On stereocomplexed polylactide materials as support for PAMAM dendrimers: synthesis and properties

Stereocomplexed polylactide materials functionalized with poly(amido-amine) (PAMAM) dendrimer units were prepared by solution blending dendritic poly(D-lactide) (PDLA) star oligomers into a commercial poly(L-lactide) (PLLA), where the dendritic PDLA star oligomers were built up by ring-opening polymerization of D-lactide using a PAMAM dendrimer as macroinitiator. Whereas the synthesized poly(D-lactide)s (whose star-like architecture, comprising the PAMAM dendrimer as the core and a multi-arm PDLA shell, was demonstrated by means of H-1 NMR spectroscopy) were observed to hardly structure/crystallize, their blended films, as revealed by DSC and WAXD measurements, proved capable of easy stereocomplexation in solution and melt crystallization alike. The stereocomplex, whose content and characteristics are greatly affected by the structure of the PDLA stars, affords improved thermal and chemical resistance, while simultaneously providing a strong link for the PAMAM units to the polymer matrix. The PAMAM dendrimers can thus manifest themselves, while being anchored onto a water/(solvent)insoluble, easy-processable polymeric support, which, in addition, is bio-based and biodegradable and keeps the characteristics of biocompatibility. Indeed, thanks to the presence of the PAMAM functionalities, and unlike the neat polylactide, the resulting materials were shown to possess significant water-absorbency and Pd(II)-uptake-ability. This latter property was exploited for the removal of Pd catalyst from a homogeneous reaction system.