Graphene Oxide Monolayer as a Compatibilizer at the Polymer–Polymer Interface for Stabilizing Polymer Bilayer Films against Dewetting

Abstract

We investigate the effect of adding graphene oxide (GO) sheets at the polymer-polymer interface on the dewetting dynamics and compatibility of immiscible polymer bilayer films. GO monolayers are deposited at the poly(methyl methacrylate) (PMMA)-polystyrene (PS) interface by the Langmuir-Schaefer technique. GO monolayers are found to significantly inhibit the dewetting behavior of both PMMA films (on PS substrates) and PS films (on PMMA substrates). This can be interpreted in terms of an interfacial interaction between the GO sheets and these polymers, which is evidenced by the reduced contact angle of the dewet droplets. The favorable interaction of GO with both PS and PMMA facilitates compatibilization of the immiscible polymer bilayer films, thereby stabilizing their bilayer films against dewetting. This compatibilization effect is verified by neutron reflectivity measurements, which reveal that the addition of GO monolayers broadens the interface between PS and the deuterated PMMA films by 2.2 times over that of the bilayer in the absence of GO.

Dynamics of Entangled Polymers Confined between Graphene Oxide Sheets as Studied by Neutron Reflectivity

“…This reduced diffusion is consistent with our previous report of dewetting dynamics, in which the dewetting hole of the PMMA thin films is completely prevented by the GO monolayer due to their attractive interactions. 26 It is known that the mobility of PMMA near the Si substrates significantly decreases due to the polymer pinning effect on the substrates. 7 Hence, to eliminate the effect of attractive Si substrates on the diffusion dynamics of the GO-confined PMMA layer, we added spin-coated films of PS with high M w (7100 kDa) between the bottom GO monolayer and Si surface, as illustrated in Figure 2e.…”

“…Recently, graphene-based polymer nanocomposites have been of particular interest due to the significant impact of graphene on polymer’s physical properties. − Graphene oxide (GO), obtained from chemical exfoliation of graphite, has been widely used for polymer nanocomposites due to good dispersion in aqueous solvents or polymer matrices, and also its functionality as a compatibilizer in immiscible polymer blends. , Simulation studies have predicted that GO sheets reduce the mobility of poly­(methyl methacrylate) (PMMA) films confined to them relative to bulk values without GO . Near the GO surface, chain mobility is significantly restricted due to interactions of the polymer with the GO surface.…”

“…This indicates that the interaction between PMMA and the GO surface is strongly attractive, significantly suppressing the mobility of confined PMMA near the GO-polymer interface. This reduced diffusion is consistent with our previous report of dewetting dynamics, in which the dewetting hole of the PMMA thin films is completely prevented by the GO monolayer due to their attractive interactions …”

Polymeric Solvation Shells around Nanotubes: Mesoscopic Simulation of Interfaces in Nanochannels

“…14,15 A common approach is the incorporation of colloidal particles at the interfaces. [16][17][18][19] In biological systems, where often multiple phases are in contact in nano-sized geometries, nanoparticles are potential carriers of anti-cancer agents. 20,21 This is in part due to their small size, which enables them to diffuse preferentially in the tumor tissue, similar to the diffusion in a nanopore.…”

“…In the presence of immiscible bilayers, the interfacial interactions begin to dominate the bilayer properties. Thus, tuning of the interface has been an ongoing challenge in this field. , A common approach is the incorporation of colloidal particles at the interfaces. − In biological systems, where often multiple phases are in contact in nanosized geometries, nanoparticles are potential carriers of anticancer agents. , This is in part due to their small size, which enables them to diffuse preferentially in the tumor tissue, similar to the diffusion in a nanopore . Such applications require a deep knowledge of the interactions between nanoparticles and their surroundings in a nanofluidic geometry.…”