DMMP: Properties, Uses in Plastics and Regulatory Status

DMMP (dimethyl methylphosphonate, CAS 756-79-6) is an alkyl phosphonate used as a liquid additive flame retardant in rigid polyurethane and polyisocyanurate foam and in unsaturated polyester resins. Its appeal is arithmetic: at 124.08 g/mol with one phosphorus atom, DMMP carries about 25 % phosphorus by weight, more than any other liquid flame retardant on this site, which raises the question of why it is not used everywhere.

Three registers hold the answer, and only one is a chemicals restriction. DMMP is not a Substance of Very High Concern, its notifiers to ECHA's classification inventory report it as a mutagen under H340, and it is a Chemical Weapons Convention Schedule 2 chemical carrying export controls and declaration duties. DMMP is one of 87 flame-retardant pages in our directory of plastic additives.

This page holds the DMMP flame retardant record in full: the identity card, the PubChem constants, the family mechanism, the two polymer systems, the three fire tests, the notified hazard classification, a regulatory matrix dated 23 September 2026, the comparison with triethyl phosphate, TCPP and DMPP, and the sourcing questions that replace a producer list.

Table T1. DMMP identity card.

Footnote: identity and physical data from PubChem CID 12958 and ECHA substance 100.010.957. Status as of 23 September 2026.

What Is DMMP (Dimethyl Methylphosphonate)?#

DMMP is the dimethyl ester of methylphosphonic acid, an alkyl phosphonate that works as an additive flame retardant rather than a reactive one: it is blended into the polyol or the resin and stays in the finished foam as a separate molecule. The name methylphosphonic acid dimethyl ester encodes that structure, a phosphorus atom carrying one methyl group directly and two more through oxygen, giving C3H9O3P and 124.08 g/mol. Which substance, then, does the abbreviation DMMP name on a formulation sheet?

One substance, under one CAS number, inside one functional class. An additive flame retardant is mixed in and not chemically bound to the chain, unlike a reactive one built into the backbone, and that distinction governs migration and volatility. The classes inside it, from mineral fillers and brominated aromatics to phosphate esters and phosphonates, are compared on the hub for flame retardants for plastics, where DMMP holds the high-phosphorus liquid position.

What does DMMP stand for in plastics?#

In plastics and foam chemistry, DMMP stands for dimethyl methylphosphonate, also written as dimethyl methyl phosphonate and listed by chemical suppliers as methylphosphonic acid dimethyl ester. All three names describe one liquid with CAS number 756-79-6 and EC number 212-052-3, so a polyol specification headed dimethyl methyl phosphonate and a catalogue entry headed methylphosphonic acid dimethyl ester name the same product.

What else does DMMP stand for?#

Outside plastics, the same four letters stand for three further things, two of them unconnected to chemistry. The three are listed below.

• Diabetes Medical Management Plan, a care document used in schools.
• Dredged Material Management Program, a planning instrument of the US Army Corps of Engineers.
• Nerve-agent simulant, the defence-research role of this same chemical.

Is DMMP a phosphonate or a phosphate ester?#

DMMP is a phosphonate, not a phosphate ester: one methyl group is bonded directly to phosphorus, so the molecule carries three carbons instead of the six in triethyl phosphate, and phosphorus makes up about 25 % of its weight against TCPP's 9.5 %. The P-C bond follows from the name methylphosphonic acid dimethyl ester and from C3H9O3P, which holds three oxygens where a phosphate ester holds four. Phosphonates and phosphate esters are the two ester branches of the phosphorus flame retardants, and the branch decides how much phosphorus a formulator buys per kilogram of liquid. The 25 % value is derived from the formula, 30.97 divided by 124.08.

How Does DMMP Work as a Flame Retardant?#

Phosphorus flame retardants act in two places at once: in the condensed phase they drive charring, intumescence and the formation of an inorganic phosphate glass, and in the gas phase they inhibit the flame, which lowers combustion efficiency and raises CO yield. DMMP delivers that phosphorus as a small liquid molecule dosed into the polyol or the resin, at about 25 wt% phosphorus per kilogram of additive.

