Curiosity about the slickness of surfaces and the urge to tame how materials behave has driven people to try all kinds of coatings for centuries. In the 1960s, chemists cracked the code on silane chemistry, opening doors to tools like N-Octadecyltrimethoxysilane. Companies didn’t jump straight into using this molecule right away; its uses trickled out of research on organosilanes that linked long-chain hydrocarbons to silicon atoms. Once labs realized these molecules bonded well to glass, ceramics, and some metals, the experiments got serious. By the late 1980s, commercial interest built up as electronics, coatings, and materials science shifted from basic protection into manipulating surfaces on a molecular level. Anyone who has ever tried to block water from soaking into glass or keep sensors clean knows the drive behind these advances.
N-Octadecyltrimethoxysilane rolls off the tongue like a mouthful of spaghetti, but its impact is straightforward: it transforms surfaces that used to grab water and dirt into clean, protective films. Makers usually deliver it as a colorless to pale yellow liquid. Lots of folks refer to it as octadecyltrimethoxysilane, ODTMS, or just C18-silane, depending on which bit of the molecule they want to focus on. It deserves its reputation for being both stubbornly hydrophobic and versatile, showing up anywhere folks need a slick, neutral surface—from lab glassware to the trickiest microchips.
Most bottles of N-Octadecyltrimethoxysilane exude a faint organic scent. The liquid weighs in at just over 300 grams per mole and boils above 340 degrees Celsius. The long octadecyl “tail”—18 carbons in a row—gives it low solubility in water, while the trimethoxysilane “head” dissolves in most organic solvents. That mix lets it spread across smooth and rough surfaces, but with enough reactivity at the head to grab onto glass, silicon wafers, or aluminum via silanol groups. In my own stubborn attempts to coat microscope slides, the stuff lays down a smooth, nearly invisible film, fending off fingerprints and droplets that used to stick with static cling.
A typical label reads like a short novel: N-Octadecyltrimethoxysilane, C18H39O3Si, purity above 98 percent, boiling point around 344°C, density just under 0.9 g/cm³ at room temperature. A chemical catalog includes everything from CAS number 3069-40-7 to details on storage—tight lid, dry and cool, and well away from acids. Users who skim past expiration dates usually learn the hard way that moisture ruins a bottle fast, leading to gunked-up solutions and odd-smelling byproducts. Suppliers package it in brown glass bottles or lined metal cans to block light and stubborn humidity.
The process of making N-Octadecyltrimethoxysilane starts with octadecyltrichlorosilane. Chemists add alcohol, driving out hydrochloric acid and locking in three methoxy groups on the silicon. There’s nothing fancy about the overall chemical equation, but controlling the air—especially moisture—makes all the difference. Any stray water kicks off unwanted silica gel instead of the beautifully mobile trimethoxysilane. Most plants stick to argon or nitrogen atmospheres, batch reactors, and careful purification to keep yields high and color low. I’ve watched this stuff form like a small miracle in specialty labs: the right pressure and temperature turn sticky, sharp-smelling precursors into a clear liquid with reliability you can actually see in every bottle.
The real value shows up when this molecule hits a surface. Those three methoxy groups hydrolyze in a little water, forming silanols that bond to glass, silica, or oxidized metal surfaces, dropping the surface tension. For those working in chromatography or sensor manufacturing, N-Octadecyltrimethoxysilane opens a quick route to functionalized surfaces. It’s possible to swap out the long tail for other groups or cross-link silane-treated layers with more siloxane chemistry, making platforms for enzyme immobilization or anti-bacterial films. If a team wants an odd twist for a biosensor or microfluidic device, they’ll probably hit up this chemistry at some stage.
Looking around catalogues, this compound often sneaks under names like Octadecyltrimethoxysilane, Stearyltrimethoxysilane, or simply ODTMS. Specialty suppliers slap on codes and batch numbers. Researchers sometimes call it C18-silane when describing functions in liquid chromatography applications. Keep an eye out for obscure spellings or trade names in technical sheets—some are only skin-deep rebrands.
