Acrylic Acid In Presence Research Articles

Quantum-Chemical Modeling of Nickel Interaction with Acrylic Acid

Quantum-chemical modeling of system Niz+ – H2O – HAk (z=+2, +1, 0) using DFT-methods allowed to prove the mechanism of the processes of Ni2+-ions electroreduction in the presence of acrylic acid (HAk). It has been shown that the initial structure is an octahedral complex [Ni2+(H2O)5Ak-], the intermediate is the complex [Ni+(H2O)2Ak-] and the final product exists in three forms: [Ni0(H2O)2Ak], [Ni0(H2O)2(σ-HАk)], [Ni0(H2O)2(π-HАk)].Due to this, the result of еn– type unsaturated organic compounds effect on nickel electrocrystallization process is not simple and depends on the nature and intensity of the effect of external factors.Nickel electrodeposition is a widespread process in electroplating industry due to a number of important properties of this metal. Electrolytes for nickel electrodeposition are used with various organic additives depending on the intended use of the coating [1]. The substances which contain a double -С=С-bond in their structure are often used as additives in the nickel-plating solutions. Molecules of such organic compounds involve centers with surplus electron density. Due to the fact that the electronic structure of nickel contains a vacant d-orbital, organic molecules tend to form a rather strong π-bond with metal ions and even with atoms [2]. As a result of this interaction the above-mentioned type of organic compounds influences effectively on the metal electrocrystallization process. Acrylic acid (HAk) was chosen as an object of reserch.Quantum-chemical modeling was carried out in WinGAMESS program using nonemperical methods. Cluster systems were calculated using B3LYP DFT method. We used 6-31G** basis set for metal atoms and 6-311G basis set for the atoms of ligands. In the article [3] it was shown that this calculation methodology provides high adequacy of the chousen model to the real processes involving 3d metals.Parameters of the optimized structures are listed in the table I and II. TABLE I. Interatomic distances (Å) between nickel and oxygen atoms in the cluster [Niz +(H2O)5Ak-] Atom number Ligand z = +2 z = +1 z = 0 O1Н2О2.0463.7473.339O2Н2О2.0433.6463.302O3Н2О2.0793.6473.557O4Н2О2.0582.0272.063O5Н2О2.0431.9782.071O6СH2=CH-COO- 2.0321.8862.103O7СH2=CH-COO- 3.3433.4652.112 TABLE II. Interatomic distance (Å) between nickel atom and some atoms of ligands in the cluster [Ni0(H2O)5HAk] (distances of more than 4 Å are not given) Atom number Ligand σ-complex π-complex O1Н2О3.341–O2Н2О3.446–O3Н2О3.611–O4Н2О2.0012.009O5Н2О2.0491.984O6СH2=CH-COOН2.0642.030O7СH2=CH-COOН2.228–С3СH2=CH-COOH–2.020 For Ni2+ ions the optimized structure is an octahedral complex with almost equivalent Ni–O bonds (Table I). Transition to Ni+ ions is accompanied by significant reorganization of inner coordination sphere of the complex (Table I). The central atom directly bonds only with two from five water molecules. The newly-formed structure [Ni+(H2O)2Аk-] is characterized by irregular allocation of electron density. Bond distance between nickel atom and oxygen atom of carboxyl group decreases from 2.032 Å to 1.886 Å, which indicates that the bond becomes significantly stronger.As a result of complete reduction of nickel ions the central atom in the complex [Ni0(H2O)2Аk-] increases the coordination number from 3 to 4 (Table I). The second oxygen atom of the carboxyl group (O7) is attracted by nickel atom forming a strong bond which is approximately the same as Ni–O6 bond.At the same time, for Ni0complexes the structures with molecular form of HAk are also identified as stable. In these complexes there occurs σ- and π-coordination of HAk with nickel atom (Table II).Based on the analysis of energies of all listed structures we have proposed the most tipical reaction route of the process of Ni2+ions electroreduction in the presence of acrylic acid: +ē +ē[Ni2+(H2O)5Аk-] → [Ni1+(H2O)2Аk-] → [Ni0(H2O)2Аk-] [1] -3H2O +H3O+ [Ni0(H2O)2Аk-] → [Ni0(H2O)2(σ-HАk)] → [Ni0(H2O)2(π-HАk)] [2]It is obvious that external influences, which are realized during nickel electrodeposition, will change the balance of the above-mentioned forms. As a result they will have an effect on the properties of the metal phase which is formed in the presence of е n– type unsaturated organic substances.References G.A. Di Bari Nickel plating // Metal Finishing, p. 209 – 225, Vol. 103, № 6. (2005)E. Fisher. G. Werner. Metal π-Complexes. – p. 264, Elsevier publishing, New York (1968)V.A Seredyuk. and V.F Vargalyuk. Estimation of Reviability of Quantum-Chemical Calculations of Electronic Transitions in Aqua Complexes of Transition Metals // Russian Journal of Electrochemistry. Vol.44, № 10, p. 20 – 27. (2008)

