This article investigates the use micro-capsules, containing a gelling agent hydroxypropyl cellulose (HPC), to alter flow paths in porous media. The aim is to preferentially block-off high permeability regions, thereby diverting the flow into adjacent un-swept low permeability regions. Micro-capsules with 2 – 7 μm in diameter, were made by polymer precipitation through solvent evaporation using...

A simple procedure is described to incorporate gold nanoparticles and control their location within symmetric poly(styrene-b-2 vinyl pyridine) (PS-PVP) diblock copolymers. Gold nanoparticles coated with thiol-terminated PS and/or PVP homopolymer chains (Mn approximately 1300 and 1500 g/mol, respectively) are incorporated into alternating lamellar layers of PS and PVP (total Mn approximately 196...

Fluorescence measurements with single-molecule sensitivity are used to measure the hydrodynamic size and local pH of a weak polyelectrolyte, poly-2-vinyl pyridine end labeled with pH-sensitive dye, the polyelectrolyte having concentration so low (nanomolars) that molecular properties are resolvable only from fluorescence experiments and cannot be accessed by light scattering. We find that the l...

The ultrasensitive differential scanning calorimetry is used to observe the glass transition in thin (1-400 nm) spin-cast films of polystyrene, poly (2-vinyl pyridine) and poly (methyl methacrylate) on a platinum surface. A pronounced glass transition is observed even at a thickness as small as 1-3 nm. Using the high heating (20-200 K/ms) and cooling (1-2 K/ms in glass transition region) rates ...

The reactions of [2+3] cycloaddition of pyridylnitrile oxides to vinyl- and allylgermanes proceed regioselectively and afford 5-Ge-substituted isoxazolines-2. We have synthesized 9 new pyridyl substituted 5-Si(Ge)-isoxazolines-2 and investigated their biological activity. The vasodilating, anticoagulant and cardioprotective activities of 5-Si(Ge) substituted isoxazolines-2 have been studied in ...

Glass transitions were observed in thin films of poly(2-vinyl pyridine) (P2VP) and poly(methyl methacrylate) (PMMA) using a scanning nanocalorimetry technique which has both high sensitivity (10−9 J/K) and high scan rates (104–105 K/s). Samples were deposited by the spin-cast method. The thickness of samples was 100–400 nm. Glass transition temperature, obtained by nanocalorimetry, is shifted t...