RESUMO
The combination of a living anionic technology and a unique alternating strategy provided an exciting opportunity to prepare novel and well-defined poly(1,3-pentadiene-co-syrene-co-1,1-diphenylethylene) resins consisting of three alternating sequences of modules (A/B/C zwitterions). "A" being Styrene (St)/1,3-pentadiene (PD), "B" being diphenylethylene (DPE)/PD, "A" being DPE/St, respectively, A wide composition range of new polyolefin resins, i.e., poly (A-co-B), poly (A-co-C), and poly (B-co-C), with controlled molecular weight and very narrow molecular weight and composition distributions have been prepared by a one-pot living characteristic method. In the section of kinetic analysis, the terpolymer yields and kinetic parameters were strongly dependent on the feed/comonomer ratio as well as the content of the alternating structure. The competition copolymerization behaviors of A/B, B/C, and A/C were studied in detail in this work. By contrast, the microstructure and the thermal property of the resulting terpolymer were investigated via Nuclear magnetic resonance (NMR) and Differential scanning calorimetry (DSC) analysis. The results of 1H NMR tracking the change of [Aromatic ring]/[C=C] value indicated the distinctive copolymer-ization behavior of the selective "alternating-modules". The glass transition temperature (Tg) was very sensitive to the terpolymer composition. By contrast to poly(A-ran-B) with only one obvious Tg, there were two Tgs in the A/C and B/C copolymerization cases. Moreover, the desirable high Tg ~ 140 °C resin was limited to the terpolymers with up to 50 mol % DPE. Finally, the "ABC-X" mechanism was proposed to interpret the unique terpolymerization behavior, which belongs to the classical "bond-forming initiation" theory.
RESUMO
A high-performance liquid chromatography coupled with photo diode array detection method is developed for simultaneous determination of seven active components in Qibaomeiran pill, including rutin, 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glycoside, ferulic acid, psoralen, isopsoralen, emodin, and physcion. The analysis is performed on a C(18) column using a mobile phase composed of A (0.1% acetic acid) and B (acetonitrile) with linear gradient elution. Four wavelengths at 245, 290, 320, and 350 nm were chosen as the monitoring wavelength to determine seven active components, respectively. All the compounds show good linearity (r > 0.999). The developed method is fully validated in respect to precision, repeatability, and accuracy. The proposed method is successfully applied to quantify the seven active components in different Qibaomeiran pill samples. The results indicate that the developed assay could be considered as a suitable quality control method for the Qibaomeiran pill.
