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Polymer Chemistry

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https://www.readbyqxmd.com/read/30336037/controlled-molecular-assembly-via-dynamic-confinement-of-solvent
#1
Jiali Zhang, Victoria A Piunova, Yang Liu, Andy Tek, Qingbo Yang, Jane Frommer, Gang-Yu Liu, Joseph Sly
Assembly from ultrasmall solution droplets follows a different dynamic from that of larger scales. Using an independently controlled microfluidic probe in an atomic force microscope, subfemtoliter aqueous droplets containing polymers produce well-defined features with dimensions as small as tens of nanometers. The initial shape of the droplet and the concentration of solute within the droplet play significant roles in the final assembly of polymers due to the ultrafast evaporation rate and spatial confinement by the small droplets...
October 18, 2018: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/30335354/potentiometric-sensing
#2
Elena Zdrachek, Eric Bakker
This review describes, with 186 references, progress in the field of potentiometric sensing in the period between January 2016 and August 2018. January 2016 was when the last fundamental review covering the topic of potentiometric sensors appeared in the special issue of Analytical Chemistry and was set as start date. This review starts with a description of progress in the development and improve-ment of reference electrodes, which represent an indispensable part of any electro-chemical cell and has a particularly important influence on the accuracy of potentiometric measurements...
October 17, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/30333795/multi-parameter-laser-imaging-reveals-complex-microscale-biofilm-matrix-in-a-thick-4-000-%C3%AE-m-aerobic-methanol-oxidizing-community
#3
John R Lawrence, Marcus Winkler, Thomas R Neu
Although methanol has frequently been used as an inexpensive supplementary carbon source to support treatment processes, knowledge of the resultant microbial biofilms, their 3D architecture, microenvironments, exopolymer chemistry and populations remains limited. We supplied methanol as a supplementary carbon source to biofilms developing in rotating annular reactors. Analysis of circulation waters (1.0 l d-1 ) indicated that dissolved organic carbon was reduced by 25%, NO3 -nitrogen by 95%, and total phosphorus by 70%...
2018: Frontiers in Microbiology
https://www.readbyqxmd.com/read/30328219/hybrid-solid-polymer-electrolytes-with-two-dimensional-inorganic-nanofillers
#4
Stephanie Chua, Ruopian Fang, Zhenhua Sun, Mingjie Wu, Zi Gu, Yuzuo Wang, Judy Hart, Neeraj Sharma, Da-Wei Wang, Feng Li
Solid polymer electrolytes are of rapidly increasing importance for the research and development of future safe batteries with extraordinary energy density. The diversified chemistry and structures of polymers allow the utilization of a wide range of soft structures for all-polymer solid-state electrolytes. With equal importance is the hybrid solid-state electrolytes consisting of both 'soft' polymeric structure and 'hard' inorganic nanofillers. The recent emergence of the re-discovery of many two-dimensional layered materials has stimulated the booming of advanced research in energy storage fields, such as batteries, supercapacitors, and fuel cells...
October 16, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30326702/minimal-attachment-of-pseudomonas-aeruginosa-to-dna-modified-surfaces
#5
Hitesh Pingle, Peng-Yuan Wang, Rosalia Cavaliere, Cynthia B Whitchurch, Helmut Thissen, Peter Kingshott
Extracellular deoxyribonucleic acid (eDNA) exists in biological environments such as those around medical implants since prokaryotic or eukaryotic cells can undergo processes such as autolysis, necrosis, and apoptosis. For bacteria, eDNA has been shown to be involved in biofilm formation and gene transfer and acts as a nutrient source. In terms of biofilm formation, eDNA in solution has been shown to be very important in increasing attachment; however, very little is known about the role played by surface immobilized eDNA in initiating bacterial attachment and whether the nature of a DNA layer (physically adsorbed or covalently attached, and molecular weight) influences biofilm formation...
