title: Formation of a polymer surface with a gradient of pore size using a microfluidic chip.
abstract: Here we demonstrate the generation of polymer monolithic surfaces possessing a gradient of pore and polymer globule sizes from ~0.1 to ~0.5 μm defined by the composition of two polymerization mixtures injected into a microfluidic chip. To generate the gradient, we used a PDMS microfluidic chip with a cascade micromixer with a subsequent reaction chamber for the formation of a continuous gradient film. The micromixer has zigzag channels of 400 × 680 μm(2) cross section and six cascades. The chip was used with a reversible bonding connection, realized by curing agent coating. After polymerization in the microfluidic chip the reversible bond was opened, resulting in a 450 μm thick polymer film possessing the pore size gradient. The gradient formation in the microfluidic reaction chamber was studied using microscopic laser-induced fluorescence (μLIF) and different model fluids. Formation of linear gradients was shown using the fluids of the same density by both diffusive mixing at flow rates of 0.001 mL/min and in a convective mixing regime at flow rates of 20 mL/min. By using different density fluids, formation of a two-dimensional wedge-like gradient controlled by the density difference and orientation of the microfluidic chip was observed.
authors: Institute of Microstructure Technology, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany.
authors: Kristina
authors: K
authors: Kreppenhofer
authors: Junsheng
authors: J
authors: Li
authors: Rodrigo
authors: R
authors: Segura
authors: Ludmilla
authors: L
authors: Popp
authors: Massimiliano
authors: M
authors: Rossi
authors: Pavleta
authors: P
authors: Tzvetkova
authors: Burkhard
authors: B
authors: Luy
authors: Christian J
authors: CJ
authors: Kähler
authors: Andreas E
authors: AE
authors: Guber
authors: Pavel A
authors: PA
authors: Levkin
mesh_terms: D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D057446:Hydrodynamics; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D016062:Porosity; D013499:Surface Properties
chemical_list: D004129:Dimethylpolysiloxanes; C013830:baysilon