Improved microwave shielding behavior of carbon nanotube-coated PET fabric using plasma technology

Abstract Four different procedures were conducted to load amine functionalized multiwall carbon nanotube (NH 2 -MWCNT) onto poly (ethylene terephthalate) (PET) fabric surface to obtain a microwave shielding sample. Plasma treated fabric which was subsequently coated with NH 2 -MWCNT in the presence of acrylic acid was chosen as the best sample. Surface changes in the PET fabrics were investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Wide-angle X-ray diffraction was used to study the crystalline structure of the PET fabric. The microwave shielding performance of the PET fabrics in term of reflection loss was determined using a network analyzer at X-band (8.2–12.4 GHz). The XPS results revealed that the carbon atomic percentage decreased while the oxygen atomic percentage increased when the fabric was plasma treated and coated with NH 2 -MWCNT. The SEM images showed that the NH 2 -MWCNTs were homogenously dispersed and individually separated in the surface of fabric. Moreover, the structural studies showed that the crystalline region of the fabrics was not affected by NH 2 -MWCNT and plasma treatment. The best microwave absorbing properties were obtained from the plasma treated fabric which was then coated with 10% NH 2 -MWCNT in the presence of acrylic acid. It showed a minimum reflection loss of ∼−18.2 dB about 11 GHz. Proper attachments of NH 2 -MWCNT on the PET fabric surface was explained in the suggested mechanism in which hydrogen bonding and amide linkage are responsible for the achievement of microwave shielding properties with high durability.

Radiation graft post-polymerization of sodium styrene sulfonate onto polyethylene.

Post-irradiation grafting of sodium styrene sulfonate (SSS) in the presence of acrylic acid (AA) has been investigated on polyethylene (PE) pre-exposed to gamma radiation at room temperature in the air. Special attention was paid to the effect of low molecular weight salt additives on the kinetics of graft copolymerization of SSS and AA. The presence of SSS links in the grafted PE copolymers was detected by the methods of UV and FTIR spectroscopy. Based on the FITR spectroscopy and element analysis data, a mechanism was proposed for graft copolymerization of SSS and AA onto PE. The mechanical properties of the graft copolymers were studied. It was established that PE copolymers grafted with sulfonic acid and carboxyl groups have higher strength characteristics (16.3 MPa) compared to the samples containing only carboxyl groups (11 MPa).

