Showing papers on "Methacrylic acid published in 2010"

Measurements of gas‐phase inorganic and organic acids from biomass fires by negative‐ion proton‐transfer chemical‐ionization mass spectrometry

Abstract: [1] Emissions from 34 laboratory biomass fires were investigated at the combustion facility of the U.S. Department of Agriculture Fire Sciences Laboratory in Missoula, Montana. Gas-phase organic and inorganic acids were quantified using negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS), open-path Fourier transform infrared spectroscopy (OP-FTIR), and proton-transfer-reaction mass spectrometry (PTR-MS). NI-PT-CIMS is a novel technique that measures the mass-to-charge ratio (m/z) of ions generated from reactions of acetate (CH3C(O)O−) ions with inorganic and organic acids. The emission ratios for various important reactive acids with respect to CO were determined. Emission ratios for isocyanic acid (HNCO), 1,2 and 1,3-benzenediols (catechol, resorcinol), nitrous acid (HONO), acrylic acid, methacrylic acid, propionic acid, formic acid, pyruvic acid, and glycolic acid were measured from biomass burning. Our measurements show that there is a significant amount of HONO in fresh smoke. The NI-PT-CIMS measurements were validated by comparison with OP-FTIR measurements of HONO and formic acid (HCOOH) and with PTR-MS measurements of HCOOH.

Block Copolymer Solid Battery Electrolyte with High Li-Ion Transference Number

Abstract: The electrochemical properties of a solid polymer electrolyte consisting of a diblock copolymer and lithium bis(oxalato)borate, LiBC 4 O 8 (LiBOB) salt, is reported The spherical microphase-separated diblock copolymer is composed of a majority poly(ethylene oxide) (PEO) block and a minority random copolymer block of methyl methacrylate (MMA) and lithium salt of methacrylic acid (MAALi), PEO-b-(PMMA-ran-PMAALi) Salt-optimized electrolyte membranes of the diblock copolymer and LiBOB salt exhibited an average lithium-ion transference number (T Li+ ) value of 09 at room temperature (21-23°C) The solid-state flexible, translucent polymer electrolyte shows a wide electrochemical stability window and excellent interface properties with the lithium metal electrode The combination of these properties makes these block copolymer membranes viable electrolyte candidates for flexible lithium-ion batteries

Polymer surface nano-structuring of reverse osmosis membranes for fouling resistance and improved flux performance

Abstract: A new class of surface-structured RO membranes was developed with a hydrophilic brush layer of terminally anchored polymer chains resulting in fouling resistant membranes of low mineral scaling propensity and high permeability. The approach is based on free-radical graft polymerization of a suitable monomer, onto the active polyamide (PA) layer of a thin film composite (PA-TFC) membrane, post-surface activation with an impinging atmospheric pressure plasma source. Two types of nano-structured (SNS) RO membranes (SNS-PA-TFC) were synthesized based on methacrylic acid (MAA-SNS-PA-TFC) and acrylamide (AA-SNS-PA-TFC) graft polymerization. The poly(methacrylic acid) and poly(acrylamide) brush layers, on the PA surface, resulted in RO membranes of significantly lower mineral scaling propensity, evaluated with respect to the mineral scalant calcium sulfate dihydrate, compared with commercial RO membrane (LFC1) of about the same salt rejection (∼95%) and surface roughness (∼70 nm). Direct membrane surface imaging indicated that the rate of nucleation and thus mineral scaling were reduced owing to the polymer brush layer. Fouling resistance of the SNS-PA-TFC membranes was also demonstrated with respect to model foulants (the protein BSA and alginic acid). The MAA-SNS-PA-TFC and AA-SNS-PA-TFC membranes had a negatively charged and near neutral surfaces, respectively, with water contact angles somewhat lower for the former and higher for the latter membranes relative to the LFC1 membrane. The AA-SNS-PA-TFC membrane displayed lower mineral scaling propensity than the MAA based membrane, although its alginic acid fouling resistance was inferior, despite its lower surface roughness (25–33 nm) relative to the MAA-SNS-PA-RFC (∼60–80 nm) and LFC1 (∼73 nm) membranes.

