Sodium Methallyl Sulfonate (SMAS) is an important organic sulfonate with the chemical formula C₄H₇NaO₃S. It contains a sulfonate group (-SO₃Na) and a reactive methallyl group (CH₂=C(CH₃)-CH₂-). Below is a detailed introduction:
1. Chemical Properties
- Molecular Formula: C₄H₇NaO₃S
- CAS Number: 1561-92-8
- Appearance: White crystalline powder, highly soluble in water.
- Reactivity:
- Contains a double bond (C=C), enabling participation in free-radical polymerization (e.g., copolymerization with acrylic acid, styrene).
- The sulfonate group provides hydrophilicity and anionic properties, enhancing water solubility and dispersibility.
2. Main Applications
(1) Polymer Industry
- Copolymerization Monomer: Used with acrylonitrile, acrylamide, etc., to improve hydrophilicity, dyeability, and antistatic properties.
- Fiber Modification: Enhances moisture absorption and softness in synthetic fibers (e.g., polyacrylonitrile).
(2) Water Treatment
- Scale Inhibitor & Dispersant: Chelates calcium/magnesium ions to prevent scaling in cooling water systems.
(3) Electroplating & Surface Treatment
- Brightener Additive: Improves uniformity and gloss of metal coatings in electroplating baths.
(4) Other Fields
- Oilfield Chemicals: Used in enhanced oil recovery or drilling fluids.
- Dye Dispersant: Improves solubility and stability of dyes.
3. Synthesis Method
Typically prepared via the addition reaction of methallyl alcohol with sodium bisulfite (NaHSO₃):CH₂=C(CH₃)-CH₂OH+NaHSO₃→CH₂=C(CH₃)-CH₂SO₃Na+H₂OCH₂=C(CH₃)-CH₂OH+NaHSO₃→CH₂=C(CH₃)-CH₂SO₃Na+H₂O
4. Safety & Storage
- Toxicity: Low toxicity, but avoid inhalation or eye contact.
- Storage: Keep sealed in a cool, dry place, away from moisture.
5. Key Features
- Advantages: Excellent water solubility, high reactivity, introduces sulfonate groups.
- Limitations: Potential side reactions (e.g., self-polymerization) require controlled conditions.
For more details on copolymer formulations or process parameters, further discussion is welcome!
Copolymer Formulations with Sodium Methallyl Sulfonate
The copolymerization of Sodium Methallyl Sulfonate (SMAS) involves combining it with various monomers to introduce sulfonate groups, enhancing hydrophilicity, ionic properties, or functionality. Below are typical copolymer formulations and applications:
1. Monomer Selection
SMAS can undergo free-radical polymerization with:
- Acrylic Monomers: Acrylic acid (AA), methacrylic acid (MAA), acrylates (e.g., methyl acrylate).
- Styrene (St): Balances hydrophobicity/hydrophilicity and improves mechanical properties.
- Acrylamide (AM): Used for superabsorbent polymers or flocculants.
- Vinyl Monomers: Vinyl acetate (VAc) for emulsion polymerization.
Example Formulation:
- SMAS + Acrylic Acid + Acrylamide: Used in water treatment scale inhibitors, where sulfonate groups enhance calcium ion chelation.
2. Key Considerations in Formulation Design
(1) Monomer Ratio Optimization
- SMAS Content: Typically 5%~20% of total monomers; excessive amounts may cause crosslinking or excessive water solubility.
- Hydrophilic-Hydrophobic Balance: Adjust SMAS ratio when copolymerizing with styrene to control solubility.
(2) Initiator System
- Free-Radical Initiators: Ammonium persulfate (APS), azobisisobutyronitrile (AIBN), suitable for aqueous or organic-phase polymerization.
- Redox Systems: e.g., persulfate/bisulfite for low-temperature polymerization.
(3) Polymerization Methods
- Solution Polymerization: Water as solvent, ideal for water-soluble polymers.
- Emulsion Polymerization: Requires emulsifiers (e.g., SDS), where SMAS can act as a co-emulsifier.
3. Application-Specific Formulations
(1) Anticoagulant Materials
- Monomer Combination: SMAS + sulfonated methacrylate (e.g., sulfobetaine methacrylate).
- Key Parameter: Sulfonate group density affects anticoagulant activity (optimal SMAS: 10%~15%).
(2) Water Treatment Dispersants
- Formulation: SMAS + Acrylic Acid + Maleic Anhydride (molar ratio 1:4:1), initiator APS (0.5%).
- Effect: Sulfonate groups improve inorganic scale dispersion.
(3) Fiber Modification
- Copolymer: SMAS + Acrylonitrile (AN), enhances dyeability and moisture absorption in polyacrylonitrile fibers.
4. Precautions
- Side Reaction Control: SMAS may self-polymerize; use inhibitors (e.g., hydroquinone) or low-temperature reactions.
- Post-Processing: Purify copolymers via dialysis or precipitation to remove unreacted monomers.
For specific conditions (e.g., temperature, pH) or detailed formulations, further literature review may be required!
