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CAS Number: 9002-98-6 (general), 25987-06-8 (linear), 26913-06-4 (branched)
EC Number: 618-473-8
Molecular Formula: (C₂H₅N)n
Molecular Weight Range: 600 Da to 2,000,000 Da (commercially available)
Synonyms:
Polyaziridine,Poly(ethylene imine),PEI,Polymin,Lupasol (BASF trademark)
Structural Variants and Characteristics:
Polyethylenimine exists in two primary structural forms that dictate its properties and applications. Linear PEI, produced by ring-opening polymerization of 2-ethyl-2-oxazoline followed by hydrolysis, features a regular backbone with secondary amines. Branched PEI, synthesized via acid-catalyzed polymerization of aziridine (ethyleneimine), presents a highly branched architecture with primary, secondary, and tertiary amines in approximately 1:2:1 ratio. The degree of branching typically ranges from 0.5 to 0.7, with higher branching correlating to increased solubility and reduced crystallinity. Molecular weights span from oligomeric (600 Da) suitable for small molecule conjugation to ultra-high molecular weights (>750 kDa) for membrane applications.
Quality Parameters:
Amine Content: 16-23 mmol/g (theoretical maximum: 23.2 mmol/g)
Degree of Branching: 0.5-0.7 for branched PEI
Molecular Weight Distribution: PDI 2.0-3.5 for branched, <1.5 for linear
Residual Monomers: <1 ppm aziridine (carcinogenic impurity)
Solution Viscosity: 100-10,000 mPa·s for 30% aqueous solutions
Global production capacity exceeds 50,000 metric tons annually, with BASF (Lupasol series) dominating the branched PEI market and niche producers supplying linear grades. Pricing reflects molecular weight and purity, ranging from $5-10/kg for standard grades to $50-200/kg for specialty pharmaceutical or electronic grades.
Comprehensive Application Spectrum
Biotechnology and Gene Delivery (25%):
Transfection Reagent: Branched PEI (25 kDa) forms polyplexes with nucleic acids through electrostatic interactions, facilitating cellular uptake and endosomal escape via the "proton sponge" effect. Standard protocols employ nitrogen-to-phosphate ratios of 5-10:1.
Case Example: In non-viral gene therapy development, PEI/DNA complexes demonstrate transfection efficiencies approaching viral vectors with lower immunogenicity risks. Clinical trials employ PEI for cancer vaccine delivery.
Protein Purification: PEI precipitation removes nucleic acids and acidic proteins from crude extracts.
Enzyme Immobilization: Covalent attachment to PEI-coated supports enhances stability and reusability.
Water Treatment and Flocculation (30%):
Primary Flocculant: For municipal and industrial wastewater, particularly effective for colloidal particles and organic matter removal. Dosages typically range 5-50 ppm.
Retention Aid: In paper manufacturing (0.1-0.5% on pulp) improves fines retention and drainage.
Reverse Osmosis Membranes: As a fouling-resistant coating layer.
Case Example: In municipal water treatment plants, PEI-based flocculants achieve >95% turbidity removal at lower doses than conventional polyacrylamides, with reduced sludge volume.
Adhesives and Coatings (20%):
Wet-Strength Resin: In paper products (0.5-2.0% on fiber) through covalent bonding with cellulose.
Corrosion-Inhibiting Primers: PEI-zinc complexes provide barrier protection and cathodic inhibition.
Ink Receptive Coatings: For non-porous substrates.
Wood Adhesives: With isocyanates or epoxies for moisture-resistant bonding.
Electronics and Energy (15%):
Lithium-Ion Battery Binders: For silicon anodes, accommodating volume expansion during cycling.
Fuel Cell Membranes: Proton-conducting properties when sulfonated.
Printed Electronics: As a surface modifier for improved ink adhesion.
Case Example: In silicon-dominant anodes for EVs, PEI-based binders maintain electrode integrity through 1000+ cycles where conventional PVDF fails at <200 cycles.
Other Applications (10%):
Catalyst Support: For homogeneous catalyst immobilization.
Gas Separation Membranes: Facilitated transport membranes for CO₂ capture.
Textile Finishing: Antimicrobial and antistatic treatments.
Personal Care: In hair care products as conditioning and setting agent.
Chemical Behavior and Functionalization Chemistry
Proton Sponge Mechanism:
PEI's high density of amine groups (pKa 4-11) enables buffering capacity across physiological pH ranges. During cellular uptake, protonation in acidic endosomes leads to chloride influx, osmotic swelling, and endosomal rupture – the "proton sponge effect" crucial for intracellular delivery.
Conjugation Chemistry:
Primary amines provide handles for diverse functionalization:
Acylation: With activated esters, acid chlorides, or anhydrides
Alkylation: With alkyl halides or epoxides
Michael Addition: To acrylates or maleimides
Schiff Base Formation: With aldehydes followed by reduction
Crosslinking Reactions:
PEI forms covalent networks with:
Epoxides: For water-insoluble coatings
Isocyanates: For polyurea networks
Glutaraldehyde: For hydrogel formation
Genipin: For biocompatible crosslinking
SAFETY INFORMATION ABOUT POLYETHYLENIMINE
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