N-Octadecyltrimethoxysilane, like most organosilanes, gives off that sharp aroma for a reason. It reacts fast with moisture, sometimes giving off methanol fumes that irritate eyes and lungs. Industries set clear safety rules: chemical splash goggles, sturdy gloves, lab coats, and big warnings about open bottles, especially in humid climates. Ventilation remains vital since accidental spills leave behind stubborn residues. Proper labeling helps too, keeping new trainees from grabbing the wrong bottle and getting an unwanted chemistry lesson. Some production lines even fit their workers with respirators, especially if they run big surface-coating jobs.
Wherever clean interfaces matter, this silane tends to show up. In my own lab days, prepping HPLC columns meant soaking glassware in dilute N-Octadecyltrimethoxysilane and rinsing off what didn’t stick. Electronics makers treat silicon wafers with it to keep away moisture and dust, while researchers painting the inside of microfluidic channels swear by its properties over plain glass. Textile companies dip synthetic fibers in dilute solutions to make raincoats that shed water for years. Even DIY enthusiasts spread diluted ODTMS on windshields and tile grout, hoping for less grime build-up—and they aren’t wrong.
The last decade has cranked up the study of superhydrophobic and oleophobic coatings, and N-Octadecyltrimethoxysilane plays a recurring role. Academic teams use it as a model chemical when testing self-cleaning coatings, bio-compatible films, or new sensor substrates that need fine-tuned interaction with water, proteins, or oils. In industrial R&D, it turns up in recipes for novel membranes, corrosion blockers, and “smart” textiles that resist scratching or soiling. These little tweaks lead to big leaps in device reliability, shelf life, and energy savings, and they show up in conference papers from big names in materials science.
People understandably worry about anything that can bond to surfaces or release volatile organics. Toxicological studies show that ODTMS isn’t nearly as nasty as some short-chain silanes related to alkoxy and chlorosilane families, but exposure still means caution, especially for those working with pure or hot solutions. Methanol byproduct poses most of the risk; good lab procedure—fume hood, goggles, and gloves—cuts that risk nearly to zero. Environmental toxicity looks low in dilute, properly cured films, but the research keeps going: some teams keep an eye on microplastic formation and runoff after ODTMS-modified fabrics hit the laundry. There hasn’t been evidence of bioaccumulation or major waterway harm, though responsible disposal and workplace ventilation stay in the spotlight.
As industries everywhere keep searching for better, safer, and longer-lasting surfaces, the role of N-Octadecyltrimethoxysilane continues to grow. Next-generation electronics, self-cleaning buildings, anti-fog and anti-smudge phone screens, or bio-friendly textiles all use this backbone chemistry in some way. Nanotechnology, especially, leans hard on this molecule for controlling how cells or proteins land on chips. With more scrutiny on chemical waste and workplace safety, companies will spend more time developing water-based or ultra-low-VOC versions that cut emissions and keep coatings effective without the knock-on effects of old-school solvents. Instead of fading out, this corner of silane chemistry looks set to underpin new materials and devices for decades, blending practical experience with molecular innovation. Anyone following the future of smart or robust coatings will keep bumping into N-Octadecyltrimethoxysilane, no matter how deep into the supply chain they dig.
N-Octadecyltrimethoxysilane doesn’t exactly snap off the tongue, but this silane compound manages to slip into all sorts of corners in science and industry. My first real encounter with it happened in a tiny chemistry lab, where we aimed to get glass to repel water. The metal spatula picked up a little glimmer of liquid, and as I transformed an ordinary glass slide into a slick, water-beading surface, the usefulness of this molecule snapped into clear view.
Most people don’t realize how many products benefit from surfaces that shrug off water. Glass, ceramics, and even metals show their best side after a treatment with N-Octadecyltrimethoxysilane. It binds to these surfaces, laying down a super-thin layer that keeps them sleek and dry. You might notice it in lab gear—pipettes, slides, or even the fancy shower doors that never seem to fog. It matters because hydrophobic surfaces resist grime, mold, fingerprints, and chemical attack. These qualities stretch out product life, cut down on cleaning, and lower maintenance costs.
