Synthesis Of Unimolecular Micelles With Incorporated Hyperbranched Boltorn H30 Polyester Modified With Hyperbranched Helical Poly(phenyl Isocyanide)Chains And Their Enantioselective Crystallization Performance

Chiral polymeric materials have received ever-growing attention in recent years and played an important role in many fields.In this contribution,we report on the fabrication of helical polymeric chains functionalized unimolecular micelles as a chiral nucleating agent in enantioselective crystallization of racemic threonine.Starting from a fractionated hyperbranched polyester(Boltom H30),the ring-opening polymerization of L-lactic acid(LLA)from the hydroxyl around H30 and subsequent terminal group modification afforded alkyne-Pd(?)anchored hyperbranched polymer-based macroinitiator(H30-PLLA-Pd).By taking advantage of a Pd(?)catalyzed living polymerization of chiral pendant modified optically active L-or D-phenyl isocyanide(PI)monomers,well-defined chiral unimolecular micelles(H30-PLLA-PPI)grafted with radiating helical PPI coronas of one predominant screw sense were obtained.Circular dichroism and UV-vis absorption spectra demonstrated that the chiral helical conformations of substituted poly(phenyl isocyanide)chains endowed the resultant unimolecular micelles excellent optical activity and exhibited excellent performance in enantioselective crystallization of racemic threonine.The enantiomeric excess(e.e.)of the induced crystal is up to 92%.We believe this present proof-of-concept and methodology are facile and powerful for preparing novel and versatile chiral materials with different topological structures,not only applicable to PPI but also to other types of polymers.