Coarse-grained molecular dynamics integrated with convolutional neural network for comparing shapes of temperature sensitive bottlebrushes

Authors:

SY Joshi, S Singh, SA Deshmukh

Affiliation:

Department of Chemical Engineering, Virginia Tech, Blacksburg, VA, 24061, USA

Description:

Quantification of shape changes in nature-inspired soft material architectures of stimuli-sensitive polymers is critical for controlling their properties but is challenging due to their softness and flexibility. Here, we have computationally designed uniquely shaped bottlebrushes of a thermosensitive polymer, poly(N-isopropylacrylamide) (PNIPAM), by controlling the length of side chains along the backbone. Coarse-grained molecular dynamics simulations of solvated bottlebrushes were performed below and above the lower critical solution temperature of PNIPAM. Conventional analyses (free volume, asphericity, etc.) show that lengths of side chains and their immediate environments dictate the compactness and bending in these architectures. We further developed 100 unique convolutional neural network models that captured molecular-level features and generated a statistically significant quantification of the similarity between different shapes. Thus, our study provides insights into the shapes of complex architectures as well as a general method to analyze them. The shapes presented here may inspire the synthesis of new bottlebrushes.

Publications:

  • Soumil Y. Joshi, Samrendra Singh, Sanket A. Deshmukh; Coarse-grained molecular dynamics integrated with convolutional neural network for comparing shapes of temperature sensitive bottlebrushes; npj Computational Materials, 2022
  • Tags:

    Atomistic simulation
    Bottlebrush polymers
    Machine learning

    Files:

    File Name File Description File Type File Size File URL
    BBP shapes CNN training data Contains BBP bead coordinates. Everything is segregated according to the shapes and temperatures. There are 500 coordinate files spanning a 500 ns simulation trajectory - separated as initial (first 150 frames), final (last 150 frames and the remaining 200 frames from the middle of the simulation. There is a different coordinate file for every frame. These files consist of three columns that contain the x, y and z coordinates for all beads in the BBP. The order of these beads remains consistent for every shape. zip 264.52 MB Login to download
    Simulation parameter files Coarse grained PNIPAM interaction parameters developed in the group used for running BBP simulations. prm 1.07 KB Login to download
    Starting configurations for BBP simulations Contains all PDB and PSF files used for running simulations using the NAMD package. zip 32.58 MB Login to download
    NAMD configuration files - Minimization Representative NAMD configuration file used for minimization. namd 1.94 KB Login to download
    NAMD configuration file - Production Representative NAMD configuration file for production run namd 2.16 KB Login to download