Bis(2-(methacryloyloxy)ethyl) phosphate
[CAS# 32435-46-4]

Identification

• Classification: Chemical reagent >> Organic reagent >> Phosphonate / phosphonate
• Name: Bis(2-(methacryloyloxy)ethyl) phosphate
• Synonyms: 2-[hydroxy-[2-(2-methylprop-2-enoyloxy)ethoxy]phosphoryl]oxyethyl 2-methylprop-2-enoate
• Molecular Formula: C₁₂H₁₉O₈P
• Molecular Weight: 322.25
• CAS Registry Number: 32435-46-4
• EC Number: 251-040-2
• SMILES: CC(=C)C(=O)OCCOP(=O)(O)OCCOC(=O)C(=C)C

Properties

• Density: 1.3±0.1 g/cm³ Calc.^*
• Boiling point: 438.2±55.0 ºC 760 mmHg (Calc.)^*, 221 ºC (Expl.)
• Flash point: 218.8±31.5 ºC (Calc.)^*
• Index of refraction: 1.472 (Calc.)^*, 1.47 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H315-H319-H335-H412
• Precautionary Statements: P261-P264-P264+P265-P271-P273-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin sensitization	Skin Sens.	1B	H317
Serious eye damage	Eye Dam.	1	H318
Skin sensitization	Skin Sens.	1	H317
Skin corrosion	Skin Corr.	1A	H314
Specific target organ toxicity - single exposure	STOT SE	2	H371
Acute toxicity	Acute Tox.	4	H302

Discovory and Applicatios

Bis(2-(methacryloyloxy)ethyl) phosphate is a diester monomer containing two methacrylate groups and a central phosphate moiety. It was developed as part of broader efforts to improve adhesion and performance of polymer-based materials, particularly in dental, biomedical, and flame-retardant applications. The methacrylate groups enable polymerization through free-radical mechanisms, while the phosphate group introduces acidic and hydrophilic character, as well as affinity for metal and mineral surfaces.

The synthesis of this compound is typically achieved through the esterification of 2-hydroxyethyl methacrylate (HEMA) with phosphoric acid or its derivatives. The product is a viscous, clear liquid with good miscibility in other (meth)acrylate-based formulations. The ability to copolymerize with a wide range of monomers has made this compound versatile in crosslinked networks. The phosphate center is particularly significant in its ability to interact with hydroxylated or metal oxide surfaces, enhancing the adhesion properties of the cured materials.

One of the earliest and most important applications of Bis(2-(methacryloyloxy)ethyl) phosphate is in dental adhesive systems. In the field of dentistry, phosphate monomers have been studied extensively for their role in improving the adhesion of resin composites to the mineralized structure of teeth. The phosphate ester functions in this compound allow for chemical bonding with calcium ions found in hydroxyapatite, the primary inorganic constituent of enamel and dentin. This interaction forms a durable adhesive interface between the polymeric restorative material and the tooth surface. The methacrylate groups polymerize with other monomers such as bisphenol A-glycidyl methacrylate (Bis-GMA), urethane dimethacrylate (UDMA), and triethylene glycol dimethacrylate (TEGDMA), allowing for integration into dental resins and adhesives.

In dental self-etch adhesives, this monomer acts as both an etchant and a functional monomer, reducing the need for separate etching steps. The phosphate group provides mild acidity that enables partial demineralization of the tooth surface while simultaneously enabling bonding. This dual function simplifies clinical procedures and enhances bond strength to both enamel and dentin. The compound has been included in several commercial adhesive systems designed for restorative dentistry.

Another major area of application is in flame-retardant materials. The phosphorus content of Bis(2-(methacryloyloxy)ethyl) phosphate contributes to the formation of a protective char layer during combustion. This char acts as a barrier that slows heat and mass transfer, thereby reducing the flammability of the polymer. The compound has been used in UV-curable and thermosetting formulations where fire resistance is a desired property. Its inclusion does not require additional flame-retardant additives, thereby maintaining the mechanical and aesthetic properties of the base material.

In coatings, the presence of phosphate groups enhances adhesion to substrates such as metals, glass, and ceramics. This makes the monomer useful in protective coatings and primers. The improved adhesion properties result from chemical interactions between the phosphate and hydroxyl or oxide groups on the substrate surface. In UV-curable coatings, the compound contributes to the formation of dense, crosslinked networks with improved mechanical performance and solvent resistance.

In biomedical applications, Bis(2-(methacryloyloxy)ethyl) phosphate has been incorporated into hydrogels and surface modification formulations. The phosphate functionality provides enhanced hydrophilicity, which supports protein adsorption and cell attachment. The compound has been investigated as a component of hydrogel networks used in tissue engineering and drug delivery systems. The dual methacrylate groups allow it to form crosslinked structures suitable for biological use, while the phosphate groups influence surface energy and biocompatibility.

Overall, Bis(2-(methacryloyloxy)ethyl) phosphate is a well-established functional monomer with documented utility in dental adhesives, flame-retardant formulations, industrial coatings, and biomedical materials. Its bifunctional polymerizable structure combined with a central phosphate group offers a unique combination of reactivity and adhesion enhancement, making it a valuable component in specialized polymer systems.

References

2010. Polymeric cation-exchange monolithic columns containing phosphoric acid functional groups for capillary liquid chromatography of peptides and proteins. Journal of Chromatography A, 1217(24).
DOI: 10.1016/j.chroma.2010.04.032

2018. Effect of bis[2-(methacryloyloxy)ethyl] phosphate as a crosslinker on poly(AAm-co-AMPS)/Na-MMT hydrogel nanocomposite as potential adsorbent for dyes: kinetic, isotherm and thermodynamic study. Journal of Polymer Research, 25(11).
DOI: 10.1007/s10965-018-1625-0

2022. Synthesis and Characterization of Sterculia Gum Polysaccharide-Poly(bis[2-methacryloyloxy]ethyl Phosphate Copolymeric Network Hydrogels for Use in Drug Delivery. Polymer Science, Series B, 64(6).
DOI: 10.1134/S1560090422700634