Skip to main content Accessibility help

Multiscale modeling of polymers closely coupled to Broad Q neutron scattering from NIMROD

  • Thomas Gkourmpis (a1), Daniel Lopez (a2) and Geoffrey R. Mitchell (a3)


We use data over an extended Q range from 0.01 to 100Å-1 from the recently commissioned NIMROD instrument at the ISIS pulsed neutron source to develop a multi-scale inverse modeling procedure which will provide insight in to the phase transformations of polymer systems. The first level of our procedure is atomistic and we use internal coordinates (bond length, bond angles and torsion angles) to define the polymer chain in full atomistic detail. Values were assigned to each internal coordinate within the chain using a stochastic Monte Carlo method in which the probabilities were drawn from distributions representing the possible range of values. Using this approach, random chain configurations could be rapidly built and the intrachain structure factor calculated utilizing a small set of parameters and compared with the experimental function. Parameters representing the probability distribution functions were systematically varied using a grid search to find the values which gave the best fit to the structure factor for Q > 3Å-1 in order to determine the details of the chain conformation in the molten phase. This process was repeated for data over the same extended Q range obtained at lower temperatures where the polymer was expected to crystallize. Polymers crystallize via chainfolded thin lamellae crystals. Such crystals give rise to an intense peak at Q ∼ 0.03Å-1. This scattering can be calculated using a lamellar stack model, coarse-grained from the single chain structure. We describe this approach using data obtained on the crystallization from the melt phase of perdeuterated polymers. The objective here is to follow the three key length scales; the chain folded lamellar thickness of ∼ 10nm, the crystal unit cell ∼ 1nm and the detail of the chain conformation is ∼ 0.1nm.



Hide All
1. Flory, P.J. J Chem. Phys 17 303 (1949)10.1063/1.1747243
2. Wright, A. C. in Experimental Techniques of Glass Science, edited by Simmons, C. and El-Bayoumi, O., (Ceramic Transactions, American Ceramic Society, 1993) p. 205314
3. Mitchell, G. R. in Essentials of Neutron Techniques for Soft Matter, edited by Imae, T., Kanaya, T. and Furusaka, M., (Wiley 2010) p. 571599
4. Mitchell, G. R., Rosi, B., Ward, D. J., Trans. Roy. Soc. (London) Series A, 348, 97115 (1994)
5. Mitchell, G. R., Lovell, R., and Windle, A. H., Polymer, 1982, 23, 1273 10.1016/0032-3861(82)90267-1
6. Rosi-Schwartz, B. and Mitchell, G. Polymer 35, 5398 (1994).10.1016/S0032-3861(05)80002-3
7. Gkourmpis, T. and Mitchell, G. R., Macromolecules, 44, 31403148 (2011)10.1021/ma102840p
8. Rosi-Schwartz, B., Mitchell, G. R., Physica T57 161167 (1995)
9. Mitchell, G.R. MESA Molecular Editor for Structural Analysis User Guide Version 4.1 Institute Polytechnic Leiria (2012)
10. Gkourmpis, T. and Mitchell, G. R., Phys. Rev. B, (submitted)
11. Tadokoro, H. in Structure of Crystalline Polymers Wiley (1979)
12. Roe, R-J. Methods of X-ray and Neutron Scattering in Polymer Science OUP USA (2000)


Multiscale modeling of polymers closely coupled to Broad Q neutron scattering from NIMROD

  • Thomas Gkourmpis (a1), Daniel Lopez (a2) and Geoffrey R. Mitchell (a3)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed