Microcapsules Loaded with Smart Polymers

These systems are based on the sensitivity of encapsulated stimuli-responsive polymers. In this case, the response of the material may also affect the microcapsule itself, depending on the interactions between the loaded substance and the polymeric microcontainer. 

Encapsulated PAA, introduced inside (PAH/PSS) capsules by changing their permeability with pH, remains sensitive to divalent ions such as Ca and the formation of an insoluble complex in the interior of the capsules was observed (Fig. 3.5) when these loaded capsules were immersed in an aqueous Ca solution [31]. 

The complexation is reversible as the addition of acid dissolves the complex with release of ions and re-solubilization of the polymer inside the capsule. 

Another way to introduce polymers inside the capsules was described by Dahne et al. [35] with the so-called ship in a bottle synthesis, applied to PSS. The resulting loaded capsules became swollen under basic conditions [36]. The diameter decreased 

F re 3.5 Confocal laser scanning micrograph of reversible precipitates of Ca +/PAA complex formed inside capsules filled with poly(acrylic acid) (PAA). 

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