Dual Responsive Methacrylic Acid and Oligo(2-ethyl-2-oxazoline) Containing Graft Copolymers

Abstract: Graft copolymers containing a poly(methacrylic acid) (PMAA) backbone and oligo(2-ethyl-2- oxazoline) (OEtOx) sidechains weresynthesizedbyreversibleaddition-fragmentationchaintransfer (RAFT) polymerization of methacrylic acid (MAA) and OEtOx methacrylate macromonomers. In order to achieve a constant backbone length of the graft copolymer, living OEtOx chains were also directly grafted onto a deprotonated PMAA backbone in grafting densities from 7% to 92%. Both methods resulted in graft copolymers which were characterized by SEC (Mn = 5500 to 18700 g mol -1 , PDI < 1.3), 1 H NMR spectro- scopy, and acid/base titrations. The solubility behavior of the graft copolymers in aqueous media was investigated using turbidity measurements revealing a lower critical solution temperature (LCST) behavior of the polymers with a grafting density above 35%. The cloud points of the solutions can be varied in a temperature range from 8 to 90 C by adjustment of the polymer composition and the pH of the solution. 1 H NMR measurements in D2O at varying temperatures revealed a collapse of the polymer backbone above the cloud point of the solution whereas parts of the OEtOx side chains remained mobile.

Synthesis and Characterization of Paraffin Wax Microcapsules with Acrylic-Based Polymer Shells

Abstract: Microencapsulation of PRS paraffin wax was carried out by means of suspension-like homopolymerization of methyl methacrylate (MMA) and by the copolymerization of this monomer with methyl acrylate (MA) and methacrylic acid (MAA). The influence of the type of monomers and their proportion as shell materials, the mass ratio of polyvinylpyrrolidone to monomers (PVP/monomers), and the mass ratio of PRS paraffin wax to monomers (PRS/monomers) on the properties of phase change material (PCM) microcapsules has been studied. The analytical techniques used for the characterization of the particles were differential scanning calorimetry (DSC) and modulated DSC, dynamic light scattering, environmental scanning electron microscopy (ESEM) and gel permeation chromatography (GPC). The chemical property differences between the encapsulating “shell” material, acrylic polymer in this case, compared to the “core” material (PRS paraffin wax), such as polarity and interfacial tensions, largely determine the thermodynamically f...

Red‐NIR Luminescent Hybrid Poly(methyl methacrylate) Containing Covalently Linked Octahedral Rhenium Metallic Clusters

Abstract: The embedding of functional inorganic entities into polymer matrices has become an intense field of investigation in which the main challenges are to keep the added value of the inorganic entities while preventing their self-aggregation within the organic matrix. We present a simple way to obtain a homogeneous highly red-NIR luminescent hybrid copolymer that contains covalently bonded nanometric-sized {Re(6)} octahedral clusters. The [Re(6)Se(i)(8)(OH)(a)(6)](4-) cluster complexes are primarily functionalized in two steps with tert-butylpyridine (TBP) and methacrylic acid (MAC) to give neutral [Re(6)Se(8)(TBP)(4)(MAC)(2)] building blocks that are copolymerized with methyl methacrylate (MMA) either in solution or in bulk in the presence of azobisisobutyronitrile as an initiator. Several samples containing 0, 0.025, 0.05, and 0.1 wt % of functionalized {Re(6)} clusters were prepared. As the {Re(6)} cluster/MMA ratio is very low, the obtained copolymers keep the entire processability of pure poly(methyl methacrylate) (PMMA), as demonstrated by differential scanning calorimetry and thermogravimetric analysis. Voltammetric and luminescence studies also indicate that the intrinsic properties of the clusters are preserved within the polymer matrix. All the samples show a bright (emission quantum yield=0.07), broad, and structureless emission band, which extends from lambda=600 nm to more than lambda=950 nm, with the maximum wavelength centered around lambda(em)=710 nm either in solution or in the solid state. Moreover, the high stability of the incorporated inorganic phosphors prevents the material from photobleaching, and thus the luminescence properties are kept entirely even after nine months of ageing.

