Effect of Homopolymer Matrix on Diblock Copolymer Grafted Nanoparticle Conformation and Potential of Mean Force: A Molecular Simulation Study

We study the effect of homopolymer A or B matrix on the conformations and effective interactions of AB diblock copolymer grafted particles using coarse-grained molecular dynamics simulations. In an A homopolymer matrix we observe patchy conformations within the AB diblock copolymer grafted layer, where the number of B patches is controlled by the A-A attractive interaction strength. In a B homopolymer matrix the grafted particle takes on a core-corona conformation, where the inner A block aggregates near the particle surface and the outer B block forms a corona that interacts with the B matrix. The potential of mean force (PMF) between two particles in an A homopolymer matrix has a long-ranged attractive well with a minima at intermediate distances corresponding to the location of the outer B block patches. The PMF between two particles in a B homopolymer matrix has an attractive well at short interparticle distances corresponding to the size of the inner A block. We isolate the contribution of the homopolymer matrix on the PMF between the two diblock copolymer grafted particles, by deducting the PMF in the absence of a matrix, assuming the contributions of the grafted particle and matrix to the PMF to be additive. (C) 2014 Wiley Periodicals, Inc.