Phosphorus flame retardants act in 3 condensed-phase ways and 1 gas-phase way, listed below.

• Charring, polymer converted into a carbon-rich residue that shields what lies underneath.
• Intumescence, that char swollen into an insulating layer.
• Inorganic phosphate glass, a non-volatile barrier over the burning surface.
• Gas-phase flame inhibition, which lowers combustion efficiency and raises CO yield.

The gas-phase and condensed-phase routes are set out in full on how flame retardants work.

Our source library records no mechanism statement for DMMP itself, so the split above belongs to the family and not to the substance. At a boiling point of 181 °C (357.8 °F) DMMP is the lowest-boiling phosphorus flame retardant on this site, so its phosphorus leaves the condensed phase readily, and no measured gas-phase share for it appears here.

What Are the Physical and Chemical Properties of DMMP?#

DMMP is a colourless liquid with a melting point of -50 °C (-58 °F), a boiling point of 181 °C (357.8 °F) and a density of 1.145 g/mL at 25 °C (77 °F). Table T2 lists the PubChem values for CID 12958.

Table T2. DMMP physical and chemical properties.

The DMMP boiling point is the number a foam formulator reads first: at 181 °C (357.8 °F) DMMP boils 34 °C (61.2 °F) below triethyl phosphate at 215 °C (419 °F), and that gap is why volatility and fogging are the first questions asked of it on a rigid-foam line. No volatility loss, fogging value, migration rate, solubility, viscosity or flash point for DMMP sits in our record, so Table T2 omits those rows.

Which Polymers Use DMMP, and at What Dosage?#

DMMP is used in two polymer systems: rigid polyurethane and polyisocyanurate (PIR) foam, and unsaturated polyester resins, in both cases as a liquid additive flame retardant blended into the polyol or the resin before cure. In rigid PIR and PUR systems it is one of five options, beside TCPP, triethyl phosphate, expandable graphite and reactive phosphorus polyols; in unsaturated polyester it is the liquid phosphorus route beside triethyl phosphate, aluminium trihydrate and ammonium polyphosphate. The rest of the rigid-foam recipe, from catalysts to blowing agents, is on additives for polyurethane and TPU.

Table T3. Polymer systems, the role of DMMP and the state of the loading evidence.

Our source library holds no verified loading for DMMP in either system. The closest verified phosphonate figure is for dimethyl propylphosphonate, which ECHA's plastic additives initiative mapping gives as about 15 wt% in polyurethane; DMMP's higher phosphorus content means a formulator would expect the same phosphorus level at a lower loading, but that is an inference, not a published number. Typical loading ranges per additive function are collected under additive dosage levels in plastics, and no wt% or phr value for DMMP stands there either.

What Is DMMP Used For in Plastics?#

DMMP has two plastics applications: flame-retarding rigid polyurethane and polyisocyanurate insulation foam, and flame-retarding unsaturated polyester resins for composites. Rigid PU and PIR foam is flame-retarded with 5 options, and DMMP is one of them.

• TCPP, the chlorinated phosphate incumbent.
• Triethyl phosphate, the second liquid phosphate ester.
• DMMP, the high-phosphorus liquid phosphonate.
• Expandable graphite, the solid intumescent.
• Reactive phosphorus polyols.

EPS, XPS, PU and PE foam each need a different package, compared on additives for plastic foams.

Rigid PU and PIR insulation foam#

Rigid polyurethane and polyisocyanurate foam is DMMP's main plastics market: the flame retardant goes into the polyol side of the system, where a liquid is the only practical form. Insulation board and spray foam are both made from that polyol blend, where a solid additive has to be dispersed and kept in suspension. Rigid and flexible systems use different chemistries, tabulated on flame retardants for polyurethane foam.

Two properties explain why a formulator looks past the incumbent. TCPP holds this market with 9.5 % phosphorus and 32.5 % chlorine, while DMMP is halogen-free at about 25 % phosphorus, which makes a halogen-free specification and a phosphorus target the two reasons to consider it. Insulation board is a construction product, so its reaction-to-fire class comes from additives for building and construction.

