Composite Tectocapsules Containing Porous Polymer Microspheres as Release Gates

Abstract

Porous and amphiphilic polymer microspheres were incorporated into polyurea capsules in order to control the release of the core solvents independently of wall formation. While nonpolar poly(divinylbenzene-55) microspheres were simply encapsulated along with the xylene core solvent, the amphiphilic poly(divinylbenzene-55-alt-maleic anhydride) microspheres, as well as maleic acid functionalized poly(divinylbenzene-55) microspheres, became embedded at the polyurea−water interface. Release of xylene from these microcapsules into air was monitored at room temperature and 50 °C. Release profiles change significantly upon addition of amphiphilic porous microspheres, with the release rates scaling with microsphere loading. Scanning transmission X-ray spectromicroscopy (STXM) indicates that the polyurea is largely excluded from the pores of the microspheres.

Molecular imprinting: perspectives and applications

“…363 Besides, precipitation polymerization is also a good choice to obtain surfactant/stabilizer-free imprinted polymer microspheres which are normally produced in a single preparation step with excellently controlled particle size and distribution. 364 To obtain more hydrophilic groups of MIPs which can be used in polar solvents, Luo et al 365 used anion compounds as hydrophilic functional monomers to synthesize water-compatible MIPs by precipitation polymerization. Compared with strong anion exchange SPE (SAX-SPE) and mixture anion exchange SPE (MAX-SPE) which were also used to determine water-soluble acid dyes in soft drinks and wastewater, only the proposed MISPE could remove almost all of the matrix interferences and exhibit higher selectivity, recovery and enrichment ability.…”

Chemical Mapping of Polymer Microstructure Using Soft X‐Ray Spectromicroscopy

“…[37,38] The properties of these systems-compatibility, release rate, resistance to a specific environment-are optimized for a given application by tuning the porosity and chemistry of the spatially differentiated components of the system. We are using STXM to assist optimization of several classes of these systems, including core-shell microspheres, [25,39] onionlike particles, [38] and polyurea and alginate capsules. [26] Recently we have combined two different encapsulation technologies-microspheres and capsules-in an assembled composite, or 'tectocapsule'.…”

“…[26] Recently we have combined two different encapsulation technologies-microspheres and capsules-in an assembled composite, or 'tectocapsule'. [24,25] In this novel approach to controlled release, the barrier functionality is provided by the capsule chemistry, while the release functionality is provided by the properties of porous microspheres embedded in an otherwise impermeable capsule wall. The polyurea capsules are generated through interfacial polymerization in an emulsion.…”

“…Use of a maleic anhydride acid linker greatly improved the microstructure, with the microspheres penetrating but sitting mostly on the outside of the capsule wall. [24,25] We used STXM to explore the spatial distribution of the acid linker, and thus to optimize its efficiency at controlling the assembly. Fig.…”

“…[24,25] Optimization of alginate microcapsules being developed for gene therapy applications. [26] Conducting polymers undergoing thermochromic transitions.…”