Oligonucleotides‐decorated‐poly(N‐vinyl pyrrolidone) nanogels for gene delivery

ABSTRACTPulsed electron‐beam irradiation of a semi‐dilute poly(N‐vinyl pyrrolidone) (PVP) aqueous solution in the presence of acrylic acid has led to a carboxyl functionalized nanogel system. Nanoparticles hydrodynamic size and surface charge density, in water and as a function of pH, were investigated by dynamic light scattering and laser doppler velocimetry, respectively. Nanogels (NGs) were proved not to be cytotoxic at the cellular level. Indeed, they rapidly bypass the cellular membrane to accumulate in specific cell portions of the cytoplasm, in the perinuclear area. The availability of pendant carboxyl groups on the crosslinked PVP NGs core prompted us to attempt their decoration with a single strand oligonucleotide, which holds a terminal amino group. The recognition ability of the attached single helix of its complementary strand was investigated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2014,131, 39774.

Adsorption of 1-Butyl-3-Methylimidazolium Chloride Ionic Liquid by Functional Carbon Microspheres from Hydrothermal Carbonization of Cellulose

Functional carbonaceous material (FCM) loaded with carboxylic groups was prepared by hydrothermal carbonization of cellulose in the presence of acrylic acid. The resulting FCM was used as adsorbent for recovery of a water-soluble ionic liquid, 1-butyl-3-methyl-imidazolium chloride ([BMIM][Cl]). The FCM consisted of microspheres (100-150 nm) and had a low surface area (ca. 20 m(2)/g), but exhibited adsorption capacity comparable to that of commercial activated carbon which can be attributed to the presence of high content of polar oxygenated groups (-OH, -C═O, -COOH) as revealed by spectral analyses. Sorption of [BMIM][Cl] onto FCM adsorbent could be well-described by pseudo-second-order kinetics. Thermodynamic and adsorption isothermal analyses revealed that the adsorption process was spontaneous, exothermic, and could be described by the Freundlich adsorption model. The FCM adsorbent could be regenerated effectively and recycled for at least three times without loss of adsorption capacity. The results of this work provide a facile method for production of functional carbonaceous materials from renewable resources that can be used for treatment of aqueous streams containing small concentrations of ionic liquid, [BMIM][Cl].

Biosynthesis and Properties of Medium-Chain-Length Polyhydroxyalkanoates with Enriched Content of the Dominant Monomer

When grown in a nonanoic acid-limited chemostat at a dilution rate of 0.25 h(-1), Pseudomonas putida KT2440 produced poly(3-hydroxynonanoate-co-3-hydroxyheptanoate) containing 68 mol % 3-hydroxynonanoate (C9) and 32 mol % 3-hydroxyheptanoate (C7). Under the same conditions, but in the presence of acrylic acid, a fatty acid β-oxidation inhibitor, the C9 monomer content increased to 88 mol %. Cofeeding glucose (3.9 g L(-1)) and nonanoic acid (2.9 ± 0.1 g L(-1)) in continuous culture with 0.2 g L(-1) of acrylic acid in the feed, further increased the C9 content to 95 mol %. A yield of PHA from nonanoic acid of 0.93 mol mol(-1) was attained. PHA with a 3-hydroxyoctanoate (C8) content of 98 mol % was produced with the same cofeeding methodology from octanoic acid. As the dominant monomer content increased, the melting point of the poly(3-hydroxynonanoate) copolymers increased from 46 to 63 °C and that of the poly(3-hydroxyoctanoate) copolymers from 54 to 62 °C. All copolymer compositions resulted in elongation to break values of about 1300%, but tensile strength at break and Young's modulus both increased with increasing amounts of the dominant monomer.

The use of poly(acrylamide-acrylic acid)-montmorillonite composite for preparing low-activity 60Co, 65Zn, 134,137Cs mixed sealed source for radiometric calibration purposes

