Abstract
A new process is proposed that can largely improve classical electrospray (ESPR) atomization, thanks to the addition of supercritical CO2 (SC-CO2) to the liquid mixture, in which a polymer is dissolved, forming an expanded liquid. The consequent reduction of surface tension and viscosity allows the production of micrometric or nanometric particles of controlled size and distribution at a production rate up to one hundred times that of the traditional process. The new process was applied to particle generation from a very high molecular weight polyvinylpyrrolidone (PVP) and tested at different polymer percentages by weight and at different pressures. Repeatable microparticle diameters and distributions were obtained, ranging between 0.55 and 2.25 µm at PVP concentrations from 1 to 5% w/w and pressures between 80 and 120 bar.
Highlights
The production of micro- and nanoparticles with regular morphology and controlled size and distribution is a relevant target for many industrial fields, with pharmaceutical, biomedical, nutraceutical, energetics and fine chemical applications [1,2,3,4]
One less conventional application to produce micro- and nanoparticles, is electrohydrodynamic atomization, called electrospraying (ESPR) [2,4,8,9,10]. This technique has been proposed by several authors [4] to overcome the limitations of the traditional processes and has been especially proposed for polymers loaded with functional materials, active pharmaceutical ingredients and so on [2]
Before starting the description of the experimental results, it is opportune to try to characterize the fluid system formed in the feeding vessel
Summary
The production of micro- and nanoparticles with regular morphology and controlled size and distribution is a relevant target for many industrial fields, with pharmaceutical, biomedical, nutraceutical, energetics and fine chemical applications [1,2,3,4]. Several techniques have been proposed and used to produce these particles (e.g., microgrinding [5], micro- and nanoemulsions [6], spray drying [7], etc.) These traditional techniques suffer of some limitations, such as high process temperatures, shear stresses and large solvent residues [5,6,7]. One less conventional application to produce micro- and nanoparticles, is electrohydrodynamic atomization, called electrospraying (ESPR) [2,4,8,9,10] This technique has been proposed by several authors [4] to overcome the limitations of the traditional processes and has been especially proposed for polymers loaded with functional materials, active pharmaceutical ingredients and so on [2]. The free charges located on the surface of the liquid tip develop electrostatic forces (Coulomb force) that, when a sufficiently high voltage is applied, compete with cohesive forces of the liquid (mainly surface tension and viscosity)
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