Structures Formed in Spin-Cast Films of Polystyrene Blends with Poly(butyl methacrylate) Isomers

Abstract

For polystyrene blends with poly(butyl methacrylate), replacing poly(n-butyl methacrylate) by poly(tert-butyl methacrylate) results in modified topography of spin-cast films (holes dominating at a surface are exchanged with islands, or vice versa, such individual surface features are increased), decreased PBMA surface excess, but similar overall domain structure. Two series (PS/PnBMA and PS/PtBMA) of films with constant thickness and PBMA fraction 0 < Φ < 1, cast from toluene onto silicon wafers, were examined with atomic force microscopy, X-ray photoelectron spectroscopy, profiling and mapping mode of dynamic secondary ion mass spectrometry. Topography was analyzed with the integral geometry approach. Film structure formation was postulated to involve surface segregation, phase separation, and instability of the transient PBMA layer [a linear relation between Φ2 and averaged size of holes (islands) was observed for PS/PnBMA (PS/PtBMA)]. Structural changes caused by isomer exchange are related to glass transition temperature and blend incompatibility; both increased for PtBMA.

Humidity and solvent effects in spin‐coated polythiophene–polystyrene blends

“…Such a blending strategy results in mixtures with novel structural and physical properties distinct from those of the pure polymers. Phase separation, initiated by solvent evaporation during spin casting, involves complex, non‐quasi‐static processes2–8 different from those in the bulk and films exposed to elevated temperatures 9–12. These not completely resolved processes result in various morphologies of spin‐coated blend films that are dependent on the exact casting conditions.…”

“…Self‐stratified films with vertical lamellar structures have been observed for spin‐cast binary mixtures [insulating–insulating (I–I),13–15 insulating–conjugated (I–C),16 conjugated–conjugated (C–C),17–20 and conjugated–nanoparticle (C–N)21, 22] of insulating and/or conjugated polymers and molecules or nanoparticles. Alternatively, lateral morphologies with in‐plane structures have been obtained for the same or similar systems (I–I,2–6, 8, 14, 15, 23–28 I–C,29–31 C–C,7, 20, 32, 33 and C–N34, 35). Finally, under specific circumstances, laterally arranged phase domains have been observed to replicate the substrate pattern predefined by soft lithography (see the reports for I–I,14, 36–41 C–C,42 and I–N mixtures43).…”

Lipophilic Ionomers with Bulky Ion‐Pairs and Effect of Counterion on Miscibility of the Ionomer Blends

“…Figure b,c shows the AFM images of typical miscible and immiscible blends. The surface of immiscible blends such as PS/PBMA was rough and formed a sea–island structure from separating two phases on a microscale, where PS assumed to be the island and PBMA was the sea part, as mentioned in some reports . In contrast, a miscible combination LI‐PS‐2% /PBMA formed the flat and smooth surface, indicating that they mixed completely at the molecular level.…”

Elasticity patterns induced by phase-separation in polymer blend films

“…This structure is very often reflected by surface topography as a consequence of different solidification rates of different phases, varied with solubility parameter [78] or glass temperature [79, 80]. Moreover, the shape and dimensions of resulting morphology may be controlled by blend composition and total polymer concentration in solution, respectively [64,81], as presented in Fig.…”