Molar Ratio Of Monomer Research Articles

The Novel Fluid Loss Additive ANMG1305 for Oil Field Cementing

Fluid loss additive is the main component of the cementing fluid. This article use monomer the monomers of 2-acrylamido-2-methyl-propanesulphonic acid (AMPS) and N, N-dimethyl acrylamide (DMAA) by the method of aqueous solution polymerization to synthesis the novel fluid loss additive ANMG1305. Discuss the amount of initiator, the molar ratio of monomer, reaction temperature, which the influence on the properties of the polymer. Through the infrared spectrum, thermo-gravimetric analyzer, viscometer, such as instrument on its microstructure and properties were characterized. We know that all the monomers are involved in the reaction and the polymer has an excellent thermal stability though the microstructural characterization and application performance of the novel fluid loss additive.

Synthesis and characterization of A2 + B3 type hyperbranched aromatic-aliphatic polyester with carboxyl end groups

New types of carboxyl-terminated hyperbranched polyesters (HBPEs) with aromatic-aliphatic structure were synthesized by single step-melt polycondensation of adipic acid (as A2 monomer) and phloroglucinol (as B3 monomer) as a core via A2 + B3 approach, at three different monomer mole ratios (A2/B3 = 1: 1, 1.5: 1, 2: 1, respectively). FTIR spectroscopy indicated that the polymers contained hydroxyl groups, ester bonds, benzene ring, methyl and methylene groups, which were in agreement with the expected HBPEs. The HBPEs have inherent viscosities about 0.24 to 0.27 dL/g. The degree of branching of the HBPEs was estimated to be 0.45–0.49% by 1H-NMR and 13C-NMR measurements. The melting temperature of HBPE-1, HBPE-2 and HBPE-3 were 154, 155 and 160°C respectively measured by differential scanning calorimetry (DSC). The synthesized polymers were thermally stable; the thermogravimetric analysis (TGA) measurement revealed that HBPEs had 10% weight loss at 310°C in nitrogen.

The control of morphological and size properties of carbamazepine-imprinted microspheres and nanospheres under different synthesis conditions

Abstract

Fabrication and Fluorescence Characterization of the Polyimides with Different Molecular Weights

In this paper, a series of polyimide (PI) films with different monomer mole ratios between PMDA and ODA (0.980: 1, 0.990: 1, 1.000: 1, 1.010: 1 and 1.015: 1) were prepared in order to investigate the effect of molecular weight on optical properties. Inherent viscosity values were taken as a measure of the molecular weight. The fluorescence properties of the PI films have been measured. The fluorescence spectra show that three obvious emission peaks can be observed at 583 nm (1.00 dL/g), 594 nm (1.42 dL/g) and 603 nm (1.57 dL/g) respectively. In addition, emission peaks show red-shift with the increase of molecular weight, which can attribute to the decease of orbital energy caused by conjugated effect.

In Situ Polymerization and Characterization of Aniline and O-Anthranilic Acid Copolymer/Pyrogenic Silica Nanocomposites

Copolymers of aniline and o-anthranilic acid/amorphous fumed silica nanocomposite are synthesized by 5:1 molar ratios of the respective monomers with different percentages of silica nanoparticles via in situ chemical co-polymerization. The electrical conductivity and spectral characteristics upon incorporation of o-anthranilic acid units into the polyaniline backbone in presence of silica nanoparticles are investigated. The results are justified by measuring the UV-Vis absorption spectra, FT-IR for PANAA copolymer, and in situ PANAA/silica nanocomposite. Also, the thermal gravimetric analysis for the copolymer powder formed in the bulk in absence and in presence of silica nanoparticles are carried out.

Synthesis, characterization and properties of TAP-6FDA hyperbranched polyimides with different branching degrees

A series of hyperbranched polyimides were successfully synthesized by condensation polymerization of A2-type dianhydride monomer 2,2-bis(3,4-dicarboxylphenyl) hexafluoropropane dianhydride (6FDA) and B′B2-type triamine monomer 2,4,6-triaminopyrimidine (TAP). Polymers with different branching degrees (DB) and terminated groups were obtained by changing the monomer addition order and the monomer molar ratio. Fourier transform infrared spectroscopy and 1H NMR were used to verify the structure of the prepared polyimides, which indicated that the amino group still existed in all the products. The DB of the polymers indicated by 1H NMR increased from 30% to 79% with the molar ratio of TAP:6FDA decreasing from 1:1 to 1:2. The absolute molecular weights were measured by size-exclusion chromatography with multi-angle laser light-scattering detection, which suggested that the highest molecular weight would be obtained when the molar ratio of amino groups:anhydride groups of the monomers was 3:3.2. With the DB increasing, the d-spacing values indicated by wide angle X-ray diffraction increased from 5.15 Å to 5.68 Å and the UV − visible spectra of the polymers exhibited decreasing cut-off wavelengths. The 5% weight loss temperature in nitrogen increased with decreasing content of TAP monomer, and the glass transition temperatures of the obtained polyimides decreased from 282 °C to 258 °C with increasing DB. © 2013 Society of Chemical Industry