Unsaturated polyester resins and composites#

In unsaturated polyester resins, DMMP is one of the liquid phosphorus options alongside triethyl phosphate, used where aluminium trihydrate at high loadings would make the resin too viscous to laminate. Unsaturated polyester composites for rail interiors are qualified to EN 45545-2 hazard levels HL2 and HL3, and that target decides the flame-retardant package, with ammonium polyphosphate as the third route in the same resins. No loading, laminate build or hazard-level result for a DMMP-containing resin sits in our record.

How Does DMMP Affect Fire Performance, and How Is It Measured?#

Three methods decide whether a flame-retarded foam works: the limiting oxygen index under ISO 4589-2 and ASTM D2863, the UL 94 burning test, and the cone calorimeter under ISO 5660-1 and ASTM E1354-26. The limiting oxygen index (LOI) is reported in vol % O2 against the roughly 21 % oxygen of air, which is the threshold a self-extinguishing material has to clear.

Węgrzyk and colleagues reported in Polymers in 2025 that a viscoelastic polyurethane foam containing expandable graphite, ammonium polyphosphate and a reactive phosphorus polyol reached an LOI of 28 to 31 vol % O2, a UL 94 V-0 rating and a 92 % reduction in peak heat release rate. That system contains no DMMP, so it stands as a reference point for a flame-retarded polyurethane foam and never as a DMMP result.

Cellular materials use the HF-1 and HF-2 classes rather than the V classes of the UL 94 flammability ratings, and a rating without its specimen thickness says nothing.

Table T4. Fire-test methods for a DMMP-containing system, and what this page publishes.

Peak heat release rate and total heat release come from cone calorimeter testing at 35 or 50 kW/m2, in kW/m2 and MJ/m2. No DMMP value for any of the four sits in our record.

How Does DMMP Interact with Other Flame Retardants and Additives?#

DMMP is rarely the whole flame-retardant package in a rigid foam: formulators combine liquid phosphorus with expandable graphite, which expands from about 200 °C (392 °F), and with ammonium polyphosphate, whose phase II decomposes from about 240 °C (464 °F). Expandable graphite expands over 140 to 230 °C (284 to 446 °F) and swells by 30 to 400 cm3/g, so it acts after a liquid phosphorus additive has begun to volatilise. Co-use is ordinary practice; a measured DMMP and expandable graphite synergy is not in our source library, so no percentage appears here.

The solid counterpart to a liquid phosphonate is ammonium polyphosphate, used in both rigid and flexible polyurethane foam. The structural argument against every additive liquid, DMMP included, is migration: a reactive phosphorus polyol builds phosphorus into the backbone and therefore cannot migrate out of it, the case set out under reactive vs additive flame retardants. That is a trade-off and not a defect: a reactive polyol has to be designed into a system, a liquid is dosed into one that runs.

What Is the Regulatory Status of DMMP?#

DMMP is not a Substance of Very High Concern, and it is a Chemical Weapons Convention Schedule 2 chemical, which makes it the only flame retardant in this directory whose main legal burden is an export-control duty rather than a chemicals restriction (status 23 September 2026). Table T5 names each gap.

Table T5. DMMP regulatory matrix, status 23 September 2026.

Direction of travel carries dates where the cells do not. ECHA's flame-retardant regulatory strategy of March 2023 found aromatic brominated flame retardants to be candidates for restriction while aliphatic brominated and organophosphorus flame retardants needed more data, and according to industry reporting the organophosphorus investigation reports in December 2026 and December 2027. Every flame retardant on the SVHC Candidate List carries its listing date there, and DMMP is absent.

California AB 2998 bans organohalogen and organophosphorus flame retardants above 1,000 ppm in juvenile products, mattresses and upholstered furniture, in force since 1 January 2020. The rule is by product category, not by substance list: DMMP is an organophosphorus flame retardant, so foam made with it for those three categories falls inside the scope, which is not a ban on the substance. US risk evaluations sit under TSCA and plastic additives, and our record holds no TSCA entry for DMMP.