N-Octadecyltrimethoxysilane helps keep sensitive electronics going even when moisture wants to cause trouble. In circuit boards, a thin silane treatment stops electrical mishaps by blocking water. Factories favor the compound because downtime from corroded parts or shorts means lost money. By protecting surfaces, companies keep production lines running smoother for longer stretches. In my work with a small electronics start-up, a little attention with this silane meant fewer customer complaints about moisture damage and ultimately shaved costs per product.
Academics and industrial designers love pushing limits. With N-Octadecyltrimethoxysilane, they get to build nanomaterials that won’t just clump together or pick up the wrong charges. Silane molecules form a nearly invisible barrier that lets nanoparticles mix with plastics, paints, or even medicines. This compatibility lets researchers fine-tune everything from drug delivery capsules to ultra-scratchproof coatings for lenses and phone screens. In hands-on workshops, I watched a team coat nanoparticles with this molecule, then blend them right into a polymer to make it repel dirt and water. The change was obvious—water droplets slid right off, taking the dust with them.
Chemistry brings responsibility. N-Octadecyltrimethoxysilane, like most potent tools, should be handled thoughtfully. Its long carbon tail can stick around in nature, so every user looks for ways to use the smallest amount that gets the job done and pick cleaning processes that keep excess out of the water system. Green chemistry teams keep searching for even “cleaner” silanes—ones that cut environmental footprints further. Some labs now combine this molecule with others to make surfaces that actually help filter air or water, pulling out oils or heavy metals instead of just resisting grime.
High-performance surfaces get better lives and new talents with N-Octadecyltrimethoxysilane. But success depends on knowledge and respect—know your process, measure the effect, and keep safety first. Training staff and investing in simple testing tools go a long way in ensuring quality and safety. Big change often starts with small, careful steps, and that’s where the real advantage lies.
N-Octadecyltrimethoxysilane doesn’t look impressive at first glance. It’s a clear liquid, usually barely aromatic, but it packs hazards if kept carelessly. This chemical reacts with moisture, breaking down into methanol and releasing heat. Methanol brings its own health problems—think headaches, nausea, vision changes. Even worse, the siloxane chains formed can cause deposits or gelling inside containers, creating waste and extra cleanup.
Over the years, I’ve seen what happens when details get overlooked. Too many warehouses keep specialty silanes on open shelves, near open doors, or under leaky pipes. That’s an invitation for moisture to worm its way in. Once the cap pops, air sneaks through, moisture condensates on the neck, and you get cloudiness, then gunk.
In one research lab, a new bottle left open a few hours started fizzing and turned hazy. The team expected it to last for months but had to order a replacement by week’s end. Waste like that hits the budget. Any compromise in purity will affect coatings, surface treatments, or any specialty process supposed to benefit from a long-chain silane like this.
I’ve learned the hard way that the container matters as much as the chemical. Upright, tightly sealed glass or HDPE bottles keep out stray humidity. Avoiding metal containers prevents unwanted reactions that discolor or degrade the product. Don’t trust snap-on caps or tired seals. A fresh, threaded cap with a new liner manages the vapor risk and air exchange.
Temperature swings speed up the breakdown. Keep things steady and cool—20 to 25°C works well, not cold enough for condensation but not warm enough for volatility. Nobody should stash these chemicals in an unventilated closet or a cabinet near heating vents. Dry cabinets fitted with desiccant cartridges make life easier. A simple silica gel pack inside the cabinet can help mop up stray moisture released from people coming in and out.
Over-label the bottles. Permanent marker plus printed stickers help trace sources in case something goes sideways—whether that’s spoilage or a splash accident. Too many times, relabelled and unlabeled containers delay emergency responses and cause confusion for newcomers on the team.
Never rely on faded safety sheets taped to the walls. Keep digital and paper safety documentation handy and update it after stock rotation or product change. Organize periodic checks to get rid of old bottles before they cause trouble.
Proper handling isn’t about a checklist. It’s about building habits that protect investments and, more importantly, people. Regular training—aimed at both new hires and seasoned hands—helps keep safety procedures front of mind. Comfortable gloves, splash goggles, and access to eye wash stations shouldn’t be optional. These steps mean small spills don’t turn into workplace emergencies.
