Giant Magnetoresistance of Electrostatic Self-Assembled Fe3O4 Nanocluster and Polymer Thin-Films

1999 ◽  
Vol 577 ◽  
Author(s):  
Yanjing Liu ◽  
Richard O. Claus ◽  
Fajian Zhang
Keyword(s):  
Aqueous Solution ◽  
Self Assembly ◽  
Giant Magnetoresistance ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Angle Measurements ◽  
Vis Spectroscopy ◽  
Contact Angle Measurements ◽  
Assembly Technique ◽  
Quartz Substrates

ABSTRACTGiant magnetoresistance (GMR) as large as 25% at 25°C has been observed for multilayer ultrathin films of iron oxide (Fe3O4) nanoclusters and polyimide molecules alternately adsorbed onto single crystal silicon and quartz substrates using a novel self-assembly technique. This process involves the alternate dipping of a substrate into an aqueous solution of anionic polyimide precursor (polyamic salt, PAA) followed by dipping it into an aqueous solution of cationic polydiallyldimethylammonium chloride (PDDA)-coated Fe3O4, nanoparticles. The regular formation of alternating monolayers is verified by UV-vis spectroscopy and contact angle measurements. Vibrating sample magnetometry indicates the formation of ultrasoft films.

A New Route to Prepare Hard and Anti-Scratching Coatings at Room Temperature

1999 ◽  
Vol 576 ◽  
Author(s):  
Yanjing Liu ◽  
Richard O. Claus ◽  
Aprillya Rosidian ◽  
Tingying Zeng
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
Room Temperature ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Linear Behavior ◽  
Vis Spectroscopy ◽  
Novel Method ◽  
Quartz Substrates ◽  
Cationic Polyelectrolytes

ABSTRACTNanocomposites of transparent, multilayer structures of different thin-films have been fabricated on single crystal silicon and quartz substrates by the new deposition technique called electrostatic self-assembly (ESA) method. The method is based on the alternating adsorption of anionic and cationic polyelectrolytes in the aqueous forms. The films were then characterized by UV/Vis spectroscopy, ellipsometry, and nano-indenter. A linear behavior of both optical absorption and film thickness as the number of bilayers increases was observed, which indicated the formation of homogeneous and uniform thin-films on both substrates. The study also observed that the films prepared by this novel method have some improved mechanical properties.

Molecular Self-Assembly of Fe3O4/Polyimide Nanocomposite Films (I)

1997 ◽  
Vol 475 ◽  
Author(s):  
Yanjing Liu ◽  
Anbo Wang ◽  
Richard O. Claus ◽  
Eric Jiang
Keyword(s):  
Aqueous Solution ◽  
Self Assembly ◽  
Single Crystal Silicon ◽  
Magnetic Films ◽  
Nanocomposite Films ◽  
Layer By Layer ◽  
Crystal Silicon ◽  
Vis Spectroscopy ◽  
Polyimide Nanocomposite ◽  
Polyimide Precursor

ABSTRACTLayer-by-layer molecular self-assembly of nanosized magnetite (Fe3O4) particles and polyimide precursor molecules into multilayer ultrathin films has been accomplished on single crystal silicon and quartz substrates. This process involves the alternate dipping of a substrate into an aqueous solution of cationic polymer which coats on nanoscale Fe3O4 particles as a stabilizer followed by dipping into an aqueous solution of anionie polyimide precursor (polyamic acid salt, PAATEA). The growth process and the structure have been characterized using UV-vis spectroscopy, FT-IR, and scanning electron microscopy. The results demonstrate that well-ordered uniform monolayer and multilayer magnetic films have been formed on silicon and silica surfaces.

