Precipitation polymerization of ε-caprolactone in water using metal triflates as catalysts
The precipitation polymerization of ε-caprolactone has been assessed in water using various commercial metal triflates as catalysts. The reaction is quantitative at 70 and 100 °C, leading to number-average molecular weights up to 5,400 g/mol and dispersities around 1.5–2.0. A polycondensation mechanism operating from in situ generated 6-hydroxyhexanoic acid is proposed. Among various salts, aluminum and tin(II) triflates lead to the higher molecular weight after 24 h reaction at 70 °C.