Influence of Grafting Density on Ultrasound-Induced Backbone and Arm Scission of Graft Copolymers

2021 ◽  
Author(s):  
Gregory I. Peterson ◽  
Jinkyung Noh ◽  
Min Young Ha ◽  
Sanghee Yang ◽  
Won Bo Lee ◽  
...  
Keyword(s):  
Graft Copolymers ◽  
Grafting Density

Influence of the Grafting Density on the Self-Assembly in Poly(phenyleneethynylene)-g-poly(3-hexylthiophene) Graft Copolymers

2015 ◽  
Vol 48 (24) ◽  
pp. 8789-8796 ◽  
Author(s):  
Joost Steverlynck ◽  
Julien De Winter ◽  
Pascal Gerbaux ◽  
Roberto Lazzaroni ◽  
Philippe Leclère ◽  
...  
Keyword(s):  
Self Assembly ◽  
Graft Copolymers ◽  
The Self ◽  
Grafting Density

Preparation of graft copolymers by the reaction of polymeric acyl chlorides with monohydroxy-terminated polymers: An introductory study

1988 ◽  
Vol 53 (8) ◽  
pp. 1735-1744 ◽  
Author(s):  
Jitka Horská ◽  
Jaroslav Stejskal ◽  
Pavel Kratochvíl ◽  
Aubrey D. Jenkins ◽  
Eugenia Tsartolia ◽  
...  
Keyword(s):  
Light Scattering ◽  
Chemical Composition ◽  
Statistical Model ◽  
Graft Copolymers ◽  
Coupling Reaction ◽  
Molecular Characteristics ◽  
Gel Formation ◽  
Acyl Chlorides ◽  
Molecular Weights

An attempt was made to prepare well-defined graft copolymers by the coupling reaction between acyl chloride groups located along the backbone chain and monohydroxy-terminated grafts prepared separately. The molecular weights and the parameters of heterogeneity in chemical composition of the products were determined by light scattering and osmometry. The determination of molecular characteristics revealed that the degree of grafting was low. The results therefore could not be confronted with a statistical model at this stage. The problems encountered in the synthesis, e.g., gel formation, and the data relating to the soluble products are discussed.

Association of Graft Copolymers of Alkyl Methacrylates with α-Methyl-ω-hydroxy-poly(oxyethylene) ethacrylates

1995 ◽  
Vol 60 (11) ◽  
pp. 1971-1985 ◽  
Author(s):  
Čestmír Koňák ◽  
Zdeněk Tuzar ◽  
Pavla Kopečková ◽  
Joseph D. Andrade ◽  
Jindřich Kopeček
Keyword(s):  
Light Scattering ◽  
Graft Copolymers ◽  
Water Solution ◽  
Pure Water ◽  
Solution Properties ◽  
Monomer Composition ◽  
Special Procedure ◽  
Methyl Cellosolve ◽  
Hexyl Methacrylate ◽  
Alkyl Methacrylates

Solution properties of the statistical copolymers of alkyl methacrylates (AMA) with α-methyl-ω-hydroxy-poly(oxyethylene) methacrylates (MPOEMA) (nonionic polysoaps) were studied using static and dynamic ligh scattering as a function of monomer composition and concentration in aqueous and methyl cellosolve solutions. The solubility of the copolymers in water was found to be dependent on molar contant of AMA. While copolymers with low content of hexyl methacrylate (HMA) (0 and 20 mole %) were directly soluble in water, forming true solutions with a low content of large swollen aggregates, copolymers with a higher content of HMA or lauryl methacrylate (LMA) were not directly dispersable in water. A special procedure, the stepwise dialysis from methyl cellosolve solutions against water, had to be used to prepare them in the pseudomicellar form. The copolymers were directly soluble in methyl cellosolve and its water solution containing up to 60 vol.% of water. Nevertheless, the light scattering experiments were dominated by light scattering of swollen particles of aggregated copolymer molecules. The copolymers were not soluble in the mixtures containing 70-100 vol.% of water. Paramaters of aggregates in the mixture with 60 vol.% of water and in pure water were found to be very similar.

