Molecular Boxes Based on Hollow Organosilicon Micronetworks

Abstract

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).

Intelligent core-shell nanoparticles and hollow spheres based on gelatin and PAA via template polymerization

“…Micelles or vesicles attained by self-assembly of block copolymers in a selective solvent are frequently used as the precursor for preparing stable core-shell nanoparticles and hollow spheres [7][8][9][10][11][12][13][14][15][16]. In addition, methods such as layer-by-layer deposition of oppositely charged species on the latex particles [17][18][19][20][21] and emulsion polymerization [22][23][24] are also used to fabricate hollow spheres. Recently, some new approaches to fabricate hollow spheres have been reported: Jiang and co-workers developed new strategies for constructing polymeric hollow spheres in solution via specific intermolecular interactions [25][26][27]; Jiang and co-workers synthesized hollow spheres via simple polymerization of acrylic acid (AA) in the presence of chitosan [28,29]; Qian and Wu prepared thermo-sensitive poly(N-isopropylacrylamide) hollow spheres by adopting a two-stage polymerization strategy [30].…”

Smart Nanocontainers: Preparation, Loading/Release Processes and Applications

“…Polymeric nanocontainers could be prepared by various methods, such as suspension polymerization [52], emulsion polymerization [53], self-assembly [54], core-shell precursors [55], dendrimer [56,57].…”

Colloidal Nanoreactors and Nanocontainers

“…A rather elegant approach to core removal under very mild conditions has recently been demonstrated. The authors report the synthesis and characterization of nanometer-sized hollow organosilicon particles [80]. The synthesis of these particles followed a two-step procedure similar to that described above.…”