ATBS (AMPS) 2-Acrylamido-2-methylpropane Sulfonic Acid · CAS 15214-89-8

What is ATBS (AMPS)?

ATBS, universally known by its older name AMPS, is a reactive vinyl monomer carrying both an acrylamide group and a strongly acidic sulfonic acid group on a tertiary carbon. Its formula is C₇H₁₃NO₄S, and at room temperature it is a white, crystalline, hygroscopic solid that is highly soluble in water.

The sulfonic acid group is what gives ATBS its value as a comonomer. Unlike carboxylic acid groups, it ionizes completely across the full pH range, so polymers built with ATBS keep their charge and solubility in acidic, neutral or high-salinity conditions and resist precipitation with calcium and magnesium ions. The acrylamide vinyl group lets it copolymerise readily with acrylamide, acrylic acid, vinyl acetate and a wide range of other monomers by standard free-radical polymerisation.

ATBS is supplied as a dry crystalline powder, typically 98–99% minimum purity, or pre-dissolved as a 50% aqueous solution or a neutralised sodium-salt solution for producers who polymerise directly from solution. Trace stabiliser is carried in the solution grades to prevent premature polymerisation in storage.

Commercially, ATBS is made on purpose by reacting isobutylene, acrylonitrile and sulfuric acid, so its supply is tied to that dedicated process rather than to a cracker co-product stream. It is not classified as a carcinogen or mutagen; the handling considerations are skin and eye irritation, dust, and the self-polymerisation risk common to uninhibited acrylic-type monomers.

Why ATBS specifically

• Permanent, fully ionised charge. The sulfonic acid group stays charged across the whole pH range, unlike carboxylate groups that lose charge in acid.
• Divalent-cation tolerance. Sulfonate does not precipitate with calcium or magnesium, so ATBS copolymers keep working in hard water and high-salinity brines.
• Hydrolytic and thermal stability. The amide linkage resists hydrolysis far better than ester-based comonomers, which matters at high temperature and over long service life.
• A versatile comonomer. It copolymerises with acrylamide, acrylic acid, methacrylates and vinyl monomers to tune charge density, salt tolerance and thermal performance in the finished polymer.

How ATBS is Manufactured

Unlike co-product petrochemicals, ATBS is made on purpose in a dedicated process, so supply tracks ATBS demand directly rather than a cracker's feed choices.

• Ritter-type reaction. Liquid isobutylene is added to a mixture of acrylonitrile and concentrated sulfuric acid under controlled temperature, forming a nitrilium / sulfonate intermediate.
• Controlled hydrolysis. Water is added under controlled conditions to complete the reaction to 2-acrylamido-2-methylpropane sulfonic acid, releasing the free acid into the reaction mass.
• Neutralisation (solution grades). For sodium-salt and aqueous-solution grades, the acid is partially or fully neutralised and diluted to the target concentration.
• Crystallisation and filtration (powder grade). The free acid is crystallised out, filtered and washed to remove residual sulfuric acid and unreacted acrylonitrile.
• Drying and milling. The crystals are dried and milled to a controlled particle size for consistent dissolution and dust behaviour.
• Stabilisation and packing. Solution grades carry a trace polymerisation inhibitor; powder is packed under a moisture barrier, since the product is hygroscopic.

Typical Commercial Specification

Figures below are representative of commercial-grade ATBS powder and aqueous solution. Tell us your polymerisation route and the grade you need, and we will advise on the specification to order against.

Physical & Chemical Properties

Behaviour in the process

ATBS has several behaviours that set its handling and polymerisation rules:

• Full ionisation. Because the sulfonic acid group ionises completely regardless of pH, polymers built with ATBS retain solubility and charge density where carboxylate-based comonomers lose performance.
• Divalent-cation resistance. Sulfonate does not form insoluble salts with calcium or magnesium the way carboxylate groups can, which is the basis of its use in hard-water and brine-tolerant polymers.
• Hygroscopic solid. The powder absorbs atmospheric moisture, which affects weighing accuracy and flow if packaging is compromised.
• Self-polymerisation risk. Like other acrylic-type monomers, uninhibited ATBS solution can polymerise exothermically under heat or light; solution grades carry a stabiliser for this reason.
• Standard free-radical reactivity. The acrylamide vinyl group copolymerises readily with acrylamide, acrylic acid and a wide range of other vinyl monomers under conventional initiator systems.

