Investigation of the sorption properties of β-cyclodextrin-based polyurethanes with phenolic dyes and naphthenates

Surface area and pore structure properties of urethane-based copolymers containing β-cyclodextrin

“…(3) represents an average value of the multiple adsorption sites (cf. Scheme 2) for the copolymer materials [35]. Experimental support in favour of the presence of multiple binding sites is further supported by the heterogeneity parameter (n s ), and the values (n s = 0.56-1.2) deviate from unity.…”

“…The relative similarity of the SA for the cellobiose-based copolymer compared to the CDI-X copolymers merit further support that dye sorption occurs at ''non-inclusion'' as well as the b-CD ''inclusion'' sites of the copolymer framework (cf. Scheme 2) [35]. Previous sorption studies have hypothesized the occurrence of inclusion binding and non-inclusion adsorption of dyes onto the copolymer framework [30,46].…”

“…Therefore, dye-based SA estimates are considered to provide reliable estimates of SA since the dye adsorption is well defined at pH 4.6 [35]. At elevated pH conditions (pH = 9.0) above the pK a of PNP, the dye is bound predominantly within the inclusion sites of b-CD [35]. Table 2 summarizes the monolayer adsorption capacity (Q m ) of the copolymer materials along with the SA estimates of the copolymers in the presence of PNP.…”

“…The published results [49] do not adequately account for the presence of multiple binding sites (i.e., inclusion vs. non-inclusion) in the urethane copolymer framework (cf. Scheme 2), as outlined previously [30,35]. Based on a comprehensive sorption study [35] of related urethane copolymers with PNP, the binding affinities (K eq $ 10 1 -10 2 M À1 ) for the copolymers are similar to those for the 1:1 native b-CD/ PNP complex in aqueous solution at 295 K. We conclude that the slightly attenuated binding affinity (K eq < 10 2 M À1 ) observed for urethane copolymer materials is attributed to steric effects of the inclusion sites and contributions arising from competitive binding equilibria at the different adsorption sites (cf.…”

In vitro Evaluation of Color Changes of Aesthetic Orthodontic Elastic Ligatures

“…Polyurethanes are not inert materials, and they decompose when in prolonged contact with enzymes, water or humid heat (Han et al, 2011;Mohamed et al, 2011). There are reports that these ligatures may discolor or stain if the patient eats certain types of foods or uses mouthwash or lipstick (Ardeshna et al;Kim & Lee, 2009).…”