducing agent (RA) for CuII /L to regenerate the main activator CuI /L...
November 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29308095/cationic-disulfide-functionalized-worm-gels
#5
L P D Ratcliffe, K J Bentley, R Wehr, N J Warren, B R Saunders, S P Armes
The recent development of polymerization-induced self-assembly (PISA) has facilitated the rational synthesis of a range of diblock copolymer worms, which hitherto could only be prepared via traditional post-polymerization processing in dilute solution. Herein we explore a new synthetic route to aqueous dispersions of cationic disulfide-functionalized worm gels. This is achieved via the PISA synthesis of poly[(glycerol monomethacrylate- stat -glycidyl methacrylate)]- block -poly(2-hydroxypropyl methacrylate) (P(GMA- stat -GlyMA)-PHPMA) block copolymer worms via reversible addition-fragmentation chain transfer (RAFT) aqueous dispersion polymerization of HPMA...
October 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29308094/stimulus-responsive-block-copolymer-nano-objects-and-hydrogels-via-dynamic-covalent-chemistry
#6
Renhua Deng, Yin Ning, Elizabeth R Jones, Victoria J Cunningham, Nicholas J W Penfold, Steven P Armes
Herein we demonstrate that dynamic covalent chemistry can be used to induce reversible morphological transitions in block copolymer nano-objects and hydrogels. Poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) (PGMA-PHPMA) diblock copolymer nano-objects (vesicles or worms) were prepared via polymerization-induced self-assembly. Addition of 4-carboxyphenylboronic acid (CPBA) leads to the formation of phenylboronate ester bonds with the 1,2-diol pendent groups on the hydrophilic PGMA stabilizer chains; such binding causes a subtle reduction in the packing parameter, which in turn induces either vesicle-to-worm or worm-to-sphere transitions...
September 21, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29104619/anti-protein-and-anti-bacterial-behavior-of-amphiphilic-silicones
#7
Melissa L Hawkins, Samantha S Schott, Bagrat Grigoryan, Marc A Rufin, Bryan Khai D Ngo, Lyndsi Vanderwal, Shane J Stafslien, Melissa A Grunlan
Silicones with improved water-driven surface hydrophilicity and anti-biofouling behavior were achieved when bulk-modified with poly(ethylene oxide) (PEO) -silane amphiphiles of varying siloxane tether length: α-(EtO)3 Si-(CH2 )2 -oligodimethylsiloxane m - block -poly(ethylene oxide)8 -OCH3 ( m = 0, 4, 13, 17, 24, and 30). A PEO8 -silane [α-(EtO)3 Si-(CH2 )3 -PEO8 -OCH3 ] served as a conventional PEO-silane control. To examine anti-biofouling behavior in the absence versus presence of water-driven surface restructuring, the amphiphiles and control were surface-grafted onto silicon wafers and used to bulk-modify a medical-grade silicone, respectively...
September 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29098018/enzyme-targeted-nanoparticles-for-delivery-to-ischemic-skeletal-muscle
#8
J L Ungerleider, J K Kammeyer, R L Braden, K L Christman, N C Gianneschi
The targeted delivery of enzyme-responsive nanoparticles to specific tissues can be a valuable, minimally invasive approach for imaging or drug delivery applications. In this study, we show for the first time enzyme-directed assembly of intravenously (IV) delivered nanoparticles in ischemic skeletal muscle, which has applications for drug delivery to damaged muscle of the type prevalent in peripheral artery disease (PAD). Specifically, micellar nanoparticles are cleavable by matrix metalloproteinases (MMPs), causing them to undergo a morphological switch and thus aggregate in tissues where these enzymes are upregulated, like ischemic muscle...
September 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/28959359/poly-n-2-hydroxypropyl-methacrylamide-valproic-acid-conjugates-as-block-copolymer-nanocarriers
#9
Jawaher A Alfurhood, Hao Sun, Christopher P Kabb, Bryan S Tucker, James H Matthews, Hendrik Luesch, Brent S Sumerlin
We report nanoassemblies based on block copolymers of N-(2-hydroxypropyl) methacrylamide (HPMA) in which drug cleavage enhances the biological compatibility of the original polymer carrier by regeneration of HPMA units. Drug release via ester hydrolysis suggests this approach offers potential for stimuli-responsive drug delivery under acidic conditions.