Is DMMP an SVHC or restricted under REACH?#

No, DMMP is not a Substance of Very High Concern: it is absent from the REACH Candidate List as of 23 September 2026. Our record does hold Candidate List entries for five flame retardants, TCEP since 13 January 2010, Dechlorane Plus since 15 January 2018, TBBPA since 17 January 2023, triphenyl phosphate since 7 November 2024 and DBDPE since 5 November 2025, and DMMP appears in none. Registration, evaluation and the Candidate List are explained on REACH and plastic additives; DMMP's registration, Annex XIV and Annex XVII positions are being verified, because an EC number is no evidence of a registration.

Why is DMMP controlled under the Chemical Weapons Convention?#

DMMP is listed as a Schedule 2 chemical under the Chemical Weapons Convention because it is a precursor to nerve agents, and that listing brings export controls and declaration duties with it. Schedule 2 covers chemicals that are not weapons themselves but serve as precursors, which is why the control attaches to trade and reporting rather than to the chemistry of a foam.

What the listing does not mean is equally definite. A Schedule 2 entry is a non-proliferation control on movement and reporting, not a health-based restriction on using the substance in a polymer: the first asks who may ship the liquid and who must declare it, the second asks what it does to a worker. Our record holds the Schedule 2 status and not the implementing instruments, thresholds or forms, so this page names none.

What do CWC Schedule 2 controls mean for a foam or resin producer?#

In practice, the control sits with whoever imports, exports or handles bulk DMMP: shipments can require an export licence, and volumes above national reporting thresholds can trigger an annual declaration. The licence attaches to movement across a border, so a compounder buying inside one country can carry a lighter duty. Buyers should ask a supplier in writing how it handles Chemical Weapons Convention declarations before placing a first order.

Is DMMP allowed in food-contact plastics?#

We do not yet publish a food-contact status for DMMP: our source library carries no Annex I entry under Regulation (EU) No 10/2011 and no US FDA citation, and an absent record is not an absent authorisation. The framework is definite where the entry is not: a substance absent from the Union list may not be used in EU food-contact plastics, the overall migration limit is 10 mg/dm2 and the generic specific migration limit is 60 mg/kg, all set out on EU 10/2011. Rigid PU and PIR insulation is not a food-contact application.

Is DMMP Safe? Hazard Classification and Health Profile#

The companies that have notified DMMP to ECHA's classification inventory report it as a mutagen: the majority notify H340, may cause genetic defects, alongside H361, suspected of damaging fertility or the unborn child, and eye damage or irritation under H318 and H319. Those notifications are collected in the PubChem record for CID 12958.

A notified classification is not a harmonised classification, and the difference decides what a label must carry. A notification is a company's own self-classification submitted to ECHA, while a harmonised classification is a legal entry in Annex VI of the CLP Regulation binding on every supplier; no Annex VI entry for DMMP sits in our record, and that position is being verified. The difference between a notified and a harmonised classification is set out on CLP classification of plastic additives. Public concern summarised on flame retardants and human health is built on the brominated and chlorinated substances, and an H340 notification on a phosphonate is a separate question.

What Are the Alternatives to DMMP?#

DMMP has 2 direct liquid alternatives in rigid foam, triethyl phosphate and TCPP, plus a solid halogen-free route through expandable graphite and the closely related phosphonate DMPP. Table T6 compares the five on identity, phosphorus content and regulatory position.

Table T6. DMMP compared with 4 alternative flame retardants.

Footnote: phosphorus percentages marked "derived" are calculated from the molecular formula, not taken from a supplier data sheet.

Buyers specifying halogen-free foam choose from the options compared on halogen-free flame retardants, where the phosphorus liquids sit beside the mineral routes.

DMMP vs TEP (triethyl phosphate)#

TEP is the safer-on-paper comparison: it carries a harmonised classification covering only Acute Tox. 4 H302, while DMMP's mutagenicity classification is a company notification rather than a harmonised entry.* The trade-off runs the other way on phosphorus: DMMP carries about 25 % against TEP's 17 %, so less liquid reaches the same phosphorus level, while TEP's 215 °C (419 °F) boiling point against 181 °C (357.8 °F) makes it the less volatile. Triethyl phosphate also doubles as a viscosity reducer in polyol blends and unsaturated polyester, a second job DMMP does not take on.

