Macromolecular Rapid Communications, Vol.34, No.20, 1642-1647, 2013
Nanoparticle-Driven Orientation Transition and Soft-Shear Alignment in Diblock Copolymer Films via Dynamic Thermal Gradient Field
Sharp dynamic thermal gradient (delta T approximate to 45 degrees C mm(-1)) field-driven assembly of cylinder-forming block copolymer (c-BCP) films filled with PS-coated gold nanoparticles (AuNPs; d(NP) approximate to 3.6 nm, phi(NP) approximate to 0-0.1) is studied. The influence of increasing AuNP loading fraction on dispersion and assembly of AuNPs within c-BCP (PS-PMMA) films is investigated via both static and dynamic thermal gradient fields. With phi(NP)increasing, a sharp transition from vertical to random in-plane horizontal cylinder orientation is observed due to enrichment of AuNPs at the substrate side and favorable interaction of PMMA chains with gold cores. Furthermore, a detachable capping elastomer layer can self-align these random oriented PMMA microdomains into unidirectional hybrid AuNP/c-BCP nanolines, quantified with an alignment order parameter, S.