Cyclodextrins in Polymer Synthesis: Influence of Acrylate Side Groups on the Initial Rate of Radical Polymerization of Various Acrylate/Methylated β-cyclodextrin Complexes in Water

Methylated β-cyclodextrin was used to complex the hydrophobic monomers n -propyl acrylate ( 1 ), n -butyl acrylate ( 2 ), n -pentyl acrylate ( 3 ), n -hexyl acrylate ( 4 ), and cyclohexyl acrylate ( 5 ) respectively yielding the corresponding water-soluble host/guest-complexes 1a − 5a . The complexes were polymerized in water by free radical mechanism and the initial polymerization rates ( v 0 ) determined. We found that v 0 increases as follows: 1a (12.5), 2a (27.5), 3a (44.2), 5a (49.4), 4a (75.8 × 10 -6 mol·L -1 ·s -1 ). To investigate the influence of the hydrophobic character of the guest monomers on the reaction rate, the water solubilities of the uncomplexed monomers 1 − 5 were determined by HPLC measurements. It was generally shown that with increase of water solubility of the free monomers the initial reaction rate ( v 0 ) decreases significantly.