Spin coating contact angle

Polymeric surface treatments are applied in similar fashion, namely spin-coating from a low-concentration solution of the polymer in organic solvent, e.g. 0.1% (w/w) polymer in toluene. Spin conditions can vary widely but, as reported by 3M [30a], 500 rpm for 20 s then 2000 rpm for 40 s provides 100 A thick dry polymer films on smooth dielectrics with good surface quality and contact-angle uniformity. Spun layers are typically air-dried for several hours, or dried at an elevated temperature of 110-130 °C for 30 min in an oven or 5 min on a hot plate. These materials are typically not rinsed after they are baked, because the homopolymer version would redissolve, removing almost all of the polymer. In a recent report from Fris-bie s group, in collaboration with 3M, device oxides were intentionally roughened... 

Methods. Polyamic acid in NMP was spin-coated onto a Si or Quartz wafer (diameter = 2.25 inches) coated with Cr, and then cured to polyimide at 400 °C. The purpose of the 500-750-A-thick layer of chromium is to enhance wettability and to give good reflectance to the Quartz wafer. Kapton H (PMDA-ODA) and Upilex S (BPDA-PDA) films were employed for gravimetric analysis. Around 5-um thick layers were used to measure the thickness change. The 100-1000-A-thick layers were employed to obtain XPS and ER IR spectra. The samples for contact angle measurement, XPS and ER IR were dried under vacuum at ambient temperature for 12-24 h and the samples for gravimetric analysis were dried at 85 °C for 12 h. The samples for film thickness measurement were fully re-cured to polyimide. 

Spin-coated PS/PMMA films were used as samples to study silica-polymer interactions. For this purpose, solutions of 10 mg polymer in 1 mL toluene were prepared flom each polymer. The PMMA and PS solutions were mixed in a ratio of 2 1. When the mixed solution was spin-coated on a fleshly cleaned silicon surface a phase-separated film of 100 nm thickness was obtained. Cantilevers were modified either by deposition in the saturated atmosphere of hexamethyldisilizane or immersion in a 2% solution of dimethyldichlorosilane in toluene. Typically, measuring the contact angle of the sample after modification gives proof of hydrophobization. However, because of the small size of the tips the contact angle cannot be estimated. Thus, at the same time as the cantilever modification, small pieces of silicon wafers were modified to enable contact angle measurements to be made. 

As discussed earlier, different solvents may result in distinct conformations and aggregation styles of the polymer chains in the solution. It is expected that such differences will be carried on into the spun film. The direct evidence for this is the solvent dependence of the surface energy for spin-coated polymer films. Shi et al.17 have observed that the contact angles (86°-87°) between H2O and the polymer films spun from THF and CHCI3 are significantly smaller than those (average 95°) spun from aromatic solvents (Table 6.1). This indicates that these films have different surface energies. On the other hand, an MEH-PPV film spun... 

Substrate preparation. Thin films of mixed transition metal oxides were deposited by spin-coating on Si (100) tiles. Before deposition Si tiles were pretreated as follows. Square pieces (0.9 x 0.9 cm ) were first cleaned by HF (2%) dipping for 20 s to remove native oxide from its surface. After several rinsings with water (HPLC grade), the tiles were kept in water. UV/O3 treatment (Jelight s UVO-Cleaner A2, % = 254 nm) was applied to obtain a static contact angle nearing 0. 

Here we have proposed a modified Cassie-Baxter model to investigate the influence of prirticle size on superhydrophobic behavior of sfiica nanosphere arrays. An assembly technique enabled to prepare well-ordered silica nanosphere arrays, and then the silica arrays were fluorinated by a spin-coating process. Compared with a F-coated flat surface, the contact angle on fluorinated silica nanoarrays reached a value of 152 1.4°. A Cassie-Baxter parameter, surface firaction (4>s), was used to simulate the hydrophobicity. It was found that the nanosphere size played an important role in affecting the hydrophobicity of the sphere arrays. The present work demonstrates that the superhydrophobicity of nanoarrays is well correlated with the modified Cassie-Baxter model. 

Contact Angle and Surface Tension of Spin-Coated TLCP Films... 

The fluorinated polymer (PFA-C, PPMA-C ) was dissolved in HCFC-225 (concentration 1 wt%), and a Si-wafer was coated with this solution by the spin-coating method (2000 rpm, 30 seconds). The static contact angle against water and methylene iodide, surface free energy [27], and dynamic contact angle against water for the PFMA-Cy thin films are summarized in Table 19.2. For the PFMA-Cj, with y < 6,... 

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