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Methylated β-cyclodextrin (me-β-CD) was used to form water-soluble host/guest complexes with the hydrophobic monomers n-butyl methacrylate (1), cyclohexyl methacrylate (2), isobornyl acrylate (3), isobornyl methacrylate (4), and styrene (5), respectively. The free-radical copolymerizations of the water-soluble N-isopropylacrylamide (NIPAAm) with these complexed monomers were carried out in water at different molar ratios.

SUMMARY: Methylated b-cyclodextrin (me-b-CD) was used to complex the hydrophobic monomers isobornyl acrylate (1) and butyl acrylate (2) yielding the water-soluble host/guest complexes isobornyl acrylate/me-b-CD (1a) and butyl acrylate/me-b-CD (2a). The included monomers were copolymerized in water by free-radical mechanism and the kinetics were studied. In order to evaluate these results, the corresponding uncomplexed monomers 1 and 2 were also copolymerized in organic solution. The reactivity ratios of 1a and 2a (r 1a = 0.3, r 2a = 1.7) differ significantly from the reactivity ratios of the corresponding uncomplexed acrylates 1 and 2 in organic solution (r 1 = 1.3, r 2 = 1.0). In addition, we found that the weight averages of the copolymers prepared by using me-b-CD are significantly higher than those of the corresponding polymers prepared from uncomplexed monomers in organic solution.

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 v0 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 (v0) decreases significantly.