Boronic Acid-Functionalized Core–Shell–Shell Magnetic Composite Microspheres for the Selective Enrichment of Glycoprotein

In this work, core-shell-shell-structured boronic acid-functionalized magnetic composite microspheres Fe3O4@SiO2@poly (methyl methacrylate-co-4-vinylphenylbornoic acid) (Fe3O4@SiO2@P(MMA-co-VPBA)) with a uniform size and fine morphology were synthesized. Here, Fe3O4 magnetic particles were prepared by a solvothermal reaction, whereas the Fe3O4@SiO2 microspheres with a core-shell structure were obtained by a sol-gel process. 3-(Trimethoxysilyl) propyl methacrylate (MPS)-modified Fe3O4@SiO2 was used as the seed in the emulsion polymerization of MMA and VPBA to form the core-shell-shell-structured magnetic composite microspheres. As the boronic acid groups on the surface of Fe3O4@SiO2@P(MMA-co-VPBA) could form tight yet reversible covalent bonds with the cis-1,2-diols groups of glycoproteins, the magnetic composite microspheres were applied to enrich a standard glycoprotein, horseradish peroxidase (HRP), and the results demonstrated that the composite microspheres have a higher affinity for the glycoproteins in the presence of the nonglycoprotein bovine serum albumin (BSA) over HRP. Additionally, different monomer mole ratios of MMA/VPBA were studied, and the results implied that using MMA as the major monomer could reduce the amount of VPBA with a similar glycoprotein enrichment efficiency but a lower cost.

Preparation, characterization and gas sensitivity of polypyrrole/γ-Fe2O3 hybrid materials

Polypyrrole (PPy)/γ-Fe2O3 hybrid materials were prepared by sol–gel polymerization in situ and characterized by Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), thermogravimetric and differential thermal analysis (TG–DTA) and high-resolution transmission electron microscope (HRTEM). The gas sensitivities in CO, H2, NH3, ethanol or acetone atmospheres were determined at 30°C, 60°C and 90°C. FT-IR and XRD patterns suggest that ferric oxide in the hybrids was γ-Fe2O3, with a diameter of approximately 5nm. TG–DTA and HRTEM analyses showed that different reactant molar ratios of pyrrole monomer: Fe(NO3)3·9H2O resulted in different microstructures of γ-Fe2O3 and molecular weights of PPy. An increased amount of Fe(NO3)3·9H2O increased the degree of uniformity of the molecular weight of PPy and resulted in a change of γ-Fe2O3 microstructure from granular to stick particles. The results of gas sensitivities showed that the PPy/γ-Fe2O3 hybrids exhibited high sensitivity to NH3 at mild operating temperature (<100°C). Furthermore, the sensing mechanism was also discussed.

Metal incorporated molecularly imprinted polymer-based electrochemical sensor for enantio-selective analysis of pyroglutamic acid isomers

This paper reports a new class of pencil graphite electrode duly modified with a molecularly imprinted metallo-polymer for enantio-selective sensing of d-/l-pyroglutamic acid, in aqueous and real samples. Herein, specific binding sites of d- and l-isomers were created in their respective three-dimensional motifs of highly conducting imprinted film. This was developed through the electro-polymerization of copper(II)–5-methyl-thiophene–2-carboxylic acid complex, in the presence of analyte (template:monomer molar ratio 1:2). The detection of isomers could be feasible at operating conditions (pH, deposition potential, deposition time, etc.) of differential pulse anodic stripping voltammetry [aqueous sample, linear range 2.8–170.0ngmL−1, limit of detection, 0.77ngmL−1 (S/N=3)]. The proposed sensor was also validated with dilute real samples (urine, cerebrospinal fluid and blood plasma). Although several chronic diseases (metabolic acidosis, 5-oxoprolinuria, etc.) are known to be manifested at hyper-concentrations of l-pyroglutamic acid (d-isomer is biologically inactive), the sample dilution by several fold, which mitigates biological matrix effect, is necessarily required. This warrants a highly sensitive probe of analysis within the linear quantitation range 1.3–180.0ngmL−1, without any cross-reactivity and false-positives. The endogenous concentrations of real samples could simply be obtained by multiplying the concentration of dilute sample with respective dilution factor.

