Nuclear Reaction Analysis Studies on the Interface Formation in Polymer Mixtures

Abstract

We have measured the composition profile between two polymer phases above and below their critical temperature for phase separation Tc, using the 2H(3He,4He)1H nuclear reaction in a direct profiling technique. Above Tc, we verify the “thtrmodynamic slowing down” effects on interdiffusion close to the critical point. Pelow Tc, we find that the width of the interface grows with time to a finite limiting value. The variation of this limiting value, as Tc, is approached from below is in good agreement with the predictions of mean-field theories. The time dependence of the initial interfacial broadening below Tc has been found to be significantly slower than t1/2.

Interdiffusion of Short Chain Oligomers into an Entangled Polymer Film

“…The technological significance of interdiffusion has driven a large number of experimental [5][6][7][8][9][10][11][12][13][14][15][16] and theoretical 12,[17][18][19][20][21][22][23] studies. Some of the these studies investigated interdiffusion of short oligomers below the entanglement length N e .…”

“…20,21 Other studies have focused on interdiffusion for two entangled polymers, for which both are much longer than the entanglement length N e . 5,6,9,11,12,[17][18][19]22,23 Kramer et al followed the diffusion of Au nanoparticles markers which were initially placed at the interface between two monodispersed entangled polystyrene (PS) films. 5 They found that the displacement of the markers scaled with time t as t 1/2 , in agreement with Fickian diffusion.…”

“…10 Other studies have used nuclear reaction analysis to study the interdiffusion of protonated and deuterated PS films. 7,9 Since the Flory-Huggins interaction parameter, χ, between protonated and deuterated segments is nonzero, the interfacial width was found to increase as t R with R between 0.27 and 0.36 depending on temperature for early times and then saturate for late times. Short oligomers interdiffusing into an entangled polymer have been studied by Bucknall et al 13 using neutron reflectivity.…”

“…The technological significance of interdiffusion has driven a large number of experimental − and theoretical ,− studies. Some of the these studies investigated interdiffusion of short oligomers below the entanglement length N e . , Other studies have focused on interdiffusion for two entangled polymers, for which both are much longer than the entanglement length N e . ,,,,,− ,, Kramer et al followed the diffusion of Au nanoparticles markers which were initially placed at the interface between two monodispersed entangled polystyrene (PS) films . They found that the displacement of the markers scaled with time t as t 1/2 , in agreement with Fickian diffusion.…”

“…Reiter et al extended this work to include diffusion of Au nanoparticle markers at the interface between PS films of different molecular weight, finding a weight-dependent induction time for the movement of the markers in addition to their eventual Fickian diffusion . Other studies have used nuclear reaction analysis to study the interdiffusion of protonated and deuterated PS films. , Since the Flory−Huggins interaction parameter, χ, between protonated and deuterated segments is nonzero, the interfacial width was found to increase as t α with α between 0.27 and 0.36 depending on temperature for early times and then saturate for late times. Short oligomers interdiffusing into an entangled polymer have been studied by Bucknall et al using neutron reflectivity.…”