October 16, 2018: Biointerphases
https://www.readbyqxmd.com/read/30326361/qcm-d-and-xps-study-of-protein-adsorption-on-plasma-polymers-with-sulfonate-and-phosphonate-surface-groups
#6
Kim S Siow, Leanne Britcher, Sunil Kumar, Hans J Griesser
As some proteins are known to interact with sulfated and phosphated biomolecules such as specific glycosaminoglycans, this study derives from the hypothesis that sulfonate and phosphonate groups on solid polymer surfaces might cause specific interfacial interactions. Such surfaces were prepared by plasma polymerization of heptylamine (HA) and subsequent grafting of sulfonate or phosphonate groups via Michael-type addition of vinylic compounds. Adsorption of the proteins fibrinogen, albumin (HSA) and lysozyme on these functionalised plasma polymer surfaces was studied by XPS and quartz crystal microbalance with dissipation (QCM-D)...
October 9, 2018: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/30316003/effect-of-surface-chemistry-of-polymeric-nanoparticles-on-cutaneous-penetration-of-cholecalciferol
#7
Augustine Lalloz, Marie-Alexandrine Bolzinger, Jimmy Faivre, Pierre-Luc Latreille, Araceli Garcia Ac, Cyrielle Rakotovao, Jean-Michel Rabanel, Patrice Hildgen, Xavier Banquy, Stéphanie Briançon
We investigated the influence of nanoparticle (NP) surface composition on different aspects of skin delivery of a lipophilic drug: chemical stability, release and skin penetration. Cholecalciferol was chosen as a labile model drug. Poly(lactic acid) (PLA)-based NPs without surface coating, with a non-ionic poly(ethylene glycol) (PEG) coating, or with a zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) coating were prepared using flash nanoprecipitation. Process was optimized to obtain similar hydrodynamic diameters...
October 10, 2018: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/30308975/significance-of-a-non-thermal-plasma-treatment-on-ldpe-biodegradation-with-pseudomonas-aeruginosa
#8
Laurence Scally, Miroslav Gulan, Lars Weigang, Patrick J Cullen, Vladimir Milosavljevic
The use of plastics has spanned across almost all aspects of day to day life. Although their uses are invaluable, they contribute to the generation of a lot of waste products that end up in the environment and end up polluting natural habitats such as forests and the ocean. By treating low-density polyethylene (LDPE) samples with non-thermal plasma in ambient air and with an addition of ≈4% CO₂, the biodegradation of the samples can be increased due to an increase in oxidative species causing better cell adhesion and acceptance on the polymer sample surface...
October 10, 2018: Materials
https://www.readbyqxmd.com/read/30308118/covalent-chemistry-with-valence-endowed-nanoparticles-towards-new-colloidal-molecules
#9
Pierre-Etienne Rouet, Cyril Chomette, Etienne Duguet, Serge Ravaine
We demonstrate a simple method to create a variety of silica-based colloidal molecules through the covalent assembly of site-specifically functionalized patchy nano-particles with complementary nanospheres. Colloidal analogues of BeBr2, BBr3 and CBr4 are obtained from sp-, sp2- and sp3-like particles, while Br2O and NBr3 analogues can be fabricated by varying the relative amounts of both colloidal precursors. We also show that it is possible to attach covalently silica nanospheres of various sizes to one central patchy nanoparticle, which leads to the formation of more complex colloidal molecules, including chiral ones...
October 11, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/30298899/3-arm-star-pyrene-functional-pmmas-for-efficient-exfoliation-of-graphite-in-chloroform-fabrication-of-graphene-reinforced-fibrous-veils
#10
Sandra S Gkermpoura, Konstantinia D Papadimitriou, Emmanuel N Skountzos, Ioannis Polyzos, Maria Giovanna Pastore Carbone, Athanasios Kotrotsos, Vlasis G Mavrantzas, Costas Galiotis, Constantinos Tsitsilianis
3-Arm PMMAs end-functionalized by pyrene were designed as dispersing/stabilizing agents for the liquid-phase exfoliation of graphite in low-boiling point solvents like chloroform. The synthetic procedure comprised ARGET ATRP controlled polymerization, click chemistry and the quaternization reaction of triazole, ensuring tailor-made, well-defined pyrene-functional star PMMAs. Among a series of different pyrene-functional macromolecular topologies, the (PMMA-py2)3 proved the most efficient exfoliation agent giving relatively high graphene concentration (0...
