Acid Homopolymer Research Articles

Eco-paints from bio-based fatty acid derivative latexes

Abstract A series of fatty acid derivative latexes has been incorporated as binders in waterborne paints: methacrylated oleic acid (MOA) and methacrylated linoleic acid (MLA) homopolymers and copolymers of the petroleum derivative monomer methyl methacrylate and its structurally analogous renewable resource monomer α-methylene-γ-butyrolactone. The performance of the resulting paints has been evaluated in terms of hardness, gloss, rheological behaviour and open time and the final properties have been compared with a commercial waterborne paint. Most of the prepared paints showed good performance properties, making these compounds good candidates for their use in the production of sustainable waterborne paints.

The impact of polymer structure on the adsorption of ionic polyamino acid homopolymers and their diblock copolymers on colloidal chromium(iii) oxide

The aim of the presented study was to investigate the influence of the structure and ionic nature of polymers on the adsorption layer architecture.

Properties of IA/SAS Copolymer and Itaconic Acid Homopolymer

The sulfo-group-containing itaconic-acid-based polymer (IA/SAS) and the itaconic acid homopolymer (PIA) were synthesized. The molecular structure of itaconic acid, copolymer and homopolymer were determined by IR analysis. The performances of inhibition against CaCO3 and Ca3(PO4)2 scale of the two polymers were compared by the static scale inhibition experiments. When the dosage exceeded 20 mg/L, both of the inhibition efficiencies against CaCO3 scale were higher than 90%. IA/SAS had obvious performance of inhibition against Ca3(PO4)2 scale, when the dosage of IA/SAS was 28 mg/L, the scale inhibition efficiency reached 100%. While PIA did not show any effect of inhibiton against Ca3(PO4)2 scale within the test range.

Metabolomic analysis of antimicrobial mechanisms of ε-poly-L-lysine on Saccharomyces cerevisiae.

ε-Poly-L-lysine (ε-PL), a naturally occurring amino acid homopolymer, has been widely used as a food preservative. However, its antimicrobial mechanism has not been fully understood. This study investigated the antimicrobial mode of action of ε-PL on a yeast, Saccharomyces cerevisiae. When treated with ε-PL at the concentration of 500 μg/mL, cell mortality was close to 100% and the phospholipid bilayer curvature, pores, and micelles on the surface of S. cerevisiae were clearly observed by scanning electron microscopy (SEM). At the level of 200 μg/mL, ε-PL significantly inhibited the cell growth of S. cerevisiae. When treated with 50 μg/mL ε-PL, the yeast cell was able to grow but the cell cycle was prolonged. A significant increase in cell membrane permeability was induced by ε-PL at higher concentrations. Metabolomics analysis revealed that the ε-PL stress led to the inhibition of primary metabolic pathways through the suppression of the tricarboxylic acid cycle and glycolysis. It is therefore proposed that the microbiostatic effect of ε-PL at lower levels on S. cerevisiae is achieved by inducing intracellular metabolic imbalance via disruption of cell membrane functions. Moreover, the results suggested that the antimicrobial mechanism of ε-PL on S. cerevisiae can in fact change from microbiostatic to microbicidal when the concentration of ε-PL increased, and the mechanisms of these two modes of action were completely different.

Improvement of the fire behavior of poly(1,4‐butanediol succinate)/flax biocomposites by fiber surface modification with phosphorus compounds: molecular versus macromolecular strategy

