Ft ir 410

Thermal properties were measured by differential scanning calorimetry (Jade DSC, PerkinElmer, Waltham, MA, USA). Samples with weights ranging from 5 to 10 mg were put into the aluminum pans with two series of heating and cooling. The samples were heated up to 150 °C and cooled down to 20 °C. All operations were conducted at the rate of 10 °C/min. The vibrational spectra of Fourier transform infrared spectroscopy were carried out on a FTIR 410 (JASCO, Tokyo, Japan) ranging from 4000 to 400 cm⁻¹. The powdery polymers were mixed with KBr powder and compressed into a disk for FTIR measurements. Two-hundred fifty-six (256) scans were performed in all specimens, and the spectrum was recorded. The average molecular weight (M_w) and the polydispersity (PDI, M_w/M_n) of the polymers were determined by Gel Permeation Chromatography (GPC 270, Viscotek, Malvern, UK) connected with a refractive index detector. Tetrahydrofuran (THF) was used as an eluent. The molecular weight was calculated using standard polystyrene samples as references. The molecular structure of the polymer was determined by nuclear magnetic resonance spectrophotometry (500 MHz, Bruker, MA, USA). The ¹H NMR spectra of the block biopolymers were recorded, using D-chloroform (CDCl₃) as the solvent. Further, the average molecular weight and grafting percentage of the biopolymers were calculated based on the spectra.

The formation of ionic bonds and hydrogen bond between quaternary ammonium pendants and PA was confirmed by FT/IR spectra (FT/IR-410, Jasco, Tokyo, Japan). For sample preparation, after submerging pTMAEMA dried gels into PA solution concentration of 1 M, pTMAEMA-PA-1 hydrogels were washed for three times with DI water to remove free and loosely bound PA in the hydrogels. The samples were then dried in the oven at 80 °C for 1 day. Then, the samples were carefully grinded into fine powder and vacuumed for 2 h before the experiment. pTMAEMA hydrogels and PA were also prepared individually and measured as control samples.

After the hydrogels were drained in a vacuum and pulverized, they were mixed evenly with potassium bromide (KBr) (Sigma) at a ratio of 1:99 and compacted into a thin disk. The measurement of Fourier transform infrared spectroscopy (FTIR) was determined by Jasco FT/IR-410, measuring wavelengths from 400 to 4000 cm⁻¹ at room temperature.

UV-vis spectroscopy was used to examine the coordination reaction of TA and Ti^IV in an aqueous solution. UV–vis spectra were obtained on a spectrophotometer (V-600, JASCO, MD) at room temperature. Three solutions were prepared prior to the measurements. Control samples of TA and Ti^IV solutions were prepared in oxygen-free deionized water at concentrations of 0.1 and 0.3455 wt%, respectively. The pH of the TA solution was controlled at 7. The TA-Ti^IV solution was prepared as above mentioned.
Fourier-transform infrared spectroscopy (FTIR, Jasco FT/IR-410) was employed to analyze chemical and coordination structures of metallogels. TA-Ti^IV metallogels were dried in liquid nitrogen under reduced pressure for 4 h. The dried TA-Ti^IV was grounded by a pestle and blended with KBr. The mixed powder was compressed into a pellet. FTIR was operated in a wavenumber range of 400 to 4000 cm⁻¹.

To determine the composition and functional groups of nanofibers, Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) were performed. After electrospinning for 2 h, the prepared nanofibers were adhered to the sample holder of FT-IR spectroscopy (FT/IR 410, JASCO, Tokyo, Japan). The measurement was in a resolution of 4 cm⁻¹ between 4000 and 600 cm⁻¹. Surface chemical analysis of nanofibers was carried out by XPS (K-Alpha, Thermo, Waltham, MA, USA). Peaks of C 1s and O 1s were resolvedly analyzed by iterative Gaussian/Lorentzian fitting (Magicplot, Saint Petersburg, Russia).