Cyclodextrins in polymer synthesis: free radical polymerization of cyclodextrin host-guest complexes of methyl methacrylate or styrene from homogenous aqueous solution

The polymerization of methylated beta-cyclodextrin (m-beta-CD) 1 : 1 host-g uest compounds of methyl methacrylate (MMA) (1) or styrene (2) is described . The polymerization of complexes 1a and 2a was carried out in water with p otassium peroxodisulfate (K2S2O8)/sodium hydrogensulfite (NaHSO3) as radica l redox initiator at 60 degrees C. Unthreading of m-beta-CD during the poly merization led to water-insoluble poly(methyl methyacrylate) (PMMA) (3) and polystyrene (4). By comparision, analogously prepared polymers from uncomp lexed monomers 1 and 2 in ethanol as organic solvent with 2,2'-azoisobutyro nitrile (AIBN) as radical initiator showed significantly lower molecular we ights and were obtained in lower yields in all cases. Polymerization of m-b eta-CD complexed MMA in water, initiated with 2,2'-azo-bis(N,N'-dimethylene isobutyroamidine) dihydrochloride, occurred much faster than the polymeriza tion of uncomplexed MMA in methanol under similar conditions. Furthermore, it was shown, that the precipitation polymerization of complexed MMA from h omogeneous aqueous solution can be described by equations (P-n(-1) proporti onal to [I](0.5)) similar to those for classical polymerization in solution .