Optimization of Hemocompatibility of Silicon Oxynitride Films

2009 ◽  
Vol 79-82 ◽  
pp. 727-730 ◽  
Author(s):  
Qi Yi Wang ◽  
Ping Yang ◽  
Ju Huang ◽  
Jun Liang ◽  
Hong Sun ◽  
...  
Keyword(s):  
Plasma Proteins ◽  
Platelet Adhesion ◽  
Single Crystal Silicon ◽  
Silicon Oxynitride ◽  
Medical Implants ◽  
Crystal Silicon ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Interventional Devices ◽  
Pyrolitic Carbon

Low hemocompatibility is a major problem of biomaterials that come in contact with blood. Surface modification has become an important way to improve the hemocompatibility of medical implants and interventional devices. Recently, researchers attempt to investigate the possibility of silicon oxynitride (Si-N-O) films to be applied as novel coating of blood-contacting biomaterials. However, no detailed investigation has been conducted. In this study, our work was focused on the optimization of the hemocompatibility of Si-N-O films prepared on single-crystal silicon wafers by unbalance magnetron sputtering (UBMS). The structure and chemical composition of films were characterized by X-ray photoelectron spectrometry (XPS), and their physical chemistry property was characterized by contact angle measurements. Platelet adhesion test was performed to investigate the platelet adhesion and activation. Our results suggested that films composed of Si3N4 and SiOx (x<2) exhibited better hemocompatibility than low temperature isotropic pyrolitic carbon (LTIC) that is a common material used in blood-contacting implants. It was also revealed that the higher N/O ratio in films composed of Si3N4 and SiOx (x<2) was attributed to the lower platelet adhesion and activation, and the interaction of samples with plasma proteins was demonstrated to play an important role in the adhesion and activation of platelets.

scholarly journals Synthesis, Hydrophilicity and Micellization of Coil–Brush Polystyrene-b-(polyglycidol-g-polyglycidol) Copolymer—Comparison with Linear Polystyrene-b-Polyglycidol

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 253
Author(s):  
Mariusz Gadzinowski ◽  
Maciej Kasprów ◽  
Teresa Basinska ◽  
Stanislaw Slomkowski ◽  
Łukasz Otulakowski ◽  
...  
Keyword(s):  
Contact Angle ◽  
Self Assembly ◽  
Original Method ◽  
Critical Micellization Concentration ◽  
Water Contact ◽  
1H And 13C Nmr ◽  
Similar Composition ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Static Conditions

In this paper, an original method of synthesis of coil–brush amphiphilic polystyrene-b-(polyglycidol-g-polyglycidol) (PS-b-(PGL-g-PGL)) block copolymers was developed. The hypothesis that their hydrophilicity and micellization can be controlled by polyglycidol blocks architecture was verified. The research enabled comparison of behavior in water of PS-b-PGL copolymers and block–brush copolymers PS-b-(PGL-g-PGL) with similar composition. The coil–brush copolymers were composed of PS-b-PGL linear core with average DPn of polystyrene 29 and 13 of polyglycidol blocks. The DPn of polyglycidol side blocks of coil–b–brush copolymers were 2, 7, and 11, respectively. The copolymers were characterized by 1H and 13C NMR, GPC, and FTIR methods. The hydrophilicity of films from the linear and coil–brush copolymers was determined by water contact angle measurements in static conditions. The behavior of coil–brush copolymers in water and their critical micellization concentration (CMC) were determined by UV-VIS using 1,6-diphenylhexa-1,3,5-trien (DPH) as marker and by DLS. The CMC values for brush copolymers were much higher than for linear species with similar PGL content. The results of the copolymer film wettability and the copolymer self-assembly studies were related to fraction of hydrophilic polyglycidol. The CMC for both types of polymers increased exponentially with increasing content of polyglycidol.

scholarly journals On the Aqueous Solution Behavior of C-Substituted 3,1,2-Ruthenadicarbadodecaboranes

Inorganics ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 91 ◽  
Author(s):  
Marta Gozzi ◽  
Benedikt Schwarze ◽  
Peter Coburger ◽  
Evamarie Hey-Hawkins
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Self Assembly ◽  
Self Assembling ◽  
Vis Spectroscopy ◽  
Assembly Behavior ◽  
Biological Performance ◽  
Type 3

