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New regulations call for the progressive substitution of harmful chemicals by sustainable alternatives with a good profile regarding environmental, health, and safety (EHS) hazards. In particular, the range of acceptable solvents for the coating and polymer industries has suffered a dramatic shrinkage over the past 10 years. The Hansen approach provides an empirical, yet effective, method for determining the solubility parameters of polymers and binders by exposing them to a predefined group of 88 solvents. As this original set of solvents is now unacceptable with regard to toxicological issues, a better set is defined in this work. This subset of greener solvents was selected from a database of 220 organic solvents using five main descriptors, namely, the dispersive (δ d ), polar (δ p ), and hydrogen (δ h ) Hansen solubility parameters and the toxicity indexes according to the CMR (carcinogenic, mutagenic, and reprotoxic) and Hodge and Sterner classifications, along with two secondary descriptors: the molecular volume and the boiling point. For this purpose, a special experimental design is introduced combining a space-filling design (SFD) based on the WSP algorithm with a desirability function to select greener solvents that span the Hansen space more evenly. By taking α-terpineol as a starting point, a new series of 40 solvents exhibiting satisfying EHS profiles and improved coverage of Hansen space was obtained. The relevancy of this new set was checked by determining the solubility parameters of cellulose acetate.

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The drug delivery through intraocular lenses (IOLs) allows the combination of cataract surgery act and postoperative treatment in a single procedure. In order to prepare such systems, "clean" supercritical CO2 processes are studied for loading commercial IOLs with ophthalmic drugs. Ciprofloxacin (CIP, an antibiotic) and dexamethasone 21-phosphate disodium (DXP, an anti-inflammatory drug) were impregnated into foldable IOLs made from poly-2-hydroxyethyl methacrylate (P-HEMA). A first pre-treatment step was conducted in order to remove absorbed conditioning physiological solution. Supercritical impregnations were then performed by varying the experimental conditions. In order to obtain transparent IOLs and avoid the appearance of undesirable foaming, it was necessary to couple slow pressurization and depressurization phases during supercritical treatments. The impregnation yields were determined through drug release studies. For both drugs, release studies show deep and reproducible impregnation for different diopters. For the system P-HEMA/CIP, a series of impregnations was performed to delimit the experimental range at two pressures (80 and 200 bar) in the presence or absence of ethanol as a co-solvent for two diopters (+5.0 D and +21.0 D). Increase in pressure in the absence of a co-solvent resulted in improved CIP impregnation. The addition of ethanol (5 mol%) produced impregnation yields comparable to those obtained at 200 bar without co-solvent. A response surface methodology based on experimental designs was used to study the influence of operating conditions on impregnation of IOLs (+21.0 D) in the absence of co-solvent. Two input variables with 5 levels each were considered; the pressure (80-200 bar) and the impregnation duration (30-240 min). CIP impregnation yields ranging between 0.92 and 3.83 μg CIP/mg IOL were obtained from these experiments and response surface indicated the pressure as a key factor in the process. The DXP impregnation in P-HEMA was higher than CIP at all the tested conditions (8.50-14.53 μg DXP/mg IOL). Furthermore, unlike CIP, highest DXP impregnation yields were obtained in the presence of ethanol as a co-solvent (5 mol%). NMR spectroscopy was performed to confirm complete removal of ethanol in the co-solvent-treated IOLs.