Organic-inorganic hybrid nanoparticles: surface characteristics and interactions with a polyester resin

Preparation and Characterization of Quartz-Reinforced Hybrid Composites Based on Unsaturated Polyester Resin from Post-Consumer PET Recyclate

The paper presents the results of research on hybrid composites made of unsaturated polyester resin based on post-consumer recycled poly(ethylene terephthalate). The polymeric materials were reinforced with quartz flour, which is a common inorganic mineral filler. An environmentally friendly cobalt polymer solution was used to cure the polyester matrix. The results showed the quantitative influence of the quartz filler on the thermal, mechanical and morphological properties of the quartz-polyester composites. A change in the surface wettability and the polarity of the polymeric materials was also noticed, with some deterioration of their gloss.

Diazonium Salts: Versatile Molecular Glues for Sticking Conductive Polymers to Flexible Electrodes

Adhesion of polymers to surfaces is of the upmost importance in timely applications such as protective coatings, biomaterials, sensors, new power sources and soft electronics. In this context, this work examines the role of molecular interactions in the adhesion of polypyrrole thin films to flexible Indium Tin Oxide (ITO) electrodes grafted with aryl layers from various diazonium salts, namely 4-carboxybenzenediazonium (ITO-CO2H), 4-sulfonicbenzenediazonium (ITO-SO3H), 4-N,N-dimethylbenzenediazonium (ITO-N(CH3)2), 4-aminobenzenediazonium (ITO-NH2), 4-cyanobenzenediazonium (ITO-CN) and 4-N-phenylbenzenediazonium (ITO-NHPh). It was demonstrated that PPy thin layers were adherent to all aryl-modified surfaces, whereas adhesive failure was noted for bare ITO following simple solvent washing or sonication. Adhesion of polypyrrole was investigated in terms of hydrophilic/hydrophobic character of the underlying aryl layer as probed by contact angle measurements. It was found that sulfonic acid-doped polypyrrole (PPy-BSA) thin films were preferably deposited on the most hydrophobic surfaces. More importantly, the redox properties and electrochemical impedance of PPy were closely related to the hydrophobic character of the aryl layers. This work demonstrates that diazonium compounds are unique molecular glues for conductive polymers and permit to tune their interfacial properties. With robust, diazonium-based architectured interfaces, one can design high performance materials for e.g., sensors, printed soft electronics and flexible thermoelectrics.

Internal Functionalization and Surface Modification of Vinylsilsesquioxane Nanoparticles

The interior of 237 nm spherical vinylsilsesquioxane nanoparticles has been covalently modified and their surface functionalized under mild conditions to yield a novel type of hybrid silsesquioxane nanoparticles. Data obtained from thermogravimetric and elemental analysis show that the vinyl groups inside the nanoparticles can be easily brominated or hydroborated, leading to the nanoparticles containing 59.9 wt% of bromine or 3.6 wt% of boron, respectively. Our results demonstrate that the vinyl groups inside the nanoparticles are highly accessible, which may lead to the preparation of a host of hybrid organosilica nanoparticles with complex structures. We also show that the surface of the brominated and boronated nanoparticles is unhindered for further amination.

Solid phase adsorption of crystal violet lactone on silica nanoparticles to probe mechanochemical surface modification

The solid phase adsorption of crystal violet lactone (CVL) on five types of Stober silica nanopowders with BET specific surface areas in the range of 50-800 m2/g under dry milling conditions was described for the first time. The hydrogen bonding between surface silanol and the carboxylate of the ring-opened triphenylmethane dye (CVL+) led to the formation of monolayers of CVL+ in a flat-laid configuration. The lambda max of CVL+ in diffusive reflection visible spectra was influenced by the particle size of silica powders, suggesting that the microenvironmental polarity of adsorbed CVL+ is considerably reduced along with the decrease of the particle size. The solid phase adsorption of CVL obeyed Langmuir adsorption isotherms to give a saturated amount of CVL+ for every silica nanoparticle. The surface concentration of CVL+ on nanoparticles at the saturation was estimated to be 0.31 mg/m2 on average, disclosing that about 52% of the surface can be covered by CVL+ under the assumption that the BET-specific surface areas are equivalent to the real surfaces active for the CVL adsorption. The generation of the blue color of CVL provided a convenient means to estimate qualitative and quantitative analysis of the surface coverage with surface-active reagents, which conceal surface silanols. Subsequently, silica nanoparticles were milled with a surface modifier, followed by milling with CVL to observe the intensity of the blue color in order to disclose that the surface coverage with oligo- and polyethylene glycols as well as with nonionic surfactants by dry milling was specifically determined by the number of repeating oxyethylene units. Although the surface-active reagents were easily desorbed in water, the desorption was notably suppressed by milling with CVL, suggesting that the surface-modified particles with the surface-active reagents are covered with ultrathin films of CVL.

Amplification of the antigen–antibody interaction from quartz crystal microbalance immunosensors via back-filling immobilization of nanogold on biorecognition surface

A new quartz crystal microbalance immunoassay method based on a novel transparent immunoaffinity reactor was developed for clinical immunoassay. To construct such an affinity reactor, resonators with a frequency of 10 MHz were fabricated by affinity binding of functionalized gold nanoparticles (nanogold) to quartz crystal with immobilized specific ligand for the label-free analysis of the affinity reaction between a ligand and its receptor. [Recombinant human tumor markers, carcinoembryonic antigen (CEA) was chosen as a model ligand.] The binding of target molecules onto the immobilized antibodies decreased the sensor's resonant frequency, and the frequency shift was proportional to the CEA concentration in the range of 3.0-50 ng/ml with a detection limit of 1.5 ng/ml at a signal/noise ration of 3. A glycine-HCl solution (pH 2.3) was used to release antigen-antibody complexes from the biorecognition surface. Good reusability was exhibited. Moreover, spiking various levels of CEA into normal human sera was diagnosed using the proposed immunoassay. Analytical results show the precision of the developed immunoassay is acceptable, implying a promising alternative approach for detecting CEA in clinical immunoassay. Compared with the conventional enzyme-linked immunosorbent assay, the proposed immunoassay system was simple and rapid without multiple labeling and separation steps. Importantly, the proposed immunoassay system could be further developed for the immobilization of other antigens or biocompounds.