A facile synthesis method for polymer nanocapsules with high diffusion barrier and stimuli-responsive release properties is presented. The highly volatile fragrance α-pinene was used as hydrophobic model compound for the encapsulation process, which is based on a miniemulsion-analogous free radical polymerization process. The copolymer composition was systematically varied, and increasing contents of methacrylic acid as functional monomer in combination with high glass transition temperatures enabled unusually high encapsulation efficiencies of ≥90% for capsules with z-average diameters of <200 nm. Temperature and pH change can be used as trigger to open the capsules, and the release kinetics can be tailored depending on the polymer shell composition. In contrast to more frequently applied barrier microcapsules the nanocapsules provide drastically improved colloidal stabilities. Furthermore, the barrier nanocapsule approach is principally not restricted to fragrances and is expected to be compatible with other hydrophobic actives.

Crystallization of the poly(ethylene oxide) (PEO) confined in narrowly distributed, stable nanodroplets with a size of about 100 nm as obtained by the miniemulsion process is analyzed using DSC measurements. It is shown that nucleation in these PEO droplets occurs only at large supercooling. It is found that the polymer structure in the crystallized droplets is topologically controlled. PEO forms loosely layered lamellar structure in the droplets. Drying of the dispersion leads to a highly ordered arrangement of PEO platelets of different sizes but a constant height of about 25 nm as detected by TEM and AFM.

The crystallization of two oil-soluble dyes, oil red and oil blue, from the 125-nm-sized nanodroplets of miniemulsions, results in larger well-crystallized species of high quality, which must have been grown by aggregation of colloidal intermediates. This model case not only allows the existence of this nonclassical crystallization process to be proven but also gives evidence for the presence of "super-van der Waals" forces operating between the single nanocrystalline moieties.

The direct enzymatic polymerization of miniemulsions consisting of lactone nanodroplets represents a new and convenient pathway for the synthesis of biodegradable polymer nanoparticles, where the chemical composition and molecular weight can be varied in a certain range. Oligoesters completely end‐capped with an alkene or diene group can also be prepared by this technique. These building blocks extend polyester application as they allow to impart improved biodegradability to both siloxane and resin chemistry.TEM image of the polyester particles obtained by enzymatic polymerization in miniemulsion.magnified imageTEM image of the polyester particles obtained by enzymatic polymerization in miniemulsion.