Good storage boils down to a few simple steps: keep bottles closed, dry, and cool. Build routines that make those steps automatic, so nobody has to think twice. Every mishap avoided means less downtime, safer staff, and better results the next time this silane hits the bench. In a tight-budget world, that edge counts.
Most work environments I’ve visited treat chemicals with a healthy respect, and N-Octadecyltrimethoxysilane deserves just that. This stuff isn’t the sort of thing you splash on your desk or handle without care. Experts recognize it for its irritating qualities. I’ve had coworkers brush off the importance of gloves, then complain about red, itchy skin later. Skin contact stings—best to keep it off your hands altogether. Inhaling its vapor can bother the throat and nose; long-term exposure could affect your respiratory tract. Most quality data sheets agree: even brief exposure shouldn’t be taken lightly.
Years ago, I learned the hard way not to underestimate personal protective equipment (PPE). A direct splash could mean a trip to occupational health. For N-Octadecyltrimethoxysilane, the basics mean donning chemical-resistant gloves, lab coats, and safety goggles. Goggles aren't just for show—one unexpected splash, and you’ll be thankful you wore them. I also recommend a proper fume hood if you’re pouring or mixing, since the vapors drift quickly through the workspace. A simple paper mask doesn’t cut it here; you want gloves made from materials like nitrile or neoprene.
Fresh air can change the safety game. In chem labs I’ve worked in, poor ventilation led to strong odors and lingering headaches. With this compound, working in open-air or well-ventilated lab stations means you avoid heavy inhalation. Even better if your space includes eye-wash stations and showers nearby. Nobody likes a chemical emergency, but quick access to water and help keeps minor mishaps from turning serious.
N-Octadecyltrimethoxysilane prefers dark, dry, and cool storage—this isn’t just preference, it matters. Keep it tightly capped, away from direct sunlight or heat sources. Once, someone left a capped bottle near a window, and a week later the pressure inside made opening it risky. Silanes tend to react with moisture in the air, so a desiccator cabinet works wonders. Avoid any close contact with acids or oxidizers; mixing these brings about nasty reactions.
Cleaning up after a spill means more than mopping with paper towels. Absorbent pads or sand should come first; then cleanup with approved waste disposal. In one training session, I watched someone wipe down a spill with a bare hand—ended up with a rash and bad mood. Not worth it. Use the right waste bags, and always dispose of everything through a hazardous waste program. Never down the drain.
Too many accidents happen because staff were thrown into handling chemicals without in-depth guidance. Proper training taught by someone who’s worked directly with silanes pays off. People absorb hands-on advice far better than endless safety posters on the wall. Regular drills, easy-to-read signage, and check-ins build confidence and keep mistakes low.
Chemical incidents stay low when individuals feel empowered to raise concerns and ask questions. Management must set an example. Double-checking bottle labels, reviewing protocols often, and marking secondary containers clearly means fewer ugly surprises. People on the floor carry the experience and know which corners are cut—giving them a real voice can highlight unseen risks.
Trusting your senses, looking out for hazards, and sticking to habits that keep everyone whole isn’t a burden—it’s part of the job. Experience shapes safer teams far more than checklists alone. The more we share lessons from close calls, the stronger our protection against any chemical in the lab.
N-Octadecyltrimethoxysilane stands out in the world of organosilanes because it combines an 18-carbon straight chain with a reactive silane head. Its formula—C21H46O3Si—tells a story about its chemistry and behavior. The structure features a long alkyl tail (octadecyl, with 18 carbons) bonded to a silicon atom, which attaches to three methoxy groups. This shape looks straightforward on paper, but the details change how it acts in real-world settings.
The backbone is simple but memorable. Start with an octadecyl chain: CH3(CH2)17-. At the end of this chain, silicon steps in, linking to the carbon through a direct Si–C bond, forming CH3(CH2)17Si. Silicon, being a connector, prefers four bonds, so three are left. Each remaining spot holds a methoxy group (–OCH3). So, fully written, you see CH3(CH2)17Si(OCH3)3 for the molecule.