Poly(acrylamide-acrylic acid)-montmorillonite composite [P(AAm-MA)-M] was synthesized and used for preparing 60Co, 65Zn, 134,137Cs mixed sealed source. The synthesis procedure was based on γ-induced polymerization of polyacrylamide (PAAm) in the presence of acrylic acid (AA), clay minerals (montmorillonite, M), and N,N′-methylenebisacrylamide (NMBA) as a cross-linker. The adsorbent functionality was assayed using FTIR spectroscopy and thermal analysis. The distribution coefficients of 60Co(II), 65Zn(II), and 134,137Cs(I) ions on P(AAm-MA)-M were determined in relation to HCl concentration. P(AAm-MA)-M was loaded with 60Co, 65Zn, and 134,137Cs by equilibrating it (0.5 g) with a mixed solution of 60Co, 65Zn, and 134,137Cs at pH 3 (HCl) for 24 h at 25 ± 1°C. Mixed sealed source containing 5.3, 0.03, 0.05, and 1.05 μCi of 60Co, 65Zn, 134Cs, and 137Cs, respectively, was prepared by packing 100 mg of the loaded matrix in the cylindrical cavity of a Chinese Artelone capsule. The sealed source was subjected to quality control tests.

Cr(VI) adsorption from electroplating plating wastewater by chemically modified coir pith

Coir pith samples were chemically modified by grafting with acrylic acid for the removal of Cr(VI) from electroplating wastewater. The presence of acrylic acid on the coir pith surface was verified by a scanning electron microscope with an electron dispersive x-ray spectrometer (SEM/EDX), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). The carbonyl groups (C==O) from the carboxylic acids (COOH) increased on the coir pith surface after grafting with acrylic acid. In addition, the thermal stability of the acrylic acid-grafted coir pith also improved. The optimum conditions for grafting the acrylic acid on the coir pith consisted of 2 M acrylic acid and 0.00125 M ceric ammonium nitrate (CAN, as an initiator). The maximum Cr(VI) removal (99.99 ± 0.07%) was obtained with the following conditions: a 1.3% (w/v) dosage of acrylic acid-grafted coir pith, a system pH of 2, a contact time of 22 h, a temperature of 30 °C, a particle size of <150 μm and an initial Cr(VI) of 1,171 mg l(-1). At system pH of 2, Cr(VI) in the HCrO(4)(-) form can be adsorbed with acrylic acid-grafted coir pith via an electrostatic attraction. The adsorption isotherm of 2 M acrylic acid-grafted coir pith exhibited a good fit with the Langmuir isotherm. The maximum Cr(VI) adsorption capacity of the 2 M acrylic acid-grafted coir pith was 196.00 mg Cr(VI) g(-1) adsorbent, whereas for coir pith without grafting, the maximum Cr(VI) removal was 165.00 mg Cr(VI) g(-1) adsorbent. The adsorption capacity of the acrylic acid-grafted coir pith for Cr(VI) was higher compared to the original coir pith. This result was due to the enhancement of the carbonyl groups on the coir pith surface that may have involved the mechanism of chromium adsorption. The X-ray absorption near edged structure (XANES) and desorption studies suggested that most of the Cr(III) that presented on the acrylic acid-grafted coir pith was due to the Cr(VI) being reduced to Cr(III) on the adsorbent surface. FTIR confirmed the involvement of the carbonyl groups (C==O) and the methoxy groups (OCH3) in the mechanism of chromium adsorption. Thermodynamic study, such as enthalpy (ΔH), free energy (ΔG) and entropy change (ΔS) indicated that the overall adsorption process was endothermic, spontaneous and randomness. In addition, the adsorption process was favored at high temperatures.

Nitrogen-enriched carbonaceous materials with hierarchical micro-mesopore structures for efficient CO2 capture

Carboxyl-rich porous carbons (CPCs) derived from glucose are prepared by a hydrothermal method in the presence of acrylic acid and non-ionic surfactant Brij 72 as structure-directing agents. Tetraethylenepentamine molecules are then grafted onto the surfaces of CPCs via acylation–amidation route, yielding nitrogen-enriched porous carbons (NPCs). Material characterizations reveal that the CPCs display high surface areas with micro and mesoporous structures. Despite the surface functionalization of CPCs via acylation–amidation route the porous structures of NPCs are maintained. As a result, the NPCs exhibit excellent CO2 capture capacity (3.2mmolg−1) with high selectivity of CO2 over N2 (>46) at 298K and 1bar. In addition, good reversibility of CO2 adsorption can be achieved at different temperatures.