October 9, 2018: Nanoscale
https://www.readbyqxmd.com/read/30297814/interparticle-hydrogen-bonding-can-elicit-shear-jamming-in-dense-suspensions
#11
Nicole M James, Endao Han, Ricardo Arturo Lopez de la Cruz, Justin Jureller, Heinrich M Jaeger
Dense suspensions of hard particles in a liquid can exhibit strikingly counter-intuitive behaviour, such as discontinuous shear thickening (DST)1-7 and reversible shear jamming (SJ) into a state where flow is arrested and the suspension is solid-like8-12 . A stress-activated crossover from hydrodynamic interactions to frictional particle contacts is key for these behaviours2-4,6,7,9,13 . However, in experiments, many suspensions show only DST, not SJ. Here we show that particle surface chemistry plays a central role in creating conditions that make SJ readily observable...
October 8, 2018: Nature Materials
https://www.readbyqxmd.com/read/30295184/phenylboronic-acid-polymers-for-biomedical-applications
#12
Ji Hyun Ryu, Gyeong Jin Lee, Yu-Ru V Shih, Tae-Il Kim, Shyni Varghese
BACKGROUND: Phenylboronic acid-polymers (PBA-polymers) have attracted tremendous attention as potential stimuli-responsive materials with applications in drug-delivery depots, scaffolds for tissue engineering, HIV barriers, and biomolecule-detecting/sensing platforms. The unique aspect for PBA-polymers is their interactions with diols, which results in reversible, covalent bond formations. This very nature of reversible bonding between boronic acids and diols has been fundamental to their applications in the biomedical area...
October 8, 2018: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/30291243/high-performance-nanomaterials-formed-by-rigid-yet-extensible-cyclic-%C3%AE-peptide-polymers
#13
Kenan P Fears, Manoj K Kolel-Veetil, Daniel E Barlow, Noam Bernstein, Christopher R So, Kathryn J Wahl, Xianfeng Li, John L Kulp, Robert A Latour, Thomas D Clark
Organisms have evolved biomaterials with an extraordinary convergence of high mechanical strength, toughness, and elasticity. In contrast, synthetic materials excel in stiffness or extensibility, and a combination of the two is necessary to exceed the performance of natural biomaterials. We bridge this materials property gap through the side-chain-to-side-chain polymerization of cyclic β-peptide rings. Due to their strong dipole moments, the rings self-assemble into rigid nanorods, stabilized by hydrogen bonds...
October 5, 2018: Nature Communications
https://www.readbyqxmd.com/read/30289243/metal-coordination-polymer-framework-governed-by-heat-of-hydration-for-noninvasive-differentiation-of-alkali-metal-series
#14
Shateesh Battu, Mahesh Itagi, Zahid Manzoor Bhat, Siddhi Khaire, Alagar Raja Kottaichamy, Lokesh Koodlur Sannegowda, Ravikumar Thimmappa, Musthafa Ottakam Thotiyl
We illustrate that the extent of hydration and consequently the heat of hydration of alkali metal ions can be utilized to control their insertion/deinsertion chemistry in a redox active metal coordination polymer framework (CPF) electrode. The formal redox potential of CPF electrode for cation intercalation is inversely correlated to hydrated ionic radii, with clear distinction between the intercalation of ions across alkali metal series. This leads to noninvasive identification and differentiation of cations in the alkali metal series by utilizing a single sensing platform...
October 18, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/30288016/mechanism-and-catalysis-of-oxidative-degradation-of-fiber-reinforced-epoxy-composites
#15
Carlos A Navarro, Elyse A Kedzie, Yijia Ma, Katelyn H Michael, Steven R Nutt, Travis J Williams
Carbon fiber-reinforced polymer (CFRP) materials are widely used in aerospace and recreational equipment, but there is no efficient procedure for their end-of-life recycling. Ongoing work in the chemistry and engineering communities emphasizes recovering carbon fibers from such waste streams by dissolving or destroying the polymer binding. By contrast, our goal is to depolymerize amine-cured epoxy CFRP composites catalytically, thus enabling not only isolation of high-value carbon fibers, but simultaneously opening an approach to recovery of small molecule monomers that can be used to regenerate precursors to new composite resin...
