SYNTECH

What Is Sodium Methallyl Sulfonate (SMAS, CAS 1561-92-8)? Structure, Properties, Production & Industrial Applications

SMAS Molecular Structure

SMAS Solid Powder

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1. Basic Introduction & Chemical Identity

Sodium Methallyl Sulfonate, abbreviated as SMAS / MAS, systematic chemical name Sodium 2-Methyl-2-propene-1-sulfonate, CAS registry number 1561-92-8, EINECS No. 216-341-5ChemicalBo….

• Molecular Formula: C_4​H₇​NaO₃​S
• Molecular Weight: 158.15
• Synonyms: Methallylsulfonic acid sodium salt, 2-methylprop-2-ene-1-sulfonic acid sodium salt

SMAS is a water-soluble anionic functional monomer with reactive carbon-carbon double bond and hydrophilic sulfonate group (−SO₃​Na). It is one of the most widely used sulfonated co-monomers in polymer synthesis, favored by R&D engineers for moderate polymerization activity, stable structure and excellent hydrophilic modification performance

2. Physical & Chemical Properties

Physical Traits

Industrial SMAS has two mainstream commercial grades:

1. 99.5% High-purity white crystalline powder: Flaky, odorless solid
2. 35% Aqueous liquid: Transparent light yellow solution for liquid polymerization process

Solubility characteristics:

• Highly soluble in deionized water
• Slightly soluble in ethanol and DMSO
• Insoluble in hydrocarbons, esters and other non-polar organic solvents

Melting point range: 270–300℃; density approx 1.26 g/cm³; no volatility under normal temperature.

Chemical Stability

1. Stable under room temperature, neutral & weak acid/alkaline environments
2. Avoid long-term contact with strong oxidants to prevent decomposition
3. Easy free-radical copolymerization with acrylic, acrylonitrile, maleic anhydride monomers via the terminal C=C double bond
4. Commercial products add 100–500 ppm MEHQ polymerization inhibitor to avoid spontaneous self-polymerization during storageChemicalBo…
5. The sulfonate group provides permanent negative charge, endowing polymers with lasting dispersion, anti-scale and anti-static functions

3. Industrial Synthesis Process

The mainstream industrial route adopts methallyl chloride sulfonation neutralization technology:

1. Sulfonation reaction: Methallyl raw material reacts with concentrated sodium bisulfite under controlled temperature to generate methallylsulfonic acid intermediate
2. Neutralization: Adjust pH with sodium hydroxide solution to produce crude SMAS liquid
3. Purification & separation: Filtration, decolorization, vacuum concentration
4. Finished product preparation:
   • Evaporative crystallization + drying → 99.5% solid powder
   • Dilution & filtration → standardized 35% liquid SMAS

Production equipment adopts sealed glass reactor to control impurity content; high-quality SMAS strictly controls sulfate, chloride and residual unsaturated hydrocarbon impurities, directly determining downstream polymer stability.

4. Core Action Mechanism of SMAS in Polymerization

The dual functional groups of SMAS determine its irreplaceable industrial value:

1. Reactive C=C double bond: Participates in free radical copolymerization, covalently bonded into polymer molecular backbone
2. Ionic sulfonate side chain −SO^3−​:
   • Generates strong electrostatic repulsion between polymer chains or solid particles
   • Boosts polymer water solubility, emulsifying capacity and dispersion performance
   • Improves salt tolerance, high-temperature resistance and anti-precipitation ability of copolymers

Compared with Sodium Allyl Sulfonate (SAS), SMAS carries methyl branch on carbon chain, forming stronger steric hindrance effect, delivering better slump retention, high-temperature stability and anti-salt performance in high-demand formulasChemicalBo….

5. Main Industrial Application Fields

5.1 Construction Industry: Core Monomer for Polycarboxylate Superplasticizer

This is the largest consumption market of Sodium Methallyl Sulfonate.

