scholarly journals Improving the colloidal stability of Cellulose nano-crystals by surface chemical grafting with polyacrylic acid

1996 ◽  
Vol 1 (3) ◽  
Keyword(s):  
Polyacrylic Acid ◽  
Colloidal Stability ◽  
Surface Chemical ◽  
Chemical Grafting

scholarly journals Heteroagglomeration of nanosilver with colloidal SiO2 and clay

2017 ◽  
Vol 14 (1) ◽  
pp. 1 ◽  
Author(s):  
Sébastien Maillette ◽  
Caroline Peyrot ◽  
Tapas Purkait ◽  
Muhammad Iqbal ◽  
Jonathan G. C. Veinot ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Polyacrylic Acid ◽  
Natural Waters ◽  
Colloidal Particles ◽  
Colloidal Stability ◽  
Analytical Techniques ◽  
Dark Field ◽  
Correlation Spectroscopy ◽  
Colloidal Clay ◽  
High Concentrations

Environmental contextThe fate of nanomaterials in the environment is related to their colloidal stability. Although numerous studies have examined their homoagglomeration, their low concentration and the presence of high concentrations of natural particles implies that heteroagglomeration rather than homoagglomeration is likely to occur under natural conditions. In this paper, two state-of-the art analytical techniques were used to identify the conditions under which nanosilver was most likely to form heteroagglomerates in natural waters. AbstractThe environmental risk of nanomaterials will depend on their persistence, mobility, toxicity and bioaccumulation. Each of these parameters is related to their fate (especially dissolution, agglomeration). The goal of this paper was to understand the heteroagglomeration of silver nanoparticles in natural waters. Two small silver nanoparticles (nAg, ~3nm; polyacrylic acid- and citrate-stabilised) were covalently labelled with a fluorescent dye and then mixed with colloidal silicon oxides (SiO2, ~18.5nm) or clays (~550nm SWy-2 montmorillonite). Homo- and heteroagglomeration of the nAg were first studied in controlled synthetic waters that were representative of natural fresh waters (50μg Ag L–1; pH 7.0; ionic strength 10–7 to 10–1 M Ca) by following the sizes of the nAg by fluorescence correlation spectroscopy. The polyacrylic acid-coated nanosilver was extremely stable under all conditions, including in the presence of other colloids and at high ionic strengths. However, the citrate-coated nanosilver formed heteroaggregates in presence of both colloidal SiO2 and clay particles. Nanoparticle surface properties appeared to play a key role in controlling the physicochemical stability of the nAg. For example, the polyacrylic acid stabilized nAg-remained extremely stable in the water column, even under conditions for which surrounding colloidal particles were agglomerating. Finally, enhanced dark-field microscopy was then used to further characterise the heteroagglomeration of a citrate-coated nAg with suspensions of colloidal clay, colloidal SiO2 or natural (river) water.

scholarly journals Synthesis, Characterizations, and 9.4 Tesla T2 MR Images of Polyacrylic Acid-Coated Terbium(III) and Holmium(III) Oxide Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1355
Author(s):  
Shanti Marasini ◽  
Huan Yue ◽  
Son Long Ho ◽  
Ji Ae Park ◽  
Soyeon Kim ◽  
...  
Keyword(s):  
Contrast Agents ◽  
Polyacrylic Acid ◽  
Colloidal Stability ◽  
Negative Contrast ◽  
Mri Contrast Agents ◽  
Mr Images ◽  
Mri Contrast ◽  
3.0 T ◽  
Magnetic Resonance Imaging Mri

Polyacrylic acid (PAA)-coated lanthanide oxide (Ln2O3) nanoparticles (NPs) (Ln = Tb and Ho) with high colloidal stability and good biocompatibility were synthesized, characterized, and investigated as a new class of negative (T2) magnetic resonance imaging (MRI) contrast agents at high MR fields. Their r2 values were appreciable at a 3.0 T MR field and higher at a 9.4 T MR field, whereas their r1 values were negligible at all MR fields, indicating their exclusive induction of T2 relaxations with negligible induction of T1 relaxations. Their effectiveness as T2 MRI contrast agents at high MR fields was confirmed from strong negative contrast enhancements in in vivo T2 MR images at a 9.4 T MR field after intravenous administration into mice tails.

