Preparation and Characterization of Hydrosoluble, Partially Charged Poly(styrenesulfonate)s of Various Controlled Charge Fractions and Chain Lengths

2002 ◽  
Vol 35 (6) ◽  
pp. 2318-2326 ◽  
Author(s):  
Damien Baigl ◽  
Thomas A. P. Seery ◽  
Claudine E. Williams
Keyword(s):  
Charge Fractions ◽  
Chain Lengths

scholarly journals Preparation of Tri(alkenyl)functional Open-Cage Silsesquioxanes as Specific Polymer Modifiers

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1063
Author(s):  
Katarzyna Mituła ◽  
Michał Dutkiewicz ◽  
Julia Duszczak ◽  
Monika Rzonsowska ◽  
Beata Dudziec
Keyword(s):  
Condensation Reaction ◽  
Polyhedral Oligomeric Silsesquioxanes ◽  
Double Decker ◽  
Application Potential ◽  
Synthetic Routes ◽  
High Yields ◽  
Chain Lengths ◽  
Tga And Dsc ◽  
Melting And Crystallization Temperatures

The scientific reports on polyhedral oligomeric silsesquioxanes are mostly focused on the formation of completely condensed T8 cubic type structures and recently so-called double-decker derivatives. Herein, we report on efficient synthetic routes leading to trifunctionalized, open-cage silsesquioxanes with alkenyl groups of varying chain lengths from -vinyl to -dec-9-enyl and two types of inert groups (iBu, Ph) at the silsesquioxane core. The presented methodology was focused on hydrolytic condensation reaction and it enabled obtaining titled compounds with high yields and purity. A parallel synthetic methodology that was based on the hydrosilylation reaction was also studied. Additionally, a thorough characterization of the obtained compounds was performed, also in terms of their thermal stability, melting and crystallization temperatures (TGA and DSC) in order to show the changes in the abovementioned parameters dependent on the type of reactive as well as inert groups at Si-O-Si core. The presence of unsaturated alkenyl groups has a profound impact on the application potential of these systems, i.e., as modifiers or comonomers for copolymerization reaction.

scholarly journals Synthesis and Characterization of Novel Copolymeric Resveratrol Conjugates

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Yan-Jing Ng ◽  
Heather A. E. Benson ◽  
David H. Brown ◽  
Yan Chen
Keyword(s):  
Micelle Formation ◽  
Rat Plasma ◽  
The Body ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene ◽  
The Stability ◽  
Chain Lengths ◽  
Cardioprotective Drug

Resveratrol (RSV), naturally found in plants, is known to have health benefits and has been proposed as a potential anticancer and cardioprotective drug. However, due to its molecular structure, it undergoes rapid metabolism in the body resulting in low bioavailability. Novel polymeric methoxy-poly(ethylene glycol)-block-poly(ε-caprolactone) (mPEG-PCL) RSV conjugates with varying PCL chain lengths have been synthesised and formulated into micelles and/or nanoparticles for preliminaryin vitrostability studies. RSV conjugated with mPEG2000-PCL9500 was found to have improved solubility and stability of RSV as compared to RSV alone. The length of the PCL chain was found to affect the micelle formation, hence the stability in physiological buffers and rat plasma.

Synthesis and characterization of some octaalkyl substituted lead phthalocyanines and unexpected variations in lead lability arising from the position of substituents and their chain length

2013 ◽  
Vol 17 (06n07) ◽  
pp. 511-521 ◽  
Author(s):  
Lydia X. Sosa-Vargas ◽  
Isabelle Chambrier ◽  
Colin J. MacDonald ◽  
Simon J. Coles ◽  
Graham J. Tizzard ◽  
...  
Keyword(s):  
Chain Length ◽  
Alkyl Chain ◽  
Lead Ion ◽  
X Ray ◽  
H Nmr ◽  
Alkyl Groups ◽  
Nmr Spectrometry ◽  
Acid Catalyzed ◽  
Chain Lengths

The preparation of some peripherally substituted (2,3,9,10,16,17,23,24) and non-peripherally substituted (1,4,8,11,15,18,22,25) octaalkyl lead(II) phthalocyanines with different alkyl chain lengths (6, 7, 8 or 9 carbons) is described and a comparison of some of their properties reported. X-ray structure analyses of the isomeric peripheral and non-peripheral octakis(octyl)phthalocyaninato lead(II) compounds reveal a greater degree of distortion of the ligand ring system from planarity in the former derivative. The series of peripherally substituted octaalkyl lead(II) phthalocyanines exhibit columnar liquid crystal behavior whereas the non-peripherally substituted isomers do not. The lability of the lead ion was investigated using 1 H NMR spectrometry under a specific set of conditions (8.8 × 10-4 M solutions of the phthalocyanine in d8-toluene containing d4-acetic acid 2.06 × 10-5 M). All the compounds underwent acid catalyzed demetalation at rates dependent upon the location of the substituents and, more surprisingly, the chain length of the alkyl groups. Under these conditions the lead ion within each of the peripherally substituted octaalkyl lead phthalocyanines was more labile than that in the non-peripherally substituted isomer.