Cationic modifications of polyalkenes II. Effect of a single or continuous supply of Co-initiator

1989 ◽  
Vol 54 (5) ◽  
pp. 1269-1275
Author(s):  
Miloslav Kučera ◽  
Dušan Kimmer ◽  
Karla Majerová ◽  
Zdeněk Fiala
Keyword(s):  
Isotactic Polypropylene ◽  
Graft Copolymers ◽  
Single Addition

For an effective modification of polyalkenes leading to the formation of block and/or graft copolymers, the presence of co-initiating water is absolutely necessary. We have compared two procedures used in the co-initiation of cationic reactions on polymers. Gradually supplied air moisture raises the efficiency of modification of isotactic polypropylene with poly(oxyethylene) several times, compared with a single addition of co-initiating water.

scholarly journals Bottlebrush polymers in the melt and polyelectrolytes in solution share common structural features

2020 ◽  
Vol 117 (10) ◽  
pp. 5168-5175 ◽  
Author(s):  
Joel M. Sarapas ◽  
Tyler B. Martin ◽  
Alexandros Chremos ◽  
Jack F. Douglas ◽  
Kathryn L. Beers
Keyword(s):  
Neutron Scattering ◽  
Correlation Length ◽  
Salt Concentration ◽  
Polymer Concentration ◽  
Structural Features ◽  
Peak Position ◽  
Correlation Peak ◽  
Grafting Density ◽  
Scattering Measurements ◽  
Polyelectrolyte Solutions

Uncharged bottlebrush polymer melts and highly charged polyelectrolytes in solution exhibit correlation peaks in scattering measurements and simulations. Given the striking superficial similarities of these scattering features, there may be a deeper structural interrelationship in these chemically different classes of materials. Correspondingly, we constructed a library of isotopically labeled bottlebrush molecules and measured the bottlebrush correlation peak position q*=2π/ξ by neutron scattering and in simulations. We find that the correlation length scales with the backbone concentration, ξ∼cBB−0.47, in striking accord with the scaling of ξ with polymer concentration cP in semidilute polyelectrolyte solutions (ξ∼cP−1/2). The bottlebrush correlation peak broadens with decreasing grafting density, similar to increasing salt concentration in polyelectrolyte solutions. ξ also scales with sidechain length to a power in the range of 0.35–0.44, suggesting that the sidechains are relatively collapsed in comparison to the bristlelike configurations often imagined for bottlebrush polymers.

scholarly journals Effects of Amino Acid Side-Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1789
Author(s):  
Dmitry Tolmachev ◽  
George Mamistvalov ◽  
Natalia Lukasheva ◽  
Sergey Larin ◽  
Mikko Karttunen
Keyword(s):  
Glutamic Acid ◽  
Chain Length ◽  
Chemical Structure ◽  
Side Chain ◽  
Side Chains ◽  
Side Chain Length ◽  
Polyelectrolyte Brushes ◽  
Grafting Density ◽  
The Difference ◽  
Cellulose Surface

We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α,L-glutamic acid and α,L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is to search for ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side-chain length, the chemical structure and their interplay are required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side-chain rotation, enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side-chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main-chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.

scholarly journals Triple‐Responsive Polyampholytic Graft Copolymers as Smart Sensors with Varying Output

2020 ◽  
pp. 2000671
Author(s):  
Johannes B. Max ◽  
Afshin Nabiyan ◽  
Jonas Eichhorn ◽  
Felix H. Schacher
Keyword(s):  
Graft Copolymers ◽  
Smart Sensors

Amphiphilic Graft Copolymers Capable of Mixed-Mode Interaction as Alternative Nonviral Transfection Agents

2021 ◽  
Vol 4 (2) ◽  
pp. 1268-1282
Author(s):  
Ivonne L. Diaz Ariza ◽  
Valérie Jérôme ◽  
León D. Pérez Pérez ◽  
Ruth Freitag
Keyword(s):  
Mixed Mode ◽  
Graft Copolymers ◽  
Mode Interaction ◽  
Amphiphilic Graft Copolymers ◽  
Nonviral Transfection
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