Cyclodextrins in polymer chemistry: Influence of methylated β-cyclodextrin as host on the free radical copolymerization reactivity ratios of isobornyl acrylate and butyl acrylate as guest monomers in aqueous medium

Abstract

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.

Cyclodextrins in polymer synthesis: Free radical polymerization of methylated β-cyclodextrin complexes of methyl methacrylate and styrene, controlled by dodecanethiol as the chain-transfer agent in aqueous medium

“…[4,5] In the case of dodecanethiol however the 1 H NMR-signals are overlayed by cyclodextrin resonances. The spot of the complex shows the same UV activity as the pure dodecanethiol and in addition it reacts with iodine in the same way as me-b-CD.…”

“…[1][2][3][4][5][6] Also, some patents describe the use of CDs, preferably in catalytic amounts, in order to improve, for example, emulsion polymerizations. [1][2][3][4][5][6] We also described that the reactivity ratios of the copolymerization of isobornyl acrylate/CD and butyl acrylate/CD complexes differ significantly from the r-values of the uncomplexed monomers in organic medium. We found that during the free-radical homopolymerization and copolymerization of the complexed monomers, the CD slips off from the monomer during chain propagation, and the polymer precipitates, while the CD remains in the aqueous phase due to its high water solubility.…”

“…[7][8][9] Generally, the hydrophobic monomers become completely soluble in water due to the formation of host/guest complexes with CD. [4] Recently, we have observed that the chain-transfer constants of the water-soluble N-acetyl-L-cysteine on methyl methacrylate and styrene is about three times higher in water in the presence of me-b-CD than in the case of a N,N 9-dimethylformamide (DMF)/water-mixture in absence of me-b-CD. [1][2][3][4][5][6] We also described that the reactivity ratios of the copolymerization of isobornyl acrylate/CD and butyl acrylate/CD complexes differ significantly from the r-values of the uncomplexed monomers in organic medium.…”

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

“…Furthermore, the preparation and polymerization of equimolar cyclodextrin complexes of commercial standard monomers like styrene 1 and methyl methacrylate (MMA have been described. It was also shown that the precipitation polymerization of a cyclodextrin complex of a poorly water-soluble monomer like MMA can be described by kinetic equations similar to those for the classical polymerization in solution [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Cyclodextrins in Polymer Synthesis: Free Radical Polymerization of β‐Cyclodextrin Complexes of Photosensitive Mesoionic 6‐Oxo‐1,6‐dihydropyrimidin‐3‐ium‐4‐olates in Aqueous Medium

“…In addition, examples whereby CDs hinder the polymerization are known 33. Furthermore, the influence of CD on the copolymerization parameters of hydrophobic monomers was examined 34,35. In some examples, it was also shown that the copolymerization of CD‐complexed hydrophobic monomers together with hydrophilic monomers in water could only be performed in good yields by the use of CDs 36,37…”