Approaching the size limit of organometallic layers: synthesis and characterization of highly ordered silver–thiolate lamellae with ultra-short chain lengths

2016 ◽  
Vol 45 (47) ◽  
pp. 18954-18966 ◽  
Author(s):  
Zichao Ye ◽  
Lito P. de la Rama ◽  
Mikhail Y. Efremov ◽  
Jian-Min Zuo ◽  
Leslie H. Allen
Keyword(s):  
Single Crystal ◽  
Chain Length ◽  
Short Chain ◽  
Synthesis And Characterization ◽  
Size Limit ◽  
Chain Conformations ◽  
Chain Lengths

Synthesis of single crystal silver alkanethiolate (any chain length) lamellae with highly ordered chain conformations, interlayer interfaces and intralayer lattices.

scholarly journals Autolysis of isolated cell walls of Bacillus licheniformis N.C.T.C. 6346 and Bacillus subtilis Marburg strain 168. Separation of the products and characterization of the mucopeptide fragments

1970 ◽  
Vol 119 (5) ◽  
pp. 849-860 ◽  
Author(s):  
R. C. Hughes
Keyword(s):  
Bacillus Subtilis ◽  
Bacillus Licheniformis ◽  
Cell Walls ◽  
Deae Cellulose ◽  
Casein Hydrolysate ◽  
Diaminopimelic Acid ◽  
Average Chain Length ◽  
Amide Bonds ◽  
Chain Lengths

1. Cell walls were isolated from Bacillus licheniformis N.C.T.C. 6346 and Bacillus subtilis Marburg strain 168 trp grown on casein hydrolysate into exponential phase. Autolysis was carried out and the soluble products, separated by chromatography on DEAE-cellulose, from the two wall preparations are broadly similar in composition and are in agreement with autolysis proceeding with hydrolysis of amide bonds between l-alanine and N-acetylmuramic acid residues in the mucopeptide components. 2. Peptides originating from the mucopeptide components were isolated and shown to be a monomer peptide, l-alanyl-d-glutamyl-meso-diaminopimelic acid and a dimer peptide containing two monomer peptides linked through a residue of d-alanine. Approximately one amide group is present for each equivalent tripeptide unit and is probably substituted on diaminopimelic acid residues. 3. Oligosaccharides originating from the mucopeptide components were isolated and after hydrolysis contained almost equimolar amounts of glucosamine and muramic acid and only very small amounts of amino acids. The number-average chain length, estimated by the release of non-reducing end groups of N-acetylglucosamine with exo-β-N-acetylglucosaminidase, is approximately ten hexosamine residues for oligosaccharides isolated from either organism. The oligosaccharides are polydisperse. 4. N-Acetylglucosamine residues are the only reducing terminals detectable in the oligosaccharides isolated from B. subtilis or B. licheniformis cell-wall autolysates. The number-average chain lengths of the oligosaccharides were determined by estimation of the content of these residues and are higher than those found by enzymic assay. Possible reasons for the discrepancy are discussed.

Marine Biosurfactants, II. Production and Characterization of an Anionic Trehalose Tetraester from the Marine Bacterium Arthrobacter sp. EK 1

1991 ◽  
Vol 46 (3-4) ◽  
pp. 204-209 ◽  
Author(s):  
A. Passeri ◽  
S. Lang ◽  
F. Wagner ◽  
Victor Wray
Keyword(s):  
Fatty Acids ◽  
Nitrogen Limitation ◽  
Marine Bacterium ◽  
Thick Layer ◽  
Growth Conditions ◽  
Main Fraction ◽  
Exact Position ◽  
Chain Lengths ◽  
Layer Chromatography

Within a screening for biosurfactants we could isolate various n-alkanes utilizing marine bacteria which were capable of synthesizing glycolipids. One strain was identified as Arthrobacter sp. EK 1 which produced trehalose lipids. After purification by column and thick layer chromatography the main fraction, an anionic 2,3,4,2′-trehalose tetraester, was obtained. The chain lengths of fatty acids ranged from 8 up to 14, furthermore succinate could be detected. Since the place of substitution of succinate has so far not been cited in literature, a definitive structural elucidation was carried out chemically by hydroboration and by 1H, 2 D1H, 13C and 13C - 1H correlation NMR measurements. All investigations confirmed the exact position of succinate at C2 atom of trehalose. After improvement of growth conditions the production of the trehalose tetraester increased up to 4.8 g/1 during a fermentation in a 20 1 bioreactor under nitrogen limitation.

