Osmotic-pressure-controlled concentration of colloidal particles in thin-shelled capsules

Abstract

Colloidal crystals are promising structures for photonic applications requiring dynamic control over optical properties. However, for ease of processing and reconfigurability, the crystals should be encapsulated to form 'ink' capsules rather than confined in a thin film. Here we demonstrate a class of encapsulated colloidal photonic structures whose optical properties can be controlled through osmotic pressure. The ordering and separation of the particles within the microfluidically created capsules can be tuned by changing the colloidal concentration through osmotic pressure-induced control of the size of the individual capsules, modulating photonic stop band. The rubber capsules exhibit a reversible change in the diffracted colour, depending on osmotic pressure, a property we call osmochromaticity. The high encapsulation efficiency and capsule uniformity of this microfluidic approach, combined with the highly reconfigurable shapes and the broad control over photonic properties, make this class of structures particularly suitable for photonic applications such as electronic inks and reflective displays.

Interfacial assembly of dendritic microcapsules with host–guest chemistry

“…In addition to self-assembled vesicles [14][15][16][17][18] or synthetic polymersomes 19 , the majority of reported structures rely on templating by exo [20][21][22] , meso 23,24 , endo 25 or exo-endo 26,27 methods. These approaches are experimentally laborious, with the use of a solid template requiring subsequent etching under relatively harsh conditions to obtain a hollow structure, lowering encapsulation and loading efficiencies.…”

Microfluidic fabrication of polymersomes enclosing an active Belousov-Zhabotinsky (BZ) reaction: Effect on their stability of solute concentrations in the external media

“…In fact, in all of the solutions from 50 mM to 600 mM, where πi> πo, water transport took place from the outer solution, through the middle oil phase and on to the inner core part, since the oil phase shows some solubility (chloroform solubility is 8.09 g/L at r.t.). Indeed, osmotic pressure differences on the size of small systems (such as microcapsules or polymersomes) have been reported in the literature [9,[35][36][37], however, to the best of our knowledge, this is the first report of osmotic pressure difference induced size change on single core double emulsion droplets [38,39].…”

Searching for imperfection insensitive externally pressurized near-spherical thin shells

“…In parallel, advances in the life sciences have drawn attention to medical implications of the buckling of spherical (or sphere-like) viral and colloidal capsules under external osmotic pressure (Kim et al, 2014;Datta et al, 2014;Vliegenthart and Gompper, 2011). Recent research has focused on differences in behavior caused by changing the boundary conditions from dead pressure to volume control (Thompson and Hutchinson, 2017).…”