Rolf H Berg | PubMed Health

PubMed2005

Photodimerization in pyrimidine-substituted dipeptides.

Ten N(epsilon)-glycylornithineamide derivatives have been synthesized containing various N(alpha)-linked pyrimidine-1-ylacetyl groups which can undergo (2pi + 2pi) photodimerization on irradiation with UV light at 254 nm. The dimerization efficiency of the free and bound pyrimidine groups was compared in aqueous solution: it was dependent on the substitution of the pyrimidine ring. N(alpha),N(alpha')-bis-(uracil-1-ylacetyl)-(N(epsilon)-glycylornithineamide) and N(alpha),N(alpha')-bis-(5-bromouracil-1-ylacetyl)-(N(epsilon)-glycylornithineamide) were identified as possible candidates for optical data storage.

Acetates↗

PubMed2003

Nanoporous materials with spherical and gyroid cavities created by quantitative etching of polydimethylsiloxane in polystyrene-polydimethylsiloxane block copolymers.

A new method for quantitative etching of the poly(dimethylsiloxane) block in polystyrene-poly(dimethylsiloxane) (PS-PDMS) block copolymers is reported. Reacting the block copolymer with anhydrous hydrogen fluoride renders a nanoporous material (NPM) with the remaining glassy PS maintaining the original bulk morphology. 1H NMR, mass difference, size exclusion chromatography, and X-ray photoelectron spectroscopy were used to characterize the materials before and after etching. NPMs containing spherical and gyroid cavities were prepared, as ascertained by small-angle X-ray scattering. This is the first report on block copolymer-based NPM films of millimeter thickness containing secluded spherical holes. Surface images by AFM and SEM are consistent with the SAXS findings.

Journal Article↗