Carboxylic-group distribution of carboxylated acrylate copolymer latexes with their properties in the presence of acrylic acid and monobutyl itaconate

A series of carboxylated acrylate copolymer latexes were prepared via two different emulsion polymerization technologies with different carboxylic-group distribution and morphologies. The effects of the emulsifier, the initiator, and the carboxylic monomers [acrylic acid (AA) or monobutyl itaconate (MBI)] on the total conversion of the monomers and the properties of acrylate latexes and films have been investigated. The distribution of carboxylic groups (−COOH) measured by conductometric titration shows that the concentration of surface –COOH (Cs) and embedded –COOH (Cb) both increase with the increase of the amount of carboxylic monomers. For the latexes containing AA, –COOH tends to distribute on the surface of latex particles and in the aqueous phase, whereas –COOH tends to concentrate inside the core of latex particles for the latexes containing MBI. Transmission electron microscopy demonstrates that the latex particles are regular with narrow size distribution and have significant differences in morphologies when different carboxylic monomers and polymerization technologies were used. The stability of latex is satisfactory through the results of common stability and zeta potential tests. Moreover, the water absorption and contact angle experiment tests also revealed that the water resistance of the latex films is good. Copyright © 2011 John Wiley & Sons, Ltd.

Surface Modification of Synthetic Polymers Using UV Photochemistry in the Presence of Reactive Vapours

AbstractPolystyrene (PS), Polyurethane (PU), Polysulfone (PSU) and Polypropylene (PP) were surface modified using UV assisted treatment in the presence of acrylic acid (AA) vapour. In this context, PU and PSU were also modified using vapour of trimethoxy propyl silane (TMPSi). The surface changes were characterized by water contact angle measurement, Fourier transform infrared spectroscopy – Attenuated total reflection and X‐ray photoelectron spectroscopy. Permanent hydrophilic surface was obtained by UV assisted treatment in the presence of AA vapour on all polymers studied. After 65 days of treatment, the polymer surfaces had the original degree of hydrophilicity as obtained immediately after treatment. By using vapour of TMPSi with UV radiation, the surface hydrophobicity of PU and PSU was increased after thermal treatment. The surface modification methodology used was simple and did not require any extensive set‐up compared to traditional surface modification techniques.

THE EFFECT OF ACETIC ACID ON PROPERTIES OF COCONUT SHELL FILLED LOW DENSITY POLYETHYLENE COMPOSITES

Natural lignocellulosics have an outstanding potential as reinforcement in thermoplastics. Coconut shell is one of natural lignocellulosic material. In this study, coconut shell (CS) was use as filler in low density polyethylene (LDPE) composites. The effect of surface treatment of coconut shell (CS) with acetic acid (acetylation) on mechanical properties, thermal properties and morphology were studied. The acetylation treatment has improved the tensile strength, elongation at break and Young's modulus of LDPE/CS composites. Thermogravimetric analysis (TGA) results show that the acetylated composites has better thermal stability compared to untreated composites at 600 °C. Differential scanning calorimetry (DSC) analysis showed that the esterification treatment increases the crystallinity of LDPE/CS composites. It was found that coconut shell acts as a nucleation agent in the presence of acrylic acid. The scanning electron microscopy (SEM) study of the tensile fracture surface of acetylated composites indicates that the presence of acetic acid increased the interfacial interaction.