Co-effects of UV/H2O2 and natural organic matter on the surface chemistry of cerium oxide nanoparticles

2018 ◽  
Vol 5 (10) ◽  
pp. 2382-2393 ◽  
Author(s):  
Xuanhao Wu ◽  
Chelsea W. Neil ◽  
Doyoon Kim ◽  
Haesung Jung ◽  
Young-Shin Jun
Keyword(s):  
Organic Matter ◽  
Surface Chemistry ◽  
Cerium Oxide ◽  
Natural Organic Matter ◽  
Colloidal Stability ◽  
Chemical Properties ◽  
Cerium Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Surface Chemical

This study delineates the co-effects of UV/H2O2 and NOM on the colloidal stability and surface chemical properties of CeO2 nanoparticles.

Sliding Friction of Polymers: The Complex Role of Interface

2005 ◽  
Author(s):  
S. Bistac ◽  
Marjorie Schmitt ◽  
Achraf Ghorbal
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Silicon Wafer ◽  
Sliding Friction ◽  
Surface Chemical ◽  
Normal Forces ◽  
Chemical Grafting ◽  
Soft Elastomer

The objective of this work is to analyse the influence of interfacial properties on the sliding friction of polymers. In order to change the nature of interface, two types of smooth and rigid substrates are used: a hydrophilic silicon wafer (hydroxylated by a piranha treatment) and a hydrophobic silicon wafer, obtained by a chemical grafting with a CH3 terminated silane. Both substrates exhibit identical stiffness and roughness and differ only by their surface chemical composition. Two different polymers are studied: crosslinked polydimethylsiloxane, PDMS (soft elastomer with a low glass transition temperature) and polystyrene (rigid thermoplastic polymer with a high glass transition temperature). Friction experiments are performed with a translation tribometer for different normal forces and friction speeds.

scholarly journals The surface chemical composition effect of a polyacrylic acid/polyvinyl alcohol nanofiber/quartz crystal microbalance sensor on ammonia sensing behavior

RSC Advances ◽  
2018 ◽  
Vol 8 (16) ◽  
pp. 8747-8754 ◽  
Author(s):  
Ying Hu ◽  
Hui Yu ◽  
Zhiyong Yan ◽  
Qinfei Ke
Keyword(s):  
Polyvinyl Alcohol ◽  
Quartz Crystal Microbalance ◽  
Polyacrylic Acid ◽  
Quartz Crystal ◽  
Surface Chemical ◽  
Composition Effect ◽  
Ammonia Sensing ◽  
Surface Chemical Composition ◽  
Quartz Crystal Microbalance Sensor ◽  
Ammonia Sensors

Polyacrylic acid (PAA)/polyvinyl alcohol (PVA)-based quartz crystal microbalance (QCM) ammonia sensors were fabricated by depositing composite PAA/PVA nanofibrous substrates onto QCM gold electrodes.

scholarly journals In Vivo Positive Magnetic Resonance Imaging of Brain Cancer (U87MG) Using Folic Acid-Conjugated Polyacrylic Acid-Coated Ultrasmall Manganese Oxide Nanoparticles

2021 ◽  
Vol 11 (6) ◽  
pp. 2596
Author(s):  
Shanti Marasini ◽  
Huan Yue ◽  
Son-Long Ho ◽  
Ji-Ae Park ◽  
Soyeon Kim ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Folic Acid ◽  
Magnetic Resonance ◽  
Brain Cancer ◽  
Polyacrylic Acid ◽  
Colloidal Stability ◽  
Particle Diameter ◽  
Cancer Targeting ◽  
Average Particle ◽  
Resonance Imaging

Ultrasmall nanoparticles are potential candidates for application as high-performance imaging agents. Herein, we present the synthesis and characterization of folic acid (FA)-conjugated polyacrylic acid (PAA)-coated MnO nanoparticles with an average particle diameter of 2.7 nm. FA conferred cancer-targeting ability, while PAA conferred good colloidal stability and low cellular cytotoxicity on the FA-PAA-coated MnO nanoparticles. Further, the nanoparticles exhibited a high relaxivity (r1) value of 9.3 s−1mM−1 (r2/r1 = 2.2). Their application potential as cancer-targeting T1 magnetic resonance imaging contrast agents was confirmed by their enhanced T1 contrast enhancements at the brain cancer (U87MG) site upon intravenous administration to mice tails.