Effect of Pre-Polymerization Conditions on the Performance of UF/Low Melting Point Paraffin Microcapsules

The reaction mole ratio of monomers, pH value, reaction temperature and time factors directly affect the properties of urea-formaldehyde resin (UF)/low melting point paraffin wax microcapsules during in situ polymerization process. The effects of these factors on the thermal storage capacity, particle size and distribution were systematically discussed. When the reaction conditions were formaldehyde and urea molar ratio of 1.8:1, the prepolymerization system pH controlled at 8.5, the reaction temperature of 60 °C, the reaction time of 60 min, the synthetic phase change materials microcapsules have good morphology and thermal storage capacity.

Synthesis and properties of a MEAS quadripolymer scale inhibitor

A novel quadripolymer scale inhibitor was prepared from maleic anhydride (MA), epoxy succinic acid sodium (ESAS), acrylamide (AM) and sodium allyl sulphonate (SAS), and the polymerisation was initiated by persulphate ammonium. This study determined the optimal synthesis conditions for the scale inhibitor by the orthogonal test, and investigated scale inhibitor dosage, systematic pH values and temperature on the scale inhibitor anti-scaling properties. The results showed that the optimal conditions of synthesis were as follows: the mass ratio of persulphate ammonium to total monomer was 15%, the monomer molar ratio for n(MA):n(ESAS):n(AM):(SAS) was 1:1:0.6:1, the reaction temperature was 90°C and the reaction time was 3 h. When the temperature was 50°C, the pH value was 10, the scale inhibitor dosage was 20 mg/L and the calcium carbonate anti-scaling rate was 96%. The infrared spectra indicated that the synthetic copolymer contained the target functional groups. Scanning electron micrographs showed that the quadripolymer scale inhibitor mainly played roles in complexation and solubilisation. The practical application of the inhibitor led to an improved anti-scaling effect.

Controlled polymerization of methylmethacrylate from fumed SiO2 nanoparticles through atom transfer radical polymerization

Atom transfer radical polymerization (ATRP) is a promising method to synthesize well-defined polymer/inorganic nanoparticles. However, the surface-initiated ATRP from commercially mass produced inorganic nanoparticles has seldom been studied. In this study, the surface-initiated ATRP of methylmethacrylate (MMA) from commercially mass produced fumed silica (SiO2) nanoparticles was investigated. Unlike the ATRP of MMA initiated from a free initiator, the controllability of ATRP of MMA from the surface of fumed silica nanoparticles was much better using ligand 2,2'-bipyridine (bpy) than N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) as the initiator was immobilized on the surface of the SiO2 nanoparticles and the presence of the SiO2 nanoparticles made the CuCl/bpy catalyst system a homogeneous catalyst system and CuCl/PMDETA a heterogeneous one. The appropriate molar ratio of monomer and initiator was essential for preparing controlled PMMA/SiO2 nanoparticles. The entire process of ATRP of MMA from the surface of SiO2 nanoparticles was controllable when using bpy as ligand, xylene as solvent and with a monomer to initiator ratio of 300:1. The 1H NMR results indicated that the PMMA on the surface of the SiO2 was prepared via ATRP initiated from 4-(chloromethyl)phenyltrimethoxysilane. The well-defined PMMA/SiO2 nanoparticles obtained have good thermal stability and are well dispersed in organic media as proved by TGA, dynamic light scattering and transmission electron microscopy. © 2013 Society of Chemical Industry

The synthesis, deprotection and properties of poly(γ-benzyl-l-glutamate)

Diethylamine, di-n-hexylamine, dicyclohexylamine and triethylamine have been used as initiators for the ring-opening polymerization of γ-benzyl-l-glutamate N-carboxyanhydride (BLG NCA) to synthesize poly(γ-benzyl-l-glutamate) (PBLG). The relationship between the molecular weight of PBLG and the molar ratio of monomer and initiator was studied. With dicyclohexylamine as initiator, the influence of monomer concentration, and reaction temperature and time on the polymerization of BLG NCA was examined. Three reagents were used for the deprotection of benzyl groups in PBLG, including hydrobromic acid/acetic acid (33 wt.%), NaOH aqueous solution and trimethylsilyl iodide (TMSI). Through examining the molecular weight of PLGA obtained using different deprotection methods, it was revealed that TMSI could minimize chain cleavage in the process of deprotection and retain the degree of polymerization. The biocompatibilities of PBLG obtained using different initiators were evaluated by a live/dead assay against L929 fibroblast cells. The in vitro cytotoxicities of PLGA obtained using different deprotecting agents were evaluated by a methyl thiazolyl tetrazolium assay. The results revealed that both PBLG and PLGA exhibited good biocompatibilities.