3,1,2-Ruthenadicarbadodecaborane complexes bearing the [C2B9H11]2− (dicarbollide) ligand are robust scaffolds, with exceptional thermal and chemical stability. Our previous work has shown that these complexes possess promising anti-tumor activities in vitro, and tend to form aggregates (or self-assemblies) in aqueous solutions. Here, we report on the synthesis and characterization of four ruthenium(II) complexes of the type [3-(η6-arene)-1,2-R2-3,1,2-RuC2B9H9], bearing either non-polar (R = Me (2–4)) or polar (R = CO2Me (7)) substituents at the cluster carbon atoms. The behavior in aqueous solution of complexes 2, 7 and the parent unsubstituted [3-(η6-p-cymene)-3,1,2-RuC2B9H11] (8) was investigated via UV-Vis spectroscopy, mass spectrometry and nanoparticle tracking analysis (NTA). All complexes showed spontaneous formation of self-assemblies (108–109 particles mL−1), at low micromolar concentration, with high polydispersity. For perspective applications in medicine, there is thus a strong need for further characterization of the spontaneous self-assembly behavior in aqueous solutions for the class of neutral metallacarboranes, with the ultimate scope of finding the optimal conditions for exploiting this self-assembling behavior for improved biological performance.

Surface Modification Energized by FIB: The Influence of Etch Rates & Aspect Ratio on Ripple Wavelengths

2006 ◽  
Vol 960 ◽  
Author(s):  
Warren MoberlyChan
Keyword(s):  
Aspect Ratio ◽  
Self Assembly ◽  
Focused Ion Beam ◽  
Process Development ◽  
Ion Beam ◽  
Natural Diamond ◽  
Single Crystal Silicon ◽  
Nanometer Scale ◽  
Crystal Silicon ◽  
Etch Rates

ABSTRACTIon beams have been used to modify surface topography, producing nanometer-scale modulations (and even subnanometer ripples in this work) that have potential uses ranging from designing self-assembly structures, to controlling stiction of micromachined surfaces, to providing imprint templates for patterned media. Modern computer-controlled Focused Ion Beam tools enable alternating submicron patterned zones of such ion-eroded surfaces, as well as dramatically increasing the rate of ion beam processing. The DualBeam FIB/SEM also expedites process development while minimizing the use of materials that may be precious (Diamond) and/or produce hazardous byproducts (Beryllium). A FIB engineer can prototype a 3-by-3-by-3 matrix of variables in tens of minutes and consume as little as zeptoliters of material; whereas traditional ion beam processing would require tens of days and tens of precious wafers. Saturation wavelengths have been reported for ripples on materials such as single crystal silicon or diamond (∼200nm); however this work achieves wavelengths >400nm on natural diamond. Conversely, Be can provide a stable and ordered 2-dimensional array of <40nm periodicity. Also ripples <0.4nm are fabricated on carbon-base surfaces, and these quantized picostructures are measured by HR-TEM and electron diffraction. Rippling is a function of material, ion beam, and angle; but is also controlled by chemical environment, redeposition, and aspect ratio. Ideally a material has a constant yield (atoms sputtered off per incident ion); however, pragmatic FIB processes, coupled with the direct metrological feedback in a DualBeam tool, reveal etch rates do not remain constant for nanometer-scale processing. Control of rippling requires controlled metrology, and robust software tools are developed to enhance metrology. In situ monitoring of the influence of aspect ratio and redeposition at the micron scale correlates to the rippling fundamentals that occur at the nanometer scale and are controlled by the boundary conditions of FIB processing.

Preparation and Characterization of Nano-Films Materials

2011 ◽  
Vol 492 ◽  
pp. 160-163
Author(s):  
Cai Xia Li ◽  
Qing Lv ◽  
Jie Song ◽  
Dan Yu Jiang ◽  
Qiang Li
Keyword(s):  
Self Assembly ◽  
Chemical Properties ◽  
Layered Compounds ◽  
Insertion Reaction ◽  
Layer By Layer ◽  
Vis Spectroscopy ◽  
Assembly Technique ◽  
Assembly Technology ◽  
Physical And Chemical

Nano-sheets are two-dimensional sheet materials exfoliated from the inorganic layered compounds by various physical and chemical methods. Their unique characteristics insertion reaction and excellent physical and chemical properties have attracted more and more researchers' widespread interests. Selecting quartz glass as the substrate, using layer by layer self-assembly technology, different nano-films materials are prepared. UV/Vis spectroscopy confirmed nano-films materials have been successfully assembled using LBL self-assembly technique. Raman spectrum are mainly used to analyze and characterize the structure of nano-films materials.

