Concept 40

The dielectric performance test was based on a broadband dielectric spectrometer (Novocontrol Concept 40). The sample thickness was precisely measured and gold was sprayed before each measurement. The measurement frequency range was 10⁰–10⁵ Hz. The temperature was measured every 5 °C starting from 25 °C, and the temperature was raised until the dielectric spectrum showed serious abnormality or the sample was damaged.

To understand the molecular dynamics of the polymer systems under consideration, dielectric spectroscopy was carried out by monitoring the relaxation processes under an electric field. On the application level, dielectric property is very significant in the sense that they represent the capability to either store or dissipate energy by that particular material. Broadband dielectric spectroscopy (BDS) measurements were performed using a Novocontrol Concept 40 instrument with an Alpha dielectric spectrometer provided by Novocontrol Technologies GmbH (Montabaur, Westerwaldkreis, Germany). The measurements were carried out at room temperature in the frequency range of 10³–10⁷ Hz.

The phase composition and crystal structure was investigated by X-ray diffraction (XRD) using a CubiX diffractometer (Panalytical, The Netherlands) with Cu Kα radiation (30 kV, 30 mA). The lattice parameters were determined using FullProf 2000. For dielectric measurements, Ag-Pd electrodes were deposited on the plane-parallel polished surfaces of the disks followed by annealing in air at 500 °C for 12 h. The dielectric properties were measured by an impedance bridge E4980A Precision LCR Meter (Agilent, Santa Clara, CA) and a dielectric spectrometer CONCEPT40 (Novocontrol Technologies, Hundsangen, Germany) in the temperature range −150–150 °C at 10²–10⁶ Hz. Polarization – electric field ferroelectric loops were recorded at room temperature on the electroded ceramics immersed in transformer oil bath by a Sawyer–Tower modified circuit fed by triangular high voltage wave (frequency: 10 Hz) by using a TREK amplifier.

The electrical properties were studied by the impedance spectroscopy technique using a Novocontrol Concept 40 broadband dielectric spectrometer (Novocontrol, Montabaur, Germany). The electrical properties were measured in the frequency range from 10 mHz to 1 MHz in a temperature range of 373 K to 613 K, with an AC voltage of 1 V_rms. The measurements were performed on polished and gold-coated plane parallel circular glass samples under air atmosphere. The temperature was controlled using a high-temperature Novotherm HT 1600 controller (Novocontrol, Montabaur, Germany).

The dielectric permittivity (ε*(ω) = ε′(ω) − iε″(ω)) measurements were conducted using the dielectric spectrometer (Novocontrol concept 40, Novocontrol Technologies GmbH & Co. KG, Montabaur, Germany). The spectrometer operated at the frequency range from 10⁻² to 10⁶ Hz, and a Quatro Cryosystem equipped with a nitrogen gas cryostat controlled the temperature stability (better than 0.1 °C). The samples were placed between two stainless-steel flat electrodes of the capacitor with a 0.1 mm gap and mounted in a cryostat. Dielectric measurements on CUR-MAG CM, CUR-MAG-HPMC CM, CUR-MAG-HPC CM, and CUR-MAG-PVP K30 CM (5% of HPMC, HPC, or PVP K30 to drugs in the ternary co-amorphous systems, w_polymer/w_drug), were performed from 16 to 40 °C under dry nitrogen gas flow.