The self-assembly of sequence-defined ionic peptoid block copolymers consisting of hydrophilic and hydrophobic segments in aqueous solution was studied by atomistic molecular dynamics simulations. These studies revealed that the micellar structure and shape can be modulated by controlling the position of the charged moiety along the amphiphilic block copolymer chain. However, the computational expense limits simulation times and system sizes to a hundred nanoseconds and tens of nanometers, respectively, necessitating the development of coarse-grained (CG) models to study larger and more complex peptoid systems with different number of ionic monomers and multiple types of hydrophilic side groups. A CG model for N, N-dimethylacetamide (DMA), which represents the polypeptoid backbone, is developed as a step towards developing a CG model of the complex polypeptoids system. The DMA CG model based on the Stillinger-Weber potential and OPLS-UA force field is parameterized to reproduce the properties of solvation structures of dilute DMA solution and DMA liquid using a reference all-atom mode, namely the OPLS-AA force field. The model is validated on thermodynamic and structural properties of different DMA-water systems as well as a simple peptoid-water system. Without long-range interactions and the absence of interaction sites on hydrogen atoms, the CG DMA model is an order of magnitude faster than the higher resolution AA model.

Computational study of self-assembly of polypeptoids in aqueous solution: From atomistic to coarse-grained simulations

2019 Spring National Meeting

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