Positronium Lifetime Study on Subnanoscopic Structure of Polyrotaxane

2012 ◽  
Vol 733 ◽  
pp. 167-170
Author(s):  
K. Ito ◽  
Chang Ming Zhao ◽  
Kohzo Ito ◽  
Yoshinori Kobayashi
Keyword(s):  
Ethylene Glycol ◽  
Temperature Dependence ◽  
Positron Annihilation ◽  
Chemical Structure ◽  
Poly Ethylene Glycol ◽  
Positron Annihilation Lifetime ◽  
Positronium Lifetime ◽  
End Groups ◽  
Poly Ethylene ◽  
Free Volume Hole

The subnanoscopic structures of polyrotaxanes, prepared from α-cyclodextrins, poly(ethylene glycol), and bulky adamantane end groups, were examined by means of the positron annihilation lifetime technique, in consideration of the free-volume hole, quantified from the long-lived ortho-positronium (o-Ps) lifetimes. The influence of the chemical structure on the temperature dependence of the o-Ps lifetimes are discussed.

Chemical Structures of Liquid Poly(ethylene glycol)s with Different End Groups at Buried Polymer Interfaces

2006 ◽  
Vol 39 (26) ◽  
pp. 9396-9401 ◽  
Author(s):  
Mark A. Even ◽  
Chunyan Chen ◽  
Jie Wang ◽  
Zhan Chen
Keyword(s):  
Ethylene Glycol ◽  
Polymer Interfaces ◽  
Poly Ethylene Glycol ◽  
Chemical Structures ◽  
End Groups ◽  
Poly Ethylene

scholarly journals Some Guidelines for the Synthesis and Melting Characterization of Azide Poly(ethylene glycol) Derivatives

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1269
Author(s):  
Daniel González-Fernández ◽  
Mercedes Torneiro ◽  
Massimo Lazzari
Keyword(s):  
Molecular Weight ◽  
Ethylene Glycol ◽  
Average Molecular Weight ◽  
Size Exclusion ◽  
Degree Of Crystallinity ◽  
Specific Class ◽  
Poly Ethylene Glycol ◽  
End Groups ◽  
Poly Ethylene

We provide fundamental guidelines in the form of a tutorial to be taken into account for the preparation and characterization of a specific class of poly(ethylene glycol) (PEG) derivatives, namely azide-terminated PEGs. Special attention is given to the effect of these chain end groups and their precursors on properties affecting the PEGylation of proteins, nanoparticles and nanostructured surfaces. Notwithstanding the presence of 13C satellite peaks, we show that 1H NMR enables not only the routine quantitative determination of chain-end substitution, but is also a unique method to calculate the absolute number average molecular weight of PEG derivatives. In the use of size exclusion chromatography to get molecular weight distributions, we highlight the importance of distinguishing between eventual secondary reactions involving molecular weight changes and the formation of PEG complexes due to residual amounts of metal cations from reactants. Finally, we show that azide end groups affect PEG melting behavior. In contrast to oxygen-containing end groups, azides do not interact with PEG segments, thus inducing defect formation in the crystal lattice and the reduction of crystal sizes. Melting temperature and degree of crystallinity decrease become especially relevant for PEGs with very low molecular weight, and its comprehension is particularly important for solid-state applications.

Modification of unsaturated polyesters by poly(ethylene glycol) end groups

1997 ◽  
Vol 64 (3) ◽  
pp. 527-537 ◽  
Author(s):  
Uwe Schulze ◽  
Mikael Skrifvars ◽  
Norbert Reichelt ◽  
Hans-Werner Schmidt
Keyword(s):  
Ethylene Glycol ◽  
Poly Ethylene Glycol ◽  
Unsaturated Polyesters ◽  
End Groups ◽  
Poly Ethylene

Supramolecular Approach to Gene Delivery

2008 ◽  
Vol 57 ◽  
pp. 144-147 ◽  
Author(s):  
Nobuhiko Yui
Keyword(s):  
Drug Delivery ◽  
Gene Delivery ◽  
Ethylene Glycol ◽  
Polymeric Chain ◽  
Poly Ethylene Glycol ◽  
Practical Applications ◽  
Polymeric Chains ◽  
End Groups ◽  
Poly Ethylene ◽  
Cyclic Compounds

The most definite feature in polyrotaxanes, in which many cyclic compounds are threaded onto a linear polymeric chains capped with bulky end-groups, is the mobility of cyclic compounds: these cyclic compounds may rotate and/or slide along the polymeric chain. Our previous studies have clarified that the mobility of ligands linked to the cyclic compounds is closely related to enhancing multivalent interaction with biological systems. This concept is now exploiting more practical applications for drug delivery such as gene delivery. We have designed biocleavable polyrotaxanes that have a necklace-like structure between many dimethylaminoethylcarbamoyl-α-cyclodextrins (DMAE-α-CDs) and a disulfide (SS)-introduced poly(ethylene glycol) (PEG) chain. The polyrotaxanes were found to show sufficient cleavage of S-S linkages under reducible condition, which led to triggering pDNA release via the dissociation of the non-covalent linkages between DMAE-α-CDs and the PEG chain. The polyrotaxanes were finally clarified to exhibit great transfection activity as well as non cytotoxicity.

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