ATBS Grades and Alternative Monomers

ATBS is bought as a comonomer, and the choice of grade or alternative depends on the polymerisation route and the properties the finished polymer needs.

Stated plainly: ATBS has no true drop-in substitute where hydrolytic stability and divalent-cation tolerance together are required, though sodium vinyl sulfonate and acrylic acid are used as lower-cost alternatives when those specific properties are not needed. The choice between ATBS grades is mostly about handling and process fit, not performance.

Industries We Supply ATBS To

The same monomer goes into a scale-inhibitor copolymer, an oilfield friction reducer and a diaper's superabsorbent core. What changes is the grade, the copolymer ratio and the documentation each application requires.

Where ATBS is Used

ATBS is bought almost entirely as a comonomer rather than a standalone chemical. These are the end-use polymers our customers build it into.

In water treatment polymer manufacture

ATBS is copolymerised with acrylic acid, acrylamide or maleic acid to give scale and corrosion inhibitors that stay soluble and effective in hard, high-TDS water. The sulfonate group's resistance to calcium and magnesium precipitation is the specific property being bought, and residual monomer and colour affect the finished polymer's clarity and performance.

In oilfield chemical manufacture

Drilling fluid and EOR polymer producers copolymerise ATBS with acrylamide to give products that keep working at high salinity, high temperature and under high shear — conditions where simpler polyacrylamides lose viscosity or precipitate. ATBS content and purity directly affect the finished polymer's thermal and salt tolerance.

In superabsorbent polymer (SAP) manufacture

A small proportion of ATBS is copolymerised with acrylic acid or acrylamide in SAP formulations to improve absorption rate and gel strength under saline conditions, which matters for both hygiene products and agricultural soil conditioners.

Quality Control & Testing

Every lot is released against a batch-specific Certificate of Analysis, with residual acrylonitrile and moisture reported alongside purity because both affect safety and downstream polymerisation.

• ATBS content — by acid-base titration or HPLC, the primary grade measure.
• Residual acrylonitrile — by GC, reported because of its toxicological significance and its effect on polymerisation.
• Moisture — by Karl Fischer titration or loss-on-drying, critical for powder handling and shelf life.
• Free sulfuric acid — reported as a process-residual impurity.
• Sulfate ash — an indicator of inorganic residue from neutralisation or crystallisation.
• Colour (Hazen / APHA) — tested on a dilute solution, since colour carries through into the finished polymer.
• Particle size — checked on powder grade for consistent dissolution behaviour.

Common Process Problems & Likely Causes

When ATBS causes trouble, it is usually moisture, residual acrylonitrile, inhibitor level or storage temperature. This table is the shortcut our technical desk works through before anyone opens a complaint file.

Packaging, Storage & Shipping

• Powder grade. Moisture-barrier-lined bags, typically 25 kg net, palletised and shrink-wrapped for export.
• Solution grades. HDPE drums, IBC totes or ISO tanks for the 50% aqueous solution and sodium-salt solution.
• Moisture control. The powder is hygroscopic; store in a cool, dry place and reseal bags promptly once opened.
• Temperature control. Avoid prolonged heat and direct sunlight on both powder and solution grades to limit self-polymerisation risk and, for solutions, cold storage below their freeze point.
• Stabiliser. Solution grades carry a polymerisation inhibitor; do not store solution near heat sources or UV exposure.
• Shelf life. Typically up to 12 months for powder in unopened, moisture-proof packaging, stored cool and dry. Re-test moisture and purity rather than assume for older stock.
• Transport. Not generally classified as a dangerous good for most grades and shipping lanes; confirm classification with your carrier and destination regulations before booking.

Hazards & Safe Handling

ATBS is not classified as a carcinogen, mutagen or flammable gas. The handling hazards are skin and eye irritation, dust inhalation, and the self-polymerisation risk shared by acrylic-type monomers when heat, light or contamination are involved.