DMMP vs TCPP#

TCPP is the incumbent DMMP competes with: it holds the rigid PU and PIR insulation market, it is not an SVHC and it is not restricted under REACH Annex XVII, but it is a chlorinated substance under active regulatory review. The incumbent in insulation board and spray foam is TCPP, which delivers 9.5 % phosphorus plus 32.5 % chlorine and acts in the gas phase through both elements and in the condensed phase through charring, while DMMP is halogen-free at about 25 % phosphorus. Regulatory pressure is the live variable: ECHA's 2018 screening report on TCEP, TCPP and TDCP in childcare articles led the Commission to request a restriction dossier, work on hold since 2019, and according to industry reporting the organophosphorus investigation can change that picture in December 2026 and December 2027.

Halogen-free alternatives: DMPP, expandable graphite and reactive P-polyols#

The closest halogen-free relative is dimethyl propylphosphonate, a phosphonate one carbon longer than DMMP that ECHA's plastic additives initiative mapping records at about 15 wt% in polyurethane. DMPP carries CAS number 18755-43-6, the formula C5H13O3P and 152.13 g/mol, is registered under REACH for intermediate use only and is not listed in Annex I of Regulation (EU) No 10/2011 as re-checked on 14 July 2026, which makes dimethyl propylphosphonate (DMPP) the one phosphonate here with a published polyurethane loading. Kabir, Brehme and Schartel at BAM reported in Polymers in 2026 that expandable-graphite-rich coatings on polyurethane foam reached an LOI of 73 vol % O2 and a MARHE of 18 kW/m2, meeting railway HL3 limits, from a coating and not a DMMP formulation. Reactive phosphorus polyols close the set, bound into the backbone and unable to migrate.

Who Manufactures DMMP? Grades and Suppliers#

We do not publish a DMMP producer list yet: our source library holds no verified manufacturer or grade for this substance, and this site names a company only when a primary source supports it. Trade names circulate on distributor listings, none is verified in our record, and none is printed here. Producers verified by family are listed under flame retardant manufacturers and suppliers, which carries the records this section leaves open.

Four documents answer the sourcing question in place of a producer name: the certificate of analysis with its assay, a written phosphorus content statement, the safety data sheet, and written confirmation of how the supplier handles Chemical Weapons Convention declarations and export licences.

Where Does DMMP Sit in the Phosphorus Flame Retardant Family?#

DMMP is the highest-phosphorus liquid member of the phosphonate branch of the phosphorus flame retardants, the group that sits beside the phosphate esters, the phosphinates, red phosphorus and the intumescent phosphates. Both branches act through the same condensed-phase and gas-phase routes and differ in phosphorus per kilogram. The larger branch, organophosphate flame retardants (phosphate esters), covers TPP, RDP, BDP and TCPP. ECHA's mapping counts 39 flame retardants among about 418 additives registered above 100 tonnes per year in the EU, and the family was worth USD 8.1 to 9.3 billion in 2025 on differing analyst estimates, with the breakdown on flame retardants market.

Non-plastics uses of DMMP#

Outside plastics, DMMP appears most often as a safe stand-in for nerve agents in detection and decontamination research, which is the same property that puts it on Schedule 2 of the Chemical Weapons Convention. Uses in fuels, coatings and battery electrolytes lie outside this site's scope, which covers additives used in plastics. No further non-plastics use is recorded.

Is DMMP a nerve agent?#

No: DMMP is a nerve-agent precursor and simulant, not a nerve agent, which is why it is a Schedule 2 chemical rather than a Schedule 1 one. Schedule 1 covers the agents themselves; this page describes DMMP in plastics and the trade controls on it.

Does DMMP need an SDS and an export licence?#

Yes to the safety data sheet, which every supplier provides for a traded chemical, and possibly to the export licence, because Chemical Weapons Convention Schedule 2 status brings export controls and declaration duties. The data sheet records the notified statements H340, H361, H318 and H319; whether a licence applies depends on instruments and thresholds our record does not hold.