Dual catalysis for the copolymerisation of epoxides and lactones

2019 ◽  
Vol 55 (48) ◽  
pp. 6914-6917 ◽  
Author(s):  
Naomi E. Clayman ◽  
Lilliana S. Morris ◽  
Anne M. LaPointe ◽  
Ivan Keresztes ◽  
Robert M. Waymouth ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Dual Catalysis ◽  
Comonomer Content

Using a dual catalysis approach, epoxide/lactone copolymers were synthesized with control over tacticity, molecular weight, crystallinity, and comonomer content.

Effect of molecular weight and average comonomer content on the crystallization analysis fractionation (Crystaf) of ethylene α-olefin copolymers

Polymer ◽  
2003 ◽  
Vol 44 (8) ◽  
pp. 2393-2401 ◽  
Author(s):  
Siripon Anantawaraskul ◽  
João B.P Soares ◽  
Paula M Wood-Adams ◽  
Benjamin Monrabal
Keyword(s):  
Molecular Weight ◽  
Comonomer Content

Relationship between Structure and Mechanical Properties of Melt Processable PTFE: Influence of Molecular Weight and Comonomer Content

2012 ◽  
Vol 298 (9) ◽  
pp. 954-966 ◽  
Author(s):  
Achim Frick ◽  
Dorota Sich ◽  
Gert Heinrich ◽  
Claudia Stern ◽  
Matthias Gössi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Comonomer Content

scholarly journals Copolymerization of Propylene with Higher α-Olefins by a Pyridylamidohafnium Catalyst: An Effective Approach to Polypropylene-Based Elastomer

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 89 ◽  
Author(s):  
Fei Yang ◽  
Xiaoyan Wang ◽  
Zhe Ma ◽  
Bin Wang ◽  
Li Pan ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Elastic Recovery ◽  
Side Chain ◽  
Narrow Molecular Weight Distribution ◽  
X Ray ◽  
Mild Conditions ◽  
X Ray Scattering ◽  
Mechanical Performances ◽  
Comonomer Content

In this contribution, we explored the copolymerization of propylene with higher α-olefins, including 1-octene (C8) 1-dodecene (C12), 1-hexadecene (C16) and 1-eicosene (C20), by using a dimethyl pyridylamidohafnium catalyst. A series of copolymers with varied comonomer incorporation, high molecular weight and narrow molecular weight distribution were obtained at mild conditions. The effects of the insertion of the comonomers on the microstructure, thermal and final mechanical properties were systemically studied by 13C NMR, wide-angle X-ray scattering, DSC and tensile test. Excellent mechanical performances were achieved by tuning the incorporation and chain length of the higher α-olefins. When the comonomer content reached above 12 mol.%, polypropylene-based elastomers were obtained with high ductility. A combination of excellent elastic recovery and flexibility was achieved for the P/C16 copolymers with about 20 mol.% monomer incorporation. The monomer incorporation and side chain length played a crucial role in determining the mechanical property of the outstanding polypropylene-based elastomers.

Impact of molecular weight and comonomer content on catalytic hydrogen-deuterium exchange in polyolefins

Polymer ◽  
2016 ◽  
Vol 102 ◽  
pp. 99-105 ◽  
Author(s):  
Shuhui Kang ◽  
Yiming Zeng ◽  
Timothy P. Lodge ◽  
Frank S. Bates ◽  
Patrick Brant ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Deuterium Exchange ◽  
Hydrogen Deuterium Exchange ◽  
Hydrogen Deuterium ◽  
Catalytic Hydrogen ◽  
Comonomer Content

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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