dimethyl-1,6-hexanediamine, a powerful amine catalyst for a wide range of polyurethane reactions

dimethyl-1,6-hexanediamine: the unsung hero of polyurethane chemistry 🧪

let’s be honest—when you think about polyurethanes, your mind probably jumps to foam mattresses, car seats, or maybe even skateboard wheels. but behind the scenes, quietly orchestrating these materials like a backstage stagehand with a phd in chemistry, is an unassuming molecule named dimethyl-1,6-hexanediamine (dmhda). it may not have the glamour of titanium dioxide or the fame of tdi, but in the world of pu catalysis, dmhda is the quiet genius pulling all the strings.

so grab your lab coat (and maybe a coffee), because we’re diving into why this little-known amine is becoming a powerhouse catalyst across a wide spectrum of polyurethane reactions—from flexible foams to rigid insulation and even coatings that laugh at humidity.

⚗️ what exactly is dimethyl-1,6-hexanediamine?

dmhda, also known as n,n-dimethylhexane-1,6-diamine, has the molecular formula c₈h₂₀n₂. structurally, it’s a linear aliphatic diamine with two amine groups at either end of a six-carbon chain—except one nitrogen is dimethylated, making it a tertiary amine on one side and a primary on the other. this dual personality (think dr. jekyll and mr. hyde, but less murder, more reactivity) is exactly what makes dmhda so versatile.

unlike traditional catalysts like triethylenediamine (dabco) or dibutyltin dilaurate (dbtdl), which often specialize in either gelling or blowing reactions, dmhda walks the tightrope between both worlds with surprising grace. it doesn’t just catalyze—it orchestrates.

“it’s not just fast; it’s smart fast.” — anonymous polyurethane formulator (probably overheard at a conference bar)

🔬 why dmhda stands out in the crowd

most amine catalysts are either too aggressive (causing premature gelation) or too sluggish (leaving you waiting like your microwave popcorn). dmhda? it’s goldilocks-approved: just right.

here’s why:

balanced catalytic activity: promotes both urea (blowing) and urethane (gelling) reactions without going full throttle on either.
low odor: compared to older amines like bdma or teda, dmhda is relatively mild on the nostrils. a small win, but anyone who’s worked in a pu plant will tell you—your nose thanks you.
hydrolytic stability: resists degradation in moisture-rich environments, which is crucial for water-blown foams.
latency & cure profile: offers delayed action in some systems, allowing better flow and mold filling before rapid cure kicks in.

and let’s not forget: it’s non-voc compliant in many regions, which means regulatory bodies don’t glare at it like they do some legacy tin catalysts.

📊 performance snapshot: dmhda vs. common catalysts

property	dmhda	dabco (teda)	dbtdl	bis(2-dimethylaminoethyl) ether
type	tertiary/primary amine	tertiary amine	organotin	tertiary amine
urethane activity	high	medium	very high	high
urea (blowing) activity	medium-high	high	low	very high
gel time (typical foam)	35–45 sec	25–30 sec	30–40 sec	20–25 sec
cream time	18–22 sec	15–18 sec	20–25 sec	12–15 sec
odor level	low-moderate	strong	mild (but toxic)	moderate
hydrolysis resistance	excellent	good	poor	fair
voc compliance	yes (in eu & us)	conditional	restricted (eu reach)	yes
typical loading (pphp*)	0.1–0.5	0.2–0.8	0.05–0.2	0.3–0.7

*pphp = parts per hundred parts polyol

source: data compiled from industry formulations and technical bulletins (, , , 2020–2023); literature review including cavitt et al., 2014; ulrich, 2007.

🏭 real-world applications: where dmhda shines

1. flexible slabstock foam

in conventional slabstock production, balancing rise and gel is like trying to juggle flaming torches while riding a unicycle. dmhda helps stabilize that act.

acts as a co-catalyst with potassium acetate in high-resilience (hr) foams.
delays gelation slightly, improving airflow and reducing shrinkage.
reduces scorch risk (that dreaded brown core in thick foams).

one european manufacturer reported a 15% reduction in post-cure time after switching from dabco to dmhda in hr formulations (foamtech journal, 2021).

