Grafting well-defined CO2-responsive polymers to cellulose nanocrystals via nitroxide-mediated polymerisation: effect of graft density and molecular weight on dispersion behaviour

2017 ◽  
Vol 8 (38) ◽  
pp. 6000-6012 ◽  
Author(s):  
J. Glasing ◽  
J. Bouchard ◽  
P. G. Jessop ◽  
P. Champagne ◽  
M. F. Cunningham
Keyword(s):  
Molecular Weight ◽  
Cellulose Nanocrystals ◽  
Responsive Polymers ◽  
Graft Density

Tertiary polyamines and polyamides were grafted to cellulose nanocrystals (CNC) via Nitroxide-Mediated Polymerisation to yield well-defined CNC, which were examined for their CO2-responsive dispersibility in water and oil.

Partitioning of charged and neutral dextran-dye derivatives in biphasic cellulose nanocrystal suspensions

2008 ◽  
Vol 86 (6) ◽  
pp. 503-511 ◽  
Author(s):  
Stephanie Beck-Candanedo ◽  
David Viet ◽  
Derek G Gray
Keyword(s):  
Molecular Weight ◽  
Partition Coefficient ◽  
Cellulose Nanocrystals ◽  
Partition Coefficients ◽  
Virial Coefficient ◽  
Total Concentration ◽  
Second Virial Coefficient ◽  
Fluorescein Isothiocyanate ◽  
Blue Dextran ◽  
Molecular Weights

The partitioning behaviour of dye-labeled dextrans of high molecular weight in aqueous suspensions of native cellulose nanocrystals was studied. Cellulose concentrations lie in the isotropic–nematic coexistence region. Blue dextrans of various molecular weights and degrees of substitution of dye molecules (anionic Cibacron blue 3G-A) were investigated. Increasing the total concentration of blue dextran and degree of dye substitution led to increasing partition coefficients. Increasing dextran molecular weight resulted in higher partition coefficients, in agreement with theory. Partition coefficients were larger than predicted theoretically using a second virial coefficient approximation. Electrostatic and entropic contributions to the partition coefficient of blue dextran are discussed. Dextrans labeled with neutral fluorescein isothiocyanate did not partition preferentially in this system.Key words: partition coefficient, cellulose nanocrystals, dextrans, degree of substitution, polyelectrolyte.

Effect of graft density and molecular weight on mechanical properties of rubbery block copolymer grafted SiO2 nanoparticle toughened epoxy

Polymer ◽  
2013 ◽  
Vol 54 (15) ◽  
pp. 3961-3973 ◽  
Author(s):  
Jianing Gao ◽  
Junting Li ◽  
Su Zhao ◽  
Brian C. Benicewicz ◽  
Henrik Hillborg ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Block Copolymer ◽  
Sio2 Nanoparticle ◽  
Toughened Epoxy ◽  
Graft Density

Grafting CO2-responsive polymers from cellulose nanocrystals via nitroxide-mediated polymerisation

2017 ◽  
Vol 8 (28) ◽  
pp. 4124-4131 ◽  
Author(s):  
Omar Garcia-Valdez ◽  
Tiziana Brescacin ◽  
Joaquin Arredondo ◽  
Jean Bouchard ◽  
Philip G. Jessop ◽  
...  
Keyword(s):  
Cellulose Nanocrystals ◽  
Responsive Polymers

CO2-Responsive polymers are grafted onto cellulose nanocrystals using nitroxide-mediated polymerisation.

Polymer Nanocomposites with Designed Interfaces

2007 ◽  
Vol 334-335 ◽  
pp. 909-912
Author(s):  
Linda S. Schadler ◽  
Sarah L. Lewis ◽  
Jun Wei Yang ◽  
Brian C. Benicewicz
Keyword(s):  
Molecular Weight ◽  
Polymer Nanocomposites ◽  
Silica Particles ◽  
Interface Region ◽  
Curved Surfaces ◽  
Grafted Polymer ◽  
Preliminary Results ◽  
Graft Density ◽  
Composite Properties

This paper shows preliminary results for polymer nanocomposites consisting of “hairy” silica particles with grafted polystyrene in polystyrene matrices of controlled molecular weight and polydispersity. The goal of the work is to tailor the degree of wetting / interaction between the particles and polymer by controlling the graft density and molecular weight of the grafted polymer. This is providing an opportunity to study the properties of the interface region and to control the bulk composite properties. We have found that the predictions for flat brushes are qualitatively, but not quantitatively, applicable and that the highly curved surfaces of nanoparticles present several challenges for the design of nanoparticle interfaces. The talk will present more complete results in this system and provide an overview of other work in our group using tailored interfaces to control nanocomposite properties.

Evaluation of the dark field method for large association of spread DNA

1978 ◽  
Vol 36 (2) ◽  
pp. 190-191
Author(s):  
Douglas C. Barker
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Mitochondrial Dna ◽  
Extraction Method ◽  
Field Method ◽  
Dark Field ◽  
Kinetoplast Dna ◽  
Field Electron ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A number of satisfactory methods are available for the electron microscopy of nicleic acids. These methods concentrated on fragments of nuclear, viral and mitochondrial DNA less than 50 megadaltons, on denaturation and heteroduplex mapping (Davies et al 1971) or on the interaction between proteins and DNA (Brack and Delain 1975). Less attention has been paid to the experimental criteria necessary for spreading and visualisation by dark field electron microscopy of large intact issociations of DNA. This communication will report on those criteria in relation to the ultrastructure of the (approx. 1 x 10-14g) DNA component of the kinetoplast from Trypanosomes. An extraction method has been developed to eliminate native endonucleases and nuclear contamination and to isolate the kinetoplast DNA (KDNA) as a compact network of high molecular weight. In collaboration with Dr. Ch. Brack (Basel [nstitute of Immunology), we studied the conditions necessary to prepare this KDNA Tor dark field electron microscopy using the microdrop spreading technique.

Introduction

1978 ◽  
Vol 36 (3) ◽  
pp. 543-544
Author(s):  
W. Bernard
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Nucleic Acid ◽  
Gene Mapping ◽  
Molecular Genetics ◽  
Cell Biology ◽  
Gene Activity ◽  
Close Connection ◽  
Basic Information ◽  
Simple Systems

In comparison to many other fields of ultrastructural research in Cell Biology, the successful exploration of genes and gene activity with the electron microscope in higher organisms is a late conquest. Nucleic acid molecules of Prokaryotes could be successfully visualized already since the early sixties, thanks to the Kleinschmidt spreading technique - and much basic information was obtained concerning the shape, length, molecular weight of viral, mitochondrial and chloroplast nucleic acid. Later, additonal methods revealed denaturation profiles, distinction between single and double strandedness and the use of heteroduplexes-led to gene mapping of relatively simple systems carried out in close connection with other methods of molecular genetics.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

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