# Empirical Potential Structure Refinement of semi-crystalline polymer systems: polytetrafluoroethylene and polychlorotrifluoroethylene

Source: [Empirical Potential Structure Refinement of semi-crystalline polymer systems: polytetrafluoroethylene and polychlorotrifluoroethylene](<https://www.sota2.com/research/paper/68fa2cb41e209131ce852799>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T15:31:06.902Z

Authors: A K Soper, K Page, A Llobet

Published: 2013-09-26T15:37:19.000Z

## Abstract

Empirical potential structure refinement (EPSR) simulations are performed on total neutron scattering data from powder samples of polytetrafluoroethylene (PTFE) and polychlorotrifluoroethylene (PCTFE), both at 300K. For PTFE a number of Bragg peaks are visible in the scattering data and these are found to be consistent with a lattice spacing $a(=b)=5.69(1)$\\AA\\ with a dihedral angle along the (helical) chain of 166$^\\circ$ which gives a repeat distance along the chain (c-axis) of $\\sim$19.6\\AA. The positions of the Bragg peaks are well reproduced by this model, although there is a mismatch in the amplitudes of some of the higher order reflections between simulation and data. For PCTFE there is only one visible Bragg peak (100) which is well reproduced by a hexagonal lattice of atactic parallel polymers with a spacing of $a(=b)=6.37(1)$\\AA. In this case the absence of distinct reflections along the polymer c-axis makes characterisation of the internal dihedral angle difficult, but a model with nearly straight \\textit{trans} (zig-zag) structure gives best agreement with the data. For PCTFE little change in structure could be discerned when the material was heated to 550K, apart from a slight increase in lattice spacing. In both cases there is substantial diffuse scattering between the Bragg peaks, and this is correctly replicated by the EPSR simulations.

## Recorded benchmark results

A research result applies to its stated dataset, split, metric and evaluation configuration. Compare like-for-like settings, preserve the metric's unit and direction, and distinguish paper-reported results from independent reproduction. The best result recorded here is not a claim of exhaustive, current global coverage.

## Original sources and implementation

[Original paper](<https://arxiv.org/abs/1309.6943>)

[PDF](<https://arxiv.org/pdf/1309.6943.pdf>)