Reactive micro-nano encapsulation: a way to high performance polymer materials

Abstract

The lecture presents the work at IPC-University of Minho towards the synthesis of advanced polymer materials via reactive microencapsulation strategy. First, the possibility to develop hybrid composite materials with tailored electromagnetic and dielectric properties from shell-core polyamide microcapsules is presented. For this purpose, polyamide microcapsules were synthesized by activated anionic ring-opening polymerization (AAROP) of ε-caprolactam. The process was carried out in solution, in the presence of various metal particles, four finely divided carbon allotropes and metal/carbon mixtures. By conventional melt processing PAMC were transformed into thermoplastic polyamide-based hybrid composites. This fabrication concept permits easy and simultaneous introduction into the polyamide matrix of different fillers, in wide concentration ranges (up to 30 wt%) and with controlled dispersion. In such a way, PA6-based hybrid composites with tailored conductivity, magnetic and dielectric properties can be produced. The loaded polyamide microcapsules can also be useful without melt processing. Combining the microencapsulation strategy with molecular imprinting allowed the preparation of smart biodegradable microparticles susceptible to external magnetic fields and bearing recognition sites sensitive to BSA as target analyte. For this reason, AAROP of 2-pyrrolidone was performed in the presence of Fe nanoparticles and BSA at 40ºC. Subsequently, the BSA was removed to produce the molecularly imprinted particles (MIP). MIP were characterized by various microscopy, spectral, X-ray and thermal techniques. The selectivity of MIP toward BSA was found to be increased by 56% as compared to neat polyamide particles. The presence of magnetic cores in MIP allows their easy and fast removal from the analytic system. Other examples of PA6 microcapsules without and with chemical functionalization potentially useful for drug delivery systems will also be presented.