• Skin and eye contact. Causes irritation. Wear chemical-resistant gloves and goggles; rinse thoroughly with water on contact.
• Dust inhalation. Avoid inhaling dust during weighing and transfer; use local exhaust ventilation and a dust mask where needed.
• Self-polymerisation. Uninhibited solution can polymerise exothermically under heat, light or contamination; keep solution grades stabilised and within their recommended storage temperature.
• Hygroscopicity. Reseal containers promptly; prolonged exposure to humid air degrades handling and flow properties.
• PPE. Gloves, safety goggles and a dust mask for powder handling; follow the SDS for your specific grade.
• Environment. Avoid uncontrolled discharge to water; follow local effluent and waste-disposal rules for the acid or its neutralised form.

Regulatory & Compliance Notes

ATBS is a registered industrial chemical with standard handling and transport considerations rather than the heightened controls that apply to carcinogens or flammable gases. Because obligations differ by territory and use, the notes below are orientation rather than legal advice — confirm your own position with your regulatory adviser.

• GHS classification. Typically classified for skin and eye irritation; not classified as a carcinogen, mutagen or flammable gas. The SDS carries the full hazard statements for your grade.
• REACH and chemical inventories. Registered under EU REACH and listed on major chemical inventories including TSCA.
• Transport. Most grades are not classified as dangerous goods for standard sea and road freight; confirm with your carrier for your specific lane and grade, since classification can vary by packing format and local rule.
• HS code. Commonly declared under the sulfonic-acid-derivative heading; confirm the exact tariff line with your customs broker for your jurisdiction.
• End-use regulation. Downstream uses such as superabsorbent polymers in hygiene products or food-contact-adjacent paper applications may carry their own regulatory requirements independent of the monomer itself.
• Quality agreements. Water treatment, oilfield and SAP producers commonly expect documented purity, moisture and residual-monomer limits and change control. Tell us what your agreement requires.

We Supply ATBS Worldwide

Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship ATBS from India and from partner sources to customers across Asia, Europe, the Middle East, Africa, and North and South America, handling the export documentation and freight so the material arrives ready to use.

• Incoterms. EXW, FOB, CIF, CFR and DAP quoted to suit your purchasing terms and freight arrangements.
• Ports. Regular shipments through Nhava Sheva (JNPT) and Mundra, with other ports arranged as routing allows.
• Documentation. Commercial invoice, packing list, certificate of origin, COA and SDS issued as a complete set.
• Flexible volumes. From single-bag and drum trial orders up to repeat bulk shipments on a supply contract.
• Supply continuity. Because we are independent of any one producer, a plant turnaround or a shipping disruption at one source does not have to become your stock-out.

Buying ATBS from Chelora

We are an independent sourcing and supply partner. For ATBS that means settling three things at enquiry: the grade (powder, aqueous solution or sodium-salt solution), the purity and residual-monomer limits your process needs, and the packing format that fits your handling setup.

• Documentation on every lot. Batch-specific COA with ATBS content, moisture, residual acrylonitrile and colour, plus the current SDS.
• Analysis before commitment. Representative analysis shared ahead of a commercial order so your lab can qualify the material.
• Grades. Powder 98–99%, 50% aqueous solution and neutralised sodium-salt solution, all available to specification.
• Quantities. Trial drum and bag quantities through to full bulk shipments on contract supply.
• Inspection. Independent third-party inspection available at loading when the contract requires it.
• Related monomers. Acrylamide, acrylic acid and sodium vinyl sulfonate alongside ATBS from one supplier.

How ordering works

• Send the enquiry. Grade, purity, quantity, destination port and the Incoterm you buy on. If you have a spec sheet, attach it — it saves a round trip.
• We quote. Price, lead time, packing format and a sample COA, normally within one working day.
• Qualify the supply. For first orders or critical applications, we share the analysis so your technical team can sign off before you commit.
• Confirm the order. Proforma invoice issued; payment terms agreed against the volume and the relationship.
• Allocation and QC. Material allocated and released against a batch-specific COA, with an independent inspection where the contract calls for it.
• Ship and document. Packed, labelled and loaded with the full export document set, and tracked through to arrival.

Related Monomers & Specialty Intermediates

Buyers of ATBS often source other comonomers alongside it — water treatment and SAP producers typically buy acrylamide and acrylic acid on the same programme, and some oilfield formulators also need sodium vinyl sulfonate or isobutylene. Consolidating them cuts freight cost and gives you a single point of contact for documentation.