scholarly journals Gold Nanoparticles Size Design and Control by Poly(N,N′-diethylaminoethyl methacrylate)

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Norma A. Cortez-Lemus ◽  
Angel Licea-Claverie ◽  
Francisco Paraguay-Delgado ◽  
Gabriel Alonso-Nuñez
Keyword(s):  
Molecular Weight ◽  
Gold Nanoparticles ◽  
Ph Value ◽  
Polymer Molecular Weight ◽  
Polar Solvents ◽  
Molecular Weights ◽  
Solvent Type ◽  
Acidic Conditions ◽  
And Control

Poly(N,N′-diethylaminoethyl methacrylate) (PDEAEM) with different molecular weights was used to stabilize gold nanoparticles (AuNPs) obtained byin situreduction of tetrachloroauric acid using citrates under acidic conditions and in organic/alcoholic medium. The influence of the pH value on gold nanoparticle size in the presence of PDEAEM was investigated. Results show that the pH of the reacting mixture has a dramatic effect on the size, polydispersity, and morphology of the resulting AuNPs. Moreover, the size of the nanoparticles (NPs) may be modified by changing the solution’s pH or by changing the solvent type. Electron microscope images showed that the sizes of AuNPs coated with PDEAEM were not sensitive to the variation of the polymer molecular weight in the range between 9000 and 29300 g/mol; however their aggregation behavior depended strongly on the polymer molecular weight as revealed by dynamic light scattering studies. AuNPs stabilized with PDEAEM (AuNP@PDEAEM) are stable in water at acidic pH and in organic polar solvents.

scholarly journals Multi Self-Healable UV Shielding Polyurethane/CeO2 Protective Coating: The Effect of Low-Molecular-Weight Polyols

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1947
Author(s):  
Mohammad Mizanur Rahman ◽  
Rami Suleiman ◽  
Md. Hasan Zahir ◽  
Aasif Helal ◽  
A. Madhan Kumar ◽  
...  
Keyword(s):  
Molecular Weight ◽  
In Situ Polymerization ◽  
Outdoor Exposure ◽  
Low Molecular Weight ◽  
Self Healing ◽  
Polydimethyl Siloxane ◽  
Molecular Weights ◽  
Uv Shielding ◽  
Ceo2 Coating

We prepared a series of polyurethane (PU) coatings with defined contents using poly(tetramethylene oxide)glycol (PTMG) with two different molecular weights (i.e., Mn = 2000 and 650), as well as polydimethyl siloxane (PDMS) with a molecular weight of Mn 550. For every coating, maximum adhesive strength and excellent self-healing character (three times) were found using 6.775 mol% mixed with low-molecular-weight-based polyols (PU-11-3-3). Defined 1.0 wt% CeO2 was also used for the PU-11-3-3 coating (i.e., PU-11-3-3-CeO2) to obtain UV shielding properties. Both the in situ polymerization and blending processes were separately applied during the preparation of the PU-11-3-3-CeO2 coating dispersion. The in situ polymerization-based coating (i.e., PU-11-3-3-CeO2-P) showed similar self-healing properties. The PU-11-3-3-CeO2-P coating also showed excellent UV shielding in real outdoor exposure conditions.

In situ formation of AuNPs using fatty N-acylamino hydrazide organogelators as templates

2019 ◽  
Vol 43 (1) ◽  
pp. 295-303 ◽  
Author(s):  
Renata Ongaratto ◽  
Naiane Conte ◽  
Caroline R. Montes D’Oca ◽  
Rafael C. Brinkerhoff ◽  
Caroline Pires Ruas ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gold Nanoparticles ◽  
Low Molecular Weight ◽  
In Situ Formation ◽  
First Time

This work reports, for the first time, the synthesis of new fatty N-acylamino hydrazides and demonstrates the activity of these compounds as low-molecular-weight organic gelators and templates for preparation of gold nanoparticles (AuNPs).

Fluorescent gold nanoparticles with chain-end grafted RAFT copolymers: influence of the polymer molecular weight and type of chromophore

2016 ◽  
Vol 7 (44) ◽  
pp. 6812-6825 ◽  
Author(s):  
Cristina Cepraga ◽  
Arnaud Favier ◽  
Frédéric Lerouge ◽  
Pierre Alcouffe ◽  
Cécile Chamignon ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gold Nanoparticles ◽  
Polymer Molecular Weight

Fluorescence of gold nanoparticles functionalized with chain-end grafted RAFT copolymers increases with polymer corona thickness.

scholarly journals How to Determine the Role of an Additive on the Length of Supramolecular Polymers?

