Chain-end functionalized nanopatterned polymer brushes grown via in situ nitroxide free radical exchange.

The patterning of biologically active materials has been accomplished by the use of imprint lithography of functional photopolymer resins to create controlled nanoscale patterns of a cross-linked photopolymer containing embedded initiator groups. Functionalized polymer brushes consisting of polystyrene and poly(N,N-dimethylacrylamide) were grown from these patterned layers by nitroxide-mediated polymerization. Chain-end functionalization of the brush layer was accomplished by nitroxide radical exchange during the polymerization.

V-shaped crystalline structures of di-n-alkyl esters of phosphoric acid.

We prepared crystals of di-n-alkyl esters of phosphoric acid with chain lengths of n = 10, 12, 14, 16, and 18. These were characterized by single-crystal X-ray analysis and differential scanning calorimetry (DSC). It was found that the alkyl chains are in an extended all-trans conformation and aligned close to perpendicular, forming V-shaped molecules.

Patterned polyfluorene surfaces by functionalization of nanoimprinted polymeric features.

A new procedure is described for surface grafting polymer brushes by step-growth polymerization from initiator-embedded polymeric thin films and micron- and nanometer-scale patterns. An imprint lithographic process, nanocontact molding, was used to prepare thin patterned cross-linked polyacrylate network films on silicon wafers that incorporated 4-bromostyrene in the networks. These networks present reactive 4-bromophenyl functionality at the surface that act as attachment sites for the subsequent Ni(0)- mediated step-growth condensation polymerization of 2,7-dibromo-9,9-dihexylfluorene The step-growth polymerization medium consisted of 2,7-dibromo-9,9-dihexylfluorene, Ni(0)-catalyst, and bipyridine in a toluene/dimethylformamide solvent mixture.

Phenylene alkylene dendrons with site-specific incorporated fluorescent pyrene probes.

This report deals with the synthesis and the spectroscopic properties of two second generation (G2) dendrons with site-specific incorporated phenyl pyrene derivatives as solvatochromic fluorescent probes. The generations that do not carry the probe are equipped with volume dummies, pyrene moieties that do not show a solvatochromic effect. Two complementary G2 phenylene alkylene dendrons were synthesized using Suzuki-Miyaura cross coupling.