Facile synthesis of high-quality ultralong poly(aniline-co-p-phenylenediamine) nanofibers

High-quality ultralong poly(aniline-co-p-phenylenediamine) nanofibers have been synthesized successfully by one-step chemical copolymerization of aniline and p-phenylenediamine using ammonium peroxydisulfate as the oxidant in aqueous solution. The addition of p-phenylenediamine in conventional polymerization system plays an important role in changing the bulk morphologies of polyaniline from irregular particle agglomerates to nanofibers. This process is rapid, facile, and free of any template and surfactant. The influences of synthetic parameters, such as the molar ratios of aniline and p-phenylenediamine, the molar ratios of monomer and ammonium peroxydisulfate, and the concentrations of HCl, on the morphologies and molecular structures of the resulting products have been investigated for elucidating the formation mechanism of poly(aniline-co-p-phenylenediamine) nanofibers.

Polymerization behaviors and polymer branching structures in ATRP of monovinyl and divinyl monomers

Polymerization behaviors and polymer branching structures in atom transfer radical polymerizations of styrene with 1,6-bismaleimidohexane (BMIH), tri-ethylene glycol dimethacrylate (tri-EGDMA) and divinylbenzene (DVB) as the branching agents have been studied, the mole ratio of monomer to branching agent is 30/1.0. Their polymerization behaviors are quite different because of the different levels of interaction between styrene and the branching agents. The charge transfer complex effect between BMIH and styrene causes core-formation. The DVB system exhibits the slowest evolution of branching because there is no interaction between styrene and DVB. The branching structure indicator b(g′ = gb) from the Zimm branching factor at the same molecular weight proves that polymers formed in the tri-EGDMA and DVB systems are randomly branched molecules because tri-EGDMA and DVB were randomly distributed in their primary chains, while the BMIH system contained randomly branched molecules besides the star-like molecules due to the subsequent coupling reactions between the branched molecules after core-formation.

Molecularly imprinted layer-coated silica nanoparticle sensors with guest-induced fluorescence enhancement: theoretical prediction and experimental observation

Molecularly imprinted fluorescence sensors operate on the basis of the recognition of imprinted sites to guest and the resultant changes of fluorescence emission have been studied. However, the origin of guest-induced fluorescence enhancement and the function of host molecule are still unclear in theory. In this work, we have first designed three isomers, 2-acrylamidoquinoline, 3-acrylamidoquinoline and 8-acrylamidoquinoline, with weak fluorescence emission, and used them as both functional monomers and signaling units in molecularly imprinted fluorescence sensors. Quantum chemical calculation within the density functional theory (DFT) framework has been introduced to accurately evaluate and predict the hydrogen bonding interaction between these monomers and the analyte melamine. As a result, the as-synthesized 2-acrylamidoquinoline exhibits a highest hydrogen bonding ability and the ideal molar ratio of monomer to template is 3:1 in molecularly imprinted polymers, which can greatly enhance the fluorescence emission of functional monomer after guest-host binding due to the strong hydrogen bonding restriction to the transformation of monomer conformations. The prediction is in good agreement with the experimental observation. Moreover, the imprinted nanoparticles display significant fluorescence enhancement upon titration with different concentrations of melamine in methanol. The fluorescence sensors can be applied to detect the melamine in dairy products with a low limit of quantification of 0.5 μM. The results reported herein supply an excellent model for the design of molecularly imprinted fluorescence sensors and their prediction of chemical sensitivity to nonfluorescent compounds.

