What Is Acryloylmorpholine (ACMO)?
Acryloylmorpholine (also called ACMO or 4-acryloylmorpholine), CAS 5117-12-4, is a mono-functional acrylate monomer. It combines a morpholine ring with a reactive acrylate group, and it is unusual among acrylate monomers in being water-soluble and low-viscosity. These two features make it a popular reactive diluent in UV- and electron-beam-curable coatings, inks and adhesives, and a useful monomer for water-based and oilfield polymer systems.
This guide covers the chemistry, specification, properties, production, reactivity and applications of ACMO, its comparison with other reactive diluents, dosage, quality and handling, and supply. PolyBlueChem supplies ACMO to the specification below with per-batch COA and SDS.
| CAS number | 5117-12-4 |
| Chemical name | 4-Acryloylmorpholine (N-acryloylmorpholine) |
| Synonyms | ACMO; 4-acryloylmorpholine; N-acryloylmorpholine; 1-morpholino-2-propen-1-one |
| Molecular formula | C7H11NO2 |
| Molecular weight | 141.17 g/mol |
| Appearance | Clear, colourless to pale yellow liquid |
Chemistry and Structure
ACMO is an acrylamide-type monomer: a morpholine ring whose nitrogen carries an acryloyl group (-CO-CH=CH2). The structure explains its behaviour:
- The acryloyl (acrylate) double bond is electron-poor and highly reactive, so it polymerises readily by a free-radical mechanism – the basis of UV/EB curing.
- The morpholine ring (a six-membered ring with one nitrogen and one oxygen) is polar and hydrophilic, and its nitrogen is an amide (not a basic amine), giving the molecule good stability and water solubility.
- The amide linkage (rather than an ester, as in most acrylates) makes ACMO more resistant to hydrolysis than a typical acrylate ester.
Because the reactive group is an acrylamide and the ring is polar, ACMO sits between the “classic” acrylate monomers and water-soluble vinyl monomers – which is exactly why it is used as a water-compatible reactive diluent.
Specifications
ACMO is supplied as a clear liquid to the following specification:
| Parameter | Specification |
|---|---|
| Purity (content) | 98% min |
| Colour | 50 APHA max |
| Viscosity (25 °C) | 9 – 15 mPa·s |
| Inhibitor (additive) | 1000 ± 100 ppm |
| Density | 1.118 – 1.122 g/cm3 |
| Flash point | 126.5 °C |
| Boiling point | 158 °C |
| Melting point | -8 °C |
| Hygroscopicity | 1.8 g/100 g (at 20 °C, 60% RH) |
| Parameter | What it controls |
|---|---|
| Purity (98% min) | Content of the monomer; a low value means residual morpholine/acrylic by-products |
| Colour (50 APHA max) | Colour – important for clear/light-coloured UV coatings and inks |
| Viscosity (9 – 15 mPa·s) | The low viscosity that makes ACMO a good reactive diluent |
| Inhibitor (1000 ± 100 ppm) | Polymerisation inhibitor (e.g. MEHQ) that keeps the monomer stable in storage |
| Flash point (126.5 °C) | Safety/handling; a comparatively high flash point for a monomer |
A specification sheet and a per-batch certificate of analysis (COA) are available on request.
Physical and Chemical Properties
| Property | Value / behaviour |
|---|---|
| Form | Clear, colourless to pale yellow liquid |
| Molecular weight | 141.17 g/mol |
| Density | 1.118 – 1.122 g/cm3 |
| Viscosity (25 °C) | 9 – 15 mPa·s (low) |
| Boiling point | 158 °C |
| Melting point | -8 °C |
| Flash point | 126.5 °C |
| Solubility | Water-soluble / water-miscible, and soluble in many organic solvents |
| Hygroscopicity | 1.8 g/100 g at 20 °C, 60% RH (moderately hygroscopic) |
| Stability | Supplied with an inhibitor; keep away from heat, light and initiators |
Two properties are decisive in use: ACMO’s water solubility (it works in aqueous and solvent systems alike) and its low viscosity (it thins a formulation while still crosslinking into the film).
How Acryloylmorpholine Is Produced
ACMO is made by acryloylating morpholine – reacting morpholine with an acryloylating agent. Two routes are used:
- Acryloyl chloride route – morpholine reacts with acryloyl chloride in the presence of a base (to neutralise the hydrogen chloride formed); the product is isolated and purified by distillation.