Analytical Electron Microscopy of Ion-Implanted Metals

1985 ◽  
Vol 43 ◽  
pp. 282-285
Author(s):  
D.I. Potter ◽  
M. Ahmed ◽  
K. Ruffing
Keyword(s):  
Electron Microscopy ◽  
Ion Implantation ◽  
Friction And Wear ◽  
Analytical Electron Microscopy ◽  
Chemical Compositions ◽  
Surface Chemical ◽  
Near Surface ◽  
The Past ◽  
Analytical Electron ◽  
Property Changes

Ion implantation, used extensively for the past decade in fabricating semiconductor devices, now provides a unique means for altering the near-surface chemical compositions and microstructures of metals. These alterations often significantly improve physical properties that depend on the surface of the material; for example, catalysis, corrosion, oxidation, hardness, friction and wear. Frequently the mechanisms causing these beneficial alterations and property changes remain obscure and much of the current research in the area of ion implantation metallurgy is aimed at identifying such mechanisms. Investigators thus confront two immediate questions: To what extent is the chemical composition changed by implantation? What is the resulting microstructure? These two questions can be investigated very fruitfully with analytical electron microscopy (AEM), as described below.

Seed-mediated synthesis and PEG coating of gold nanoparticles for controlling morphology and sizes

MRS Advances ◽  
2020 ◽  
Vol 5 (63) ◽  
pp. 3353-3360
Author(s):  
Susana Helena Arellano Ramírez ◽  
Perla García Casillas ◽  
Christian Chapa González
Keyword(s):  
Gold Nanoparticles ◽  
Polyethylene Glycol ◽  
Room Temperature ◽  
Colloidal Stability ◽  
Infrared Spectrometry ◽  
Ammonium Bromide ◽  
Chloroauric Acid ◽  
Vis Spectroscopy ◽  
Seed Mediated ◽  
Peg Coating

AbstractA significant area of research is biomedical applications of nanoparticles which involves efforts to control the physicochemical properties through simple and scalable processes. Gold nanoparticles have received considerable attention due to their unique properties that they exhibit based on their morphology. Gold nanospheres (AuNSs) and nanorods (AuNRs) were prepared with a seed-mediated method followed of polyethylene glycol (PEG)-coating. The seeds were prepared with 0.1 M cetyltrimethyl-ammonium bromide (CTAB), 0.005 M chloroauric acid (HAuCl4), and 0.01 M sodium borohydride (NaBH4) solution. Gold nanoparticles with spherical morphology was achieved by growth by aggregation at room temperature, while to achieve the rod morphology 0.1 M silver nitrate (AgNO3) and 0.1 M ascorbic acid solution were added. The gold nanoparticles obtained by the seed-mediated synthesis have spherical or rod shapes, depending on the experimental conditions, and a uniform particle size. Surface functionalization was developed using polyethylene glycol. Morphology, and size distribution of AuNPs were evaluated by Field Emission Scanning Electron Microscopy. The average size of AuNSs, and AuNRs was 7.85nm and 7.96 x 31.47nm respectively. Fourier transform infrared spectrometry was performed to corroborate the presence of PEG in the AuNPs surface. Additionally, suspensions of AuNSs and AuNRs were evaluated by UV-Vis spectroscopy. Gold nanoparticles were stored for several days at room temperature and it was observed that the colloidal stability increased once gold nanoparticles were coated with PEG due to the shield formed in the surface of the NPs and the increase in size which were 9.65±1.90 nm of diameter for AuNSs and for AuNRs were 29.03±5.88 and 8.39±1.02 nm for length and transverse axis, respectively.

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