Matrix Effects .on Interdiffusion at the Polystyrene and Poly(viny1 methyl ether) Interface

The effect of polystyrene (PS) matrix relaxation on interdiffusion at a PS and poly(viny1 methyl ether) (PVME) interface was investigated with attenuated total internal reflectance infrared spectroscopy (ATR-FTIR) at 105 and 85 "C, corresponding to 5 "C above and 15 "C below the Tg of PS, respectively. Monodisperse PS samples with M, of 3.0 x lo6 and 1.05 x lo5 were used to simulate relaxation in the PS matrix corresponding to chain reptation and constrained-releasemechanisms, respectively. A binary-blend of monodisperse PS samples consisting of short chains with M , of 3.0 x 104 and long chains with M , of 3.0 x lo6 was used to simulate relaxation in the PS matrix by tube dilation. In the binary PS blend, the short chains were deuterated in order to monitor the concentration of each component independently. Non-Fickian diffision was observed above and below the Tg of the PS matrix. Above the Tg of PS, interdiffusion was enhanced as the matrix relaxation mechanism changed from chain reptation to tube dilation to constrained release, consistent with the predicted relaxation time of these matrices. Below the Tg of PS, interdiffusion was controlled by the rate of swelling of PS by PVME and interdiffusion was faster in the binary PS blend due to the reduced entanglement density between the long chains.