  In this work, methods are presented to automatically generate a fully
atomistic LAMMPS models of arbitrary linear multiblock polyurethane copolymers.
The routine detailed here receives as parameters the number of repeat units per
hard block, the number of units in a soft block, and the number of soft blocks
per chain, as well as chemical formulae of three monomers which will form the
hard component, soft component, and chain extender. A routine is detailed for
converting the chemical structure of a free monomer to the urethane bonded
repeat units in a polymer. The python package RadonPy is leveraged to assemble
these units into blocks, and the blocks into copolymers. Care is taken in this
work to ensure that plausible atomic charges are assigned to repeat units in
different parts of the chain. The static structure factor is calculated for a
variety of chemistries, and the results compared with wide angle x-ray
scattering data from experiments with corresponding composition. The generated
models reproduce the amorphous halo observed in the scattering data as well as
some of the finer details. Structure factor calculations are decomposed into
the partial structure factors to interrogate the structural properties of the
two block types separately. Parametric surveys are carried out of the effects
of various parameters, including temperature, soft block length, and block
connectivity on the observed structure. The routine detailed here for
constructing models is robust enough to be executed automatically in a high
throughput workflow for material design and discovery.
