10.1021/la0351461.s001
L. Hamon
L.
Hamon
Y. Grohens
Y.
Grohens
Y. Holl
Y.
Holl
Thickness Dependence of the Glass Transition
Temperature in Thin Films of Partially Miscible Polymer
Blends
American Chemical Society
2003
Glass Transition Temperature
poly
PMMA
film
conformation energy Δ E
glass transition temperature
Partially Miscible Polymer Blends
modification
miscibility
bulk
stereoregular
T g
PEO
blend
2003-11-25 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Thickness_Dependence_of_the_Glass_Transition_Temperature_in_Thin_Films_of_Partially_Miscible_Polymer_Blends/3358975
The thickness dependence of the glass transition temperature, <i>T</i><sub>g</sub>(<i>h</i>), has been investigated using
ellipsometry at a variable temperature for thin films of partially miscible stereoregular poly(methyl
methacrylate) (PMMA)−low-molecular-weight poly(ethylene oxide) (PEO) blends. These values were
compared to <i>T</i><sub>g</sub>(h) values of pure stereoregular PMMA thin films, and the miscibility of PMMA/PEO
systems is assessed by the so-called plasticizing effect of PEO, that is, Δ<i>T</i><sub>g</sub>*. In thin-film geometry, the
miscibility of i-PMMA is enhanced compared with that in the bulk and becomes higher than that for
s-PMMA in contrary to the bulk behavior of the blends. The conformation energy Δ<i>E</i> of the PMMA chains
in the thin film increase much more for s-PMMA than for i-PMMA, indicating larger gauche to trans
conformational rearrangement for the former isomer in the confined geometry. These large local modifications
of the s-PMMA conformation in the thin film could result in modification of the mixing entropy and,
therefore, be the main reason for the lower miscibility of PEO in s-PMMA as compared to that in i-PMMA.