Effect of Polyvinyl Alcohol in Inner Aqueous Phase on Stability of Millimeter-scale Capsules

The millimeter-scale capsules with controllable morphology,ultra-low permeability and excellent mechanical stability were fabricated by millifluidics.Viscosity of inner phase was adjusted to control the morphology and properties of the capsules.In detail,as the concentration of polyvinyl alcohol(PVA)increased from 0 to 8% in the inner phase of the capsules,the diameter of capsules decreased from 3.33 ± 0.01mm to 2.97 ± 0.01 mm,the shell thickness of capsules decreased from 0.183 ± 0.004 mm to 0.155 ± 0.003 mm.While the capsules had round shape and high sphericity.Notably,the capsules with 2% PVA in the inner phase had remarkably decreased water permeability and good morphological stability.Specifically,the end-time of water losing of the capsules was up to 49 days,while the dehydrated capsules maintained spherical appearance,and crushing force of the capsules was up to 13.73 ± 0.79 N,which ensured stability during processing and transportation.This research provides a new strategy for stable encapsulation of small molecules.