Influence of Architecture on the Interaction of Negatively Charged Multisensitive Poly(N-isopropylacrylamide)-co-Methacrylic Acid Microgels with Oppositely Charged Polyelectrolyte: Absorption vs Adsorption

Abstract: Two sets of core−shell microgels composed of temperature-sensitive poly(N-isopropylacrylamide) (PNiPAM) with different spatial distribution of pH-sensitive methacrylic acid (MAA) groups were prepared. The cores consist of either PNiPAM (neutral core; nc) or PNiPAM-co-MAA (charged core; cc). A charged shell existing of PNiPAM-co-MAA was added to the neutral core (yielding neutral core−charged shell; nccs), on the charged core, on the other hand, a neutral shell of PNiPAM was added (charged core−neutral shell; ccns). Complexes of these microgels with positively charged poly(diallyldimethylammonium chloride) (PDADMAC) of different molar masses were prepared. The amount of bound polyelectrolyte was quantified, and the microgel−polyelectrolyte complexes were characterized with respect to electrophoretic mobility and hydrodynamic radius. The penetration of polyelectrolyte into the microgel was also monitored by means of lifetime analysis of a fluorescent dye covalently bound to poly(l-lysine) providing informat...

Importance of Functional Monomer Dimerization in the Molecular Imprinting Process

Abstract: We examined the influence of functional monomer dimerization on the efficiency of the molecular imprinting process. Specifically, the influence of methacrylic acid (MAA) dimerization on the binding properties of molecularly imprinted polymers (MIPs) was studied. First, the dimerization of MAA and the association between MAA and template molecular ethyl adenine-9-acetate (EA9A) were characterized in solution. Next, a series of MIPs and control nonimprinted polymers (NIPs) were made under varying conditions that systematically disrupted the monomer dimerization and templation process by the addition of polar solvents to the polymerization mixture. The results showed that even a monomer such as MAA with low dimerization constant is able to efficiently suppress the formation of background binding sites. To isolate the influence of monomer dimerization on the imprinting effect, the equilibrium processes in the prepolymerization mixture were modeled using the computer program COPASI. The simulation was able to ...

Two-photon polymerization of titanium-containing sol-gel composites for three-dimensional structure fabrication

Abstract: In this work, we have synthesized and characterized a novel, titanium-containing hybrid material that can be structured three-dimensionally using two-photon polymerization. We investigate the effect on the structurability of the increase of titanium isopropoxide and methacrylic acid in this photosensitive composite. We show that while it is possible to make transparent thin films with a titanium isopropoxide molar content as high as 90%, three-dimensional structures can be made only when the titanium isopropoxide molar content is less than 50%. We measure the refractive index of films with different titanium isopropoxide: methacrylic acid concentrations and we show that while the refractive index increases linearly with the titanium isopropoxide, the increase of the methacrylic acid content does not affect the refractive index of the material.

Copolymerization of methacrylic acid with methyl methacrylate by SET‐LRP

Abstract: Single-electron transfer living radical polymerization (SET-LRP) has developed as a reliable, robust and straight forward method for the construction well-defined polymers. To span an even larger variety of functional monomers, we investigated the copolymerization of methyl methacrylate with methacrylic acid by SET-LRP. Copolymerizations were catalyzed by Cu(0)/Me6-TREN and performed in MeOH/H2O mixtures at 50 °C. The SET-LRP copolymerizations of varying methacrylic acid content were evaluated by kinetic experiments. At low (2.5%) and moderate (10%) MAA loadings, the copolymerizations obeyed perfect first order kinetics (kpapp = 0.008 min−1 and kpapp = 0.006 min−1) and exhibited a linear increase in molecular weights with conversion providing narrow molecular weight distributions. The SET-LRP of MMA/25%-MAA was found to be significantly slower (kpapp = 0.0035 min−1). However, a reasonable first-order kinetics in monomer consumption was maintained, and the control of the polymerization process was preserved since the molecular weight increased linearly with conversion and could therefore be adjusted. This work demonstrates that the copolymerization of methacrylic acid by SET-LRP is feasible and the design of well-defined macromolecules comprising acidic functionality can be achieved. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Hybrids of Magnetic Nanoparticles with Double‐Hydrophilic Core/Shell Cylindrical Polymer Brushes and Their Alignment in a Magnetic Field