September 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29181096/structure-activity-relationship-of-heparin-mimicking-polymer-p-ss-co-pegma-effect-of-sulfonation-and-polymer-size-on-fgf2-receptor-binding
#10
Samantha J Paluck, Heather D Maynard
Fibroblast growth factor-2 (FGF2) is a heparin binding protein that plays a role in a range of biological functions such as wound healing and bone regeneration. Heparin, a highly sulfated glycosaminoglycan, is required for FGF2 to bind to its receptor. Therefore, polymeric mimics of heparin are widely studied for their ability to manipulate FGF2-induced biological interactions. It is known that altering the degree of sulfonated monomer incorporation and size of heparin-mimicking polymers can affect protein-receptor binding...
August 20, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29104618/application-of-an-addition-fragmentation-chain-transfer-monomer-in-di-meth-acrylate-network-formation-to-reduce-polymerization-shrinkage-stress
#11
Parag K Shah, Jeffrey W Stansbury, Christopher N Bowman
A new addition-fragmentation chain transfer (AFT) capable moiety was incorporated into a dimethacrylate monomer that participated readily in network formation by copolymerizing with multifunctional methacrylates or acrylates. The process of AFT occurred simultaneously with photopolymerization of the AFT monomer (AFM) and other (meth)acrylate monomers leading to polymer stress relaxation via network reconfiguration. At low loading levels of the AFM, a significant reduction in shrinkage stress, especially for acrylate monomers, was observed with nominal effects on conversion...
August 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29057012/one-pot-blue-light-triggered-tough-interpenetrating-polymeric-network-ipn-using-cuaac-and-methacrylate-reactions
#12
Abhishek U Shete, Christopher J Kloxin
An interpenetrating polymeric network (IPN) is formed in a one-pot blue-light activated scheme, where the step- and chain- growth polymerizations of the CuAAC and methacrylate reactions, respectively, are simultaneously triggered but proceed sequentially. The glassy IPN is polymerized under ambient conditions and is able to withstand high strain before failure owing to its significantly enhanced toughness. Additionally, this material exhibits shape memory attributes with readily tunable mechanical properties at high temperature...
June 28, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29225706/comparison-of-photo-and-thermally-initiated-polymerization-induced-self-assembly-a-lack-of-end-group-fidelity-drives-the-formation-of-higher-order-morphologies
#13
Lewis D Blackman, Kay E B Doncom, Matthew I Gibson, Rachel K O'Reilly
Polymerization-induced self-assembly (PISA) is an emerging industrially relevant technology, which allows the preparation of defined and predictable polymer self-assemblies with a wide range of morphologies. In recent years, interest has turned to photoinitiated PISA processes, which show markedly accelerated reaction kinetics and milder conditions, thereby making it an attractive alternative to thermally initiated PISA. Herein, we attempt to elucidate the differences between these two initiation methods using isothermally derived phase diagrams of a well-documented poly(ethylene glycol)- b -(2-hydroxypropyl methacrylate) (PEG- b -HPMA) PISA system...
May 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29057011/selective-monophosphorylation-of-chitosan-via-phosphorus-oxychloride
#14
Dakota J Suchyta, Robert J Soto, Mark H Schoenfisch
Chitosan was selectively monophosphorylated via reaction with phosphorus oxychloride (POCl3 ) to enhance water solubility while avoiding polyphosphate formation. The use of POCl3 resulted in negligible product degradation (i.e., breakdown of O -glycosidic bonds) even after a 3 d reaction period (<5% weight loss). X-ray photoelectron spectroscopy (XPS) characterization of the POCl3 -phosphorylated chitosan (P-chitosan) revealed a phosphorus to nitrogen (P/N) atomic ratio of 0.30. Phosphorus-31 nuclear magnetic resonance (31 P NMR) spectroscopy verified the monophosphorylation of chitosan's primary and secondary alcohols, and primary amines...
April 28, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/28496524/long-term-stability-and-reusability-of-molecularly-imprinted-polymers
#15
Jozsef Kupai, Mayamin Razali, Sibel Buyuktiryaki, Rustem Kecili, Gyorgy Szekely
Molecularly imprinted materials are man-made mimics of biological receptors. Their polymer network has recognition sites complementary to a substrate in terms of size, shape and chemical functionality. They have diverse applications in various chemical, biomedical and engineering fields such as solid phase extraction, catalysis, drug delivery, pharmaceutical purification, (bio)sensors, water treatment, membrane separations and proteomics. The stability and reusability of molecularly imprinted polymers (IPs) have crucial roles in developing applications that are reliable, economic and sustainable...
