Pattern Formation in Dewetting Poly(tert-butyl acrylate)/Polyhedral Oligomeric Silsesquioxane (POSS) Bilayer Films

Abstract

The surface morphology of dewetting poly(tert-butyl acrylate) (PtBA) and trisilanolphenyl-POSS (TPP) bilayers has been studied as a function of time at 95 degrees C. For short annealing times, only the upper nanoparticle (TPP) layer dewets from the underlying PtBA layer. The number and lateral dimensions of the holes in the upper TPP layer increase with increasing annealing times, forming interconnected rim structures. At later annealing times, scattered holes that reach down into the PtBA layer are observed among the interconnected rim structures. Fractal nanofiller (TPP)-rich aggregates are found at the bottom of the scattered holes.

Instability, self-organization and pattern formation in thin soft films

“…Instability of a bilayer may either involve dewetting of a thin polymer film on a thick, viscous stable bottom layer, [264][265][266][267][268][269][270][271][272][273] or both the layers can become unstable sequentially. [274][275][276][277][278][279][280][281][282][283][284][285][286][287][288] The final dewetted droplet geometry over a non-wetting soft bottom layer is given by the well-known Neumann configuration, instead of Young's configuration, which specifies the drop shape over a solid substrate. 264,265 In case the viscosity vis-a `-vis the molecular weight of the bottom layer is high, then the system behaves identical to dewetting of a thin film on a rigid substrate.…”

“…275 Paul et al studied dewetting of poly(tert-butyl acrylate) (PtBA) and trisilanolphenyl-POSS (TPP) bilayers and observed fractal nanofiller (TPP)-rich aggregates at the bottom of the scattered holes upon prolonged annealing, as the holes reach down into the PtBA layer. 277,278 de Silva et al showed that there is a switching of the instability mode in PMMA on a PS bilayer coated on silicon by simply changing the film thickness. While a thin PMMA film on a thick PS film becomes unstable due to dispersion forces, thin PS layers buried under PMMA film dewets spinodally due to longrange forces.…”

Liquid–liquid interfacial slip induced layer instability in a thin polymer bilayer

“…Bandyopadhyay et al 21,22 have studied the instability of thin bilayer system using long-wave nonlinear theory and also found that a large variety of self-organized interfacial patterns were formed on different types of prepatterned substrates. The instability of thin polymer bilayer is in general governed by thermodynamic forces when the two layers are of M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 similar viscosity [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] . Pototsky et al 31,32 have investigated the instability of thin bilayer system using long-wave theory and shown that for a relatively small thickness ratio between the upper layer and the lower layer, the instability of thin bilayer system is via a varicose mode (out-ofphase) and the upper layer ruptures during the dewetting process; for a larger thickness ratio, the instability of thin bilayer system is via a zigzag mode (in-phase) and the lower layer ruptures at the substrate.…”

Dendritic networks containing polyhedral oligomeric silsesquioxane (POSS) and carborane clusters

“…4 POSS clusters, especially the ones that contain metals, have also been known to cause reductions in flammability and heat evolution in a wide range of thermoplastic and some thermoset polymeric systems. 5 In addition, POSS polymers have found applications in photoresist coatings for electronic and optical devices, 6 interlayer dielectrics and protective coating films for semiconductor devices, 7 liquid crystal display elements, 8 magnetic recording media, 9 optical fiber coatings, 10 selective permeability membranes, 11 binders for ceramics, 12 and as carcinostatic drugs. 13 Carboranes possess astonishing chemical inertness arising from their low nucleophilicity, high hydrophobicity, and their electron-withdrawing properties, since they possess a highly polarizable r-aromatic character.…”