Structure-Scavenging Abilities of Cyclodextrin-Based Polyurethanes

Abstract

Cyclodextrins are ring-shaped molecules containing an apolar cavity with a diameter 4-8 Ä wide and approximately 8 Ä deep. Because of the hydrophilic nature of the surface, the materials are readily dispersed in water. However, hydrophobic groups on the inner surface of the nanoporous molecules attract hydrophobic organics that bind noncovalently to the apolar cavity. Recently, polycyclodextrins have been developed as binders for energetic materials and as sorbants for biological materials, and exhibit potential for development as sorbant materials for water filtration. Studies using these polymers have been reported in the literature and show that the polycyclodextrins are very effective scavengers of organic contaminants in water. Our work expands on the use of cyclodextrins in polymers through the synthesis of several organic cyclodextrinbased polymers. These filtering materials have been shown to scavenge several different kinds of contaminants up to parts per million concentrations from water. Some neutron work has been done to try to ascertain the nature of capture of these contaminants.u

Cyclodextrin polymer coatings resist protein fouling, mammalian cell adhesion, and bacterial attachment

“…The polymers produced by HDI-crosslinking were more robust, therefore we considered HDI a more useful crosslinker for preparation of pCD coating materials here. There are many other possible crosslinkers that could be considered 90,[111][112][113][114] . Similarly, different CD subunits were not evaluated in this study.…”

“…This result may reflect diffusion of RIF into the water droplet, or increased presentation of polar functionalities that conceal nonpolar HDI crosslinks at the surface as RIF molecules complex with CD subunits. Normalized FTIR spectra (Fig 3) revealed that increased crosslinking ratio led to relatively larger peak sizes at 1256cm -1 , 2856 cm -1 , and 2926 cm -1 corresponding to alkane C-H stretch 87,88,[90][91][92] , at 3332 cm -1 corresponding to both hydrogen-bonded alcohol O-H and secondary amide N-H stretch 90,93 , at 1576 cm -1 corresponding to urethane N-H stretch 87,94 , at 1624 cm -1 corresponding to urethane C=O bending 87 , at 1278 cm -1 corresponding to urethane C-N stretch 90 , and at 1460 cm -1 corresponding to C-H bending 92 . Together, these peak size increases confirm increased abundance of HDI crosslinks with increased crosslink ratio.…”

“…Together, these peak size increases confirm increased abundance of HDI crosslinks with increased crosslink ratio. Additionally, for pCD spectra, disappearance of the peak seen in the HDI spectrum at 2270 cm -1 indicates that isocyanates were fully converted (most likely to urethanes) in crosslinking reactions 90,91,94,95 . for the alkane C-H stretch peak, 2270 cm -1 for the isocyanate peak only seen in the HDI spectrum, and 1576 cm -1 for the urethane N-H stretch peak which appears only after pCD crosslinking.…”