Controlled Photooxidation of Nanoporous Polymers

Ndoni, Sokol; Li, Li; Schulte, Lars; Szewczykowski, Piotr; Hansen, Thomas Willum; Guo, Fengxiao; Berg, Rolf H.; Vigild, Martin Etchells

doi:10.1021/ma900485q

Cited by 34 publications

(26 citation statements)

References 21 publications

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“…The morphology of the self assembly determines the distribution of pores in the polymer matrix. The material was further cross-linked at 140°C in an argon/nitrogen atmosphere for 2 hours in order to provide mechanical stability to the PB [11,15]. This morphology provides bicontinuous porosity and high transparency, which are important for the liquid transport and for waveguiding characteristics of the obtained device.…”

Section: Device Fabricationmentioning

confidence: 99%

UV patterned nanoporous solid-liquid core waveguides

Gopalakrishnan¹,

Sagar²,

Christiansen³

et al. 2010

Opt. Express

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Nanoporous Solid-Liquid core waveguides were prepared by UV induced surface modification of hydrophobic nanoporous polymers. With this method, the index contrast (δn = 0.20) is a result of selective water infiltration. The waveguide core is defined by UV light, rendering the exposed part of a nanoporous polymer block hydrophilic. A propagation loss of 0.62 dB/mm and a bend loss of 0.81 dB/90° for bend radius as low as 1.75 mm was obtained in these multimode waveguides.

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Section: Device Fabricationmentioning

confidence: 99%

UV patterned nanoporous solid-liquid core waveguides

Gopalakrishnan¹,

Sagar²,

Christiansen³

et al. 2010

Opt. Express

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“…We created a series of nanoporous membranes with varying active porosity as a means to tune the glucose permeation. We previously reported that the originally hydrophobic membranes can be turned into hydrophilic via UV photooxidation 20 or thiolÀene photochemistry. 21 Water can spontaneously and exclusively fill the hydrophilized nanopores.…”

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confidence: 99%

Gyroid Nanoporous Membranes with Tunable Permeability

Li¹,

Schulte²,

Clausen³

et al. 2011

ACS Nano

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104

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Understanding the relevant permeability properties of ultrafiltration membranes is facilitated by using materials and procedures that allow a high degree of control on morphology and chemical composition. Here we present the first study on diffusion permeability through gyroid nanoporous cross-linked 1,2-polybutadiene (1,2-PB) membranes with uniform pores that, if needed, can be rendered hydrophilic. The gyroid porosity has the advantage of isotropic percolation with no need for structure prealignment. Closed (skin) or opened (nonskin) outer surface can be simply realized by altering the interface energy in the process of membrane fabrication. The morphology of the membranes' outer surface was investigated by scanning electron microscopy, contact angle, and X-ray photoelectron spectroscopy. The effective diffusion coefficient of glucose decreases from nonskin, to one-sided skin to two-sided skin membranes, much faster than expected by a naive resistance-in-series model; the flux through the two-sided skin membranes even increases with the membrane thickness. We propose a model that captures the physics behind the observed phenomena, as confirmed by flow visualization experiments. The chemistry of 1,2-PB nanoporous membranes can be controlled, for example, by hydrophilic patterning of the originally hydrophobic membranes, which allows for different active porosity toward aqueous solutions and, therefore, different permeability. The membrane selectivity is evaluated by comparing the effective diffusion coefficients of a series of antibiotics, proteins, and other biomolecules; solute permeation is discussed in terms of hindered diffusion. The combination of uniform bulk morphology, isotropically percolating porosity, controlled surface chemistry, and tunable permeability is distinctive for the presented gyroid nanoporous membranes.

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“…The radiation is primarily in the wavelength range from 300 nm to 400 nm. The UV radiation causes hydrophilic groups to form on the inner surface of the pores [11], [12], meaning it is able to fill with an aqueous solution by micro-capillary forces.…”

Section: Uv Exposurementioning

confidence: 99%

UV defined nanoporous liquid core waveguides

et al. 2010

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Nanoporous liquid core waveguides, where both core and cladding are made from the same material, are presented. The nanoporous polymer used is intrinsically hydrophobic, but selective UV exposure enables it to infiltrate with an aqueous solution, thus raising the refractive index from 1.26 to 1.42. The waveguides are promising for integrated optofluidic sensor systems, where a long optical interaction length can be achieved with a small fluid sample. The propagation loss of a 200×200 m waveguide is measured to 0.62 dB/mm.

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Controlled Photooxidation of Nanoporous Polymers

Cited by 34 publications

References 21 publications

UV patterned nanoporous solid-liquid core waveguides

UV patterned nanoporous solid-liquid core waveguides

Gyroid Nanoporous Membranes with Tunable Permeability

UV defined nanoporous liquid core waveguides

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