Synthesis of bottlebrush block copolymers from bottlebrush polystyrene and bottlebrush random copolymer of ω‐end‐norbornyl polymethacrylates and their self‐assembly

Abstract

Six different bottlebrush block copolymers (BBCPs) (A‐b‐(B‐co‐C)) from bottlebrush polystyrene (A) and bottlebrush random copolymers (B‐co‐C) of polymethacrylates were synthesized through living anionic polymerization and ring‐opening metathesis polymerization. To induce the phase separation of bottlebrush polystyrene (PNB‐g‐PS) (A) and bottlebrush poly(benzyl methacrylate) (PNB‐g‐PBzMA) (C)‐based BBCP with an extremely low Flory–Huggins interaction parameter (χ), three kinds of bottlebrush polymethacrylates (B): poly(norbornene‐g‐methyl methacrylate) (PNB‐g‐PMMA), poly(norbornene‐g‐tert‐butyl methacrylate) (PNB‐g‐PtBMA), and poly(norbornene‐g‐methacrylic acid) (PNB‐g‐PMAA), respectively, were randomly combined with C. An order–disorder phase transition of the BBCPs (A‐b‐(B‐co‐C)) was observed with a change in mole ratios of PMMA, PtBMA, or PMAA to PBzMA of 25, 50, and 75% in random copolymer blocks using field‐emission scanning microscopy. While the BBCP with 25% of PMAA in the random copolymer block showed an ordered lamellar nanostructure, a disordered morphology was revealed at 75% PMAA. SEM showed that the incorporation of PtBMA and PBzMA showed better‐ordered lamellar morphologies than was the case with PMMA and PBzMA at the same mole ratios.