Life in the lab taught me that the structure isn’t just about lines on a diagram. The long alkyl tail brings both challenges and advantages. It hates water. The more atoms stacked up in a hydrocarbon chain, the more this trait shows itself. This nature gives N-Octadecyltrimethoxysilane serious power in creating water-resistant surfaces. Think of glass or silica—both love water by default. Brush a coat of this silane on, and water beads right up instead of soaking in.
The methoxy groups get to work only with a nudge—usually water or humidity in the air. They react and form bonds with surfaces loaded with hydroxyl groups (–OH), such as on silica or certain metals. As a kid, I watched my teacher show how a drop of silane magic kept chalk drawings intact after a rainstorm. Years later, that memory helped me understand why engineers reach for N-Octadecyltrimethoxysilane in the lab or in industry lines. Its power comes directly from the structure described in the formula: C21H46O3Si.
Silanes, especially ones with a hefty alkyl tail like N-Octadecyltrimethoxysilane, don’t only offer water-repellent properties. Manufacturers treasure this type of chemistry for making surfaces oily, slippery, and less likely to foul up with dirt or biomolecules. Small syntheses I handled in an academic lab always felt like magic—one clear drop changed a boring, plain glass slide into something that sent water droplets rolling away. Scientists use this effect in microfluidics and lab-on-chip systems, fields that demand absolute control over where liquids travel.
Working with any silane means dealing with strong odors, flammability, and the potential for forming tough residues. I learned to respect labels and store these chemicals with care, as contact with water before application can ruin a batch. Strong safety protocols and proper training help limit accidents, not just in factories but also where research or custom synthesis happens. It always struck me that chemists, from their first undergraduate project to high-scale production, learn the hard way that molecules like this demand attention. Awareness and simple best practices—using gloves, working in ventilated spaces, and keeping reagents dry—go a long way to keep things safe and predictable in the lab.
| Property | Detail |
|---|---|
| Chemical Formula | C21H46O3Si |
| Structure | CH3(CH2)17Si(OCH3)3 |
| Key Features | 18-carbon alkyl chain, three methoxy groups on silicon |
| Main Uses | Surface modification, hydrophobic coatings, microfluidics |
Almost everyone who’s worked in a lab has seen N-Octadecyltrimethoxysilane—ODTMS for short—make a mess or work wonders, depending on the day and the approach. This silane gets called up for all sorts of surface treatments, but its behavior with different solvents raises valid questions. Not all chemicals play nice with others.
Chemists know ODTMS holds long hydrophobic chains. Once you start dissolving or dispersing it, the type of solvent changes the process dramatically. I remember trying to get a uniform layer on glass. Acetone brought trouble—cloudiness, often leading to poor cover. Toluene or hexane, on the other hand, delivered that clean, streak-free coat. This isn’t just anecdotal. N-Octadecyltrimethoxysilane shows reliable compatibility with non-polar solvents like toluene, hexane, and chloroform. These solvents dissolve the material well due to their own non-polar character, helping ODTMS spread evenly across surfaces, whether that’s silicon wafers or gold-coated substrates used in electronics.
It’s a different story with polar choices. Ethanol or methanol sound attractive because they’re easy to work with and dry fast. Still, their polar nature can kickstart hydrolysis of the silane. Instead of nicely organized layers, you end up with clumps and half-bonded messes due to premature reaction with water traces. For researchers chasing reproducible results, soaking ODTMS in polar solvents often wastes material and time.
These choices also influence downstream applications. In microfabrication, a messed-up monolayer leads to weak binding or contamination issues. Cleanroom engineers find that avoiding polar solvents saves both money and rework, since device failure rates drop with proper solvent selection.
Picking the right base for silanization matters just as much as solvent. Glass and silicon love ODTMS—hydroxyl groups on their surfaces welcome the silane’s attachment, especially if they’re activated by plasma or acid washing. My runs on untreated glass slid off, while cleaned, etched glass took up the silane strongly, repelling water in seconds.
