Glass transition induced by solvent desorption
Glass transition and aging of polymers have been often studied using the temperature
as control parameter. A glassy polymer swollen by a solvent also shows a glass transition for a given solvent
concentration. Dynamic properties of polymer solutions have been less investigated, compared to pure polymers.
Experimental: A gravimetry set-up in a pressure (i.e. activity) controlled chamber is used
to get the drying and swelling kinetics of a polymer film. The glassy film is out of equilibrium so that
its structure strongly depends on all the previous history.
For example, Figure 2 shows the isotherms obtained for the three protocoles depicted in Figure 1 for a PMMA/Toluene film:
for each one the film is aged during 10 hours at a constant activity (a=0.4). In the first protocole (green curve), the film is brought to
a high activity after aging. In the two other protocoles, the activity is decreased to zero after (red curve) or before (blue curve)
As can be seen, the behavior of the film is not the same for the three protocoles:
it swells much more rapidly when it has been quenched at small activity after aging (red curve).
Using the approach proposed by Leibler et Sekimoto [Macromol. 1993, 26] and adding a glassy dynamics in the same way than classical TNM
models [Hodge, J. of Non-Crystalline Solids 169, 1994], a sorption model in the glassy state has been developped. Many observed phenomena
are qualitatively well captured by this model, but some of the obtained behaviors are still not understood (as the one of Figure 2) and
other theoratical approaches should be used (collaboration avec D.Long, UPS/LPMA).
- Mutual diffusion in PMMA/PnBMA copolymer films - Influence of the solvent induced glass transition
A.C.Dubreuil, F.Doumenc, B.Guerrier, C. Allain, Macromolecules 36, 14 (2003).
- Estimation of the characteristic times of solvent diffusion and polymer relaxation in glassy polymer films by a set inversion method
F.Doumenc, B.Guerrier IPSE 14, 7 (2006).
- Aging and history effects in solvent induced glass transition of polymer films
F.Doumenc, B.Guerrier, C.Allain EuroPhys. Lett. 76, 4 (2006).
- Physical aging of glassy PMMA/toluene films: Influence of drying/swelling history
F. Doumenc, H.Bodiguel, B.Guerrier EPJ-E 27, (2008).