Model 1000

The crystal structure identification of the powdered samples is carried out with an X-ray diffractometer (Rigaku miniflex, Cedar Park, TX, USA) with a monochromatic CuK_α radiation source in the 2θ range of 10–80° with a scan rate of 4°/min. FTIR is carried out for all the samples by mixing powder with KBr and pressing it to form pellets and then analyzing it with a PerkinElmer (model-1000, perkin Elmer, Waltham, MA, USA) spectrometer in the wavenumber range of 400 to 4000 cm⁻¹. SEM analysis was carried with a scanning electron microscope PHENOM PROX for morphological study. To study the AC conductivity of the samples, pellets are prepared with a hydraulic press and silver paste is used to make contacts on either side for electrical measurements. The dielectric data are obtained with a PC-based LCR meter (HIOKI 3532-50 HITESTER, TEquipment, Long Branch, NJ, USA) and AC conductivity is calculated from the dielectric data, as a function of frequency at room temperature, in the frequency range of 50 Hz to 5 MHz. DC conductivity is measured with a Keithley electrometer [Model: 6514] for a temperature range of 45 °C to 180 °C. The optical absorption data are recorded with a double beam monochromatic T90+ UV–visible spectrophotometer in the wavelength range of 200–800 nm at room temperature.

The ¹H-NMR spectra of PBLG and Mal-PEG-PBLG diblock at room temperature in CDCl₃ and DMSO-d₆ respectively and CNMR spectra of Mal-PEG-COOH, PBLG and Mal-PEG-PBLG diblock at room temperature in DMSO-d_6, CDCl₃ and DMSO-d₆ respectively were recorded using Bruker Avance 300 MHz NMR spectrometer. Moreover, the chemical structures of PBLG and Mal-PEG-PBLG diblock copolymer were assessed via FTIR analysis using Perkin-Elmer Model 1000. Molecular weight and polydispersity of PBLG polymer was determined using GPC system (Shimadzu LC-20A) with StyragelHR2 Column model in THF as solvent with a flow rate of 1.0 ml/min at 35 °C.
The thermal properties of Mal-PEG-COOH, PBLG and Mal-PEG-PBLG diblock copolymer were evaluated through DSC (Mettler Toledo DSC 822, Greifensee, Switzerland). For DSC, 2 mg of block copolymer was analyzed in thermal cycles from 0 to 200 °C with heating rate of 10 °C/min. The thermal stability of the Mal-PEG-COOH, PBLG and Mal-PEG-PBLG were investigated via thermo-gravimetric analysis (TGA) under nitrogen atmosphere at heating rate of 10 °C/min from room temperatures to 600 °C.