Optimizing Chain Topology of Bottle Brush Copolymer for Promoting the Disorder-to-Order Transition

The order-disorder transitions (ODT) of core-shell bottle brush copolymer and its structural isomers were investigated by dissipative particle dynamics simulations and theoretically by random phase approximation. Introducing a chain topology parameter lambda which parametrizes linking points between M diblock chains each with N monomers, the degree of incompatibility at ODT ((chi N)ODT; chi being the Flory-Huggins interaction parameter between constituent monomers) was predicted as a function of chain topology parameter (lambda) and the number of linked diblock chains per bottle brush copolymer (M). It was found that there exists an optimal chain topology about lambda at which (chi N)ODT gets a minimum while the domain spacing remains nearly unchanged. The prediction provides a theoretical guideline for designing an optimal copolymer architecture capable of forming sub-10 nm periodic structures even with non-high chi components.