What is MMA monomer? Methyl methacrylate (MMA) is a monomer that’s also known as methacrylic acid, methyl ester.
A key building block for acrylic-based polymers, MMA has applications that include safety glazing, exterior paints, vinyl impact modifiers, adhesives, illuminated light displays, and more. There are several synthetic ways to make the MMA chemical as the one most widely used is the three-step process of adding acetone to hydrogen cyanide (HCN) and moves to acetone cyanohydrin.
History of Methyl Methacrylate
The history of the formulation of methyl methacrylate monomer began during a time when acrylic acids were first being synthesized in the early 1800s. German chemists took roughly 85 years to develop acrylic acid in 1843. Then it took another 22 years for them to make methacrylic acid, and then from that step methanol was added to form the chemical reaction of methyl methacrylate, which would become known as acrylic polymer.
Yet still in that time, the possibilities of using methacrylic acid to make was still not readily understood. It wasn't until roughly the 1930s when acrylic polymers appeared with the polymerization of metal acrylate.
In this article, we provide a general overview of this important monomer, covering everything from its polymerization to important safety and handling considerations. Here are 5 key facts about methyl methacrylate monomer (MMA):
1. The Basics of Methyl Methacrylate
As previously mentioned, MMA is foundational for many acrylate polymers and is an essential comonomer in paint, coatings, and adhesives resin formulations. A comonomer consists of one monomer that is added to another monomer to become a copolymer. In free radical initiated copolymers, MMA chemical structure elevates the Tg (glass transition) and contributes durability, strength, transparency, and UV and abrasion resistance.
Here are several other key pieces of information about methyl methacrylate:
CAS Number: 80-62-6
EINECS Number: 201-297-1
Empirical Formula: C5H8O2
Molecular Weight: 100.12
Melting Point: -48 °C (-54℉)
Boiling Point: 101°C (214℉)
Flash Point: 2°C (36℉)
Additionally, it’s important to note that the Tg value for PMMA homopolymer is 105°C. In polymers, MMA contributes durability, hardness, impact strength, scratch resistance, and clarity.
2. Polymerization of MMA
Polymerization entails the bonding of smaller monomers to form a polymer. In the case of MMA, a wide array of acrylic copolymers can be utilized for polymerization. Various monomer feeds may include:
- Butyl acrylate
- 2-Ethylhexyl acrylate
- Methyl methacrylate and other methacrylate esters
- Acrylic acid and methacrylic acid
- Styrene
- Butadiene
The selection of monomer composition for copolymers is guided by the desired glass transition temperature (Tg) of the resin, ranging from -30°C to over 30°C. Free-radical reactivity ratios for MMA copolymer systems have been extensively researched and are documented in literature sources.
Safety and Handling of MMA
Attention to safety protocols is paramount when handling methyl methacrylate (MMA) due to several factors.
MMA is a flammable, colorless liquid with a melting point of -48˚C and a boiling point of 101˚C. While MMA readily dissolves in most organic solvents, it remains insoluble in water.
In addition to its flammability, direct contact with MMA can lead to irritation of the eyes, skin, nose, and throat. Classified as a skin sensitizer, MMA can trigger allergic reactions upon contact, resulting in itching and skin rash upon subsequent exposures.
Furthermore, inhalation of MMA vapor or mist can cause irritation of the nose, throat, and lungs and may prove fatal in high concentrations.
Due to its propensity for violent homopolymerization, MMA is supplied in a stabilized form. Proper storage of MMA under air and maintenance of dissolved oxygen levels are crucial to ensure the effective function of its stabilizer.
3. Applications of Methyl Methacrylate
Methyl methacrylate monomer readily undergoes polymerization to form high molecular weight homopolymers (where polymers are created from many copies of a single monomer) and copolymers.
The primary use of MMA monomer is in the production of polymethyl methacrylate (PMMA) homopolymer for casting and extruding acrylic sheets. These cast PMMA sheets exhibit excellent optical clarity, high transparency, and UV stability. Applications of methyl methacrylate (MMA) include:
- Replacement for shatterproof glass
- Safety glazing
- Panels and lighting displays
- Outdoor lighting fixtures
- Plumbing fixtures and components
Outside of glazing and sheet applications, MMA finds extensive use as a comonomer in paints and coatings, including exterior paints and paper coatings. Polymers and copolymers of methyl methacrylate are utilized in:
- Metal and foil coatings
- Industrial finishes
- Floor polishes
- Textile finishes
- Adhesives
- Sealants
- Construction materials
- PVC impact modifiers
- Packaging
- Inks
These polymers are manufactured as waterborne, solvent-based, and dispersion resins for various applications. Methyl methacrylate-butadiene-styrene (MBS) resins serve as impact modifiers for clear, rigid PVC, for instance in bottles. Moreover, MMA can partially replace styrene monomer in unsaturated polyester resins, enhancing weather resistance and extending outdoor lifespan.
For products like signage, displays, bath enclosures, spas, tabletop surfaces, automotive lights, and fixtures, methyl methacrylate polymerization enables casting into solid forms.
MMA is also utilized in engineering adhesives, liquid, reactive, durable adhesives for bonding different substrates. These adhesives, containing MMA monomer with PMMA, cure rapidly at room temperature and offer high resistance to fatigue and temperature. MMA adhesives are valued for their ability to bond diverse surfaces and their suitability for sealing and filling cracks and pores in concrete structures.
Other applications of MMA copolymers include mining flocculants, soil stabilization polymers, waterproofing agents, and oil field drilling fluids. While MMA can pose safety concerns upon direct contact with the skin, eyes, and respiratory system, PMMA demonstrates compatibility with human tissue. It finds use in medical technologies such as acrylic bone cement and intraocular lenses for eye implants.
MMA was previously utilized in nail enhancements, but FDA research deemed it toxic and unsuitable for this purpose. While some states have banned MMA nails, others have not, leading to its continued presence in certain nail salons.
4. Safety and Handling of MMA
Attention to safety protocols is paramount when handling methyl methacrylate (MMA) due to several factors.
MMA is a flammable, colorless liquid with a melting point of -48˚C and a boiling point of 101˚C. While MMA readily dissolves in most organic solvents, it remains insoluble in water.
In addition to its flammability, direct contact with MMA can lead to irritation of the eyes, skin, nose, and throat. Classified as a skin sensitizer, MMA can trigger allergic reactions upon contact, resulting in itching and skin rash upon subsequent exposures.
Furthermore, inhalation of MMA vapor or mist can cause irritation of the nose, throat, and lungs and may prove fatal in high concentrations.
Due to its propensity for violent homopolymerization, MMA is supplied in a stabilized form. Proper storage of MMA under air and maintenance of dissolved oxygen levels are crucial to ensure the effective function of its stabilizer.
