Precipitation of a biodegradable polymer using compressed carbon dioxide as antisolvent

Submicronic and micronic particles of a promising biodegradable polymer, poly(desamino tyrosyl-tyrosine ethyl ester carbonate) [poly(DTE carbonate)], were produced by precipitation with compressed carbon dioxide as antisolvent. The effects of temperature, pressure, as well as initial concentration and flow rate of polymer solution on the particle size, size distribution, and morphology were investigated on a lab-scale apparatus with a coaxial injection nozzle. Among these operating parameters, pressure and temperature were found to have only mild effect on the product. Instead, the degree of agglomeration of the products can be manipulated with adjusting the operating parameters. The relationship between the operating variables and the sizes of primary particles reveals that the nature of this polymer is the dominant factor on its solid-state engineering in the course of its precipitation.