- Acrylic acid / transamidation route – morpholine is reacted with acrylic acid (or an acrylic ester) under conditions that form the amide; this route avoids handling acryloyl chloride.
Both routes must control two things carefully: inhibition (the product is a reactive monomer and must be kept from polymerising) and purity (residual morpholine and acrylic by-products affect colour and cure). The finished monomer is stabilised with an inhibitor (about 1000 ppm) and filtered to the clear, low-colour liquid.
Reactivity and Curing
ACMO cures by free-radical polymerisation, the same mechanism used in UV/EB and peroxide-cure systems.
| Reaction | Description |
|---|---|
| Free-radical polymerisation | The acrylamide double bond reacts with radicals (from a photoinitiator under UV, or a thermal initiator) to form polymer chains |
| Copolymerisation | Copolymerises readily with acrylates, methacrylates and other vinyl monomers |
| Amide stability | The amide linkage is more hydrolysis-resistant than an acrylate ester |
| Inhibition | A small amount of inhibitor prevents premature polymerisation in storage |
Because ACMO is mono-functional, it acts as a reactive diluent: it lowers viscosity like a solvent, but unlike a solvent it reacts into the cured film rather than evaporating. This improves film properties and reduces volatile emissions.
ACMO vs Other Reactive Diluents and Monomers
| Monomer | Type | Water solubility | Character | Typical use |
|---|---|---|---|---|
| ACMO | Acrylamido-morpholine (mono-functional) | Water-soluble | Low viscosity; good adhesion; water-compatible | UV coatings, inks, adhesives; water-based systems |
| NVP (N-vinylpyrrolidone) | Vinyl lactam (mono-functional) | Water-soluble | Low viscosity; strong solubiliser | UV inks, adhesives, water-based |
| HDDA / TPGDA | Di-/tri-functional acrylates | Water-insoluble | Higher reactivity; crosslinking | Solvent/100% solids UV systems |
| Isobornyl acrylate | Mono-functional acrylate | Water-insoluble | Hard, hydrophobic films | Coatings, adhesion |
Guidance: choose ACMO where a water-compatible, low-viscosity reactive diluent with good adhesion is wanted; choose NVP for a similar water-soluble diluent; use multifunctional acrylates where higher crosslink density is the goal.
Applications
| Industry | Role of ACMO |
|---|---|
| UV/EB-curable coatings | Reactive diluent that lowers viscosity and cures into the film |
| UV inks | Reactive diluent/monomer for radiation-curable inks |
| Adhesives | Monomer for radiation-curable and specialty adhesives |
| Water-soluble polymers | Comonomer for water-soluble or water-dispersible polymers |
| Oilfield / water treatment | Comonomer in polymers for scale, flocculation and drilling-fluid applications |
| Surface modification | Monomer for grafting and surface functionalisation |
- Coatings, inks and adhesives – the main use; ACMO is a reactive diluent in UV/EB systems, improving wetting and adhesion (especially to difficult substrates) while keeping viscosity low.
- Water-based and oilfield systems – because it is water-soluble, ACMO is a comonomer in water-soluble polymers used for scale control, flocculation and drilling fluids.
- Functional materials – used in specialty polymers and for surface/grafting chemistry.
Dosage and Formulation Notes
| Application | Starting-point guidance |
|---|---|
| UV/EB coating or ink | Used as a reactive diluent at a level set by the target viscosity and cure speed |
| Adhesive | Set by the required tack, adhesion and cure |
| Water-soluble polymer | Comonomer ratio set by the polymer’s target properties |
ACMO is added as a diluent/monomer in the formulation and cures with the rest of the system. Because it is hygroscopic, formulation and storage should account for moisture pickup, and the level is confirmed by cure and performance testing.
Quality and Handling Notes
- Inhibitor – the product contains about 1000 ppm of inhibitor; do not remove it, and check it is still present if the drum has been open a long time.
- Colour – a low APHA colour matters for clear and light-coloured coatings/inks; buy against the colour spec.
- Moisture – moderately hygroscopic (1.8 g/100 g at 60% RH); keep sealed.
- Heat and light – keep away from heat, light and radical initiators to avoid premature polymerisation.
