Distribution of nanoparticles in lamellar domains of block copolymers

Polystyrene-coated gold nanoparticles (molecular weight (M-n) of PS similar to 1300 g/mol, average particle diameter d (core + shell) similar to 9.2 +/- 2.2 nm, corresponding to a high areal chain density of PS) are incorporated into symmetric poly(styrene-b-2 vinylpyridine) diblock copolymers with total M-n similar to 60 000-380 000 g/mol at volume fractions of 0.07-0.32. For all M-n of diblock copolymers and particle filling fractions examined, particles are centralized in the PS domains with Gaussian distribution profiles. The distribution width generally decreases as the PS domain size decreases or as the particle weight fraction increases. These observations are discussed in terms of the relative entropic contributions of the polymer chains and particles.