The grafting of phosphorus compounds onto natural fibers has been investigated as a strategy for improving poly(1,4‐butanediol succinate)/flax biocomposite fire behavior. Three phosphorus compounds − dihydrogen ammonium phosphate, poly(methacryloyloxy)methyl phosphonic acid homopolymer and poly(methacryloyloxy)methyl phosphonic acid methylmethacrylate copolymer − were selected. The aim of this work was to compare the fire performance conferred by the grafted compounds depending on whether phosphorus is brought by a molecule or a macromolecule. TGA, pyrolysis combustion flow calorimetry and cone calorimetry were used to characterize the thermal stability and fire behavior of the samples. The pyrolysis combustion flow calorimetry results showed that in all cases the presence of phosphorus changes the degradation pathway and thus the flammability properties of flax. The ability of the grafted flame retardant to promote char formation and residue formation was found to be dependent on the nature and quantity of phosphorus covalently bonded to flax. Conversely, cone calorimeter tests revealed similar fire behavior whatever the grafting agent. A significant increase of the char amount and a global enhancement of fire parameters were observed with increasing grafting rate. Moreover, phosphonated polymers promoted a charred sheath around the fibers which acts in addition to their charring, conferring a fire performance close to that of dihydrogen ammonium phosphate for the biocomposite.

Research on Performances of Environmentally Friendly Multi-Component Corrosion Inhibitor

A new multi-component corrosion inhibitor was prepared from itaconic acid homopolymer, polyepoxysuccinic acid ,polyaspartic acid derivative and sodium gluconate. The preformances of the corrosion inhibition and biodegradability were studied by rotary hanging piece weight-loss tests,electrochemical and biodegradability tests. The corrosion test piece was observed by SEM.The results showed that the multi-component corrosion inhibitor had good performances of corrosion inhibition and biodegradability.

Interaction of Tricationic Corroles with Single/Double Helix of Homopolymeric Nucleic Acids and DNA

In this manuscript a multitechnique approach is proposed to characterize the interaction between new tri-N-methylpyridyl corrole (TMPC) and its germanium(IV) derivative (GeTMPC), with single- and double-stranded nucleic acid homopolymers and calf thymus DNA. The specificity of each spectroscopic technique has been exploited to analyze the different aspects of corrole binding. Noteworthy, this approach allows us to distinguish between H aggregation of TMPC in the presence of polyriboadenilic acid (poly(rA)) and J aggregates in the presence of polyribocytidinic acid (poly(rC)) as well as to identify the formation of GeTMPC dimers in the presence of single-stranded poly(rA) and pseudointercalation with single-stranded poly(rC).

Efficacy of a new colloidal form of low-sialylated polylactide-based erythropoietin in experimental hemorrhagic stroke in rats

The aim of the present work was to develop methods for the preparation of a nanosomal form of low-sialylated recombinant human erythropoietin (ls-rhEPO), which has neurotropic antihemorrhagic activity. Measurements were made of the sorption of erythropoietin to nanoparticles made of lactic acid homopolymer or lactic acid/glycolic acid copolymer, mean nanoparticle size, and the resistance of the resulting complex to aggregation. The most effective sorption (greater than 80%) was achieved using a copolymer with equal proportions of lactic and glycolic acids (50:50). Experiments using an intracerebral post-traumatic hematoma model in rats demonstrated that nanosomal ls-rhEPO had neuroprotective actions, based on its ability to decrease death in the experimental animals (77.8% survived, which was 40% more than in the control group). Nanosomal ls-rhEPO was found to have no effect on hematopoiesis in conditions of chronic administration.

Global Studies of Single-Stranded Nucleic Acid Conformation

Unstructured regions of RNA molecules require flexibility to accomplish many biological tasks such as conformational switching and protein recognition. Due to its highly charged backbone, the flexibility of single-stranded RNA is influenced by counterions. In this presentation, we continue to explore RNA flexibility using single-stranded nucleic acid homopolymers as a model system [1]. We investigate the role of counterion valence in nucleic acid flexibility using a combination of small-angle X-ray scattering (SAXS) and single-molecule Forster resonance energy transfer (smFRET). We also study how charge-screening of these model systems are affected by mono- and divalent ions in competition. The results imply that various factors can alter the polymeric properties of unstructured nucleic acids, and may be important for tuning RNA conformational dynamics in vivo.Reference: [1] Chen et al. PNAS 2012 109 (3) 799-804

Poly(acrylic acid) Undergoes Partial Esterification During RAFT Synthesis in Methanol and Interchain Disulfide Bridging Upon NaOH Treatment

