Thms600 hot stage

All chemicals were used as supplied. C, H, N analyses were carried out with an EuroEA 3300 instrument. IR spectra were recorded on a Bruker spectrophotometer using KBr discs or by using a Jasco FTIR 4200 spectrophotometer coupled to an ATR PIKE GladiATR device. ¹H and ¹³C NMR spectra were recorded on a Bruker spectrometer operating at 500 MHz, using CDCl₃ as solvent. ¹H chemical shifts were referenced to the solvent peak position, δ = 7.26 ppm. The phase assignment for the bisimidazolium salt was evaluated by polarizing optical light microscopy (POM) [56 (link)–57 (link)], placed on untreated glass slides, using a Nikon 50iPol microscope equipped with a Linkam THMS600 hot stage and TMS94 control processor. Temperatures and enthalpies of transitions were recorded by using differential scanning calorimetry (DSC) technique employing a Diamond DSC Perkin Elmer instrument. The bisimidazolium salt was studied at a scanning rate of 10 K/min after being encapsulated in an aluminum pan. Three heating–cooling cycles were performed for this sample.

Sample solutions of 5% wt./vol were prepared by stirring magnetically powdered PHBV, PHBH, and their blends in TFE at room temperature for 24 h, and sonicating for 1 h until the powder was completely dissolved. These solutions, previously filtered by a 0.22 µm PVDF filter, were cast onto a glass coverslip at 50 °C for 5 min and finally dried for 24 h at 40 °C in a vacuum to eliminate residual solvent. The crystallization process was observed using an Olympus BX51 polarized microscopy (Tokyo, Japan) with a 10x times objective and equipped with a Linkam THMS600 hot stage (Salfords, United Kingdom). Cast samples were heated up to 190 °C and maintained for 2 min to ensure complete melting. Then, they were quenched at a cooling rate of 100 °C/min to 100 °C and maintained for 15 min. This temperature cycle was repeated for a second time. Images were taken with a digital camera attached to the objective and the crystalline-growth rate (G) was calculated from the radial crystal growth and expressed in µm/min.

The crystallizing processes of the PLLA and mHA_1–3/PLA nanocomposites were observed under a DM2500 polarized optical microscope (Leica, Weztlar, Germany) on a THM S600 hot stage (Linkam, Lincoln, UK). The samples were heated from 30 °C to 250 °C at a rate of 30 °C/min and maintained at 250 °C for 3 min. Micrographs of the spherulites were taken after a predetermined time interval during the isothermal crystallization at 120 °C.

All the reagents and solvents were purchased from Sigma-Aldrich (Milan, Italy) and used without further purification. Optical observations were performed by using a Jenapol microscope (Zeiss S.p.A., Milano, Italy) fitted with a THMS 600 hot stage (Linkam, Waterfield, Epsom, Tadworth, UK). Phase transition temperatures and enthalpies were measured using a Pyris 1 DSC scanning calorimeter (PerkinElmer, Waltham, MA, USA) at a scanning rate of 10 °C/min, under nitrogen flow. UV-Vis absorption spectra of the samples were recorded at 25 °C in acetonitrile solution, on a Perkin Elmer Lambda 19 spectrophotometer. The spectral region 650−240 nm was investigated by using cell path length of 1.0 cm. Azobenzene chromophore concentration of about 3.0 × 10⁻⁵ mol L⁻¹ was used. ¹H-NMR spectra were recorded with a DRX/400 spectrometer (Bruker, Billerica, MA, USA). Chemical shifts are reported relative to the residual solvent peak (dimethylsulfoxide-d₆: H = 2.50 ppm). HPLC runs were carried out on a C₁₈ column (Jupiter, 5 μm, 300 Å, LC column 150 × 4.60 mm, Phenomenex, Torrance, CA, USA) at a flow rate of 1.0 mL/min. The gradient [solution A: TFA (0.1%); solution B: TFA (0.07%), H₂O (5%), CH₃CN (95%)] was 20−70% B over 20 min. HPLC analysis was performed on an 1260 Infinity Series system (Agilent, Santa Clara, CA, USA) with UV detection at 280, 320, 350 and 380 nm.

WAXS of the samples were recorded by employing the Ganesha system (SAXSLAB, U.S) equipped with a multilayer focused Cu Kα radiation as the X-ray source (Genix3D Cu ULD) and a semiconductor detector (Pilatus 300 K, DECTRIS, Swiss). A Linkam THMS600 hot stage was utilized to study the structure evolution as a function of temperature. The heating and cooling rates in the experiments were 10 °C/min.