4,4′-Azobis(4-cyanovaleric acid)

ACVA (4,4′-Azobis(4-cyanovaleric acid)) is a water-soluble thermal radical initiator used extensively in polymer chemistry and bioconjugation applications.

Primary applications:

• Aqueous polymerization: Free radical polymerization of water-soluble and dispersed monomers
• Emulsion polymerization: Production of latexes, adhesives, and coatings
• Hydrogel synthesis: Crosslinked networks for biomedical and materials applications
• Protein crosslinking: Formation of protein hydrogels and biomaterials
• Bioconjugation: Polymer-protein and polymer-drug conjugates
• Controlled polymerization: RAFT, NMP, and other controlled radical techniques

How it works: ACVA undergoes thermal decomposition at elevated temperatures (typically 60-80°C) to generate carbon-centered free radicals through homolytic cleavage of the azo bond (N=N), releasing nitrogen gas. These radicals initiate polymerization of vinyl monomers or abstract hydrogen atoms for crosslinking reactions.

Advantages: Water solubility, predictable decomposition kinetics, biocompatibility, carboxylic acid functionality for further modification, and moderate decomposition temperature suitable for temperature-sensitive applications.

ACVA has well-characterized thermal decomposition properties that make it ideal for controlled polymerization.

Decomposition parameters:

• 10-hour half-life: ~70°C in water
• 1-hour half-life: ~85°C in water
• Typical polymerization temp: 60-80°C
• Activation energy: ~125 kJ/mol
• Radical efficiency (f): 0.6-0.7

Temperature selection guide:

• 60-65°C: Slow, controlled polymerization (10-24 hours)
• 70-75°C: Moderate rate (4-8 hours) – most common
• 80-85°C: Faster polymerization (1-3 hours)
• >90°C: Rapid decomposition, less control

Solvent effects: Half-life values are typically reported in water. In organic solvents or mixed solvent systems, decomposition rates may differ slightly. Always verify kinetics for your specific conditions.

Storage stability: When stored refrigerated (2-8°C) and protected from light, ACVA is stable for 24+ months with minimal decomposition.

Standard protocol for ACVA-initiated polymerization is straightforward and reliable.

General aqueous polymerization procedure:

• Step 1: Dissolve monomer(s) in deoxygenated water or buffer
• Step 2: Add ACVA (typically 0.1-5 mol% vs monomer)
• Step 3: Purge with nitrogen or argon (15-30 minutes)
• Step 4: Seal reactor and heat to desired temperature (60-80°C)
• Step 5: Stir for specified time (typically 2-12 hours)
• Step 6: Cool, precipitate, and purify polymer

Initiator loading guidelines:

• 0.1-0.5 mol%: Controlled polymerization, higher MW polymers
• 0.5-2 mol%: Standard polymerizations
• 2-5 mol%: Faster kinetics, lower MW polymers
• >5 mol%: Rapid polymerization, oligomers

Critical factors:

• Oxygen removal: Essential – oxygen inhibits free radical polymerization
• Temperature control: ±2°C for reproducible results
• pH: Carboxylic acids (pKa ~4.5) – consider pH effects
• Monomer concentration: Typically 10-50 wt%
• Solvent quality: Use fresh, degassed water or buffer

For hydrogel synthesis: Add crosslinker (e.g., N,N’-methylenebisacrylamide, 0.5-5 mol%), adjust initiator to 0.5-2 mol%, polymerize in mold or in situ.

ChemContract supplies ACVA at >98% purity, verified by multiple analytical techniques.

