Apparatus, methods, and fluid compositions for electrostatically-driven solvent ejection or particle formation

A method comprising:

• introducing a fluid composition into one or more emitters, wherein (i) each emitter comprises an electrically insulating material and has a corresponding emitter orifice, (ii) the fluid composition comprises a first material having a dielectric constant greater than about 25 mixed into a liquid solvent having a dielectric constant less than about 15, (iii) the fluid composition further comprises a polymer dissolved, emulsified, or dispersed in the liquid solvent, and (iv) conductivity of the fluid composition is less than about 1 mS/cm;
• applying a voltage to the fluid composition to cause non-evaporative ejection of the solvent from the fluid composition after the fluid composition exits the emitters through the corresponding emitter orifices;
• and
• collecting polymer particles, formed by ejection of the solvent from the fluid composition, on a collection surface, wherein the collected polymer particles comprise polymer fibers,
• wherein the fluid composition that exits the emitter orifice forms one or more discrete fluid jets, and each jet ejects solvent and breaks up within about 3 mm of its corresponding point of formation.