Eur. Phys. J. E 8, 121-128 (2002)
DOI: 10.1140/epje/i2001-10059-9
Film thickness effects on the distribution of high-molecular-weight heterotelechelic polymers
L.R. Hutchings1, R.W. Richards1, R.L. Thompson1 and D.G. Bucknall21 Interdisciplinary Research Centre in Polymer Science and Technology, University of Durham, Durham DH1 3LE, UK
2 ISIS Science Division Rutherford Appleton Laboratory Didcot, Oxon OX11 0QZ, UK
r.w.richards@durham.ac.uk
(Received 21 August 2001 and Received in final form 7 January 2002)
Abstract
High-molecular-weight heterotelechelic deuteriopolystyrene, NDPSF,
possessing an amine functional group at one end of the chain and a
fluorocarbon group at the other was tethered to a silicon substrate by its
amine functional group. These layers were coated with an unfunctionalised
polystyrene matrix, HPS, such that the total film thickness covered a range
from 2.2 to 9 times the radius of gyration of NDPSF. The detailed
distribution of the polymers after annealing for times much greater than the
reptation period of either of the components, was obtained using neutron
reflectometry. No evidence for bridging of the two interfaces was found for
the thicker films, but the finite concentration of the NDPSF polymer
observed for the thinnest films may be due to bridging since the energy gain
of the fluorocarbon end is just greater than the loss due to
configurational entropy losses. A linear increase in the ellipsometric
thickness of the excess of NDPSF at the substrate was discovered and we
attribute this to the NDPSF slowly being leached out of the layer initially
at the substrate followed by diffusion into the bulk of the film. The
concentration profiles obtained are consistent with hindered relaxation of
the large NDPSF molecules, when they are tethered at the substrate or at the
vacuum surface.
82.35.Gh - Polymers on surfaces; adhesion.
68.47.Mn - Polymer surfaces.
61.12.Ha - Neutron reflectometry.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002