Safety, Handling and Storage
- Reactive monomer – acrylate/acrylamide monomers are skin and eye irritants and potential sensitisers; avoid contact and use protective equipment.
- Ventilation – handle in a well-ventilated area; avoid breathing vapour.
- Storage – keep sealed, cool and dark; the monomer should be stored within its shelf life, and drums should be kept closed to preserve the inhibitor and prevent moisture pickup.
- Incompatibilities – keep away from strong oxidisers, acids/bases and radical initiators.
Packaging, Logistics and Supply
| Item | Standard options |
|---|---|
| Packaging | 200 kg drums or IBCs (or as agreed) |
| Documentation | Per-batch COA and SDS |
| Incoterms | FOB and CIF |
| Storage | Cool, dry, dark; sealed |
ACMO price tracks the morpholine and acrylic (acid/ester) feedstock and the cost of stabilisation and purification. Buying on committed tonnage gives the best terms.
ACMO in UV/EB-Curable Coatings, Inks and Adhesives
UV/EB curing forms a film in seconds by using light (or an electron beam) to trigger free-radical polymerisation. The formulation needs reactive monomers, and ACMO is a valued one.
| Role | How ACMO helps |
|---|---|
| Reactive diluent | Lowers viscosity like a solvent, but reacts into the film instead of evaporating |
| Adhesion | Polar, water-soluble monomer that improves wetting and adhesion, including to difficult substrates |
| Low viscosity | Lets formulators reach the target application viscosity with less monomer weight |
| Low colour | Suits clear and light-coloured coatings and inks |
Because ACMO is a reactive diluent, it improves both process (viscosity) and product (cured-film properties) while reducing volatile organic emissions – a key advantage in radiation-curing systems. It is used in coatings, graphic-arts inks, overprint varnishes and specialty adhesives.
ACMO in Water-Soluble and Oilfield Polymers
ACMO’s water solubility makes it useful beyond solvent-free UV systems, as a comonomer in water-based chemistry.
| Application | Role of ACMO |
|---|---|
| Water-soluble polymers | Comonomer that adds polar, water-compatible character |
| Scale and deposit control | Comonomer in polymers used to inhibit scale in industrial water |
| Flocculation / water treatment | Comonomer in water-treatment polymers |
| Drilling fluids | Comonomer in oilfield polymer systems |
In these systems ACMO contributes a polar, hydrolysis-resistant amide functionality, helping build polymers that perform in water-based environments.
ACMO in Adhesives and Functional Materials
- Adhesives – as a monomer in radiation-curable and specialty adhesives, improving adhesion and flexibility.
- Functional/specialty polymers – used where a water-soluble, reactive monomer is needed for a tailored polymer.
- Surface modification and grafting – the reactive double bond allows ACMO to be grafted onto surfaces and backbones.
Because it is a monomer rather than a finished additive, ACMO’s value lies in the polymer it helps build: the formulator chooses it where water compatibility, low viscosity and reactivity are all needed at once.
Frequently Asked Questions about Acryloylmorpholine (ACMO)
What is ACMO used for?
Mainly as a reactive diluent/monomer in UV/EB-curable coatings, inks and adhesives, and as a comonomer for water-soluble and oilfield/water-treatment polymers.
What is the CAS number of acryloylmorpholine?
5117-12-4 (4-acryloylmorpholine).
Is ACMO water-soluble?
Yes – it is water-soluble/miscible, which is one of the features that sets it apart from most acrylate monomers.
What is the viscosity?
9 – 15 mPa·s at 25 °C – low, which is why it works well as a reactive diluent.
What is the flash point?
126.5 °C, comparatively high for a reactive monomer.
Why does it contain an inhibitor?
Because it is a reactive monomer; about 1000 ± 100 ppm of inhibitor prevents premature polymerisation in storage.
How is it stored?
Sealed, cool and dark, away from heat, light and initiators.
Related reading
- Acryloylmorpholine in UV-curable coatings and adhesives
- How to buy acryloylmorpholine (ACMO)
- Morpholine as a chemical intermediate
- Acryloylmorpholine (ACMO, CAS 5117-12-4) – product page
PolyBlueChem supplies Acryloylmorpholine (ACMO, CAS 5117-12-4) to the specification above, with per-batch COA and SDS and FOB/CIF delivery. Contact us with your application, tonnage and delivery port.