AbstractIn this work, poly(acrylic acid) was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization using 4,4′‐azobis(4‐cyanopentanoic acid) and 4‐cyanopentanoic acid dithiobenzoate as a radical initiator and chain transfer agent, respectively. By varying the reactant ratios, we achieved poly(acrylic acid) with molecular weights up to 55 100 and polydispersities of ≈1.2. Upon characterization of the final products, we detected, as a side reaction, partial esterification of the carboxyl side chain groups when the polymerization was conducted in methanol. Treatment of the esterified polymer with base resulted in acrylic acid homopolymers, but also led to end‐group disulfide bridging, which was reversed using a reducing buffer.

Carbomer Dispersions: A New Calibration Method for Quantifying Shear-Thinning and Shear-Thickening Effects

This article introduces a new method to quantify non-Newtonian behavior of polymer dispersions, while, at the same time, taking into consideration the instrumental accuracy for measuring rheological properties of such dispersions. As a case study, rheological properties of carbomer dispersions have been investigated as a function of carbomer concentration. Carbomer, 2-propenoic acid homo-polymer, is classified as a synthetic polymer and used as an emulsion stabilizer as well as an aqueous thickening agent. The apparent viscosity, η, was measured as a function of shear rate for different carbomer contents. The calibration method introduces a dimensionless viscosity change, , and a dimensionless change in shear rate, Φ. A straight-line relationship was used as a model to describe how changes as a function of Φ. The model, based on the proposed calibration method, managed to quantitatively and qualitatively describe the shear-thinning behavior of carbomer dispersions. Carbomer dispersions have values less than one for diluted concentrations (less than 0.45 wt% carbomer). Above this threshold, carbomer dispersions exhibited a non-Newtonian behavior manifested byvalues greater than one.

Development and Mechanism of Multiple Non-Phosphorus Corrosion Inhibitor

A multiple non-phosphorus corrosion inhibitor was prepared by mixing polyaspartic acid with itaconic acid homopolymer, sodium gluconate and surfactant alkylolamide in a certain proportion. The corrosion inhibition performance was tested and the mechanism was studied by electrochemical process. The results showed that synergies among components of the agent made the corrosion inhibition rate on carbon steel reach up to 96.96%. This mainly because that a dense adsorbed film formed on the surface of the carben steeel.

Application of anionic acrylamide‐based hydrogels in the removal of heavy metals from waste water

AbstractCrosslinked acrylamide (AM) and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) homopolymers and copolymers were prepared by free radical solution polymerization using N,N′‐methylenebisacrylamide as the crosslinker. The chemical structures of hydrogels were characterized by FTIR analysis and the results were consistent with the expected structures. These hydrogels were used for the separation of Cd(II), Cu(II), and Fe(III) ions from their aqueous solutions. The influence of the uptake conditions such as pH, time and initial feed concentration on the metal ion binding capacity of hydrogel was also tested. The selectivity of the hydrogel towards the different metal ions tested was Cd(II) > Cu(II) > Fe(III). It was observed that the specific interaction between metal ions and ionic comonomers in the hydrogel affected the metal binding capacity of the hydrogel. The recovery of metal ions was also investigated in acid media. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The inhibition abilities of multifunctional polyelectrolytes for silica scale formation in cooling water systems: Role of the nonionic functional group

The abilities of multifunctional polyelectrolytes to enhance aluminum hydroxide dispersion and inhibit silica scale formation were examined in a pilot cooling water system. The following multifunctional polyelectrolytes were studied: a terpolymer of acrylic acid (AA), 2-acrylamide-2-methyl propane sulfonic acid (SA) and N-vinylpyrrolidone (NVP) (P(AA/SA/NVP)), acrylic acid homopolymer (P(AA)) and a copolymer of AA and SA (P(AA/SA)). The order of inhibition ability was P(AA/SA/NVP)>P(AA/SA)>P(AA), and was consistent with that of the dispersing ability for aluminum hydroxide. Other terpolymers incorporating different nonionic monomers were also examined and factors affecting their inhibition abilities were investigated, based on interaction energies calculated by density functional theory. Based on the correlation between scale inhibition abilities and interaction energies, we elucidated that the effective nonionic monomer of terpolymer for silica scale inhibition had low affinity for aluminum hydroxide and high affinity for H2O and Si(OH)3O−. The affinities of nonionic monomer for aluminum hydroxide and H2O suggested that there was proper conformation of polyelectrolyte adsorbed for effectively dispersing aluminum hydroxide. Also, high affinity of nonionic monomer for Si(OH)3O− suggested that interacting Si(OH)3O− is an important role of inhibition of silica scale formation.