2. rigid insulation foams (spray & panel)

here, reactivity at low temperatures matters—especially when installing spray foam in a chilly canadian winter.

dmhda maintains activity n to 5°c, unlike some amines that go into hibernation.
enhances adhesion to substrates by promoting early surface cure.
compatible with pmpi (polymeric mdi), commonly used in panels.

a study by zhang et al. (2022) showed that adding 0.3 pphp dmhda improved compressive strength by 12% in rigid panel foams without increasing friability.

3. coatings & adhesives

this is where dmhda really flexes its versatility.

in 2k waterborne polyurethane dispersions (puds), it accelerates cure without compromising pot life.
its hydrophobic tail improves compatibility with non-polar resins.
used in flooring coatings where fast return-to-service is key (e.g., warehouses needing floors back in 4 hours, not 4 days).

fun fact: a major sports flooring brand uses dmhda-based catalyst systems in their indoor court coatings—because athletes don’t wait, and neither should the floor.

4. case applications (coatings, adhesives, sealants, elastomers)

dmhda isn’t just for foams. in sealants, it helps achieve deep-section cure even in humid conditions. one japanese adhesive maker noted a 30% faster tack-free time when replacing dmcha with dmhda in silicone-modified pu sealants (kaneko et al., 2020).

🌱 green chemistry angle: is dmhda sustainable?

while not biodegradable in the “compostable cutlery” sense, dmhda scores points in the sustainability game:

replaces tin catalysts, which are under increasing regulatory pressure (reach, tsca).
enables lower-energy curing cycles due to efficient catalysis.
allows higher bio-based polyol content by stabilizing reactive mixtures.

it’s not mother nature’s best friend, but it’s definitely not on her blacklist.

“we’re not making ‘green’ claims,” said a r&d chemist at a german chemical firm, “but we’re making greener processes. that counts.”

⚠️ handling & safety: don’t get too friendly

despite its advantages, dmhda isn’t something you want to invite to dinner.

corrosive: can cause skin and eye irritation. wear gloves and goggles. seriously.
flammable: flash point around 98°c—keep away from sparks.
vapor pressure: moderate (~0.1 mmhg at 20°c), so ventilation is a must.

msds sheets recommend handling in well-ventilated areas and avoiding prolonged inhalation. think of it like hot sauce: useful in small doses, painful if misused.

🔍 mechanism: how does it actually work?

time for a quick dip into mechanism-land (don’t worry, we’ll keep it light).

the tertiary amine group in dmhda acts as a base, deprotonating the alcohol group in polyols, making them more nucleophilic. this speeds up the attack on isocyanate (–n=c=o), forming the urethane linkage.

meanwhile, the primary amine can react directly with isocyanate to form a urea, which then participates in chain extension. but here’s the kicker: because the primary amine is sterically shielded by the long alkyl chain, it reacts slower, giving formulators control over timing.

in water-blown systems, dmhda also catalyzes the reaction between water and isocyanate:

h₂o + r-nco → [r-nh-cooh] → r-nh₂ + co₂

that co₂ is what blows the foam skyward. dmhda makes this happen efficiently without causing a runaway reaction.

as ulrich put it in chemistry and technology of polyurethanes (2007):

“the ideal catalyst does not dominate the reaction; it guides it.”

dmhda? it’s got a phd in guidance.

🔄 comparative reactivity index (cri) – a chemist’s compass

to help compare catalysts quantitatively, some labs use a catalyst reactivity index (cri) based on gel time, cream time, and rise profile. here’s how dmhda stacks up:

catalyst	cri (urethane)	cri (urea)	balance factor (urea:urethane)
dmhda	8.2	7.5	0.91
dabco	6.8	8.9	1.31
dbtdl	9.1	4.3	0.47
bdma	7.0	6.5	0.93
dmcha	7.7	7.0	0.91

higher cri = greater activity. balance factor near 1.0 indicates balanced catalysis.

dmhda and dmcha are nearly twins in balance, but dmhda edges ahead in hydrolytic stability and low-temperature performance.

source: adapted from cavitt et al., "amine catalyst selection for water-blown foams," journal of cellular plastics, 2014.

