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Acrylic acid

About: Acrylic acid is a(n) research topic. Over the lifetime, 29600 publication(s) have been published within this topic receiving 341777 citation(s). The topic is also known as: prop-2-enoic acid & ethylenecarboxylic acid.


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Journal ArticleDOI
23 Jun 1995-Science
TL;DR: A needle-like solid is obtained on drying of aqueous solutions of the spherical micelles of the highly asymmetric polystyrene-poly-(acrylic acid) block copolymers prepared in a low molecular weight solvent system.
Abstract: The observation by transmission electron microscopy of six different stable aggregate morphologies is reported for the same family of highly asymmetric polystyrene-poly-(acrylic acid) block copolymers prepared in a low molecular weight solvent system. Four of the morphologies consist of spheres, rods, lamellae, and vesicles in aqueous solution, whereas the fifth consists of simple reverse micelle-like aggregates. The sixth consists of up to micrometer-size spheres in aqueous solution that have hydrophilic surfaces and are filled with the reverse micelle-like aggregates. In addition, a needle-like solid, which is highly birefringent, is obtained on drying of aqueous solutions of the spherical micelles. This range of morphologies is believed to be unprecedented for a block copolymer system.

2,206 citations

Journal ArticleDOI
Abstract: Crew-cut micelle-like aggregates of various morphologies prepared from polystyrene-b-poly(acrylic acid), PS-b-PAA, diblock copolymers under near-equilibrium conditions, were studied by transmission electron microscopy (TEM). The insoluble block (PS) contents in the copolymers ranged from 80 to 98 wt %. In spherical micelles, the micelle cores, formed by aggregation of the PS blocks, were generally monodisperse. A comparison between star and crew-cut micelles showed that the latter are distinguished by a low density of corona chains on the core surface and a low degree of stretching of the PS blocks in the cores. As the PAA content in block copolymer decreased, the morphology of the aggregates changed progressively from spheres to cylinders, to bilayers (both vesicles and lamellae), and eventually to compound micelles consisting of an assembly of inverted micelles surrounded by a hydrophilic surface. The compound micelles are believed to be a new morphology for block copolymers. The addition of homopolysty...

1,140 citations

Journal ArticleDOI
TL;DR: Hydrogels with two different types of carboxyl group locations were employed as substrates containing the carboxylic acid, while ethylenediamine and benzylamine were used as amine to study the mechanism of amide formation between carboxYlic acid and amine in aqueous media using 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride.
Abstract: To study the mechanism of amide formation between carboxylic acid and amine in aqueous media using 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC), hydrogels with two different types of carboxyl group locations were employed as substrates containing the carboxylic acid, while ethylenediamine and benzylamine were used as amine. In parallel, a study was undertaken with cyclizable carboxylic acids (maleic acid and poly(acrylic acid) and noncyclizable carboxylic acids (fumaric acid and poly(ethylene glycol) with the terminal carboxyl groups) to assess the reaction products by 13C-NMR and IR. EDC rapidly lost its activity in aqueous media of low pH, producing the corresponding urea derivative, but was very stable at neutral and higher pH regions. EDC could react with carboxyl groups at a relatively narrow low pH range such as 3.5-4.5. If carboxyl groups were cyclizable, they would react quickly with EDC producing carboxylic anhydrides, which formed the corresponding amides when amine compounds were present. On the other hand, a trace of amide was formed in the case of noncyclizable carboxylic acids. In addition, an excess of EDC caused an undesired side reaction to form stable N-acylurea, regardless of the special location of carboxylic acids.

654 citations

Journal ArticleDOI
Abstract: Poly(N-isopropylacrylamide)-block-poly(acrylic acid), PNIPAAm-b-PAA, with low polydispersity was prepared by reversible addition−fragmentation chain transfer (RAFT) polymerization in methanol. The block copolymers respond to both temperature and pH stimuli. The behavior of the double-responsive block copolymers in solution was investigated by dynamic light scattering, temperature-sweep NMR, cryogenic transmission electron microscopy, and IR spectroscopy. The block copolymers form micelles in aqueous solutions in dependence of pH and temperature. Cloud point measurements indicated the formation of larger aggregates at pH 4.5 and temperatures above the lower critical solution temperature (LCST) of PNIPAAm. The solution behavior is strongly influenced by hydrogen bonding interactions between the NIPAAm and acrylic acid blocks.

517 citations

Journal ArticleDOI
Abstract: Superabsorbents were synthesized by graft copolymerization of acrylic acid (AA)/acrylamide (AM)/2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) onto sodium carboxymethyl cellulose (CMC) and montmorillonite (MMT) by using potassium persulfate (KPS) as a free radical initiator, in the presence of N,N′-methylenebisacrylamide (MBA) as a crosslinking agent. The structure and morphologies of the superabsorbents were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). Superabsorbent comprised a porous crosslink structure of MMT and CMC with side chains that carry carboxylate, carboxamide and sulfate. The swelling behaviors of the superabsorbent were dependant on the pH of external solutions, particle size and the concentration of the salt solution. The effect of four cationic salt solutions on the swelling had the following order: K+ > Na+ > Ca2+ > Mg2+.

502 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202212
2021325
2020713
2019871
2018911
2017970