Effect of scCO2 sorption capacity on the total amount of borage oil loaded by scCO2 impregnation/deposition into a polyurethane-based wound dressing

• A gravimetric method was used to measure the scCO2 sorption capacity in a commercial polyurethane-based wound dressing.
• Experimental data were modeled using both numerical and analytical solution of Fick's second law, with deviations below 10% in both cases.
• The highest scCO2 sorption capacity (∼70%) was achieved at the lowest temperature and highest solvent density studied (308 K and 850 kg m−3).
• The highest borage oil loaded yield was observed at the highest temperature and solvent density studied (328 K and 850 kg m−3).
• The total amount of borage oil loaded into PUR mainly depends on its solubility in scCO2.

In this work, experimental equilibrium solubility data of scCO2 in polyurethane (PUR) foam (scCO2 sorption capacity) was measured by a gravimetric method for different isotherms (308, 318 and 328 K), scCO2 densities (650, 750 and 850 kg m−3) and scCO2 exposure times (0.5, 2, 4, 8 and 16 h). Sorption data and CO2 desorption coefficients were estimated from desorption curves that were modeled using both numerical and analytical solution of Fick’s second law, with deviations below 10% in both cases. The influence of scCO2 sorption capacity on the amount of borage oil impregnated/deposited into the PUR foamed matrix was studied for selected pressure and temperature conditions and based on scCO2 sorption data. Results showed that the highest solubility of scCO2 in PUR (∼70%) was achieved at the lowest temperature and highest solvent density studied (308 K and 850 kg m−3) while the highest borage oil loaded yield was observed at the highest temperature and solvent density studied (328 K and 850 kg m−3), meaning that the impregnation/deposition process is controlled by the solubility of borage oil in scCO2. All the compounds present in borage oil (and which are detected by HPLC) were successfully loaded into the PUR matrix which confirms the feasibility of the impregnation/deposition process. Moreover, the amount of loaded oil did not significantly affect the neat properties of the PUR matrix (mainly its hydrophobicity, thermal resistance and water vapor permeation capacity).

Figure optionsDownload as PowerPoint slide