1,3-Butanediol dimethacrylate is a clear, low-viscosity difunctional methacrylate ester monomer. Because each molecule carries two reactive methacrylate groups on a short aliphatic backbone, the product is widely used as a crosslinking coagent, a reactive diluent and an adhesion promoter in free-radical curing systems. This guide covers its chemistry, typical properties, major industrial applications, storage requirements and safe handling practice.
What Is 1,3-Butanediol Dimethacrylate?
1,3-Butanediol dimethacrylate is the diester produced by esterifying 1,3-butanediol with methacrylic acid. Its molecular formula is C12H18O4, corresponding to a molar mass of 226.27 g/mol. The two methacrylate end groups are separated by a short, flexible four-carbon chain, which gives the monomer a low viscosity, high reactivity and broad compatibility with unsaturated polyester, vinyl ester, acrylic and PVC plastisol systems.
As a difunctional monomer, 1,3-butanediol dimethacrylate reacts at both ends during free-radical polymerisation. The result is a three-dimensional crosslinked network instead of a linear chain, which raises hardness, modulus and tear strength and improves resistance to heat and chemicals in the cured article. Elongation at break normally falls as crosslink density rises.
Typical Physical and Chemical Properties
| Property | Typical value |
|---|---|
| Chemical name | 1,3-Butanediol dimethacrylate |
| Molecular formula | C12H18O4 |
| Molar mass | 226.27 g/mol |
| Appearance | Transparent, colourless to pale yellow liquid |
| Density | About 1.011 g/cm3 at 20 C |
| Boiling point | About 290.5 C at 760 mmHg |
| Flash point | About 135 C |
| Vapour pressure | About 0.002 mmHg at 25 C |
| Refractive index | About 1.451 at 20 C |
| Polymerisable groups | Two methacrylate groups (functionality 2) |
The figures above describe standard commercial grades and are indicative only. The certificate of analysis issued for each batch is the authoritative reference for specification purposes.
Main Industrial Applications
Crosslinking coagent for elastomers - in peroxide-cured rubber compounds it raises crosslink density, giving higher hardness, better heat ageing and improved compression set.
PVC plastisols and sealants - acts as an adhesion promoter and hardener, improving cohesion between the plastisol and metal, textile or concrete substrates.
UV- and electron-beam curable coatings, inks and varnishes - the monomer cures almost instantaneously under ultraviolet light or an electron beam, so formulators can build high-solids products without volatile organic solvents.
Adhesives and structural bonding systems - improves adhesion and heat resistance in acrylic and anaerobic adhesives, sealants and elastomeric jointing compounds.
Unsaturated polyester and vinyl ester composites - functions as a reactive diluent that lowers system viscosity while contributing to the final mechanical strength of the laminate.
Electronics and matrix materials - used in encapsulants, laminates and potting compounds where dimensional stability and thermal resistance are required.
Crosslinking Behaviour and Processing Notes
Because 1,3-butanediol dimethacrylate has a low viscosity, it blends with oligomers and resins at almost any ratio, which makes viscosity adjustment straightforward. Its reactivity is higher than that of monofunctional methacrylates, so initiator levels and cure schedules normally need to be reviewed when it replaces a monofunctional diluent in an existing formulation.
Typical loading rates range from a few percent as a coagent up to the main reactive diluent fraction in UV-curable systems. Excessive dosage increases shrinkage and brittleness, so the optimum level is usually established through hardness, tensile and impact testing on the finished part. In peroxide-cured elastomers the coagent is added on the mill or in an internal mixer together with the peroxide, and cure temperature is kept inside the decomposition window of the selected peroxide.
Storage, Safety and Handling
Store below 38 C in the original, securely sealed containers.
Keep in a cool, dry, well-ventilated area away from direct sunlight, heat sources and oxidising agents.
Methacrylate esters can irritate skin and eyes and may cause skin sensitisation, so nitrile gloves, safety goggles and suitable protective clothing should be worn.
Avoid prolonged or repeated skin contact and avoid breathing mist or vapour; local exhaust ventilation is recommended where the product is handled in bulk.
Commercial grades contain a polymerisation inhibitor; keep the product aerated and avoid extended storage above the recommended temperature.
Frequently Asked Questions
Q: What is 1,3-butanediol dimethacrylate used for?
It is used mainly as a crosslinking coagent and reactive diluent in UV-curable coatings, printing inks, adhesives, PVC plastisols and peroxide-cured elastomers, where it increases hardness, modulus and chemical resistance.
Q: Is it a monofunctional or a difunctional monomer?
It is difunctional. Each molecule contains two methacrylate groups, giving a functionality of two and enabling the formation of a crosslinked three-dimensional network.
Q: What are its molecular formula and molar mass?
The molecular formula is C12H18O4 and the molar mass is 226.27 g/mol.
Q: How does it differ from a monofunctional methacrylate?
A monofunctional methacrylate forms linear polymer chains, while 1,3-butanediol dimethacrylate links chains together. The crosslinked structure gives higher hardness, better heat and chemical resistance, but also lower elongation and higher shrinkage.
Q: How should 1,3-butanediol dimethacrylate be stored?
Store below 38 C in tightly sealed original containers in a cool, dry, well-ventilated place away from heat, sunlight and oxidising materials.
Q: Can it be used in UV-curable formulations?
Yes. It cures almost instantly under ultraviolet light or high-speed electrons and allows high-solids coatings, inks and adhesives to be produced without volatile organic solvents.