Synthesis,swelling capacity,and texture of polymers from monomers of sulfonic acid and acrylamide

The monomers 2‐acrylamido‐2‐methyl‐propanosulfonic acid and acrylamide, and methyleno‐bisacrylamide (BA) whenever a crosslinker was added, were selected for the synthesis of superabsorbent polymers. Texture was observed by scanning electronic microscopy, and specific gravity and swelling were measured. The influence of synthesis conditions—polymerization technique, reaction medium pH, and BA addition—on the texture of the synthesized polymer and its influence on polymer characteristics were assessed. The tests showed that the pores' sizes and distribution in the polymer depend on the polymerization conditions. Swelling rate of the polymers, namely from inverse emulsion technique, with BA and at pH 9, is remarkably high, suiting applications. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Profiling Water-Soluble Organic Matter from Urban Aerosols Using Comprehensive Two-Dimensional Liquid Chromatography

Comprehensive two-dimensional liquid chromatography (LC×LC) coupled with a diode array detector (DAD) has been used for the first time to investigate chemical heterogeneity and map the hydrophobicity versus molecular weight distribution of the most hydrophobic acid fractions in water-soluble organic matter (WSOM) from fine atmospheric aerosols collected over different seasons at a urban location. The use of LC×LC–DAD, combining the use of two independent separation mechanisms (per aqueous liquid chromatography [PALC] versus size-exclusion chromatography [SEC]), has shown a great potential for unraveling and resolving the heterogeneity of WSOM, further providing a deeper insight into how size-distinguished aerosol WSOM fractions differ in hydrophobicity during different seasonal events. The combination of PALC×SEC–DAD data with an already proposed data treatment procedure revealed that the WSOM samples collected during warm seasons are enriched in aliphatic structures, while those collected during colder seasons exhibit a higher degree of structures with conjugation of π-bonds (e.g., aromatics) alongside aliphatic structures.

Copyright 2015 American Association for Aerosol Research     

Synthesis and Properties of Thermotropic Poly(Ester-Amide)S Having Semiregular Monomer Sequences

Dichloride of 4,4′-(carbonylimino)dibenzoic acid was polymerized in 1,1,2,2-tetrachloroethane with a series of monosubstituted hydroquinone (series I) or α, ω-bis(4-hydroxyphenoxy)alkanes (series II) having alkane units of varying length. the polymers obtained were characterized by IR and NMR spectroscopy, solution viscosity measurements, and differential scanning calorimetry (DSC). Formation of mesophase and thermal behavior also were studied on a hot-stage attached to a polarizing microscope. All of the polymers were thermotropic and the transition temperatures were highly dependent on the nature of substituents on hydroquinone in the first series and on the length of alkylene spacers in the second series.     

Non-methylene Interrupted and Hydroxy Fatty Acids in Polar Lipids of the Alga Grateloupia turuturu Over the Four Seasons

Phospholipids (PL) and glycolipids (GL) FA in the edible Rhodophyta Grateloupia turuturu, from Brittany, France, were investigated over four seasons. The major lipid class was GL in all seasons (around 45 %). More than 80 FA occurred in polar lipids, with chains from C₁₂ to C₂₆, identified as methyl esters and N-acyl pyrrolidides by gas chromatography–mass spectrometry (GC–MS). PUFA occurred at up to 47.1 % (summer) in PL, and up to 43.6 % (summer) in GL. The major PUFA were 20:5n-3 (12.2 % in PL and 29.0 % in GL) and 20:4n-6 (25.6 % in PL and 10.4 % in GL). The unusual 18:3n-7 acid was identified in PL up to 2.2 %. Several minor unsaturated FA were identified in PL and are previously unreported in seaweeds, namely 14-tricosenoic, 15-tetracosenoic, 5,11-octadecadienoic and 5,9-nonadecadienoic. Also unprecedented in seaweeds, ten 2-hydroxy and three 3-hydroxy FA occurred mainly in PL, 13.9 % in spring with the 3-hydroxyhexadecanoic acid as the major one (8.1 % winter). Three n-9 monounsaturated 2-hydroxy FA occurred in PL. The 2-hydroxy-15-tetracosenoic acid was characterized as the dimethyl disulfide adduct of its methyl ester. The 2-hydroxy-16-pentacosenoic and 2-hydroxy-17-hexacosenoic acids were identified by comparison of mass spectra and GC mobilities with those of the 2-hydroxy-15-tetracosenoic acid, and of other homogeneous FA series. These rare n-9 monounsaturated 2-hydroxy FA are unprecedented in seaweeds.     

Synthesis of branched carbon nanotubes by carbonization of solid polyvinylidene fluoride fibers

Branched carbon nanotubes (b-CNTs) were synthesized by carbonization of polyvinylidene fluoride (PVDF) fibers containing a Pt catalyst. The solid fibrous polymer converted into carbon nanotubes with simultaneous growth of branches on the surface of the tubes during carbonization. The Pt particles were expected to decompose PVDF polymer inside the tubes into volatile carbonaceous species leaving a hollow center, and also to act as catalytic sites for the growth of carbon branches. The resulting b-CNTs had a high degree of graphitization and a large electrochemical surface area, and also showed a possibility as a supporting material for electrocatalysts.     

A promising bioelectrode based on gene of Mycobacterium leprae immobilized onto poly(4‐aminophenol)

A new bioelectrode for gene detection of Mycobacterium leprae, also known as Hansen's bacillus, was produced by immobilizing of single‐stranded DNA (ssDNA) with 78 bases long (specific gene related to Mycobacterium leprae) on graphite electrode modified with poly(4‐aminophenol). This biosensing platform was able to recognize complementary DNA molecules via hybridization process. Hybridization between probe and target was monitored by voltammetry, using ferrocenecarboxyaldehyde as electrochemical DNA hybridization indicator. The hybridization of nucleic acid probe with the DNA target resulted in significant decrease in the oxidation peak current of ferrocenecarboxyaldehyde, indicating greater affinity of this compound for ssDNA than for double‐strand DNA (dsDNA). The linear range of detection for the DNA target was found to be 0.35 – 35 ng/μL. ssDNA hybridization with the DNA target was also investigated by electrochemical impedance spectroscopy (EIS), showing significant modification in Nyquist plot, by modification in electrode surface after addition of the complementary target. The effective immobilization of specific gene of Mycobacterium leprae onto graphite electrode modified with poly(4‐aminophenol) and the detection of the hybridization process with the DNA target, monitored by voltammetry and EIS indicate that this is a new and promising biosensing platform to gene detection of Hansen's bacillus. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010