Studies on the effect of epoxide equivalent weight of epoxy resins on thermal, mechanical, and chemical characteristics of vinyl ester resins

AbstractThree samples of vinyl ester resins (VERs) were synthesized using bisphenol‐A‐based epoxy resins of varying epoxide equivalent weights (EEW) and acrylic acid in presence of triphenylphosphine as a catalyst at 80 ± 2°C. The cresyl glycidyl ether was used as reactive diluent during the synthesis of VERs. A suitable reaction mechanism was proposed and discussed for the reactions involving epoxide group and acid groups. This was further confirmed by infrared spectroscopic analysis. The maximum peak temperature from DSC were at 106.05°C, 114.20°C, and 128.86°C for benzoyl peroxide initiated VERs viz. samples V1CV, V2CV, and V3CV, respectively, increased with the increase of EEW of the parent epoxy resin. It has also been found that the films of VER having highest EEW of bisphenol‐A epoxy resin showed best chemical resistance amongst all other VERs in this study. The mechanical properties such as hardness and flexibility also showed a similar trend. The thermal stability was found to decrease with the increase of EEW of bisphenol‐A epoxy resin in the VERs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Ultrasensitive determination of serum albumin using resonance light scattering based on ZnS-polyacrylic acid nanoparticles

ZnS-polyacrylic acid (ZnS-PAA) was prepared by an in situ polymerization method using nano-ZnS as core in the presence of acrylic acid (AA), and ZnS-PAA nanoparticles was characterized by ultraviolet spectrometry (UV) and transmission electron microscopy (TEM). Based on the significant increase of the resonance light scattering (RLS) intensity with the interaction between nanoparticles and serum albumin, RLS method was developed for the sensitive determination of serum albumin (BSA and HSA). Under optimum conditions, the change of the intensity (DeltaI) of the RLS spectra at lambda=392nm was linearly proportional to the concentration of BSA and HSA. The linear range was 1-100ngmL(-1) for HSA and 1-120ngmL(-1) for BSA, and the limit of detection (LOD) was 0.4ngmL(-1) for HSA and 0.5ngmL(-1) for BSA. This method proved to be very sensitive, rapid, simple and tolerant of most interfering substances.

Novel carbonaceous nanocomposite pellicle based on bacterial cellulose

A novel carbonaceous nanocomposite pellicle was prepared by one-step mild hydrothermal carbonization of bacterial cellulose pellicle soaked in glucose solution. The nano-fibrous structure of bacterial cellulose remains intact while carbonaceous spheres with nanometre sizes were generated from glucose during hydrothermal carbonization at 180 °C for 3 h. The carbonaceous spheres formed in situ and anchored on the nanofibers’ surface expanded the nanostructure of bacterial cellulose and the water-holding capacity decreased slightly from 98% to 93%. Approximately 80% w/w of the dried carbonaceous pellicle was found to be nanometre sized carbonaceous spheres. The size of carbonaceous spheres decreased significantly but had a 60% increase of surface carboxyl groups when the carbonaceous pellicle was prepared in the presence of acrylic acid. The carbonaceous spheres in the never-dried pellicle demonstrate a high adsorption capacity towards heavy metal ions. Approximately, 200 mg of Pb(II) and 1134 mg of Fe(III) can be adsorbed per gram of carbonaceous pellicle, respectively.

Carboxylate-Rich Carbonaceous Materials via One-Step Hydrothermal Carbonization of Glucose in the Presence of Acrylic Acid

The present study concerns the one-step aqueous route production of carbonaceous materials loaded with carboxylic groups using hydrothermal carbonization of glucose in the presence of acrylic acid. This method provides a “green” solvent and surfactant free access to hydrophilic functionalized carbons with very good water dispersivity. The resulting materials were characterized using various methods including, FT-IR, Zeta Potential, N2 adsorption, Raman Spectroscopy, SEM, TGA, and 13C solid-state NMR. Among other possible applications of these types of materials, here, we discuss their use as adsorbents for heavy metals removal from aqueous solutions

Synthesis, characterization, and swelling studies of pH‐ and thermosensitive hydrogels for specialty applications

