Efficient synthetic procedures for the preparation of aroyl hydrazones were developed by converting the corresponding ethyl ester into hydrazides, followed by a reaction with 4-hydroxy-3-methoxy-benzaldehyde. A series of aromatic hydrazides and aroyl hydrazones were characterized by elemental analysis, IR, 1H NMR, 13C NMR and thermogravimetric analysis. The thermal gravity analysis showed that the compounds 3a–3d were stable below 228.23, 227.65, 118.97 and 179.51 °C, respectively. The aromatic hydrazides and aroyl hydrazones showed antimicrobial activity towards Staplylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The antibacterial activity experiments indicated that aroyl hydrazones had higher activity than the hydrazides. The presence of a hydroxyl group, as well as the number and position of the hydroxyl groups, were important and further enhance the antimicrobial activity.
1 February 2022 in Journal of the Mechanical Behavior of Biomedical Materials
A UV-curable poly(butyl fumarate) (PBF)/poly(propylene fumarate)-diacrylate (PPF-DA) hybrid material with good performance for LED encapsulation is introduced in the paper. They have been prepared by radical polymerization using PBF and PPF-DA macromers with a UV curing system. PBF and PPF-DA were characterized by Fourier-transform infrared (FT-IR) and H-nuclear magnetic resonance (1H NMR). The thermal behavior, optical and mechanical properties of the material were examined by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), ultraviolet-visible spectroscopy (UV–vis), and a material testing system mechanical testing machine, respectively. The results indicated that the hybrid material has a suitable refractive index (n = 1.537) and high transmittance (99.64% in visible range) before/after thermal aging. With the increasing of the double bond ratio from 0.5 to 2, the water absorption ratios of the prepared encapsulation material were 1.22%, 1.87% and 2.88%, respectively. The mechanical property experiments showed that bonding strength was in the range of 1.86–3.40 MPa, tensile-shear strength ranged from 0.84 MPa to 1.57 MPa, and compression strength was in the range of 5.10–27.65 MPa. The cured PBF/PPF-DA hybrid material can be used as a light-emitting diode (LED) encapsulant, owing to its suitable refractive index, high transparency, excellent thermal stability, lower water absorption, and good mechanical properties.
25 February 2022 in Journal of Applied Polymer Science