Topic
Acrylic acid
About: Acrylic acid is a research topic. Over the lifetime, 29600 publications have been published within this topic receiving 341777 citations. The topic is also known as: prop-2-enoic acid & ethylenecarboxylic acid.
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TL;DR: In this paper, the formation of crew-cut aggregates of various structures prepared from polystyrene-b-poly(acrylic acid) diblock copolymers in DMF/water mixtures is explored.
Abstract: Thermodynamic vs kinetic aspects of the formation of crew-cut aggregates of various structures prepared from polystyrene-b-poly(acrylic acid) diblock copolymers in DMF/water mixtures are explored. In particular, the reversibility of the transitions between the crew-cut aggregates of various morphologies is studied by “jumps” in the polymer or ion concentration at various water contents. The aggregates are prepared by two different methods: micellization is induced either by the addition of water to polymer/DMF solutions or by the direct dissolution of the polymer in DMF/water mixtures. It is shown that as the polymer concentration increases, the morphology of the aggregates changes from spheres to rodlike micelles, to interconnected rods, and then to bilayers. As the water content increases, the boundaries for the formation of the different morphologies move toward lower polymer concentrations. The thermodynamic vs kinetic control of the morphology depends largely on the water content and the method of a...
390 citations
TL;DR: In this paper, a water-soluble acrylic acid (AAc) was covalently grafted to silicon nanoparticles to increase their dispersibility and improve their photoluminescence stability against degradation by water.
Abstract: UV-induced graft polymerization of acrylic acid (AAc) on the surface of silicon nanoparticles was used to prepare a stable aqueous luminescent silicon nanoparticle solution. By grafting a water-soluble polymer on the particle surface, the dispersions in water of the silicon nanoparticles became very stable and clear aqueous solutions could be obtained. XPS and NMR spectroscopy confirmed that PAAc was covalently grafted to the silicon nanoparticles. The grafted PAAc on silicon particles increased not only the dispersibility but also improved the photoluminescence stability of the silicon nanoparticles against degradation by water. The surface-modified nanoparticles were used as biological labels for cell imaging. The Si quantum dot labels exihibited bright fluorescence images and provided higher resistance to photobleaching than the commonly used organic dyes.
389 citations
TL;DR: Methods for stabilizing these multilayers to high pH through cross-linking by heating or UV-irradiation and introducing photoreactive groups in the multilayer have succeeded in micropatterning these films by ink-jet printing and photolithography to create subtractive patterns.
Abstract: Polyelectrolyte multilayers of poly(acrylic acid) (PAA) and polyacrylamide (PAAm) were prepared via hydrogen-bonding interactions. These multilayers as assembled were stable at low pH but dissolved quickly in neutral pH water. We developed methods for stabilizing these multilayers to high pH through cross-linking by heating or UV-irradiation. Thermal treatment of the multilayers, which resulted in a partial imidization between carboxylic acid and amide groups, gave the multilayer good stability at high pH. In addition, we introduced photoreactive groups in the multilayer, which rendered the film insoluble after UV irradiation. Using these selective stabilization approaches, we have succeeded in micropatterning these films by ink-jet printing and photolithography to create subtractive patterns.
380 citations
TL;DR: In this paper, a new approach for the fabrication of a multilayer film assembly is explored, which is based on the alternating assembling of poly(4-vinylpyridine) and poly(acrylic acid) via hydrogen bonding.
Abstract: A new approach for the fabrication of a multilayer film assembly is explored, which is based on the alternating assembling of poly(4-vinylpyridine) and poly(acrylic acid) via hydrogen bonding. The homogeneous multilayer films were characterized by UV-Vis, X-ray diffraction and atomic force microscopy (AFM) measurements. The nature of interaction between the two polymers is identified as hydrogen bonding by IR spectroscopy.
371 citations
TL;DR: In this article, the morphology of crew-cut aggregates of amphiphilic block copolymers in dilute solutions can be controlled by the addition of ions in micromolar (HCl, NaOH, CaCl2, Ca(Ac)2) or millimolar (NaCl) concentrations.
Abstract: The morphology of crew-cut aggregates of amphiphilic block copolymers in dilute solutions can be controlled by the addition of ions in micromolar (HCl, NaOH, CaCl2, Ca(Ac)2) or millimolar (NaCl) concentrations. The copolymers are highly asymmetric polystyrene-b-poly(acrylic acid) diblocks, PS-b-PAA, in which the lengths of the insoluble PS blocks are much longer than those of the soluble PAA blocks. In addition to spherical, rodlike, and univesicular or lamellar aggregates, large compound vesicles (LCVs), a new morphology, can be obtained from a single block copolymer. The morphogenic effect of different added ions on the crew-cut aggregates can be ascribed to the changed repulsive interactions among the hydrophilic PAA segments, due to neutralization by NaOH, protonation by HCl, ion-binding or bridging by Ca2+, and electrostatic screening by NaCl, respectively. The formation of the LCVs may involve a secondary aggregation of individual vesicles and a subsequent fusion process. Some features of the sponta...
367 citations