RESUMO
As their service life increases, cement-based materials inevitably undergo microcracking and local damage. In response to this problem, this study used phacoemulsification-solvent volatilization to prepare a multifunctional sustained-release microcapsule (SFRM) with self-healing and flame-retardant characteristics. The synthesis of SFRM is based on the modification of ethyl cellulose with nano-SiO2 particles and cross-linking with a silane coupling agent to form an organic-inorganic hybrid wall material. The epoxy resin is blended with hexaphenoxy cyclotriphosphazene (HPCTP) to form a composite core emulsion. The surface morphology, particle size distribution, core-shell composition, and thermal stability of SFRM were analyzed via scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), Malvern, Fourier-transform infrared (FT-IR), and TD-DSC-DTG. It is concluded that SFRM was successfully synthesized with superior particle size distribution and thermal stability. When the ratio of SiO2 solution and EC alcohol solution reached 1:2, the particle size distribution of the microcapsules was 30-190 µm, and the D50 decreased to 70 µm. The core material content, slow-release performance, and flame retardancy of SFRM were measured using a UV-1800 spectrophotometer and Hartmann tubes, and the compressive and repair properties of SFRM were evaluated by uniaxial compression tests. The results demonstrate that SFRM has satisfactory slow-release and flame-retardancy properties, the LC is 67%, and the first-order kinetic model shows the best fit and conforms to the non-Fickian diffusion mechanism. The SFRM repair rate can reach approximately 61%. This is of substantial significance to the field of self-repairing cement-based materials.
RESUMO
OBJECTIVE: This study aims to investigate the preparation of sustained-release microcapsules of salvianolic acid. METHODS: The stability of salvianolic acid microcapsules was improved, and the time of action was prolonged in the present study. This was prepared using the spray-drying method, with chitosan as the carrier. In the preparation process, the prescription and process were optimized by L9 (34) using an orthogonal design, with yield and drug loading as indexes, in order to obtain optimum conditions. RESULTS: The optimal process and prescription for the preparation of salvianolic acid microcapsules were found to be as follows: mass concentration of chitosan, 1.5%; mass ratio of salvianolic acid to chitosan, 1:3; inlet air temperature, 190°C; and peristaltic pump speed, 300 mL·h-1. The surface of the microcapsules was round, the drug loading was 25.99% ± 2.14%, the yield was 51.88% ± 2.84%, the entrapment efficiency was 86.21% ± 2.89%, and the average particle size was 105.6 ± 2.56 nm. The microcapsules in vitro had certain sustained release characteristics. The internally fitted first-order release model equation was ln(1-Q) = -0.236 t + 4.591 7, r = 0.920. In addition, the results of differential scanning calorimetry show that the properties of salvianolic acid were not changed by the microcapsules. CONCLUSION: Sustained-release microcapsules of salvianolic acid can be successfully prepared by adopting marine polysaccharide as a carrier.