Effect of cross-link density on optoelectronic properties of thermally cured 1,2-epoxy-5-hexene incorporated polysiloxane

The synergesic effect from copolymerising polysiloxane and epoxy functionality offer a viable encapsulant material for use in electronic devices. A series of epoxy group-containing organopolysiloxane without ether bond spacer was prepared. The cross-link density was progressively monitored by controlling the mole ratio of the epoxy monomer. Thermal, optical, dielectric and hardness properties were measured and related to the cross-link density. The crosslink density affect an increase in refractive indices in the range 1.4359–1.4655 and dielectric constants in the range 2.78–3.34 at 500MHz. Transparency were in the range 60–80% in visible region. A higher crosslink structure displays an improved transparency in the UV–visible region. These observations were related to changes in free volume and group polarizability and discussed within the scope of Lorentz–Lorenz relationship.

Rational design of potent domain antibody inhibitors of amyloid fibril assembly

Antibodies hold significant potential for inhibiting toxic protein aggregation associated with conformational disorders such as Alzheimer's and Huntington's diseases. However, near-stoichiometric antibody concentrations are typically required to completely inhibit protein aggregation. We posited that the molecular interactions mediating amyloid fibril formation could be harnessed to generate antibodies with potent antiaggregation. Here we report that grafting small amyloidogenic peptides (6-10 residues) into the complementarity-determining regions of a single-domain (V(H)) antibody yields potent domain antibody inhibitors of amyloid formation. Grafted AMyloid-Motif AntiBODIES (gammabodies) presenting hydrophobic peptides from Aβ (Alzheimer's disease), α-Synuclein (Parkinson's disease), and islet amyloid polypeptide (type 2 diabetes) inhibit fibril assembly of each corresponding polypeptide at low substoichiometric concentrations (1:10 gammabody:monomer molar ratio). In contrast, sequence- and conformation-specific antibodies that were obtained via immunization are unable to prevent fibrillization at the same substoichiometric concentrations. Gammabodies prevent amyloid formation by converting monomers and/or fibrillar intermediates into small complexes that are unstructured and benign. We expect that our antibody design approach--which eliminates the need for immunization or screening to identify sequence-specific domain antibody inhibitors--can be readily extended to generate potent aggregation inhibitors of other amyloidogenic polypeptides linked to human disease.

Effect of Nucleation of Tricalcium Phosphate and Isothermal Annealing on the Crystallization of Poly(l-lactide-co-glycolide)

We investigated the effect of nucleation and isothermal annealing on the crystallization behavior of a random copolymer, poly(l-lactide-co-glycolide) (PLLGA), with monomer molar ratios of 85/15 (PLLGA85/15) by scanning electron microscopy, polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction, and examination of the tensile properties of the resultant product. The effect of heterogeneous nucleation was assessed by the addition of tricalcium phosphate (TCP) as a nucleating agent. Nucleation and isothermal annealing of PLLGA at 130 °C were conducted to improve the degree of crystallinity of the copolymer. The fracture surfaces of the TCP/PLLGA85/15 composite bar showed a considerable number of spherulites with TCP as their nucleus. Addition of TCP and subsequent annealing improved the degree of crystallinity. After annealing, the TCP/PLLGA85/15 composite samples gained nearly the same strength that the pure PLLGA85/15 samples possessed. It is believed that this method will enhance the practical application of this nucleating agent in the processing of polymers.

Kinetic study of dichlorocarbene addition to olefins via a quaternized highly branched polyacrylamide as a new multi-site phase transfer catalyst

A quaternized highly branched polyacrylamide was synthesized and used as an efficient multi-site polymeric phase transfer catalyst in dichlorocyclopropanation reaction. The quaternized highly branched polyacrylamide was synthesized via two steps. First, a highly branched polyacrylamide was synthesized via self-condensing vinyl polymerization using appropriate molar ratio of monomer to diperiodatocuprate(III) solution. In the second step, 3-acrylamidopropyltrimethylammonium iodide was polymerized on peripheral area of the highly branched polyacrylamide in the presence of diperiodatocuprate(III) solution. The thermal behavior of highly branched polyacrylamide and that of the quaternized highly branched polyacrylamide was studied by DSC and TGA analyses. Then the activity of the synthesized quaternized highly branched polyacrylamide was investigated as phase transfer catalyst in dichlorocyclopropanation of olefins in biphasic medium. To this purpose, the synthesized catalyst was used in generating dichlorocarbene from chloroform in aqueous sodium hydroxide solution which was subsequently added to olefins. This catalyst is very active and its application yields high volume of products which are obtained in relatively short time. Various factors which influence the rate of dichlorocyclopropanation reaction, such as base concentration, stirring speed, temperature and amount of catalyst, are studied and a mechanism for addition reaction of dichlorocarbene to olefins is proposed. This efficient phase transfer catalyst was reused several times without any loss of activity.