Characterization of Spin-Coated Polymer Films

Abstract

Neste trabalho a morfologia de filmes obtidos por revestimento rotacional foi explicada como sendo resultante de forças competitivas entre polímero, solvente e substrato. Lâminas de silício (superfícies polares) suportaram os filmes. Tolueno e tetrahidrofurano (THF) foram os solventes escolhidos para dissolver poliestireno (PS), poli(cloreto de vinila) (PVC) e poli(butiral vinílico) (PVB). Análises de microscopia de força atômica mostraram que filmes de PS obtidos a partir de soluções preparadas em tolueno são homogêneos e lisos, enquanto filmes de PS e PVC obtidos a partir de soluções preparadas em THF são muito rugosos e segregados. Entretanto, filmes de PVB preparados a partir de soluções em THF são contínuos e homogêneos. Quando as interações entre substrato e solvente são mais favoráveis que as interações entre substrato e polímero, o filme se torna rugoso e segrega. Contrariamente, quando as interações entre substrato e polímero são mais favoráveis que as interações entre substrato e solvente, ou quando as interações são muito fracas, os filmes obtidos são homogêneos e lisos. Os filmes homogêneos e lisos também foram caracterizados por elipsometria e medidas de ângulo de contato.In this work the morphology of spin-coated polymer films is explained based on the competitive interactions between polymer, solvent and substrate. The films were formed on silicon wafers, a polar surface. Toluene and tetrahydrofuran (THF) were chosen for the dissolution of polystyrene (PS), poly(vinyl chloride) (PVC) and poly(vinyl butyral) (PVB). PS spin-coated films from solutions prepared in toluene were homogeneous and flat, while PS and PVC films obtained from solutions prepared in THF were very rough and presented segregation on the surface, as revealed by the atomic force microscopy. However, PVB films prepared from THF are continuous and homogeneous. When the interaction energy between substrate and solvent overcomes that between substrate and polymer, the films become rough and segregate. On the contrary, when the interaction energy between substrate and polymer is stronger than that between substrate and solvent, or when both interaction energies are weak, the films obtained are homogeneous and flat. These homogeneous and flat films were also characterized by ellipsometry and contact angle measurements.

Characteristics of thin cellulose ester films spin-coated from acetone and ethyl acetate solutions

“…The film thickness is mainly controlled by the concentration of the polymer in solution, while polymer molecular weight (Schubert 1997), spinning velocity (Hall et al 1998), spinning time (Gu et al 1996) and solvent evaporation rate (Meyerhofer 1978;Walsh and Franses 2003;Strawhecker et al 2001) are less important. On the other hand, morphology and roughness of thin polymer films depend on the solvent chosen for polymer solution preparation (Walsh and Franses 2003;Strawhecker et al 2001;Müller-Buschbaum et al 2001;Cui et al 2006;Lin et al 2004;Petri 2002), solution concentration (Schubert and Dunkel 2003) and spinning velocity. The solvent must be a good solvent for the polymer, but one should be aware that it competes for the substrate (Silberberg 1968).…”

“…The solvent must be a good solvent for the polymer, but one should be aware that it competes for the substrate (Silberberg 1968). The balance between substrate-polymer interaction and substrate-solvent interaction plays a very important role on the resulting surface morphology of spincoated films (Cheung et al 2005;Lin et al 2004;Petri 2002;Silberberg 1968). …”

Assembling of xyloglucans and lectin onto si wafers and onto amino-terminated surfaces

“…Immobilization of TXG and HXG onto Si/SiO 2 wafers 22 Under equilibrium conditions XGs did not adsorb from solution onto Si/SiO 2 surfaces, indicating that negatively charged SiO -groups on the surface do not attract XG chains. Interestingly, TXG and HXG formed films by casting onto Si/SiO 2 surfaces with mean thickness of (2.4 ± 0.4) nm and (3.8 ± 0.9) nm, respectively.…”

Effects of Polymeric Dielectric Morphology on Pentacene Morphology and Organic TFT Characteristics

“…2b. It has been known that many parameters such as the solvent quality, solution viscosity and solvent vapor post-treatment control the resulting structure on spin-coated polymer films [4][5][6][7][8]. Lower the solvent's BP is, faster the volatile organic solvent evaporates during the spin-coating process.…”