Dewetting dynamics in miscible polymer-polymer thin film mixtures

Abstract

Thin polystyrene films supported by oxidized silicon (SiOx/Si) substrates may be unstable or metastable, depending on the film thickness, h, and can ultimately dewet the substrate when heated above their glass transition. In the metastable regime, holes nucleate throughout the film and subsequently grow due to capillary driving forces. Recent studies have shown that the addition of a second component, such as a copolymer or miscible polymer, can suppress the dewetting process and stabilize the film. We examined the hole growth dynamics and the hole morphology in thin film mixtures composed of polystyrene and tetramethyl bisphenol-A polycarbonate (TMPC) supported by SiOx/Si substrates. The hole growth velocity decreased with increasing TMPC content beyond that expected from changes in the bulk viscosity. The authors show that the suppression of the dewetting velocity is primarily due to reductions in the capillary driving force for dewetting and to increased friction at the substrate-polymer interface. The viscosity, as determined from the hole growth dynamics, decreases with decreasing film thickness, and is connected to a depression of the glass transition of the film.

Investigation of the dewetting inhibition mechanism of thin polymer films

“…There are some reports about the kinetic mechanism. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] Barnes et al 17 inhibited the dewetting of the thin polymer films based on the introduction of C 60 fullerene nanopaticles into the spin-coating polymer solution. Mackay and coworkers 18,19 discovered that polyether dendrimers and polystyrene nanoparticles could inhibit dewetting of thin polystyrene films.…”

Post-deposition reorganization of pentacene films deposited on low-energy surfaces

“…Post-deposition reorganization of thin films, for example by dewetting, intermixing 24,25 or Ostwald ripening 26,27 can introduce significant errors and artifacts when characterization is performed post-mortem, and may get in the way of serious progress in the field of organic electronics. Dewetting has been reported in vacuum-deposited 28 and solutionprocessed polymers, 29,30 polymer blends, 31 and even in some inorganic systems. 32,33 Dewetting has also been observed in hybrid organic-inorganic epitaxial systems, such as pentacene and perylene on gold and copper, [34][35][36] and C 60 and 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) on KBr(001) and NaCl(001) surfaces.…”

Dewetting of Stable Thin Polymer Films Induced by a Poor Solvent: Role of Polar Interactions

“…These features are especially attractive in the creation and miniaturization of self-organized ordered micro/ nano polymer structures by directed dewetting of thin films. [16][17][18][19][20][21][22]34,35…”

“…Ultrathin (<100 nm) polymer films on solid substrates have attracted considerable attention owing to interesting behavior of highly confined soft matter and their numerous technological applications including functional coatings, sensors, multilayer adsorption, patterns on solar panels, fuel cell electrodes, smart adhesives, optoelectronic devices, biological membranes, micro/nano fluidic devices, and drug delivery modules. − The instability frequently manifests in spontaneous dewetting by the formation of holes, which subsequently grow and coalesce, leading structures with a characteristic length scale. − Dewetting of thin polymer film also provides an effective pathway to self-organize ultrathin polymer films to fabricate ordered micro/nano polymer structures. − However, growth of surface instability in air by thermal or solvent vapor annealing is opposed by a strong surface tension effect which increases the length scale of structures. Miniaturization of the instability length scale to smaller sizes remains a major challenge.…”