研究目的
Investigating the controlled transition of microcapsules from coil conformation to globule during the expansion of the pulse jet of nanoparticle suspension of TiO2 in supercritical (CO2) polyethylene glycol solution.
研究成果
The study demonstrated the possibility of a controlled transition of microcapsules from coil conformation to globular during the expansion of a pulsed jet into a vacuum and background gas. The position of the transition point depends on the initial conditions in the reactor and the background gas pressure. A re-entrant 'coil?globule' transition was observed, and optimal conditions for microcapsule formation with maximum TiO2 content were identified.
研究不足
The study is limited by the experimental conditions such as the pressure and temperature ranges in the reactor, the concentration of cosolvent, and the background gas pressure. The qualitative explanation of microcapsule formation lacks a rigorous model for jet expansion into background gas.
1：Experimental Design and Method Selection:
The study involved the expansion of a supersonic jet of TiO2 suspension in a solution of polyethylene glycol (PEG 8000) in supercritical CO2 into a vacuum and background gas (helium). The process was controlled by conditions in the nozzle chamber and the state of the environment.
2：Sample Selection and Data Sources:
The experiment used nanoparticles of titanium oxide (IV), polyethylene glycol (PEG 8000), carbon dioxide (CO2), and ethanol.
3：List of Experimental Equipment and Materials:
High pressure reactor, Laval nozzle, solenoid valve, receiving chamber, forevacuum pump, deposition substrates (copper foil plates), scanning electron microscopes (JEOLYSM-6490LV and LEO-1430VP).
4：Experimental Procedures and Operational Workflow:
The deposition from the jet was carried out by loading calculated amounts of TiO2, PEG 8000, and ethanol into the reactor, followed by the introduction of CO
5：The suspension was mixed, and the jet was expanded into a vacuum or background gas. The deposited material was analyzed using SEM and EDX spectroscopy. Data Analysis Methods:
The analysis involved determining the conformational composition and sizes of deposited microcapsules using SEM and EDX spectra.
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