Abstract: The synthesis of double-hydrophilic core/shell cylindrical polymer brushes (CPBs), their hybrids with magnetite nanoparticles, and the directed alignment of these magnetic hybrid cylinders by a magnetic field are demonstrated. Consecutive grafting from a polyinitiator poly(2-(2-bromoisobutyryloxy)ethyl methacrylate) (PBIEM) of tert-butyl methacrylate (tBMA) and oligo(ethylene glycol) methacrylate (OEGMA) using atom-transfer radical polymerization (ATRP) and further de-protection yields core/shell CPBs with poly(methacrylic acid) (PMAA) as the core and POEGMA as the shell, which is evidenced by 1 H NMR, gel permeation chromatography (GPC), and dynamic and static light scattering (DLS and SLS). The resulting core/shell brush is well soluble in water and shows a pH responsiveness because of its weak polyelectrolyte core. Pearl-necklace structures are observed by cryogenic transmission electron microscopy (cryo-TEM) at pH 4, while at pH 7, these structures disappear owing to the ionization of the core. A similar morphology is also found for the polychelate ofthe core/shell CPBs with Fe 3+ ions. Superparamagnetic magnetite nanoparticles have also been prepared and introduced into the core of the brushes. The hybrid material retains the superparamagnetic property of the magnetite nanoparticles, which is verified by superconducting quantum interference device (SQUID) magnetization measurements. Large-scale alignment of the hybrid cylinders in relatively low magnetic fields (40-300 mT) can easily be performed when deposited on a surface. which is clearly revealed by the atomic force microscopy (AFM) and TEM measurements.

Synthesis of reactive soybean oils for use as a biobased thermoset resins in structural natural fiber composites

Abstract: Biobased thermosets resins were synthesized by functionalizing the triglycerides of epoxidized soybean oil with methacrylic acid, acetyl anhydride, and methacrylic anhydride The obtained resins were characterized with FTIR, 1H-NMR, and 13C-NMR spectroscopy to confirm the functionalization reactions and the extent of epoxy conversion The viscosities of the methacrylated soybean oil resins were also measured for the purpose of being used as a matrix in composite applications The cross-linking capability was estimated by UV and thermally initiated curing experiments, and by DSC analysis regarding the degree of crosslinking The modifications were successful because up to 97% conversion of epoxy group were achieved leaving only 22% of unreacted epoxy groups, which was confirmed by 1H-NMR The 13C-NMR confirms the ratio of acetate to methacrylate methyl group to be 1 : 1 The viscosities of the methacrylated soybean oil (MSO) and methacrylic anhydride modified soybean oil (MMSO) were 02 and 048 Pas, respectively, which indicates that they can be used in resin transfer molding process © 2009 Wiley Periodicals, Inc J Appl Polym Sci, 2010

Ce:YAG Nanoparticles Embedded in a PMMA Matrix: Preparation and Characterization

Abstract: A Ce:YAG-poly(methyl methacrylate) composite was prepared using in situ polymerization by embedding the Ce:YAG nanopowder in a blend of methyl methacrylate (MMA) and 2-methacrylic acid (MAA) monomers and activating the photopolymerization using a radical initiator. The obtained nanocomposite was yellow and transparent. Its characterization was performed using transmission electron microscopy, small angle X-ray scattering, 13C cross-polarization magic-angle spinning nuclear magnetic resonance, and photoluminescence spectroscopy. Results showed that Ce:YAG nanoparticles are well dispersed in the polymeric matrix whose structure is organized in a lamellar shape. The luminescence properties of the nanocomposite do not show quenching or a significant spectral shift, indicating that the nanocomposite can be useful for advanced applications such as white LED construction.

Smart Hydrogels Co-switched by Hydrogen Bonds and π–π Stacking for Continuously Regulated Controlled-Release System

Abstract: A series of hydrogels with continuously regulatable release behavior can be achieved by incorporating hydrogen bonding and π–π stacking co-switches in polymers A poly(nitrophenyl methacrylate-co-methacrylic acid) hydrogel (NPMAAHG) for control over drug release is fabricated by copolymerizing 4-nitrophenyl methacrylate and methacrylic acid using ethylene glycol dimethacrylate as a crosslinker The carboxylic acid groups and nitrylphenyl groups form hydrogen bonds and π–π stacking interactions, respectively, which act as switches to control the release of guest molecules from the polymers As revealed by the simulated gastrointestinal tract drug release experiments, the as-synthesized NPMAAHG hydrogels can be regulated to release only 47% of drugs after 3 h in a simulated stomach and nearly 926% within 43 h in the whole digestive tract The relation between the release kinetics and structures and the mechanism of the smart release control are analyzed in terms of diffusion exponent, swelling interface number, drug diffusion coefficient, and velocity of the swelling interface in detail The results reveal that the release of guest molecules from the hydrogels can be continuously regulated for systemic administration by controlling the ratio of the hydrophilic hydrogen bonds and the hydrophobic π–π stacking switches