1. Chemical Structure and Properties
Molecular Formula: C₁₂H₁₈O₃
Structural Formula:
C₆H₅-O-(CH₂CH(CH₃)O)₂H
A branched glycol ether composed of a phenyl group linked to two propylene oxide units via an ether bond.
Physical Properties:
Appearance: Clear to pale yellow viscous liquid with a faint aromatic odor.
Boiling Point: 280–290°C; Density: 1.03–1.05 g/cm³; Vapor Pressure: <0.001 mmHg at 25°C.
Solubility: Low in water (<0.1% w/w); miscible with alcohols, esters, and hydrocarbons.
Chemical Properties:
Hydrolysis Stability: Resistant to hydrolysis under neutral and mildly acidic/alkaline conditions.
Thermal Stability: Stable up to 200°C; decomposes above 250°C, releasing phenol and propylene oxide derivatives.
Flammability: Combustible (flash point: ~150°C).
2. Industrial Applications
Coatings & Adhesives:
High-Performance Solvent: Enhances adhesion and film formation in epoxy, polyurethane, and acrylic coatings.
Plasticizer: Improves flexibility in sealants and composite materials.
Electronics:
Photoresist Stripper: Removes hardened resists from semiconductor wafers without damaging silicon layers.
Personal Care:
Emollient & Stabilizer: Used in high-end cosmetics and sunscreens for its low volatility and skin compatibility.
Chemical Synthesis:
Intermediate: Produces surfactants and specialty polymers via ethoxylation or crosslinking reactions.
3. Safety and Toxicology
Health Hazards:
Acute Exposure:
Skin Contact: Mild irritation (rabbit skin LD₅₀: >2,000 mg/kg); prolonged exposure may cause defatting.
Inhalation: Low volatility minimizes risk (TLV-TWA: Not established; handle as nuisance vapor).
Ingestion: Low acute toxicity (oral LD₅₀ rat: >5,000 mg/kg); gastrointestinal discomfort.
Chronic Effects:
Reproductive Toxicity: No teratogenicity observed in OECD 414 studies.
Carcinogenicity: Not classified (IARC Group 4); limited evidence of organ toxicity in chronic rodent studies.
Protection Measures:
PPE: Nitrile gloves, safety goggles, and general ventilation.
Storage: Stable in glass or stainless steel containers; avoid prolonged light exposure.
4. Environmental and Regulatory Compliance
Environmental Impact:
Biodegradability: Slow (OECD 301F: <20% in 28 days); moderately persistent in soil and water.
Aquatic Toxicity: LC₅₀ (fish, 96h): >100 mg/L; EC₅₀ (daphnia): >50 mg/L.
Bioaccumulation: Low (log Kow: ~2.3).
Regulatory Frameworks:
EU:
REACH: Registered with no SVHC listing; CLP classification Not Hazardous.
USA:
EPA: Exempt from VOC status under 40 CFR 51.100(s)(1); TSCA-listed.
China:
GB 13690-2009: Classified as General Chemical (non-hazardous).
Waste Management:
Incinerate in approved facilities; landfill disposal permitted for small quantities.
5. Case Studies and Application Insights
Case 1: High-Temperature Epoxy Coatings (Huntsman, 2023):
Challenge: Develop a heat-resistant coating for aerospace components (>200°C).
Solution: Dipropylene glycol phenyl ether (8% w/w) improved resin solubility and thermal stability.
Result: Achieved 250°C resistance (ASTM D2481) and 30% lower VOC emissions.
Case 2: Green Semiconductor Manufacturing (TSMC, 2022):
Process: Replaced toluene with dipropylene glycol phenyl ether in photoresist stripping.
Impact: Reduced worker exposure risks by 70% and met EU RoHS compliance.
Comparative Analysis:
Dipropylene Glycol Phenyl Ether vs. Ethylene Glycol Phenyl Ether:
Pros: Higher thermal stability, lower volatility, and reduced skin absorption.
Cons: Higher viscosity (~30 mPa·s) limits use in low-viscosity applications.
Dipropylene Glycol Phenyl Ether vs. Benzyl Alcohol:
Pros: Better solvency for polar polymers; lower aquatic toxicity.
Cons: Benzyl alcohol is biodegradable but less effective in high-temperature processes.