Synthesis of Poly(N-H benzamide)-b-poly(lauryl methacrylate)-b-poly(N-H benzamide) symmetrical triblock copolymers by combinations of CGCP, SARA ATRP, and SA ATRC

Abstract

We design a novel ABA type triblock copolymer (triBCP) by performing efficient synthetic methods of chain-growth condensation polymerization (CGCP), supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP), and styrenics-assisted atom transfer radical coupling (SA ATRC). A well-defined poly(3-(N-(octyloxy)benzyl benzamide) having a 2-bromo-2-phenylacetate effective ATRP initiating site (i.e., POOBBA-BrPA) through CGCP following quantitative chain end modifications, was firstly synthesized. The POOBBA-BrPA macroinitiator then conducted chain extension with lauryl methacrylate (LMA) via SARA ATRP to obtain the POOBBA-b-PLMA-Br diBCP (Mn = 8800 and Mw/Mn = 1.15). This was followed by SA ATRC of POOBBA-b-PLMA-Br with a high extent of coupling (xc = 0.85, Mn = 15300, and Mw/Mn = 1.26). The obtained triBCP was further purified and the selective removal of the protecting group yielded poly(N-H benzamide)-b-poly(lauryl methacrylate)-b-poly(N-H benzamide) (i.e., PNHBA-b-PLMA-b-PNHBA) was conducted. The characterization of these copolymers was performed using 1H NMR, GPC, FT-IR, TGA, DSC, AFM and SAXS.