2020 ◽  
Vol 02 (02) ◽  
pp. 129-142 ◽  
Author(s):  
Elisabeth Weyandt ◽  
Mathijs F. J. Mabesoone ◽  
Lafayette N. J. de Windt ◽  
E. W. Meijer ◽  
Anja R. A. Palmans ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Control ◽  
Degree Of Polymerization ◽  
Supramolecular Polymers ◽  
Molecular Weights ◽  
Molecular Weight Control ◽  
A Chain ◽  
And Control ◽  
Supramolecular Polymerization

In polymer chemistry, modulation of sequence and control over chain length are routinely applied to alter and fine-tune the properties of covalent (co)polymers. For supramolecular polymers, the same principles underlying this control have not been fully elucidated up to this date. Particularly, rational control over molecular weight in dynamic supramolecular polymers is not trivial, especially when a cooperative mechanism is operative. We start this review by summarizing how molecular-weight control has been achieved in seminal examples in the field of supramolecular polymerizations. Following this, we propose to classify the avenues taken to control molecular weights in supramolecular polymerizations. We focus on dynamic cooperative supramolecular polymerization as this is the most challenging in terms of molecular weight control. We use a mass-balance equilibrium model to predict how the nature of the interaction of an additive B with the monomers and supramolecular polymers of component A affects the degree of aggregation and the degree of polymerization. We put forward a classification system that distinguishes between B acting as a chain capper, a sequestrator, a comonomer, or an intercalator. We also highlight the experimental methods applied to probe supramolecular polymerization processes, the type of information they provide in relation to molecular weight and degree of aggregation, and how this can be used to classify the role of B. The guidelines and classification delineated in this review to assess and control molecular weights in supramolecular polymers can serve to reevaluate exciting systems present in current literature and contribute to broaden the understanding of multicomponent systems.

Effect of pH on the Fine Structure of Pectic Acid

1970 ◽  
Vol 28 ◽  
pp. 130-131
Author(s):  
George F. Leeper
Keyword(s):  
Molecular Weight ◽  
Fine Structure ◽  
Molecular Species ◽  
Phosphotungstic Acid ◽  
Ph Value ◽  
Water Soluble ◽  
Pectic Acid ◽  
Molecular Weights ◽  
Ph Values ◽  
Elementary Fibrils

Elementary fibrils, about 35 Å wide, have been demonstrated for cellulose by a variety of techniques. More recently, they have been demonstrated for xylan, chitin, and mannan. However, their existence has not been previously reported for any of the water soluble polysaccharides.Pectic acid molecules of about 200,000 molecular weight and enzymatically abbreviated derivatives with molecular weights of 60,000 and 9,000 were negatively stained at various pH values with 2% phosphotungstic acid to demonstrate elementary fibrils. The width and degree of fasciation of these elementary fibrils varies with pH. Pectic acid elementary fibrils exhibit a 64 Å dimensional stability above a certain pH value which varies inversely with molecular weight. Below this pH, elementary fibrils exhibit a marked increase in width. At still lower pH values, the elementary fibrils are no longer demonstrable, presumably because of their dissociation to a molecular species.

In situ molecular weight determination of rat brain [3H]phenytoin binding sites

1985 ◽  
Vol 63 (5) ◽  
pp. 515-516 ◽  
Author(s):  
Lawrence Spero
Keyword(s):  
Molecular Weight ◽  
Rat Brain ◽  
Binding Sites ◽  
Molecular Weight Determination ◽  
Lower Affinity ◽  
Molecular Weights

Using irradiation inactivation analysis of specific [3H]phenytoin binding to rat brain we have demonstrated that there are two different binding sites involved, with molecular weights of 73 238 ± 1535 (higher affinity site) and 108 121 ± 6935 (lower affinity site).

Evaluation of Chitosan Nanomaterials in the Treatment of Helicobacter pylori Mediated Gastric Diseases

2020 ◽  
Vol 20 (12) ◽  
pp. 7464-7468
Author(s):  
Xiaobo Wang ◽  
Feng Ji
Keyword(s):  
Molecular Weight ◽  
Helicobacter Pylori ◽  
Metal Ions ◽  
Antibacterial Effect ◽  
Ph Value ◽  
Hole Drilling ◽  
Gastric Diseases ◽  
Molecular Weights ◽  
Significant Difference

We assessed the effect of chitosan on Helicobacter pylori (HPY) in vitro to provide an experimental basis for the clinical application of chitosan in the treatment of gastric diseases. Here, the method of hole drilling was used to detect the bacteriostatic effect of different concentrations and pH values of chitosan on the standard bacterial strain Sydney strain I (SSI) and two strains of HPY isolated from patients. The bacteriostatic test was used to explore the effect of different molecular weights of chitosan and metal ions on the antibacterial effect of chitosan. The effect of chitosan showed no significant difference among three HPY strains (p < 0.05); moreover, in the range of pH 5.5–8.5, the antibacterial effect of chitosan increased with decrease in pH value (p < 0.01). A significant difference in the antibacterial effect of chitosan was observed at different concentrations (p < 0.01), reaching a peak at 40 g/mL. The molecular weight of chitosan was within 400 kb. With increasing molecular weight, the antibacterial activity of chitosan increased initially and then decreased. The molecular weight of 0.200 kb demonstrated the strongest anti-HPY effect, with the antibacterial effect observed for up to 134 h. Metal ions such as NaCl and MgCl2 affected the anti-HPY effect of chitosan; with increasing concentration, the antibacterial percentage decreased.

scholarly journals Influence of polymer molecular weight on the properties of in situ synthesized silver–methylcellulose nanocomposite films with a CO2 laser

2019 ◽  
Vol 55 (5) ◽  
pp. 2090-2100 ◽  
Author(s):  
Hayato Nishikawa ◽  
Eiji Nakata ◽  
Shun Nakano ◽  
Takashi Nakajima ◽  
Takashi Morii
Keyword(s):  
Molecular Weight ◽  
Co2 Laser ◽  
Nanocomposite Films ◽  
Polymer Molecular Weight
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