June 2018: Topics in Catalysis
https://www.readbyqxmd.com/read/30285474/electrochromic-sensors-based-on-conducting-polymers-metal-oxides-and-coordination-complexes
#16
Raimonda Celiesiute, Almira Ramanaviciene, Mindaugas Gicevicius, Arunas Ramanavicius
Electrochromic sensors offer multi-mode registration of analytical signal based on combination of electrochemical and optical techniques. This emerging direction of analytical chemistry is relatively new; therefore, it has very high potential for various applications in chemical and biochemical analysis. Properties of sensors based on various electrochromic materials such as polymers, polymer derivatives, polymer composites, metal oxides, metal oxide complexes, phthalocyanines, porphyrins, and dyes are critically overviewed, evaluated, and compared...
October 4, 2018: Critical Reviews in Analytical Chemistry
https://www.readbyqxmd.com/read/30285418/surface-fouling-of-ultrananocrystalline-diamond-microelectrodes-during-dopamine-detection-improving-lifetime-via-electrochemical-cycling
#17
An-Yi Chang, Gaurab Dutta, Shabnam Siddiqui, Prabhu Arumugam
In this work, we report the electrochemical response of a boron-doped ultrananocrystalline diamond (BDUNCD) microelectrode during long-term dopamine (DA) detection. Specifically, changes to its electrochemical activity and electroactive area due to DA-by products and surface oxidation are studied via scanning electron microscopy, energy dispersive spectroscopy, electrochemical impedance spectroscopy and silver deposition imaging (SDI). The fouling studies with amperometry (AM) and fast scan cyclic voltammetry (FSCV) methods suggest that the microelectrodes are heavily fouled due to poor DA-dopamine-o-quinone cyclization rates followed by a combination of polymer formation and major changes in their surface chemistry...
October 4, 2018: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/30276257/on-demand-switching-of-polymerization-mechanism-and-monomer-selectivity-with-orthogonal-stimuli
#18
Brian M Peterson, Veronika Kottisch, Michael J Supej, Brett P Fors
The development of next-generation materials is coupled with the ability to predictably and precisely synthesize polymers with well-defined structures and architectures. In this regard, the discovery of synthetic strategies that allow on demand control over monomer connectivity during polymerization would provide access to complex structures in a modular fashion and remains a grand challenge in polymer chemistry. In this Article, we report a method where monomer selectivity is controlled during the polymerization by the application of two orthogonal stimuli...
September 26, 2018: ACS Central Science
https://www.readbyqxmd.com/read/30273747/peroxidase-immobilized-porous-silica-particles-for-in-situ-formation-of-peroxidase-free-hydrogels-with-attenuated-immune-responses
#19
Li Li, Ki Hyun Bae, Shengyong Ng, Atsushi Yamashita, Motoichi Kurisawa
Enzymatic crosslinking chemistry using horseradish peroxidase (HRP) has been widely utilized as an effective approach to fabricating injectable hydrogels with high efficiency under mild reaction conditions. However, their clinical applications are limited by the immunogenicity of the plant-derived enzyme. Herein we report the design, synthesis and characterization of HRP-immobilized porous silica particles (HRP-particles) and their use for in situ formation of HRP-free hydrogels. HRP was immobilized on aminopropyl-modified porous silica particles of 70-140 µm in diameter via poly(ethylene glycol) spacers of different molecular weights by reductive amination reaction...
September 28, 2018: Acta Biomaterialia
https://www.readbyqxmd.com/read/30264062/benzoins-and-cyclobenzoins-in-supramolecular-and-polymer-chemistry
#20
Maymounah Alrayyani, Ognjen Š Miljanić
Benzoin condensation is one of the oldest rigorously described organic reactions, having been discovered in 1832 by Liebig and Wöhler. It creates a new C-C bond and a stereocenter from ubiquitous aldehyde starting materials under simple cyanide-catalyzed conditions. We have recently discovered cyclobenzoins: a class of macrocyclic compounds prepared by a benzoin cyclooligomerization of simple aromatic dialdehydes. Cyclobenzoins' internal cavities suggest they should be intriguing solution-phase supramolecular hosts, while their crystallographic packing aligns these cavities into potentially useful pores in the solid state...
September 28, 2018: Chemical Communications: Chem Comm
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