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

Methylated beta -cyclodextrin (me-beta -cD) was used to complex the hydroph obic monomers n-butyl acrylate (I), n-hexyl acrylate (2) and cyclohexyl acr ylate (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 l a and 2a: r(1) = 1.01 +/- 0.01; r(2) = 1.04 +/- 0.01; copolymerization of 3 a and 2a: r(1) = 0.74; r(2) = 1.28; copolymerization of 3a and la: r(1) = 0 .75 +/- 0.04; r(2) = 1.13 +/- 0.01. In contrast to that, the copolymerizati on of the uncomplexed monomers 1-3 in organic medium (DMF/H2O) leads to nea rly ideal statistical copolymers in all cases.