Monodisperse Polystyrene Foams via Microfluidics – A Novel Templating Route

Abstract

We have developed a templating route for the synthesis of monodisperse and highly ordered polystyrene foams. The route is based on the generation of monodisperse templates, namely of foamed emulsions and emulsions, respectively, via microfluidic techniques. The polymerization of the templates leads to polystyrene foams with controllable pore size, pore size distribution and connectivity and thus opens up a new arena for the synthesis of tailor-made polymer foams.

Toward Functionally Graded Polymer Foams Using Microfluidics

“…The emulsion for the foamed emulsion template was prepared as reported recently [28,34] Styrene (64.5 vol%), water (20 vol%), and glycerol (15 vol%) were emulsified with the surfactant sodium dodecyl sulfate (SDS, 5 wt% per volume unit). After emulsification, 0.38 mol% of the VIS-initiator phenylbis (2,4,6-trimethybenzoyl) phosphine oxide were dissolved and the mixture was homogenized by ultrasonication.…”

“…[28] First, the components of the dispersed and continuous phase were weighed separately in glass vessels. [28] First, the components of the dispersed and continuous phase were weighed separately in glass vessels.…”

“…[28] The liquid templates are produced by means of pressure-driven microfluidic devices and are based on either foamed styrene-in-water emulsions or on high internal phase emulsions (HIPEs) with water as the dispersed phase and a 1:1 mixture of styrene and divinylbenzene (DVB) as continuous phase (see Figure 1). The approaches are based on routes to produce monodisperse polystyrene foams, which we developed in our group.…”

Using flow technologies to direct the synthesis and assembly of materials in solution

“…13). In later work more rigid foams were generated using polyurethane [27] or polystyrene [28], 3D dry foams were obtained with a connectivity and pattern directly related to the bubble density (determined by the liquid: gas ratio and net flow rate) and drying period (Fig. 14).…”

Foamed emulsion drainage: flow and trapping of drops

“…Oil foams being notoriously difficult to stabilize [5,6], emulsification is an interesting alternative that offers the possibility to obtain stable aqueous foams containing significant amounts of oil. Foamulsions have already been shown to be useful precursors for the generation of porous materials, where the non-aqueous phase is solidified through polymerization [7,8] or carbonization [9].…”