title: Effects of mold rising angle and polymer concentration in solvent-assisted molding.
abstract: We investigated the capillary rise of a thin polymer solution in a simple soft lithographic technique termed "solvent-assisted molding (SAMo)" by using various mold rising angles and polymer concentrations in a good solvent. For patterning and mold materials, poly(methyl methacrylate) (PMMA, M(w) = 120,000) in toluene and poly(dimethyl siloxane) (PDMS) were mostly used. It was found that the capillary rise takes place in two steps: (i) a low-viscosity polymer solution rapidly rises into the cavity (<10 s) with the aid of solvent wetting and (ii) continuous solvent absorption into the mold and evaporation into air. In addition, five distinct microstructures were observed by testing 24 different experimental combinations, which can be classified into completely molded (I), humped (II), completely molded but non-fully filled (III), partially filled (IV), and partially filled meniscal (V) microstructures.
authors.affiliation: School of Mechanical and Aerospace Engineering, World Class University Program on Multiscale Mechanical Design, Seoul National University, Seoul, 151-742, Korea.
authors.forename: Sung-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Hong-Nam
authors.initials: HN
authors.lastname: Kim
authors.forename: Rho-Kyun
authors.initials: RK
authors.lastname: Kwak
authors.forename: Kahp Y
authors.initials: KY
authors.lastname: Suh