Polymerization and copolymerization of functionalized 2-alkoxy-1-methylenecyclopropanes to form new polymers having alkoxy substituents

The polymers with functionalized alkoxy groups and with narrow molecular weight distribution (Mw/Mn < 1.12) are obtained from the living polymerization of 2-alkoxy-1-methylenecyclopropanes using π-allylpalladium complex, [(PhC₃H₄)Pd(μ-Cl)]₂, as the initiator. The polymers with oligoethylene glycol groups in the alkoxy substituent are soluble in water, and hydroboration of the C==C double bond and ensuing addition of the OH groups to C==N bond of alkyl isocyanate produce the polymers with urethane pendant groups. The reaction decreases solubility of the polymer in water significantly. Di- and triblock copolymers of the 2-alkoxy-1-methylenecyclopropanes are prepared by consecutive addition of the two or three 2-alkoxy-1-methylenecyclopropane monomers to the Pd initiator. The polymers which contain both hydrophobic butoxy or tert-butoxy group and hydrophilic oligoethylene glycol group dissolve in water and/or organic solvents, depending on the substituents. The ¹H NMR spectrum of poly(1a-b-1h) (---(CH₂C(==CH₂)CHOBu)n---(CH₂C(==CH₂)CH(OCH₂CH₂)₃OMe)m---) in D₂O solution exhibits peaks because of the butoxy and ==CH₂ hydrogen in decreased intensity, indicating that the polymer forms micelle particles containing the hydrophilic segments in their external parts. Aqueous solution of the polymer with a small amount of DPH (DPH = 1,6-diphenyl-1,3,5-hexatriene) shows the absorbance due to DPH at concentration of the polymer higher than 5.82 x 10⁻⁵ g mL⁻¹. Other block copolymers such as poly(1b-b-1h) and poly(1a-b-1g) also form the micelles that contain DPH in their core.