title: Preparation of patterned ultrathin polymer films.
abstract: Though patterned ultrathin polymer films (<100 nm) are of great importance in the fields of sensors and nanoelectronic devices, the fabrication of patterned ultrathin polymer films remains a great challenge. Herein, patterned ultrathin polymer films are fabricated facilely on hydrophobic substrates with different hydrophilic outline patterns by the pinning of three-phase contact lines of polymer solution on the hydrophilic outlines. This method is universal for most of the water-soluble polymers, and poly(vinyl alcohol) (PVA) has been selected as a model polymer due to its biocompatibility and good film-forming property. The results indicate that the morphologies of ultrathin polymer films can be precisely adjusted by the size of the hydrophilic outline pattern. Specifically, patterned hydrophilic outlines with sizes of 100, 60, and 40 μm lead to the formation of concave-shaped ultrathin PVA films, whereas uniform ultrathin PVA films are formed on 20 and 10 μm patterned substrates. The controllabilities of morphologies can be interpreted through the influences of the slip length and coffee ring effect. Theoretical analysis shows that when the size of the hydrophilic outline patterns is smaller than a critical value, the coffee ring effect disappears and uniform patterned ultrathin polymer films can be formed for all polymer concentrations. These results provide an effective methodology for the fabrication of patterned ultrathin polymer films and enhance the understanding of the coffee ring effect.
authors: Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, PR China.
authors: Huige
authors: H
authors: Yang
authors: Meng
authors: M
authors: Su
authors: Kaiyong
authors: K
authors: Li
authors: Lei
authors: L
authors: Jiang
authors: Yanlin
authors: Y
authors: Song
authors: Masao
authors: M
authors: Doi
authors: Jianjun
authors: J
authors: Wang
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D011142:Polyvinyl Alcohol / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D011142:Polyvinyl Alcohol