Surface dynamics of a thin polystyrene film probed by low-energy muons

Pratt, F. L.; Lancaster, Thomas M.; Brooks, Michael; Blundell, Stephen J.; Prokscha, T.; Morenzoni, E.; Suter, A.; Luetkens, H.; Khasanov, R.; Scheuermann, R.; Zimmermann, U.; Shinotsuka, Kei; Assender, Hazel E.

doi:10.1103/physrevb.72.121401

Cited by 27 publications

(28 citation statements)

References 21 publications

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“…The dependence of T g on the mean implantation depth below the free surface is very similar for both analysis methods and shows significant suppression with respect to the bulk value for depths of 20 nm and below. The fractional suppression of T g at the surface is of order 20%, which is comparable with that seen in our other LEM studies of PS [10] and PB [15], as well as matching the reduction found at a free polymer surface in molecular dynamics simulations [23]. The length scale for this surface T g suppression is comparable to the random coil end-to-end distance R EE for this molecular weight of polymer.…”

Section: Data For Pdmssupporting

confidence: 73%

“…an environment without unpaired electronic spins. This is in contrast to the two earlier LEM reports on PS that used paramagnetic muoniated radicals as the probe states [10,13].…”

Section: Introductioncontrasting

confidence: 50%

“…In the decade since the first LEM studies of a polymer surface were made in 2005 [10] the capabilities of the PSI-LEM instrument have significantly improved, with data rates being enhanced following the construction of a new beamline. Recently a spin rotator has been installed that allows both TF and LF studies to be made.…”

Section: Discussionmentioning

confidence: 99%

“…Our previous LEM study of PS used the zero field (ZF) configuration [10], where the relaxation is dominated by paramagnetic muoniated radical states [11,12] (the various types of muon probe state are discussed in detail in section 3). Evidence was found there for a significant suppression of T g compared to the bulk value, with the region of suppressed T g extending over a length scale of order 40 nm below the free surface.…”

Section: Introductionmentioning

confidence: 99%

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Nanoscale depth-resolved polymer dynamics probed by the implantation of low energy muons

Pratt

Lancaster

Baker

et al. 2016

Polymer

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(2016) 'Nanoscale depth-resolved polymer dynamics probed by the implantation of low energy muons. ', Polymer., Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThe low energy muon (LEM) technique has been used to probe local changes in the dynamical spectrum of thin film polymer samples taking place as a function of the temperature and the implantation depth below the free surface. The studies have been made on samples of polydimethylsiloxane (PDMS) and polybutadiene (PB) using the transverse magnetic field (TF) configuration and diamagnetic probe muons. In PDMS evidence is found for suppression of the glass transition temperature near the surface, along with significantly modified dynamics in the near-surface region as well as at depths significantly below the surface. For PB the LEM technique reveals well-defined layers of dynamical and spatial inhomogeneity at depths of order 0.1 to 0.2 µm below the free surface. These inhomogeneous regions may be assigned to nanopores produced by solvent streaming during preparation of spin-cast films. A thermal annealing procedure is shown to significantly reduce the thickness of these inhomogeneous layers. These results demonstrate that using LEM in the TF configuration provides a promising new method for studying surface-modified local dynamics of polymers that is also able to reveal nanostructured buried layers in polymer films.

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Section: Data For Pdmssupporting

confidence: 73%

“…an environment without unpaired electronic spins. This is in contrast to the two earlier LEM reports on PS that used paramagnetic muoniated radicals as the probe states [10,13].…”

Section: Introductioncontrasting

confidence: 50%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nanoscale depth-resolved polymer dynamics probed by the implantation of low energy muons

Pratt

Lancaster

Baker

et al. 2016

Polymer

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“…Is there an alternative method for evaluating heterogeneous dynamics without resorting to labeling or multilayered methods? Pratt et al [69] studied the dynamics of polymer thin films at different positions in a polymer thin film using slow muons with different incident energies. The advantage of their method is that the dynamics at the desired position in a thin film can be probed just by changing the incident muon energy, which corresponds to changing the interpenetration depth in the thin film.…”

Section: Discussionmentioning

confidence: 99%

Heterogeneous Dynamics of Polymer Thin Films as Studied by Neutron Scattering

Inoue

Kanaya

2012

Glass Transition, Dynamics and Heterogeneity of Polymer Thin Films

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This review covers recent progress in studies on the dynamics of polymer thin films in the glassy state and near the glass transition temperature, as revealed by neutron scattering. First, the glassy dynamics including low energy excitation (Boson peak) and the fast localized process of polymer thin films at the picosecond timescale was studied to reveal the effect of film thickness. The dynamic heterogeneity of polymer thin films in the glassy state was also evaluated in terms of non-Gaussian parameters. Second, the glass transition temperature of polymer thin films was investigated using inelastic neutron scattering with highenergy resolution to clarify the mechanism of its dependence on film thickness. Finally, neutron reflectivity was used to study the distribution of glass transition temperature in a multilayered thin film consisting of deuterated polymer and hydrogenated polymer.

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In situ AFM study of near‐surface crystallization in PET and PEN

Shinotsuka

Assender

2016

J of Applied Polymer Sci

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The surface crystallization behavior of poly(ethylene terephthalate) (PET) and poly(ethylene 2,6-naphthalate) (PEN) spincoated thin films was compared by means of atomic force microscopy (AFM) with an in situ heating stage. As the films were heated up stepwise, characteristic surface crystals appeared at a crystallization temperature (T c ) in the near-surface region which is about 15 8C under the bulk T c , and were replaced by bulk crystals when the temperature was increased to the bulk T c . In the case of films whose thickness is less than 70 nm (PET) and 60 nm (PEN), significant increases in the bulk T c were observed. Scanning force microscopy (SFM) force-distance curve measurements showed that the glass transition temperature (T g ) of the near-surface region of PET and PEN were 22.0 and 26.6 8C below their bulk T g (obtained by DSC). After the onset of surface crystallization, edge-on and flat-on crystals appeared at the free surface of PET and PEN thin films, whose morphologies are very different to those of the bulk crystals. Although the same general behavior was observed for both polyesters, there are significant differences both the influence of the surface and substrate on the transition temperatures, and in morphology of the surface crystals. These phenomena are discussed in terms of the differences in the mobility of polymer chains near the surface.

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Surface dynamics of a thin polystyrene film probed by low-energy muons

Cited by 27 publications

References 21 publications

Nanoscale depth-resolved polymer dynamics probed by the implantation of low energy muons

Nanoscale depth-resolved polymer dynamics probed by the implantation of low energy muons

Heterogeneous Dynamics of Polymer Thin Films as Studied by Neutron Scattering

In situ AFM study of near‐surface crystallization in PET and PEN

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