Light- and Heat-Triggered Reversible Linear–Cyclic Topological Conversion of Telechelic Polymers with Anthryl End Groups

2016 ◽  
Vol 138 (11) ◽  
pp. 3904-3911 ◽  
Author(s):  
Takuya Yamamoto ◽  
Sakyo Yagyu ◽  
Yasuyuki Tezuka
Keyword(s):  
Telechelic Polymers ◽  
End Groups

scholarly journals A Molecular Picture for the Thermo-Reversibility of Gels Formed by Isophthalic Acid-Ended Telechelic Polymers

2015 ◽  
Vol 1794 ◽  
pp. 9-14
Author(s):  
Boyu Li ◽  
Joey Kim ◽  
Julie Kornfield
Keyword(s):  
Hydrogen Bonding ◽  
Aggregation Number ◽  
Polymer Concentration ◽  
Isophthalic Acid ◽  
Solution Temperature ◽  
Present System ◽  
Measured Temperature ◽  
Telechelic Polymers ◽  
End Groups ◽  
Molecular Picture

ABSTRACTWe demonstrate that isophthalic acid-ended telechelic poly(1,5-cyclooctadiene)s (A-PCODs) form thermo-reversible gels in non-polar solvent with a unique molecular mechanism for their thermo-reversibility. Like other associative telechelic polymers, A-PCODs form “flower-like” micelles at low concentration and form gels through bridging at higher concentration which exhibit linear viscoelasticity. However, unlike the widely studied hydrophobically end-capped PEOs, A-PCODs show clear thermo-reversibility in viscosity and dynamic modulus around 30 °C due to the hydrogen-bonding end groups. In addition, they differ from other reported thermo-reversible gelators (eg. Pluronics, PNIPAm containing block copolymers, etc.): neither the end group nor the backbone in the present system has a critical solution temperature within the measured temperature range (0 °C to 60 °C), indicating that the present system has a unique mechanism for its thermo-reversibility. To obtain a molecular picture of the mechanism, rheology and small angle neutron scattering (SANS) studies were implemented. Topological changes above the transition temperature (30 °C) were observed in both oscillatory rheology and SANS. SANS reveals that the size of clusters, which are formed by interacting micelles, depends highly on temperature (T) but independent of polymer concentration. These results cannot be explained by current theories on associative telechelic polymers which assume constant and large aggregation number of end groups at all temperatures and concentrations. We hypothesize that the temperature-sensitive sol-gel transition is due to a decrease in aggregation number for T above the critical temperature in our system, and this temperature-dependence of aggregation number is further determined by the chemical structure and hydrogen-bonding property of isophthalic acid ends.

Microstructure of halato telechelic polymers bearing group IVb metal carboxylate end-groups

1990 ◽  
Vol 51 (16) ◽  
pp. 1721-1731
Author(s):  
Jean-René Regnard ◽  
Pierre Lagarde ◽  
Claudine E. Williams ◽  
Gilberto Vlaic ◽  
Pascal Charlier ◽  
...  
Keyword(s):  
Metal Carboxylate ◽  
Telechelic Polymers ◽  
End Groups

Photoyellowing behavior of non-phenolic lignin models representative of end groups and β-ether structures

2004 ◽  
Vol 19 (2) ◽  
pp. 146-154
Author(s):  
Jim Parkås ◽  
Magnus Paulsson ◽  
Shiming Li ◽  
Knut Lundquist ◽  
Ulla Westermark
Keyword(s):  
End Groups

Synthesis, Characterization, and Dynamic Behavior of Well-defined Dithiomaleimide-functionalized Maltodextrins

2020 ◽  
Vol 17 (2) ◽  
pp. 85-89
Author(s):  
Francisco J. Hidalgo ◽  
Nathan A.P. Lorentz ◽  
TinTin B. Luu ◽  
Jonathan D. Tran ◽  
Praveen D. Wickremasinghe ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Dynamic Behavior ◽  
Industrial Applications ◽  
19F Nmr ◽  
Nmr Studies ◽  
Synthetic Pathway ◽  
End Groups ◽  
Sugar End

: Maltodextrins have an increasing number of biomedical and industrial applications due to their attractive physicochemical properties such as biodegradability and biocompatibility. Herein, we describe the development of a synthetic pathway and characterization of thiol-responsive maltodextrin conjugates with dithiomaleimide linkages. 19F NMR studies were also conducted to demonstrate the exchange dynamics of the dithiomaleimide-functionalized sugar end groups.

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