Atomic force microscopy study of self-assembly behaviors of hydrophobic poly(n-butyl methacrylate)-block-polydimethylsiloxane-block-poly(n-butyl methacrylate) ABA triblock copolymers

Poly(n‐butyl methacrylate)‐block‐polydimethylsiloxane‐block‐poly(n‐butyl methacrylate) (PBMA‐block‐PDMS‐block‐PBMA) ABA triblock copolymers were synthesized successfully via atom‐transfer radical polymerization using PDMS as macroinitiator. The effects of PDMS content and substrate nature on self‐assembly behaviors of PBMA‐block‐PDMS‐block‐PBMAs were systematically studied using atomic force microscopy. Two series of triblock copolymers with different molecular weights and compositions, i.e. PBMA‐block‐PDMSA12‐block‐PBMAs and PBMA‐block‐PDMSA21‐block‐PBMAs, were used, where the latter were of a higher PDMS content than the former. On silicon wafer, it was found that only spherical structures formed after annealing films spin‐coated from chloroform solutions of PBMA‐block‐PDMSA12‐block‐PBMAs. In contrast, films of PBMA‐block‐PDMSA21‐block‐PBMAs formed semi‐continuous structures. On mica wafer, it was found that ordered cylindrical pores formed after annealing films spin‐coated from chloroform solutions of PBMA‐block‐PDMSA12‐block‐PBMAs. In contrast, films of PBMA‐block‐PDMSA21‐block‐PBMAs formed isolated cylinders or worm‐like morphologies. Copyright © 2011 Society of Chemical Industry Highly ordered microdomains formed on films of poly(n‐butyl methacrylate)‐block‐polydimethylsiloxane‐block‐poly(n‐butyl methacrylate) for samples with (a) fPDMS = 0.178 and (b) fPDMS = 0.403 on silicon wafer, and for samples with (c) fPDMS = 0.178 and (d) fPDMS = 0.403 on mica wafer (where fPDMS is the volume fraction of polydimethylsiloxane).