Characterization of electrospraying process for polymeric particle fabrication

Polymeric particles were fabricated using the electrohydrodynamic atomization (EHDA) process in a modified electrospray system where nozzle and ring are enclosed in a shuttle chamber. Two organic liquids (PLGA+DCM(w/v=7%), PLGA+ACN(w/v=8%)) were tested. The spray current (I)(I) scaling laws with liquid flow rate (Q)(Q) were found to be I∼Q1/4I∼Q1/4 and the droplet size (dd)(dd) scaling laws dd∼Q1/2dd∼Q1/2, which agrees with the work [Gañán-Calvo, A. M., Dávila, J., & Barrero, A. (1997). Current and droplet size in the electrospraying of liquids. Scaling laws. Journal of Aerosol Science, 28, 249–275] conducted using a regular electrospray system. The size of the fabricated particles decreased with decreasing nozzle–plate distance as well as with increasing conductivity of polymer solution or with decreasing liquid flow rate. The morphology of the fabricated particles became less spherical with increasing Peclet number (Pe). The variation of Pe values due to either using a different polymer or a different ambient temperature resulted in comparable changes in particle morphology. An Okuyama Peclet number analogy has been shown to be promising for characterizing the formation of particle morphology under the use of different solvents.