TEM of electron-beam induced crystallization of an amorphous AuFe.03/Si Spin-Glass Multilayer

1993 ◽  
Vol 51 ◽  
pp. 1098-1099
Author(s):  
D.A. Howell ◽  
L. Hoines ◽  
M.A. Crimp ◽  
J. Bass ◽  
J.W. Heckman
Keyword(s):  
Thin Film ◽  
Spin Glass ◽  
Cross Sections ◽  
Silicon Substrate ◽  
Giant Magnetoresistance ◽  
Finite Size ◽  
Single Crystal Silicon ◽  
Film Surface ◽  
Glass Slide ◽  
Crystal Silicon

The use of thin film multilayers for the study of physical phenomena (e.g. spin-glass dc magnetic susceptibility, giant magnetoresistance, and x-ray reflectivity) has grown recently as the technology for their preparation has improved. The multilayers in this study were produced for an investigation of finite-size effects in a AuFe.03 spin-glass.We prepared the samples by dc sputtering of a AuFe.03, alloy and a Si target in an UHV system. The specimen in this investigation had 67 bilayers of 3 nm spin-glass layers alternating with 7 nm amorphous silicon (a-Si) layers on a (001) single-crystal silicon substrate for a total film thickness of 670 nm. Ultrathin cross-sections were prepared by cleaning the thin-film surface in Freon TF and gluing this surface to a clean ground-glass slide with epoxy. We removed the thin-film from its silicon substrate by peeling the substrate from the film which remained on the glass slide.

Coating Polyelectrolyte Multilayers Loaded with Quercetin on Titanium Surfaces by Layer-By-Layer Assembly Technique to Improve Surface Osteogenesis Under Osteoporotic Condition

2021 ◽  
Vol 17 (7) ◽  
pp. 1392-1403
Author(s):  
Bingzhang Wang ◽  
Liang Chen ◽  
Jun Xie ◽  
Jiahao Tang ◽  
Chenxuan Hong ◽  
...  
Keyword(s):  
Contact Angle ◽  
Controlled Release ◽  
Multilayer Films ◽  
Titanium Implants ◽  
Titanium Matrix ◽  
Release System ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Assembly Technique ◽  
Controlled Release System

Titanium (Ti) and its alloy implants are widely used in the field of orthopedics, and osteoporosis is an important reason for implantation failure. This study aimed to establish a quercetin (QTN) controlled release system on the surface of titanium implants and to study its effects on osteogenesis and osseointegration on the surface of implants. Polyethylenimine (PEI) was first immobilized on a titanium substrate as the base layer, and then, hyaluronic acid/chitosan-quercetin (HA/CS-QTN) multilayer films were assembled on the PEI layer by a self-assembly technique. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and contact angle measurements were used to characterize and analyze the samples. The release characteristics of QTN were studied by release assays. The osteogenic ability of the samples was evaluated by experiments on an osteoporosis rat model and MC3T3-E1 cells. The FTIR, SEM, and contact angle measurements all showed that the PEI substrate layer and HA/CS-QTN multilayer film were successfully immobilized on the titanium matrix. The drug release test showed the successful establishment of a QTN controlled release system. The in vitro results showed that osteoblasts exhibited higher adhesion, proliferation and differentiation ability on the coated titanium matrix than on the pure titanium surface. In addition, the in vivo results showed that the HA/CS-QTN coating significantly increased the new bone mass around the implant. By depositing a PEI matrix layer and HA/CS-QTN multilayer films on titanium implants, a controlled release system of QTN was established, which improved implant surface osseointegration under osteoporotic conditions. This study proposes a new implant therapy strategy for patients with osteoporosis.

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