Plastic substrates complicate things. Many offer poor bonding because they lack enough reactive surface groups. Polymers like polyethylene or polypropylene barely hold the silane at all, unless you blast them with corona or plasma first. This fact shapes industries like packaging and microfluidics. Using untreated plastic frustrates newcomers every time, no matter how pure their chemical batch or solvent might be.
Experience and solid study back up the need to use non-polar, dry solvents. Manufacturers tend to ship ODTMS in small, airtight bottles for a reason: humidity sparks premature hydrolysis, ruining shelf life and performance. Storing containers with desiccant and prepping substrates with strong oxidizers helps build up those reactive silanol groups without introducing excess moisture.
Surface cleaning works wonders. Labs that take time to use piranha solution, UV-ozone, or plasma treatments routinely get reliable coatings with strong adhesion and hydrophobicity. By pairing the solvent and the cleaned substrate, researchers see ODTMS reach its full potential, whether making self-cleaning glass, water-resistant coatings, or modifying sensor chips.
Plenty of research and practical troubleshooting have taught labs that silane behavior depends so much on solvent and substrate. Training young scientists to respect these chemical quirks matters, because real-world reliability comes from understanding the details, not just the datasheet.
| Names | |
| Preferred IUPAC name | octadecyl(trimethoxy)silane |
| Other names |
Octadecyltrimethoxysilane n-Octadecyltrimethoxysilane Trimethoxyoctadecylsilane n-Octadecyl silane n-Octadecyltri(methoxy)silane |
| Pronunciation | /ɛnˌɒk.stəˌdeɪ.sɪlˌtraɪˌmiːθ.ɒk.siˈsaɪ.leɪn/ |
| Identifiers | |
| CAS Number | 112-92-5 |
| Beilstein Reference | 1363327 |
| ChEBI | CHEBI:85189 |
| ChEMBL | CHEMBL3716523 |
| ChemSpider | 2020709 |
| DrugBank | DB14545 |
| ECHA InfoCard | 100.091.162 |
| EC Number | 206-487-5 |
| Gmelin Reference | 69168 |
| KEGG | C19563 |
| MeSH | D000072633 |
| PubChem CID | 11312 |
| RTECS number | GU4375000 |
| UNII | 1R3EWT5I8F |
| UN number | UN1993 |
| CompTox Dashboard (EPA) | DTXSID7044364 |
| Properties | |
| Chemical formula | C21H46O3Si |
| Molar mass | 325.58 g/mol |
| Appearance | Colorless to pale yellow transparent liquid |
| Odor | Odorless |
| Density | 0.874 g/mL at 25 °C (lit.) |
| Solubility in water | insoluble |
| log P | 13.5 |
| Vapor pressure | <0.01 mmHg (20°C) |
| Acidity (pKa) | 12.5 |
| Basicity (pKb) | 13.5 |
| Magnetic susceptibility (χ) | -79.0e-6 cm³/mol |
| Refractive index (nD) | 1.430 |
| Viscosity | 2.5 mPa·s (25 °C) |
| Dipole moment | 2.17 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 921.6 J·mol⁻¹·K⁻¹ |
| Hazards | |
| GHS labelling | GHS02, GHS07 |
| Pictograms | GHS02,GHS07 |
| Signal word | Danger |
| Hazard statements | H226, H315, H318, H411 |
| Precautionary statements | P261, P264, P271, P272, P273, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P337+P313, P362+P364, P403+P233, P501 |
| NFPA 704 (fire diamond) | 1-1-0-🛐 |
| Flash point | 85 °C |
| Autoignition temperature | 275 °C |
| Lethal dose or concentration | LD50 Oral Rat: 21,700 mg/kg |
| LD50 (median dose) | LD50 (median dose): > 5,000 mg/kg (Rat, Oral) |
| PEL (Permissible) | Not established |
| REL (Recommended) | 10 mg/m³ |
| Related compounds | |
| Related compounds |
Octadecyltrichlorosilane Dimethyloctadecylchlorosilane Tridecafluorooctyltrimethoxysilane Triethoxy(octyl)silane Hexadecyltrimethoxysilane |