AbstractIn this article, we describe a novel pH‐and temperature‐sensitive and moderately salt tolerant hydrogels based on acrylic acid (AAc) and methacrylic acid (MAAc) by employing a novel research plan. AAc and MAAc have been converted to N‐isopropylacrylamide (N‐i‐PAAm) and N‐isopropyl methacrylamide (N‐i‐PMAAm), respectively, via amidation with isopropyl amine, followed by polymerization to respective polymers. These polymers were further converted into networks in the presence of AAc and MAAc and N,N‐methylene bisacrylamide (N,N‐MBAAm). The networks thus formed consist of both amides and carboxylic acid groups. Characterization of these networks has been carried out by nitrogen analysis, FTIR, NMR, and scanning electron microscopy for the investigation of different structural aspects of the synthesized polymers. Swelling studies of these networks have been carried out as a function of time, temperature, pH, and in the presence of additives, sodium dodecyl sulfate, cetyl trimethyl ammonium bromide, and 5% NaCl solution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

The Olefin Metathesis Reactions in Dendrimers

Dendrimers containing terminal olefins or ruthenium-benzylidene terminal groups undergo olefin metathesis reactions (RCM and ROMP types), and essentially results from our group are reviewed here. Dendrimers have been loaded at their periphery with ruthenium-chelating bis-phosphines, which leads to the formation of dendrimer-cored stars by ring-opening-metathesis polymerization (ROMP). CpFe+-induced perallylation of polymethylaromatics (Cp = η5-C5H5) followed by ring-closing metathesis (RCM) and/or cross metathesis (CM) leads to poly-ring, cage, oligomeric and polymeric architectures. In the presence of acrylic acid or metha-crylate, stereospecific CM inhibits oligomerization, and dendritic olefins yield polyacid dendrimers. Finally, cros-metahesis reactions with dendronic acrylate allow dendritic construction and growth.

Chemical modification of metallocene‐based polyethylene–octene elastomer through solution grafting of acrylic acid and its effect on the physico‐mechanical properties

AbstractIn the present work, the metallocene‐based polyethylene–octene elastomer (POE) was chemically modified by solution grafting of acrylic acid in presence of benzoyl peroxide. The relative proportions of graft and gel formation were optimized through %weight gain, Fourier Transform infrared spectroscopy, elemental analysis and proton nuclear magnetic resonance spectroscopy. The gel formation in the POE matrix was found to be the prime competitor. The effect of grafting at its maximum level on various physicomechanical properties was thoroughly investigated, using X‐ray diffraction analysis, differential scanning calorimetry, mechanical, dynamic mechanical, and thermogravimetric analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Monodisperse Micrometer-Size Carboxyl-Functionalized Polystyrene Particles Obtained by Two-Stage Dispersion Polymerization

Monodisperse carboxylated micrometer-sized polystyrene particles were synthesized by dispersion polymerization of styrene in ethanol and in 95% ethanol−water in the presence of acrylic acid (AA) as a functional comonomer. When AA was present at the onset of the reaction, the resulting particles had an increased particle size and a broader size distribution than those prepared in the absence of AA. If, however, the addition of AA was delayed ca. 1 h, so that the particle nucleation stage was complete, then 2 wt % AA, dissolved in monomer plus solvent, could be added to the reaction without a deleterious effect on particle formation. When larger amounts of AA (e.g., 4 wt % based on styrene) were added, most resulting particles became unstable and coagulated if PVP55 (Mw ≈ 55000) was used as the stabilizer. Some evidence points to interaction between −COOH groups on the particles as the origin of particle aggregation. Improved colloidal stability was achieved by decreasing the solids content, increasing the polarity of the medium, and switching to PVP360 (Mw ≈ 360000) as the polymeric stabilizer. Coagulum-free particles with a very narrow size distribution containing 2%, 4%, and 6 wt % AA could be obtained in this way. Under these conditions, adding different amounts of AA in the particle growth stage did not change the particle size or size distribution.