Synthesis of polydopamine capsules via SPG membrane emulsion templating: Tuning of capsule size

Abstract

Monodisperse polydopamine capsules with thin shells are synthesized by dopamine polymerization using toluene emulsion droplets as templates. Aqueous emulsions of monodisperse toluene droplets stabilized by the anionic surfactant sodium dodecyl sulfate are prepared by use of Shirasu porous glass membrane emulsification. This approach allows convenient tuning of the polydopamine capsule size via the membrane emulsification pore size, as exemplified by providing access to well‐defined capsules with diameters in the submicron – micron‐size range.

Anisotropic polydopamine capsules with an ellipsoidal shape that can tolerate harsh conditions: efficient adsorbents for organic dyes and precursors for ellipsoidal hollow carbon particles

“…16,18,19 In terms of such challenges, PDA coating is valuable due to its capability to form a conformal coating layer on particulate templates with any kinds of shapes. 5,6,[9][10][11][12] Even so, PDA capsules with an anisotropic shape have barely been reported. 20 Besides the shape of the polymeric capsules, the rigidity or mechanical stability, especially, the ability to keep the shape intact under some extreme conditions is one of the key traits of hollow capsules for many practical applications.…”

“…S4 †). 4,6,7,9,12,24,37,38,40 Interestingly, although collapsing of the spherical PDA capsules isotopically occurs to all directions around the curved surface (Fig. S4 in ESI †), 9,38 the micrometersized ellipsoidal PDA capsules collapse along their side of the long axis into attered shells.…”

“…5,6,[8][9][10][11][12] It is noted that most of PDA capsules prepared so far have a spherical shape, [4][5][6][7]11 while non-spherical ones may have additional advantages in cargo loading, cell uptake and enhanced packing efficiency in energetic materials. [13][14][15] However, preparation of non-spherical polymeric capsules is generally challenging.…”

“…Even so, PDA capsules are oen in the bulked or collapsed state aer airdrying, indicating a moderate mechanical strength. 4,6,7,9,10,12,22,37,38 Especially, although PDA have emerged as a very attractive precursor for nitrogen-doped carbon materials, preparation of hollow carbon particles or carbon capsules by carbonization of PDA involves multiple steps including PDA coating of hard templates, carbonization and template removing. 30,31,33,34 Carbonization of PDA coated templates might lead to the contamination of the carbon materials by the underlying templating materials, which can be avoid by direct carbonization of pure PDA capsules into carbon capsules.…”

Interfacial crosslinking of self‐assembled triblock copolymer nanoparticles via alkoxysilane hydrolysis and condensation

“…In addition, interfacial crosslinking can be carried out at high copolymer concentration as the intermicellar coupling is avoided by steric stabilization of polymer chains at the outermost corona . Interfacial polymerization and crosslinking also provide a simple and convenient route toward the preparation of polymer capsules using (mini)emulsion droplets as a soft template, where the polymerization process is constrained to the interface. Such polymer capsules have demonstrated application in the encapsulation of proteins, enzymes, and delivery of anti‐cancer therapies …”