Variations in the glass transition temperature of polyester with special architectures confined in thin films

A molecular-level computational study of the diffusion and solubility of water and oxygen in carbonaceous polyethylene nanocomposites

“…In addition, when the distance between two confining surfaces (or additives) is decreased, the gradient disappears because of the overlap of the immobilized regions; however, interestingly, the overall mobility increases . Weak or repulsive interactions have been reported to increase the dynamics and hence lower the T g . As discussed below, the static and dynamic properties of the polymer matrix affect the solubility, diffusion, and permeation of water and oxygen in the studied nanocomposites.…”

“…An attractive interaction leads to an increase in monomer density in the vicinity of the additive, when compared with the bulk, whereas a repulsive interaction results in a depletion in the vicinity of the additive . Slower dynamics (and thus an increased glass transition temperature, T g ) close to the confining surface has been reported when there are attractive interfacial forces between the additive surface and the polymer chains . The dynamics is hence slower in this region than in the bulk, and a gradient between the two regions can exist .…”

“…6 One way to control the permeability of water and oxygen through PE is to include additives in the matrix. 18 These additives can act either as physical barriers, 19 affect the structure 8,9,[20][21][22][23] and dynamics [23][24][25] of the polymer matrix, or bond physically or chemically with the penetrant molecules.…”

“…26,27 The introduction of relatively rigid additives like these in polymer systems induces confinement effects in the surrounding polymer chains. [22][23][24][25] Both the structural (static) and the dynamic behavior of confined polymer matrices have been studied extensively. 8,9,[20][21][22][23][24][25] The effect on the polymer structure is dependent on the interactions between the polymer and the additive.…”

“…[22][23][24][25] Both the structural (static) and the dynamic behavior of confined polymer matrices have been studied extensively. 8,9,[20][21][22][23][24][25] The effect on the polymer structure is dependent on the interactions between the polymer and the additive. An attractive interaction leads to an increase in monomer density in the vicinity of the additive, when compared with the bulk, whereas a repulsive interaction results in a depletion in the vicinity of the additive.…”