Molecular-weight dependence of the formation of highly ordered lamellar structures of poly(N-dodecyl acrylamide) by humid annealing

2019 ◽  
Vol 10 (7) ◽  
pp. 835-842 ◽  
Author(s):  
Kazuki Ebata ◽  
Yuki Hashimoto ◽  
Kohei Ebara ◽  
Mayu Tsukamoto ◽  
Shunsuke Yamamoto ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
Side Chains ◽  
Molecular Weights ◽  
Lamellar Structures ◽  
Molecular Weight Dependence ◽  
Alkyl Side Chains

Highly oriented lamellar films of poly(N-dodecylacrylamide) with high molecular weights were formed by nanosegregation between alkyl side chains and a water-adsorbed main chain.

Nanophase Separation of Poly(N-alkyl acrylamides): The Dependence of the Formation of Lamellar Structures on Their Alkyl Side Chains

2019 ◽  
Vol 52 (24) ◽  
pp. 9773-9780 ◽  
Author(s):  
Kazuki Ebata ◽  
Yuki Hashimoto ◽  
Shunsuke Yamamoto ◽  
Masaya Mitsuishi ◽  
Shusaku Nagano ◽  
...  
Keyword(s):  
Side Chains ◽  
Lamellar Structures ◽  
Alkyl Side Chains ◽  
Nanophase Separation ◽  
Alkyl Acrylamides

Molecular Weight Effects in Adsorption of Rubbers on Carbon Black

1968 ◽  
Vol 41 (5) ◽  
pp. 1256-1270 ◽  
Author(s):  
Gerard Kraus ◽  
J. T. Gruver
Keyword(s):  
Molecular Weight ◽  
Carbon Black ◽  
Large Particle ◽  
Molecular Weights ◽  
Molecular Weight Dependence ◽  
Bound Rubber ◽  
Sieve Effect ◽  
High Structure ◽  
Very High ◽  
Poor Solvent

Abstract The molecular weight dependence of the adsorption of polybutadiene on carbon black from a poor solvent, n-heptane, and bulk, i.e., the phenomenon of “bound rubber”, was investigated. For narrow distribution polymers the adsorption is proportional to Mn, where n = 0.14 for adsorption from n-heptane solution; n = 0.5 for adsorption from bulk. Anomalously low solution adsorption was observed for polymers of very high molecular weight (> 500,000). This is ascribed to a sieve effect by aggregates of carbon black particles which cannot be penetrated by the large molecular coils. In high structure blacks, which pack more loosely, and in large particle blacks, which form larger interstices between particles, onset of anomalous adsorption is shifted toward higher molecular weights.

Protein

1995 ◽  
Author(s):  
Roland Lüthy ◽  
David Eisenberg
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Isoelectric Point ◽  
Extinction Coefficient ◽  
Titration Curve ◽  
Side Chains ◽  
Pka Values ◽  
Extinction Coefficients ◽  
Molecular Weights

Given a protein sequence, the amino acid composition can be determined by counting the number of residues of each type. Then a molecular weight can be calculated by summing the molecular weights of the individual amino acid residues, taking into account the loss of one H2O molecule per peptide bond. Table 1 lists the molecular weights of the twenty amino acids and water. This approach assumes that the protein has not been covalently modified. Because of extensive glycosylation of some proteins, this approach can significantly underestimate the actual molecular weight. With the pKa values of Table 1, it is possible to calculate the theoretical charge of a protein at a given pH by summing the charges of the amino acid side chains and of the amino terminus and carboxyl terminus. By performing this calculation over a pH range, one obtains a theoretical titration curve and an isoelectric point (the pH at which the protein hasanetchargeof zero). This method assumes that all normally titratable groups are accessible to water, and that all side chains have the intrinsic pKa values listed in Table 1. This assumption is not completely correct, and consequently, the theoretical isoelectric point may differ from the experimentally determined value. Figure 1 shows the calculated titration curve for pancreatic ribonuclease: the calculated isoelectric point is 8.2, whereas the measured value is 9.6 (Lehninger, 1977). The calculation of extinction coefficients (Gill and von Hippel, 1989) is performed in much the same way as that of the isoelectric point Individual residues are treated as if they are free amino acids, and the overall extinction coefficient is calculated as the sum of the extinction coefficients of the residues. The same basic assumption is made: Residues are assumed to be in typical environments and not to show unusual absorption due to their local environments. In the case of the extinction coefficient, however, this assumption seems to be generally acceptable; calculated extinction coefficients are typically within a few percent of the experimentally determined value, and errors of more than 15% are rare (Gill and von Hippel, 1989).

scholarly journals On the molecular-weight-dependence of the anticoagulant activity of heparin

1979 ◽  
Vol 181 (1) ◽  
pp. 241-243 ◽  
Author(s):  
L Thunberg ◽  
U Lindahl ◽  
A Tengblad ◽  
T C Laurent ◽  
C M Jackson
Keyword(s):  
Molecular Weight ◽  
Anticoagulant Activity ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Molecular Weights ◽  
High Affinity ◽  
Polysaccharide Chain ◽  
Molecular Weight Dependence ◽  
Heparin Fractions

The inactivation of thrombin and factor Xa by antithrombin was determined in the presence of heparin fractions of different molecular weights and with high affinity for antithrombin. The ability to potentiate the inactivation of either coagulation factor increased with increasing length of the polysaccharide chain.

Molecular-weight changes in the degradation of long-chain polymers

1954 ◽  
Vol 224 (1156) ◽  
pp. 120-128 ◽  
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
High Energy ◽  
Initial Distribution ◽  
Weight Changes ◽  
Chain Polymer ◽  
High Energy Radiation ◽  
Molecular Weights ◽  
Random Fracture ◽  
Long Chain

The changes in molecular weight of a long-chain polymer (initially of arbitrary molecular-weight distribution) are studied when the main chain is subjected to random fracture, such as occurs when certain polymers are exposed to high-energy radiation. For several distributions studied, all trace of the initial distribution curve is lost after an average of some 3 to 8 main-chain fractures per molecule. For lower degrees of degradation the shape of the curve of weight average against degradation can provide information as to the initial weight average, z average, z + 1 average molecular weights. The initial number-average can be obtained by a method of extrapolation.

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