Cyclodextrins in polymer synthesis: Influence of methylated β-cyclodextrin as host on the free radical copolymerization reactivity ratios of hydrophobic acrylates as guest monomers in aqueous medium

Summary

Methylated (β-cyclodextrin (me-β-CD) was used to complex the hydrophobic monomers n-butyl acrylate (1), n-hexyl acrylate (2) and cyclohexyl acrylate (3) yielding the corresponding water soluble host/guest complexes 1a–3a. The complexes were copolymerized in water by free radical mechanism and the reactivity ratios were determined by measuring the monomer consumption by HPLC. The following reactivity ratios were found: copolymerization of 1a and 2a: r₁= 1.01 ± 0.01; r₂= 1.04 ± 0.01; copolymerization of 3a and 2a: r₁= 0.74; r₂= 1.28; copolymerization of 3a and 1a: r₁= 0.75 ± 0.04; r₂= 1.13 ± 0.01. In contrast to that, the copolymerization of the uncomplexed monomers 1–3 in organic medium (DMF/H₂O) leads to nearly ideal statistical copolymers in all cases.