Combined atom-transfer radical polymerization and ring-opening polymerization to design polymer-polypeptide copolymer conjugates toward self-aggregated hybrid micro/nanospheres for dye encapsulation

Abstract

This paper describes the designed synthesis of well-defined poly (methyl methacrylate)-block-polytyrosine (PMMA-b-Ptyr) copolymer conjugate from a dual initiator via combination of atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA), “Click chemistry” and ring-opening polymerization (ROP) of tyrosine-N-carboxyanhydride (NCA). The initial study of self-aggregation of PMMA-b-Ptyr conjugate in DMF reveals formation of hybrid micro/nanospheres as confirmed by field emission scanning electron microscopy (FESEM) and dynamic light scattering (DLS). It is observed that the sizes of the hybrid spheres increase with the increase of time of aggregation of PMMA-b-Ptyr conjugate in DMF. However, in depth study reveals that PMMA-b-Ptyr conjugate self-aggregates into different morphologies depending on the relative ratio of PMMA and Ptyr blocks in DMF as well as in alkaline water. We devised a simple solution-based approach to encapsulate an organic dye (Rhodamine-6G) into the aggregated hybrid micro/nanospheres as established by fluorescence microscopy and time-correlated single photon counting (TCSPC) techniques. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015