Biocatalytic synthesis of new copolymers from 3-hydroxybutyric acid and a carbohydrate lactone

Abstract Lipase-catalyzed reaction of 3-hydroxybutyric acid with d -glucono-δ-lactone at 5:1 molar ratio and 80 °C yielded a mixture of moderate molecular weight linear and cyclic oligomers. The most efficient biocatalyst, Candida antarctica B lipase (Novozyme 435), allowed the synthesis of new oligomeric compounds with ring-opened gluconolactone units included in the oligomeric chain, without previous derivatization of the sugar, or activation of the acid monomer. The reaction medium nature had an important influence on the product composition. Although the main copolymer amount was synthesized in tert-butanol/dimethylsulfoxide medium, the highest polymerization degrees, up to 9 for the copolymer, and 10 for the 3-hydroxybutyric acid homopolymer co-product, were achieved in solventless conditions.

Comparative genomics of the social amoebae Dictyostelium discoideum and Dictyostelium purpureum

BackgroundThe social amoebae (Dictyostelia) are a diverse group of Amoebozoa that achieve multicellularity by aggregation and undergo morphogenesis into fruiting bodies with terminally differentiated spores and stalk cells. There are four groups of dictyostelids, with the most derived being a group that contains the model species Dictyostelium discoideum.ResultsWe have produced a draft genome sequence of another group dictyostelid, Dictyostelium purpureum, and compare it to the D. discoideum genome. The assembly (8.41 × coverage) comprises 799 scaffolds totaling 33.0 Mb, comparable to the D. discoideum genome size. Sequence comparisons suggest that these two dictyostelids shared a common ancestor approximately 400 million years ago. In spite of this divergence, most orthologs reside in small clusters of conserved synteny. Comparative analyses revealed a core set of orthologous genes that illuminate dictyostelid physiology, as well as differences in gene family content. Interesting patterns of gene conservation and divergence are also evident, suggesting function differences; some protein families, such as the histidine kinases, have undergone little functional change, whereas others, such as the polyketide synthases, have undergone extensive diversification. The abundant amino acid homopolymers encoded in both genomes are generally not found in homologous positions within proteins, so they are unlikely to derive from ancestral DNA triplet repeats. Genes involved in the social stage evolved more rapidly than others, consistent with either relaxed selection or accelerated evolution due to social conflict.ConclusionsThe findings from this new genome sequence and comparative analysis shed light on the biology and evolution of the Dictyostelia.

Effect of Ferrous Ion on ε-Poly-l-Lysine Biosynthesis by Streptomyces diastatochromogenes CGMCC3145

ε-Poly-L-lysine (ε-PL) is known as an amino acid homopolymer occurring in nature. It is mainly produced by bacteria belonging to the family of Streptomycetaceae. In this study, the effect of ferrous ion on the metabolic pathway such as key enzyme activities and substrate consumptions relating to ε-PL production were investigated. When 0.1 mM Fe(2+) was supplemented into the culture medium of Streptomyces diastatochromogenes CGMCC3145 for 72 h of cultivation, the yield of ε-PL and biomass were enhanced by 29.2 and 41.9%, respectively, compared with those of the control. Synchronously, consumptions of glucose, ammoniac nitrogen, and phosphorus were increased by 50, 67.6, and 35.7%, respectively. The enzyme activity measurements showed that the specific activities of proteinase, phosphatase, glutamate dehydrogenase, and aspartate aminotransferase activities were improved for 2.32, 3.68, 1.72, and 1.50 folds, respectively, however, aspartokinase and ε-PL synthetase were hardly affected by ferrous ion. These results manifested that Fe(2+) can improve the yield of ε-PL by promoting aspartate production, and the aspartate was further catalyzed to produce much more L-lysine, precursor for ε-PL biosynthesis.

