Block copolymers are made of two or more polymeric blocks, each a sequence of identical monomers, attached by covalent bonds. At a low enough temperature, the incompatibility between different blocks leads to a micro-phase separation, and the copolymer self-assembles into an ordered morphology, such as lamellae, cylinders or spheres. The extraordinary variety of possible morphologies and their molecular dimension (5-100 nm) make block copolymers ideal materials to create structures at the nanoscale. To predict the self-assembly of block-copolymers, we have developed Monte Carlo simulations of a coarse-grained model . We focus on three different lines of research, often in close contact with the experimental work done in Prof. Nealey’s group.
- The directed assembly of block copolymers is a promising approach to extend lithographic processes and fabricate devices with critical dimensions below 10 nm. However, morphologies produced through spontaneous self-assembly usually lack the long-range order which is desirable for applications. The use of patterned substrates, either chemically or topographically, are two proposed solutions to enforce long-range order. We use our simulation to compare those strategies and identify under which conditions a defect-free assembly is obtained.
- Incorporating nanoparticles into self-assembling copolymers could prove useful for design of new functional materials. We have investigated how a mixture of nanoparticles (8 nm in diameter) and copolymers self-assemble when deposited in a thin film over patterned substrate. The distribution of nanoparticles predicted by simulation is in good agreement with the experimental result.
- Our simulations are used to predict the phase diagram of triblock copolymers, which remains largely unexplored.