2-Acrylamido-2-methylpropane sulfonic acid

AMPS

White solid

Fixed

1.1 g · cm -3 ( 15.6 ° C)

185 ° C

Soluble in water ( 1500 g · l-1 at 25 ° C)

Attention

5400 mg · kg -1 ( LD50, rat, oral)

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2-acrylamido- 2-methylpropanesulfonic acid (AMPS (R) trademark of the Lubrizol Corp.). Is a chemical compound from the group of sulfonic acids. Also known as 2-acrylamido- tert. butyl- sulfonic acid ( ATBS ) named compound is a highly reactive and readily water- soluble acrylic monomer, the high molecular weight homopolymers ( MW > 2 million) forms with extraordinary product properties and is used by radical copolymerization with other monomers to hydrophilisation of the obtained copolymers. Originally proposed to improve the dyeability of polyacrylonitrile fibers, AMPS has found wide use in a variety of applications because of its functionality.

Occurrence

It is produced synthetically. A natural occurrence is not known.

Production

2 -acrylamido -2-methylpropane produced in a Ritter reaction of acrylonitrile and isobutene in the presence of highly concentrated or fuming sulfuric acid and water. The more recent patent literature describes discontinuous and continuous processes, the AMPS in a high purity (up to 99.7 %) and improved yield generate (up to 89 %, based on isobutene ) for adding liquid isobutylene to acrylonitrile / sulfuric acid / phosphoric acid mixture at 40 ° C..

Properties

AMPS is a white, crystalline, hygroscopic solid which is very readily soluble in water and forms easily soluble salts with alkali and alkaline earth metals. Aqueous AMPS solutions are strongly acidic due to the complete dissociation of the sulfonic acid group. Commercially the solids in powder and granular form and aqueous 50 % solutions of sodium ( Na - AMPS ) and ammonium salts. AMPS has as acrylic monomer on unusual material properties that make it particularly as a comonomer in functional polymers interesting:

• high thermal and hydrolytic stability: the amide function in the AMPS molecule is spatially shielded by the geminal methyl groups, and sulfomethyl and protected against hydrolytic and thermal degradation. The decomposition of AMPS homopolymers occurs from 225 ° C, Na - AMPS homopolymers even until 307 ° C.

• Strong hydrophilicity and acidity: the sulfonic AMPS gives a permanently hydrophilic character and is far ahead in the acidic pH range as a sulfonate anion. Even small amounts of AMPS (< 5% ) increase the hydrophilicity of copolymers significantly.

• Good solubility: AMPS dissolves very well in water and good in the aprotic dipolar solvents dimethylformamide and N -methyl-2 -pyrrolidone.

The high stability of AMPS imply its low biodegradability. In contrast, AMPS is not mutagenic and has a neutral AMPS -Na- salt solution has a very low toxicity LD50> 16,000 mg / kg rat.

It polymerizes easily, even under the influence of light.

Use

As a constituent of copolymers with acrylic acid, acrylamide, and other functional acrylic and vinyl monomers. AMPS is a set of applications - especially as a comonomer - in:

1 Textile: increases the dyeability of polyacrylic and polyester textiles.

2 Paints, varnishes and coating paper: requires a higher chemical and mechanical stability of polymer emulsions, stabilized the particle distribution, suppresses the formation of Gries and increases the abrasion resistance of paints and papers.

3 adhesives: it improves the thermal and mechanical properties, and increases the adhesive strength of the pressure-sensitive adhesive formulations.

4 detergent: enhances the detergent effect of surfactants by binding of multivalent cations and reduces the Schmutzanlagerung.

5 cosmetics and medicine: forms with other comonomers high molecular weight polymers which are used as hydrogels and emulsions as a thickener, stabilizer, dispersant and lubricant in cosmetic, dermatological preparations and medical application. If because of its high water absorption and retention capacity as a comonomer in SAPs for example, Baby diapers used.

6 Water Treatment: stabilized, especially in co-and terpolymers with other ionic and neutral monomers multivalent cations in hard water and prevents as 'scale inhibitor ' scale formation and corrosion.

7 Plant Protection: increases in dissolved and nanoparticulate polymer formulations, the bioavailability of pesticides in aqueous-organic preparations.

8 membranes: increases water flow, retention and fouling resistance of asymmetric ultra-and microfiltration membranes and is being studied as an anionic component in polymer fuel cell membranes.

9 Construction: acts in copolymers as water retention agents in mortars and plasters, leads to increasing dispersibility of particles increases lubricity and improved in copolymers, in particular with methacrylic or acrylic acid, as Superplasticizer the mechanical and chemical stability of high-flow and self-compacting concrete.

10 oil and gas exploration: increases the stability of polymers in oil and gas field applications to high temperatures and pressures, and high salt concentrations, reduces friction and fluid loss in drilling and Zementierungsflüssigkeiten and finds application in tertiary oil recovery ( engl. enhanced oil recovery, EOR) and mentioned in the " hydraulic fracturing " breaking rock formations for shale gas.

The current capacity of the three main AMPS manufacturer is about 30,000 tons / year.

Pictures of 2-Acrylamido-2-methylpropane sulfonic acid

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