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 beta -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 (nu (0)) determined. We found that nu (0) increases as follows: 1a(12.5), 2a (27.5), 3a (44.2), 5a (49.4), 4a (75.8 x 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 Gee monomers the initial reaction rate (nu (0)) decreases significantly.