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Poly(organosiloxane) microgels are highly cross-linked rather monodisperse spherical particles of radius about 10 nm. Using a functionalized silane comonomer, i.e., (chlorobenzyl)trimethoxysilane, model particles suitable for studies in colloid physics are available:  photoreactive and fluorescent dyes can be covalently bound within the microgels to prepare tracers for diffusion studies using forced Rayleigh scattering (FRS) and fluorescence correlation spectroscopy (FCS). For the application as tracer particles, it is important not to influence the diffusion behavior by the coupled chromophores. Therefore, functionalized precursors with a core−shell architecture are used to minimize labeling effects. The photochromic dye ortho-nitrostilbene (ONS) and the fluorophores rhodamine B, coumarin 343, and pyrene, respectively, were then coupled to the functionalized cores. The dye content of the labeled μ-gels strongly decreases with increasing thickness of the protective shell. A higher polarity of the used chromophores also lowers the dye content significantly, while differences in the size of the used label molecules are less important. The fluorescence intensity of the dye-labeled spheres is also influenced by the size of the protective shell which has been explained by differences in mobility of the labels (caging effects) and, at high dye concentration (thinner shell), by reabsorption.

Novel short chain R,ω-heterotelechelic amphiphilic poly(dimethylsiloxane)-b-poly(ethylene oxide) diblock copolymers (PDMS-PEO) with total molecular weights below 10 000 g/mol are synthesized, characterized, and used as basic constituent parts for functionalized nanoparticles. The self-assembly of the amphiphilic diblock copolymer in water as a solvent selective for the PEO block leads to the formation of spherical and cylindrical micellar structures with diameters between 10 and 25 nm. The core of the micelles is built of the hydrophobic PDMS chains, whereas the corona is set up by the hydrophilic PEO blocks. By using R,ω-heterotelechelic diblock copolymers, it is possible to fix the core of the micelles by cross-linking of the PDMS-sided (R) methacrylic end groups. The resulting nanoparticles possess the PEO-sided (ω) functional end groups introduced during the synthesis of the amphiphilic diblock copolymer. In the present study, these functionalities are hydrophilic, uncharged hydroxy end groups (-OH), hydrophilic, charged carboxylate (-COOH) end groups, or hydrophobic benzylic end groups (-CH 2C6H5).

SUMMARY: Methacryloyl-endfunctionalized block copolymers consisting of styrene and 2-vinylpyridine were polymerized to polyblockcomacromonomers with a much higher main chain than side chain degree of polymerization. Like homopolymacromonomers these molecules exhibit the structure of cylindrical brushes. Since the vinylpyridine block is coupled to the polymerizable group, the resulting cylindrical macromolecules exhibit a core of vinylpyridine and a shell of polystyrene, thus resembling an amphipolar unimolecular micelle of cylindrical shape. The micellar character of the structure is demonstrated by loading the cylindrical brushes with tetrachloroauric acid in toluene. Subsequent reduction leads to the formation of colloidal gold, most probably within the brush in analogy to similar work on block copolymer micelles.

rials with optical chemical sensors allows the optical temperature compensation of optode signals. These so-called hybrid optodes have a temperature element integrated into the chemical sensing layer. Finally, there is a broad potential of the films for use as temperature-sensitive paint. ExperimentalMaterials: Ruthenium(II)-tris-1,10-phenanthroline chloride hydrate (M w : 712 g/mol, Aldrich, prod. no. 34,; tetramethoxysilane (TMOS, Fluka, prod. no. 87 682); poly(acrylonitrile) (Faserwerk Kehlheim, technical grade); silicon rubber (Wacker, E4).Preparation of Sol-Gel Sensor Membranes: 4.94 mL (33.3 mmol) tetramethoxysilane (2 g sol-gel matrix) was added to a solution of different amounts of (see Table 1) Ru(phen) 3 Cl in 4 mL methanol and 2 mL distilled water. The sol-gel process was started by adding 0.4 mL of 0.1 N HCl. After a 10 min condensation reaction the solvents were removed within a few seconds at 30 torr and 100 C. The dense sol-gel obtained was powdered and heated to 300 C for 10 h. The cold powder was dispersed in 10 mL of methanol and a new sol-gel process was started by adding 2.47 mL of TMOS, 1 mL of distilled water, and 0.2 mL of 0.1 N HCl. While stirring, the solution was heated to 100 C until dryness (~10 min) and then tempered at 300 C for 2 h. Equal quantities of powder and silicone prepolymer E4 were mixed and spread onto the polyester support at a layer thickness of 250 mm. After 1 day of curing in ambient air the sensing layer was ready for use.Preparation of PAN Sensor Membranes: Ru(phen) 3 (PF 6 ) 2 (M w : 985 g/mol) was precipitated from an aqueous Ru(phen) 3 Cl 2 solution by adding NaPF 6 dissolved in water. Different amounts (see Table 1) of Ru(phen) 3 (PF 6 ) 2 were added to a solution of 1.0 g of poly(acrylonitrile) in 10 mL of DMF. The cocktail was spread onto a 125 mm thick polyester support (Mylar, DuPont) in a wet layer thickness of 120 mm under nitrogen. After drying at room temperature under nitrogen, the membrane was tempered at 100 C for 4 h. The resulting sensing layer was ready for use. From the volume employed, the dried layers are estimated to be 10 mm thick.Experimental Set-Up: The excitation light of a blue LED (l max 470 nm, NSPB 500, Nichia) passing a blue glass filter (BG 12, Schott, Mainz) was sinusoidally modulated at 75 kHz using a two-phase lock-in amplifier (DSP830, Stanford Research Inc.). Luminescence was detected with a photomultiplier tube (H5701-02, Hamamatsu) equipped with a longpass filter (OG 570, Schott, Mainz). A bifurcated fiber bundle (n.a. 0.46, d = 2 mm, Laaber LWL GmbH) was used to separate the luminescence signal with a peak at 610 nm from backscattered blue excitation light.Calibration and investigation of response time and reversibility were performed by immersing the sensors alternately in different water baths whose temperatures were controlled by a Lauda cryostat (RC6).