January 28, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/28596807/aqueous-sara-atrp-using-inorganic-sulfites
#16
Carlos M R Abreu, Liye Fu, Sheiliza Carmali, Arménio C Serra, Krzysztof Matyjaszewski, Jorge F J Coelho
Aqueous supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) using inorganic sulfites was successfully carried out for the first time. Under optimized conditions, a well-controlled poly[oligo(ethylene oxide) methyl ether acrylate] (POEOA) was obtained with <30 ppm of soluble copper catalyst using tris(2-pyridylmethyl)amine (TPMA) ligand in the presence of an excess of halide salts (e.g. NaCl). Inorganic sulfites (e.g. Na2 S2 O4 ) were continuously fed into the reaction mixture...
January 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/28261331/a-biocompatible-macromolecular-two-photon-initiator-based-on-hyaluronan
#17
Maximilian Tromayer, Peter Gruber, Marica Markovic, Arnulf Rosspeintner, Eric Vauthey, Heinz Redl, Aleksandr Ovsianikov, Robert Liska
The possibility of the direct encapsulation of living cells via two-photon induced photopolymerization enables the microfabrication of hydrogel scaffolds with high initial cell loadings and intimate matrix-cell contact. While highly efficient water-soluble two-photon initiators based on benzylidene ketone dyes have been developed, they exhibit considerable cyto- and phototoxicity. To address the problem of photoinitiator migration from the extracellular matrix into the cytosol, a two-photon initiator bound to a polymeric hyaluronan backbone (HAPI) was synthesized in this work...
January 14, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29081844/fingerprinting-antibiotics-with-pae-based-fluorescent-sensor-arrays
#18
Jinsong Han, Benhua Wang, Markus Bender, Jessica Pfisterer, Wei Huang, Kai Seehafer, Mahdieh Yazdani, Vincent M Rotello, Caren M Rotello, Uwe H F Bunz
We outline an evolution process for tongue elements composed of poly( p -aryleneethynylene)s (PAE) and detergents, resulting in a chemical tongue (24 elements) that discerns antibiotics. Cross-breeding of this new tongue with tongue elements that consist of simple poly( p -phenyleneethynylene)s (PPE) at different pH-values leads to an enlarged sensor array, composed of 30 elements. This tongue was pruned, employing principal component analysis. We find that a filial tongue featuring three elements from each original array (i...
2017: Polymer Chemistry
https://www.readbyqxmd.com/read/28496523/probing-the-causes-of-thermal-hysteresis-using-tunable-nagg-micelles-with-linear-and-brush-like-thermoresponsive-coronas
#19
L D Blackman, M I Gibson, R K O'Reilly
Self-assembled thermoresponsive polymers in aqueous solution have great potential as smart, switchable materials for use in biomedical applications. In recent years, attention has turned to the reversibility of these polymers' thermal transitions, which has led to debate over what factors influence discrepancies in the transition temperature when heating the system compared to the temperature obtained when cooling the system, known as the thermal hysteresis. Herein, we synthesize micelles with tunable aggregation numbers (Nagg) whose cores contain poly(n-butyl acrylate-co-N,N-dimethylacrylamide) (p(nBA-co-DMA)) and four different thermoresponsive corona blocks, namely poly(N-isopropylacrylamide) (pNIPAM), poly(N,N-diethylacrylamide) (pDEAm), poly(diethylene glycol monomethyl ether methacrylate) (pDEGMA) and poly(oligo(ethylene glycol) monomethyl ether methacrylate) (pOEGMA)...
January 1, 2017: Polymer Chemistry
https://www.readbyqxmd.com/read/29093759/increased-hydrophobic-block-length-of-ptdms-promotes-protein-internalization
#20
Coralie M Backlund, Federica Sgolastra, Ronja Otter, Lisa Minter, Toshihide Takeuchi, Shiroh Futaki, Gregory N Tew
The plasma membrane is a major obstacle in the development and use of biomacromolecules for intracellular therapeutic applications. Protein transduction domains (PTDs) have been used to overcome this barrier, but often require covalent conjugation to their cargo and can be time consuming to synthesize. Synthetic monomers can be designed to mimic the amino acid moieties in PTDs, and their resulting polymers provide a well-controlled platform to vary molecular composition for structure-activity relationship studies...
December 28, 2016: Polymer Chemistry
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