Joachim Storsberg

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 β-cyclodextrin (m-β-CD) 1 : 1 host-guest compounds of methyl methacrylate (MMA) (1) or styrene (2) is described. The polymerization of complexes 1 a and 2 a was carried out in water with potassium peroxodisulfate (K2S2O8)/sodium hydrogensulfite (NaHSO3) as radical redox initiator at 60°C. Unthreading of m-β-CD during the polymerization led to water-insoluble poly(methyl methacrylate) (PMMA) (3) and polystyrene (4). By comparison, analogously prepared polymers from uncomplexed monomers 1 and 2 in ethanol as organic solvent with 2,2′-azoisobutyronitrile (AIBN) as radical initiator showed significantly lower molecular weights and were obtained in lower yields in all cases. Polymerization of m-β-CD complexed MMA in water, initiated with 2,2′-azobis(N,N ′-dimethyleneisobutyroamidine) dihydrochloride, occurred much faster than the polymerization of uncomplexed MMA in methanol under similar conditions. Furthermore, it was shown, that the precipitation polymerization of complexed MMA from homogeneous aqueous solution can be described by equations (Pn–1 ∝ lsqb;Irsqb;0.5) similar to those for classical polymerization in solution.

Cyclodextrins in polymer synthesis: photocrosslinkable films via free radical copolymerization of methylated β-cyclodextrin-complexed styrene with sodium 4-(acrylamido)-phenyldiazosulfonate in aqueous medium

The copolymerization of a methylated-β-cyclodextrin (m-β-CD) 1:1 host-guest compound of styrene (1a) with various molar ratios of sodium 4-(acrylamido)-phenyldiazosulfonate (2) is described. The copolymerization of complex 1a with 2 was carried out in water with 2,2′-azobis(N,N′-dimethyleneisobutyramidine)-dihydrochloride as the free radical initiator at 40°C. Depending on the amount of 2 incorporated in the copolymer, water- or DMF-soluble copolymers of high molar mass were obtained. Irradiation of the copolymers with UV light in solution resulted in rapid decomposition of the azo chromophore, and irradiation of the polymers as films led to crosslinking and thus to insolubility.

Cyclodextrin in polymer chemistry: Kinetic studies on the free-radical polymerization of cyclodextrin-complexed styrene from homogeneous aqueous solution

Abstract Styrene was encapsulated by an equimolar amount of randomly methylated β-cyclodextrin (CD) in water resulting in a water-soluble CD complex. Polymerization of this complex was carried out at 50°C using different amounts of the water-soluble azo-initiator 2,2’-azobis[N,N’-dimethyleneisobutyramidine] dihydrochloride. Unthreading of CD during polymerization led to water-insoluble polystyrene. Analysis of the polymers obtained showed that the polymerization from homogenous aqueous solution can be described by an equation similar to the classical polymerization in solution (number-average degree of polymerization vs. initiator concentration: Pn -1 ~ [I]0.5).