Quality control methods:

• HPLC analysis: Purity >98% by peak area at 254 nm
• ¹H NMR spectroscopy: Structure confirmation and purity
• ¹³C NMR spectroscopy: Complete structural verification
• Acid-base titration: Carboxylic acid content determination
• DSC/TGA: Decomposition temperature verification

Certificate of Analysis includes:

• Batch number and manufacturing date
• HPLC chromatogram with purity calculation
• ¹H NMR and ¹³C NMR spectra
• Titration results (acid content)
• Decomposition temperature (DSC)
• Appearance and solubility data
• Storage recommendations

Functional testing:

• Polymerization test reactions to verify initiating activity
• Half-life determination in standard conditions
• Batch-to-batch consistency in decomposition kinetics

Proper storage is important to maintain ACVA activity and prevent premature decomposition.

Storage conditions:

• Temperature: 2-8°C in refrigerator (essential)
• Light protection: Store in amber bottle or wrapped in foil
• Container: Tightly sealed to prevent moisture uptake
• Atmosphere: Normal atmosphere acceptable (not oxygen-sensitive as solid)
• Shelf life: 24 months when stored properly at 2-8°C

Handling recommendations:

• Allow container to warm to room temperature before opening
• Weigh quickly and reseal immediately
• Return to refrigerator promptly after use
• Do not expose to elevated temperatures unnecessarily
• Use clean, dry spatula for transfer

Solution storage:

• Stock solutions: Prepare fresh for best results
• If stored: Keep at 2-8°C, use within 1 week
• Aqueous solutions: More susceptible to decomposition
• DMSO solutions: Slightly more stable than aqueous

Signs of degradation:

• Color change from white to yellow/brown
• Reduced initiating activity in polymerizations
• Lower purity by HPLC analysis
• Change in melting point or decomposition temperature

ACVA offers unique advantages compared to other radical initiators.

vs. AIBN (azobisisobutyronitrile):

• Solubility: ACVA is water-soluble; AIBN is oil-soluble
• Applications: ACVA for aqueous polymerization; AIBN for organic solvents
• Decomposition temp: Similar (t½ ~70°C for ACVA, ~65°C for AIBN)
• Functionality: ACVA has carboxylic acids for further modification

vs. Potassium persulfate (KPS):

• Mechanism: Both are water-soluble; KPS is ionic initiator
• Temperature: KPS needs higher temps (>70°C); ACVA more flexible
• pH sensitivity: KPS very pH-sensitive; ACVA more tolerant
• Redox systems: KPS often used with reducing agent; ACVA thermal only

vs. VA-044 (water-soluble azo):

• Decomposition temp: VA-044 lower (44°C); ACVA higher (70°C)
• Applications: VA-044 for temperature-sensitive systems; ACVA for standard
• Cost: ACVA typically more economical

ACVA advantages:

• Water-soluble for aqueous and emulsion systems
• Predictable, well-characterized decomposition kinetics
• Carboxylic acid functionality for conjugation/modification
• Biocompatible for biomedical applications
• Moderate temperature suitable for many monomers
• Works well in controlled/living radical polymerization

We offer multiple pack sizes for research and industrial applications.

Available quantities (in stock):

• 1 g – Initial studies and optimization
• 5 g – Standard research quantity
• 10 g – Extended research projects
• 25 g – Pilot-scale polymerization
• 100 g – Production quantities
• 500 g – 1 kg: Industrial scale
• Custom quantities: Available for large-scale manufacturing

Usage estimates:

• 1 g = ~3.6 mmol (sufficient for 10-20 polymerizations at 10g monomer scale)
• Typical loading: 0.1-2 mol% vs monomer
• For 10g monomer (e.g., acrylamide): ~3-60 mg ACVA needed

Delivery times:

• Stock quantities (1-25g): Ships within 24-48 hours
• Domestic USA: 2-3 business days (FedEx/UPS with ice packs)
• International: 5-7 business days (DHL/FedEx, refrigerated)
• Large quantities (100g-1kg): 1-2 weeks
• Custom quantities (>1kg): 3-4 weeks

Packaging:

• Amber glass bottle or foil-wrapped container
• Tightly sealed to prevent moisture
• Shipped refrigerated with ice packs or dry ice
• Certificate of Analysis included
• Safety Data Sheet included
• Storage and handling instructions