Molecular Simulations Integrated Machine Learning Study of Bottlebrush Polymers

Thermosensitive bottlebrush polymers (BBPs) are a type of graft polymers in which thermosensitive polymer side-chains are grafted to a polymer backbone. Most of these thermosensitive polymers with lower critical solution temperature (LCST) can undergo a coil-to-globule conformational transition with increasing temperature. This further results in a change in the overall shape of the BBPs, which is one of the most important properties needed in many biomedical applications including drug delivery, molecular actuators, etc. In this talk, I will discuss our recent coarse-grained (CG) molecular dynamics (MD) simulations study of poly(N-isopropylacrylamide) (PNIPAM; LCST= 305 K) BBPs of four different shapes: 1. Worm-like, 2. Cone-like, 3. Cake-like and 4. Dumbbell-like. The CG MD simulations were performed at 290 K (below LCST) and 320 K (above LCST) in the presence of explicit CG water for 500 ns. The similarities and differences in the shapes of these BBPs were quantified by analyzing the simulation trajectories using machine-learning. Unexpectedly, both Cone-like and Cake-like BBPs were more similar to that of Worm-like BBPs compared to the Worm-like and Dumbbell-like BBPs.