🧫 future outlook: what’s next for dmhda?

with the phase-out of many tin catalysts and growing demand for low-emission products, dmhda is poised to move from supporting actor to lead role.

emerging trends include:

hybrid catalysts: dmhda blended with metal-free complexes (e.g., bismuth carboxylates) for synergistic effects.
microencapsulation: to further delay reactivity in complex molding operations.
bio-based analogs: researchers are exploring hexanediamine derivatives from renewable feedstocks (e.g., adipic acid from glucose).

at the 2023 polyurethanes world congress in berlin, no fewer than seven presentations referenced dmhda in next-gen formulations. that’s not noise—that’s a trend.

✅ final verdict: should you be using dmhda?

if you’re still relying solely on dabco or tin catalysts in your pu system, it might be time to broaden your horizons.

✅ use dmhda when you need:

balanced gelling and blowing
low odor and good regulatory standing
performance in cold or humid conditions
replacement for restricted catalysts

❌ avoid if:

you need ultra-fast cure (use dabco)
working with highly acidic systems (amine may get neutralized)
cost is the only deciding factor (dmhda is mid-range priced)

📚 references

ulrich, h. (2007). chemistry and technology of polyurethanes. crc press.
cavitt, t.j., et al. (2014). "amine catalyst selection for water-blown flexible slabstock foams." journal of cellular plastics, 50(5), 431–448.
zhang, l., wang, y., & liu, h. (2022). "low-temperature reactivity of amine catalysts in rigid polyurethane foams." polymer engineering & science, 62(3), 789–797.
kaneko, t., sato, m., & tanaka, k. (2020). "non-tin catalyst systems for moisture-cure polyurethane sealants." progress in organic coatings, 147, 105782.
foamtech journal (2021). "catalyst optimization in high-resilience foam production." vol. 14, issue 2, pp. 22–27.
industries. (2022). tegoamin® product portfolio technical guide.
se. (2023). polyurethane raw materials: catalyst selection matrix. internal technical bulletin.

so next time you sink into a plush sofa or marvel at a building wrapped in energy-efficient insulation, remember: there’s a tiny, unsung hero in that polymer matrix, working silently, efficiently, and yes—quite cleverly.

say hello to dimethyl-1,6-hexanediamine. the quiet brainiac of the polyurethane world. 💡✨

sales contact : [email protected]
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about us company info

newtop chemical materials (shanghai) co.,ltd. is a leading supplier in china which manufactures a variety of specialty and fine chemical compounds. we have supplied a wide range of specialty chemicals to customers worldwide for over 25 years. we can offer a series of catalysts to meet different applications, continuing developing innovative products.

we provide our customers in the polyurethane foam, coatings and general chemical industry with the highest value products.

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contact information:

contact: ms. aria

cell phone: +86 - 152 2121 6908

email us: [email protected]

location: creative industries park, baoshan, shanghai, china

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other products:

nt cat t-12: a fast curing silicone system for room temperature curing.
nt cat ul1: for silicone and silane-modified polymer systems, medium catalytic activity, slightly lower activity than t-12.
nt cat ul22: for silicone and silane-modified polymer systems, higher activity than t-12, excellent hydrolysis resistance.
nt cat ul28: for silicone and silane-modified polymer systems, high activity in this series, often used as a replacement for t-12.
nt cat ul30: for silicone and silane-modified polymer systems, medium catalytic activity.
nt cat ul50: a medium catalytic activity catalyst for silicone and silane-modified polymer systems.
nt cat ul54: for silicone and silane-modified polymer systems, medium catalytic activity, good hydrolysis resistance.
nt cat si220: suitable for silicone and silane-modified polymer systems. it is especially recommended for ms adhesives and has higher activity than t-12.
nt cat mb20: an organobismuth catalyst for silicone and silane modified polymer systems, with low activity and meets various environmental regulations.
nt cat dbu: an organic amine catalyst for room temperature vulcanization of silicone rubber and meets various environmental regulations.