Effect of Spin Speed and Solution Concentration on the Directed Assembly of Polymer Blends

Abstract

Directed assembly of polymer blends using chemically heterogeneous patterns during spincoating can be used to produce nanopatterned polymer structures. Well-ordered morphologies are obtained when the characteristic length of a polymer blend is commensurate with pattern periodicity. In this paper, spin-coating speed and solution concentration were used to control the characteristic length of a polystyrene (PS)/poly(acrylic acid) (PAA) blend. With increasing spin speed or reducing solution concentration, the characteristic length decreased. Critical spin speeds or solution concentrations that produced the required characteristic length commensurate with the given pattern periodicity were predicted. Well-ordered morphologies were obtained when spin speed or solution concentration was close to the critical value. A new method of image analysis was introduced to quantitatively evaluate the quality of replication of the underlying pattern. The range of commensurability between characteristic length and pattern periodicity for well-ordered morphologies was investigated. When the range of commensurability was within 20%, well-ordered morphologies were produced.

Polymer masks for structured surface and plasma etching

“…The average center to center distance between the domains also increased from 308 ± 21 nm for a thickness of 20 to 1961 ± 189 nm for a thickness of 220 nm. These variations of the size and center to center distance with the thickness have also been observed on others polymer blend systems like PS/poly(acrylic acid) [55] and PS/PMMA [57]. In our case, it is worth to note that despite a relatively high incompatibility of the two polymers used ( PS/PLA = 0.22) [40], a macro-phase separation was prevented in all the studied conditions.…”

“…The film was then exposed to THF vapor, a nearly neutral solvent ( (PS/THF) = 0.15, (PLA/THF) = 0.62) [55] with a relatively high vapor pressure (129 mmHg at 25 • C). After 5 min exposure, the film exhibited depressions on the surface as displayed in AFM images in Fig.…”

Random lasing from granular surface of waveguide with blends of PS and PMMA

“…During the spin-casting process, since the solvent evaporates relatively fast, the polymer chains are generally frozen in the thin films before reaching a thermodynamically stable state. Although PS has a marginally lower surface free energy than PMMA, due to a higher solubility of the PMMA in the chloroform, PS is more quickly depleted from the solvent and solidifies first onto the substrate and PMMA tends to stay longer in the liquid phase and forms a second layer at the surface [24,27,28], thus forming a granular surface structure on the glass substrate. Figure 3 shows how the pump energy can affect ASE spectra, input-output intensity and FWHM of Samples A, B and C. Clearly, as shown in Fig.…”

High transparent mid-infrared silicon “window” decorated with amorphous photonic structures fabricated by facile phase separation

“…Phase separation of polymer blends has been extensively studied theoretically and experimentally, due to their potential applications in photovoltaic devices, light-emitting diodes, antireflection coatings and biological devices [12,29,30,[33][34][35][36][37][38][39][40][41][42][43]. Furthermore, when one phase is removed from the blends, various nano-and microporous structures are readily obtained and they can serve as templates for novel applications.…”