Genome Nucleotide Composition Shapes Variation in Simple Sequence Repeats

Simple sequence repeats (SSRs) or microsatellites are a common component of genomes but vary greatly across species in their abundance. We tested the hypothesis that this variation is due in part to AT/GC content of genomes, with genomes biased toward either high AT or high CG generating more short random repeats that are long enough to enhance expansion through slippage during replication. To test this hypothesis, we identified repeats with perfect tandem iterations of 1-6 bp from 25 protists with complete or near-complete genome sequences. As expected, the density and the frequency are highly related to genome AT content, with excellent fits to quadratic regressions with minima near a 50% AT content and rising toward both extremes. Within species, the same trends hold, except the limited variation in AT content within each species places each mainly on the descending (GC rich), middle, or ascending (AT rich) part of the curve. The base usages of repeat motifs are also significantly correlated with genome nucleotide compositions: Percentages of AT-rich motifs rise with the increase of genome AT content but vice versa for GC-rich subgroups. Amino acid homopolymer repeats also show the expected quadratic relationship, with higher abundance in species with AT content biased in either direction. Our results show that genome nucleotide composition explains up to half of the variance in the abundance and motif constitution of SSRs.

Effects of Adsorption Conformation on the Dispersion of Aluminum Hydroxide Particles by Multifunctional Polyelectrolytes

The influence of multifunctional polyelectrolytes on the dispersion of aluminum hydroxide particles was studied, in particular the influence of monomer units acting as functional groups, with respect to particle size and zeta potential. The conformation of polyelectrolytes adsorbed on aluminum hydroxide particles, which affects their dispersion abilities, was investigated via their adsorption isotherms and (1)H NMR spectral analysis. Furthermore, the functions of monomer units were evaluated by the calculation of the interaction energies between each monomer unit and aluminum hydroxide or H(2)O by density functional theory. Three multifunctional polyelectrolytes were compared: a terpolymer of acrylic acid (AA), 2-acrylamide-2-methyl propane sulfonic acid (AMPS), and N-vinylpyrrolidone (NVP) (P(AA/SA/NVP)), acrylic acid homopolymer (P(AA)), and a copolymer of AA and AMPS (P(AA/SA)). The most effective dispersant was P(AA/SA/NVP), which prevented further coagulation among the initial particles and shifted the zeta potential to the most negative value. The conformations of the adsorbed polyelectrolytes exhibited the following order of extended conformation (larger loops and longer tails): P(AA) > P(AA/SA/NVP) > P(AA/SA). From these results, we reasonably concluded that the prominent dispersing capability of P(AA/SA/NVP) was due to its preferred extended conformation on the particle surface due to a subtle balance between the moderate affinity of NVP and the relatively higher affinities of AA and AMPS for aluminum hydroxide in an aqueous solution and the hydrophobicity of the amide groups of AMPS.

The role of vinyl sulfonic acid homopolymer in calcium oxalate crystallization

In this study, the effect of water soluble homopolymer of vinylsulfonic acid on spontaneous crystallization of calcium oxalate (CaOx) was investigated. CaOx crystals exhibiting different shapes and phase structures were produced in the presence of polymer. While the crystal growth of calcium oxalate was inhibited by homopolymer, the morphology of calcium oxalate transformed from monohydrate to dihydrate. Inhibition of calcium oxalate crystallization was provided by adsorption of homopolymer onto the active growth sites of crystals on account of the charge and hydrophilic effects. Polyelectrolyte effects were interpreted in terms of the adsorption of inhibitors onto the active growth sites on the crystal surface.