In this work, the complex between three hydrophobic efficacious components of plants (anisole, asarone, curcumin) and modified cyclodextrin (2-hydroxypropyl-β-cyclodextrin, methyl-β-cyclodextrin) was investigated in supercritical carbon dioxide medium; and compared with the corresponding complex in air circumstance. The effect of the substitute group in the drug molecule on the complex reaction was also discussed.

In this work, the glass transitions of poly(methyl methacrylate) and polystyrene in compressed gaseous acetone/carbon dioxide were measured by an in situ creep compliance method at pressures lower than 7.0 MPa and at 318−338 K. When a small amount of acetone (x = 0.01−0.02) was added to a polymer-compressed carbon dioxide system, the glass transition pressure of polymer was further depressed by 1.0−4.0 MPa. The observed glass transition pressure depression increased with the acetone concentration in carbon dioxide and decreased with the temperature rise. A simple model was used to estimate the glass transition temperature depressions for the polymers in compressed gaseous acetone/carbon dioxide solution. The calculated results were in good agreement with the determined ones, except for the retrograde vitrification region.

In this work, the temperature influence and blending effect on the partition of methyl methacrylate between poly(methyl methacrylate) and compressed gaseous carbon dioxide were investigated; the cosolvent effect of ethanol on the partition of acetone between poly(carbonate biphenol A) and compressed gaseous carbon dioxide was also studied by using an in situ IR spectroscopy method at fluid pressure lower than 7.0 MPa. The temperature increase and the cosolvent addition decreased the partition coefficient of solute between polymer and compressed gaseous carbon dioxide. Interestingly the blending of the polymers increased the partition coefficient, and the distribution of methyl methacrylate between the poly(methyl methacrylate)/poly(vinylidene fluoride) complex and compressed gaseous CO2 was not a simple additive of the distribution of the two separate at a pressure lower than 6.0 MPa.

Partition coefficients of methyl methacrylate and acetone between some polymer and compressed gaseous carbon dioxide phases were determined by an in situ Fourier transform infrared (FTIR) spectroscopy method with a special designed high pressure IR cell at 318.2 K and 2.0−7.0 MPa. At the same temperature and pressure, the partition coefficient for methyl methacrylate was higher than that for acetone between the same polymer and subcritical carbon dioxide. For most solute/polymer/CO2 systems, the partition coefficient of solute between the polymer and compressed gaseous carbon dioxide decreased with the pressure increase. Only for a methyl methacrylate/poly(methyl methacrylate)/CO2 system, the partiton coefficient was not sensitive to the pressure change at pressures lower than 3.9 MPa. A linear solvation free energy relationship was used to estimate the main tendency of the pressure dependency. With the pressure dependent polarizability−dipolarity parameter of carbon dioxide, the calculated results were in accord with some experimental results.

Firstly, the interaction between cinnamaldehyde (CIN) and methyl-β- cyclodextrin (MBCD) was studied in aqueous solution. 1:1 inclusion complex was formed and the association constant was 187 ± 9 M−1. Then the complex of CIN–MBCD and muscone–MBCD was prepared both by sealed heating method and by supercritical carbon dioxide (sc CO2) approach. Complete complex was obtained by both methods for CIN–MBCD. Some CIN molecules was weakly associated with MBCD molecules in products by sealed heating method, all CIN molecules was strongly associated with MBCD molecules in products by sc CO2 processing. Complete complex between muscone and MBCD was not obtained. The choice for the size of guest molecule still existed for MBCD cavity in sealed heating method and sc CO2 processing.

In this work, the complex of shikonin-methyl-β-cyclodextrin and shikonin-2-hydroxypropyl-β-cyclodextrin were studied in supercritical carbon dioxide (sc CO2) at moderate pressure and temperature much lower than the melting point of shikonin. For comparing, the complex was also prepared by sealed heating method. Complex efficiency between shikonin and 2-hydroxypropyl-β-cyclodextrin (HPBCD) was quite low. Partly formation of shikonin—methyl-β-cyclodextrin (MBCD) was obtained by sealed heating method. Complete formation of shikonin—MBCD was obtained in sc CO2 media in short reaction time. This complexation was accelerated and enhanced by the rise in both the reaction temperature and carbon dioxide pressure up to 100 °C 100 bar. The physical state of cyclodextrins in complex reaction has remarkable influence on the complex. The aqueous solubility of shikonin could be enhanced about 75 times by complexing with MBCD.