SMAS copolymerizes with methacrylic acid, polyether macromonomer and maleic anhydride to synthesize third-generation polycarboxylate superplasticizer.

• Sulfonate groups disperse cement particles via electrostatic repulsion + steric hindrance
• Features low dosage (0.1%–0.3% of cement mass), high water reduction rate (35%–45%), excellent slump retention
• Widely used in high-speed rail, sea-crossing bridges, ultra-high-rise buildings, precast concrete projects

5.2 Textile Industry: Third Monomer for PAN Acrylic Fiber

In polyacrylonitrile (acrylic fiber, artificial wool) production, SMAS acts as critical third monomer co-polymerized with acrylonitrile:

• Introduce anionic sulfonate groups inside fiber molecules to enhance dye absorption speed and color fastness
• Optimize fiber flexibility, anti-static property, heat resistance and spinnability
• Also used as raw material for carbon fiber PAN precursor to narrow molecular weight distribution and boost fiber tensile strengthChemicalBo…

5.3 Water Treatment Chemicals: Anti-Scale & Dispersant Monomer

Copolymerized with acrylic acid, acrylamide to produce organic scale inhibitors and circulating water dispersants:

• Inhibit scaling of calcium phosphate, calcium carbonate and zinc salt in industrial cooling water
• Adapt to high-hardness, high-temperature and high-salinity circulating water systems for power plants, chemical factories and steel millsyaodonghg….

5.4 Oilfield Chemical Additives

Synthesize high temperature resistant fluid loss control agents and tertiary oil displacement polymers:

• Sulfonate structure resists divalent metal ions (Ca²⁺, Mg²⁺) in formation water
• Stabilize drilling fluid filtration loss under deep well high temperature environment, improve oil recovery efficiency

5.5 Other Widely Used Scenarios

1. Water-based acrylic coatings & emulsion polymerization: Functional hydrophilic monomer to improve coating stability, adhesion and pigment dispersion
2. Papermaking dry strength agent copolymer: Enhance paper tensile and folding resistance
3. Ion exchange resin & separation membrane raw material: Introduce permanent ion exchange groups
4. Emulsifier, flocculant and analytical chromatographic auxiliary reagent

6. Storage, Transportation & Safety Operation Guidelines (MSDS Core Tips)

Storage Requirements

• Seal packages tightly, store in cool, dry, ventilated warehouse
• Storage temperature below 30℃, separate from strong oxidants, acid raw materials
• Solid SMAS adopts 20kg/25kg woven bag with plastic inner liner; liquid uses IBC ton tank for export logistics

Safe Operation

1. Avoid long-term skin contact; wear gloves and dust mask during powder feeding
2. In case of eye contact, flush continuously with clean water for 10+ minutes and seek medical treatment
3. Dust should not be inhaled; maintain ventilation in workshop processing environment
4. Low toxicity conventional industrial chemical, non-flammable; combustion produces sulfur oxide gas, use water mist fire extinguishing

Export Customs Information

HS Code: 2904100000; compliant with general chemical export inspection standards, factory can provide COA, MSDS and free test samples for global buyers

7. Grade Selection Guide for Buyers

1. 99.5% Solid Powder SMAS: For high-purity polycarboxylate superplasticizer, carbon fiber precursor, lab fine synthesis
2. 35% Aqueous Liquid SMAS: Directly used in liquid emulsion polymerization, water treatment agent continuous production, no dissolving process required
3. Low-purity industrial grade: For general low-demand water treatment dispersants with lower cost

8. Summary

Sodium Methallyl Sulfonate (SMAS) is a versatile sulfonated functional monomer integrating reactive double bond and strong hydrophilic sulfonate group. Its unique molecular structure enables irreplaceable advantages across construction additives, textile fiber, water treatment, oilfield and fine polymer materials. With the booming development of high-performance concrete, new fiber materials and environmental water treatment industry, global market demand for high-purity SMAS maintains steady growth year by year, making it an indispensable upstream fine chemical intermediate in modern polymer manufacturing.

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