## 2 Materials and Methods
### Methods of Analysis  
ATR-FTIR spectra were recorded using the Tensor 27 spectrometer (Bruker, Germany), equipped with a diamond crystal. The spectrum was made in the spectral range of 600-4000 cm\({}^{-1}\) with a resolution between 4 cm\({}^{-1}\) and 16 scans per spectrum. Carbon-13 Cross-Polarization Magic-Angle Spinning Nuclear Magnetic Resonance (\({}^{13}\)C CP/MAS NMR) measurements were completed on a Avance 300 MSL instrument (Bruker, Germany). The number of scans was 2048, and the spin rate was 7300 Hz. The morphology and the internal structure of microspheres were examined using scanning electron microscope SEM (FEI Quanta 3D FEG, Fei, Hillsboro, Oregon, USA). Polymeric particles were coated with a thin layer of gold. To determine the number average diameter (D\({}_{\text{n}}\)) and coefficient of variation (CV) Morphologi G3 particle analyzer (Malvern, UK) was used. Parameters characterizing the porosity of the copolymers were determined by nitrogen adsorption-desorption method (LTNA) at \(-\)196 \({}^{\circ}\)C using ASAP 2420 analyzer (Micromeritics, Norcross, GA, USA). Before measurements, samples were degassed at 60 \({}^{\circ}\)C under vacuum. The specific surface area, S\({}_{\text{BET}}\), was evaluated using the standard Brunauer-Emmett-Teller (BET) method for the nitrogen adsorption data in the range of a relative pressure p/p\({}_{0}\) from 0.05 to 0.25, assuming that the area of a single nitrogen molecule is 16.2 A\({}^{2}\). The total pore volume was estimated from single-point adsorption at a relative  
Figure 1: The schematic chemical structures of obtained 4 VP copolymers. pressure of 0.985. The pore size distributions (PSD) were obtained from the desorption branch of the isotherm using the Barrett-Joyner-Halenda (BJH) procedure [24]. In a swollen state the copolymers were characterized by inverse size exclusion chromatography (ISEC) [25] using the following as probe molecules: toluene, acetophenone, butylrophenone, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dibutyl phthalate, dibutyl phthalate, dionyl phthalate, dinonyl phthalate, dilauryl phthalate, and monodisperse polystyrene standards of molecular weights (M\({}_{\text{W}}\)) of 580, 2450, 5100, 11,600, 30,300, 68,000, 120,000, 390,000, 750,000, 1,260,000, and 2,750,000 Da. The standards were dissolved in THF. Pure THF was also used as the mobile phase during ISEC measurements. Microspheres under study suspended in methanol were slurry packed into stainless HPLC columns (100 mm \(\times\) 4.6 mm i.d.) using Pack in a Box system (SSI, Woodlawn, MD, USA). Methanol was used as packing solvent; the filling process was performed under the constant pressure of 20 MPa. The diameter of the probe molecules (\(\Phi\), in A) was calculated from the following Equation (1) [25]:  
\[\Phi=0.62\times M_{W}^{0.59} \tag{1}\]  
where \(M_{W}^{0.59}\) is the molecular weight of the probe molecule. The cumulative pore size distribution was determined from the plot 1--\(K_{0}(EC)\) versus \(log\Phi\), where \(K_{0}(EC)\) is the distribution constant in ISEC calculated as follows (2) [26; 27; 28]:  
\[K_{0}(EC)=\frac{V_{R}-V_{0}}{V_{p}}=\frac{V_{R}-V_{0}}{V_{i}-V_{0}} \tag{2}\]  
where: \(V_{R}\)--the retention volume of the probe; \(V_{0}\)--the interstitial volume equal to the retention volume of a totally excluded molecule; \(V_{i}\)--the retention volume of a totally included molecule; \(V_{p}\)--the pore volume. The simultaneous thermogravimetric analysis (TG) was performed on an STA 449 F1 Jupiter (Netzsch, Selb, Germany) at the heating rate of 10 K/min, in the temperature range of 30-700 \({}^{\circ}\)C, with the sample mass of 10 mg in air atmosphere. The gas flow was 20 mL/min. As the reference, the empty Al\({}_{2}\)O\({}_{3}\) crucible was used. For both static and dynamic sorption experiments, and for calibration curve, the stock solution of ibuprofen and ketoprofen was prepared in acetonitrile. The concentration of ibuprofen and ketoprofen was of 5.07 mg/mL and 5.06 mg/mL, respectively.