Biomedical Engineering Reference
In-Depth Information
Fig. 6
Quercetin (full symbols) and thymol (open symbols) total loaded amounts into CBC foams
(
), AGA foams (
♦
) and CBC films (
N
) at 10 MPa and 303 K and 20 MPa and 323 K. Lines serve
only as guides for the eye
1. Higher pressure and higher temperature led to higher quercetin and thymol
loaded amounts for all the employed polymeric samples. Despite both working
conditions (10 MPa/303 K and 20 MPa/323 K) correspond to similar solvent
densities (17.5 mol/L), in this case, the different transport properties (viscosity
and diffusivity) characterizing each condition, as well as the higher scCO
2
swelling and plasticization of most polymers that is usually favored at this
conditions led to an improve in the impregnation/loading efficiency [
45
,
48
,
98
];
2. Foam like structures permit to load higher amounts of quercetin and thymol
(15-30
<
g/mg polymer) when compared to CBC films (
12
g/mg polymer)
m as confirmed by
mercury porosimetry, which has as main consequence the significant increase in
diffusivity and in the available surface area of this porous structures;
3. Contrary to foams, CBC film structures permit to load higher amounts of thymol
when compared to quercetin due to shape/molecular volume factors that limit the
amount of loaded quercetin;
4. Specific and favorable interactions between quercetin and CBC (enhancing
quercetin polymer/mobile phase partition coefficient) and the higher solubility
of thymol in scCO
2
justifies the similar amounts loaded for each compound in
CBC foams [
45
]. In fact, the higher affinity of thymol for the solvent phase also
promotes its removal during the depressurization step, being this effect more
pronounced in foam-like structures.
due to their higher porosities, in the range from 10 to 500