scholarly journals Characterization of a Phosphotriesterase-Like Lactonase fromSulfolobus solfataricusand Its Immobilization for Disruption of Quorum Sensing

2010 ◽  
Vol 77 (4) ◽  
pp. 1181-1186 ◽  
Author(s):  
Filomena S. W. Ng ◽  
Daniel M. Wright ◽  
Stephen Y. K. Seah
Keyword(s):  
Quorum Sensing ◽  
Virulence Factors ◽  
Acyl Chain ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Homoserine Lactones ◽  
Specificity Constant ◽  
Chain Lengths ◽  
Quorum Sensing Signals

ABSTRACTSsoPox, a bifunctional enzyme with organophosphate hydrolase andN-acyl homoserine lactonase activities from the hyperthermophilic archaeonSulfolobus solfataricus, was overexpressed and purified from recombinantPseudomonas putidaKT2440 with a yield of 9.4 mg of protein per liter of culture. The enzyme has a preference forN-acyl homoserine lactones (AHLs) with acyl chain lengths of at least 8 carbon atoms, mainly due to lowerKmvalues for these substrates. The highest specificity constant obtained was forN-3-oxo-decanoyl homoserine lactone (kcat/Km= 5.5 × 103M−1·s−1), but SsoPox can also degradeN-butyryl homoserine lactone (C4-HSL) andN-oxo-dodecanoyl homoserine lactone (oxo-C12-HSL), which are important for quorum sensing in ourPseudomonas aeruginosamodel system. WhenP. aeruginosaPAO1 cultures were grown in the presence of SsoPox-immobilized membranes, the production of C4-HSL- and oxo-C12-HSL-regulated virulence factors, elastase, protease, and pyocyanin were significantly reduced. This is the first demonstration that immobilized quorum-quenching enzymes can be used to attenuate the production of virulence factors controlled by quorum-sensing signals.

scholarly journals Synthesis and Characterization of Graft Copolymer of Dextran and 2-Acrylamido-2-methylpropane Sulphonic Acid

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Venkanna Azmeera ◽  
P. Adhikary ◽  
S. Krishnamoorthi
Keyword(s):  
Graft Copolymer ◽  
Sulphonic Acid ◽  
Ceric Ammonium Nitrate ◽  
Side Chain ◽  
Synthesis And Characterization ◽  
Grafted Polymers ◽  
X Ray ◽  
Chain Lengths ◽  
Scanning Electron

A novel biodegradable graft copolymer of dextran (Dx) and 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) was synthesized by grafting poly-AMPS chains onto dextran backbone by free radical polymerization using ceric ammonium nitrate (CAN) as an initiator. Different amounts of AMPS were used to synthesize four different grades of graft copolymers with different side chain lengths. These grafted polymers were characterized by elemental analysis, FTIR, 1HNMR, rheological technique, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray diffractometry (XRD). They exhibited efficient flocculation performance in kaolin suspension.

Characterizations of radicals formed in radical polymerizations and transfer reactions by electron spin resonance spectroscopy

2018 ◽  
Vol 90 (8) ◽  
pp. 1237-1254 ◽  
Author(s):  
Atsushi Kajiwara
Keyword(s):  
Electron Spin Resonance ◽  
Radical Polymerization ◽  
Electron Spin ◽  
Transfer Reactions ◽  
Resonance Spectroscopy ◽  
Spin Resonance ◽  
Radical Transfer ◽  
Radical Polymerizations ◽  
Chain Lengths

Abstract Electron spin resonance (ESR, aka electron paramagnetic resonance, EPR) investigations have been conducted on radicals formed during radical polymerizations and provide a detailed characterization of the active radical species. Active propagating radicals can be observed during actual radical polymerizations by ESR/EPR. The chain lengths of the observed radicals were estimated by a combination of atom transfer radical polymerization (ATRP) and ESR/EPR. The structures of the chain end radicals were determined by analysis of the ESR/EPR spectra. An increase in the dihedral angles between terminal p-orbital of radical and Cβ–H bonds was observed with increasing chain lengths of methacrylate polymers. Radical transfer reactions were observed during radical polymerization of acrylates. A combination of ATRP and ESR/EPR clarified a 1,5-hydrogen shift mechanism of the radical transfer reactions using model adamantyl acrylate radicals. Penultimate unit effects were also observed. Time-resolved ESR/EPR (TR ESR) spectroscopy clarified the initiation processes of an alternating copolymerization of styrene with maleic anhydride and the copolymerization of styrene with 1,3-butadiene. Several unsolved problems in conventional radical polymerization processes have been clarified using combinations of ATRP with ESR/EPR and TR ESR. Characterization of the radicals in radical polymerizations using various ESR techniques would definitely provide interesting and useful information on conventional radical polymerizations.

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