Polymers in prison
15 Nov 2011



High-resolution inelastic neutron scattering experiments reveal that the polymer, poly(ethylene oxide), under extreme confinement adopts a conformation different to that of the bulk crystal.

Poly(ethylene oxide) confined between two graphite-oxide sheets, leading to a single polymer layer of thickness ~3.4 Å. Neutron spectroscopy shows that the polymer is forced to adopt an unfolded planar conformation.

Polymer confinement at nanometer length scales can lead to significant changes in physicochemical properties including chain conformation and macromolecular relaxation. In this work, two-dimensional confinement of the ubiquitous polymer poly(ethylene oxide) was achieved via its intercalation into graphite oxide, leading to well defined (subnanometer) polymer layers of thickness ~3.4 Å.

 The extreme spatial confinement of the polymer phase is responsible for the suppression of crystallization and cooperative relaxation processes. For the first time, high-resolution inelastic neutron scattering experiments on Tosca show that poly(ethylene oxide) under these extreme confinement conditions adopts a planar zig-zag conformation which in no way resembles the characteristic helical structure of the bulk crystal. Moreover, the neutron data also account for a drastic reduction in long-range order and chain mobility.

F Barroso-Bujans, S Cerveny, A Alegría, J Colmenero (CSIC/UPV-EHU, Spain), F Fernandez-Alonso, SF Parker (ISIS)

Research date: August 2011

Further Information

Contact: Dr F Barroso-Bujans, fbarroso@ehu.es
Further reading: F Barroso-Bujans et al.,
Soft Matter 7 (2011) 7173