Individual Contributions of Adsorbed and Free Chains to Microscopic Dynamics of Unentangled poly(ethylene Glycol)/Silica Nanocomposite Melts and the Important Role of End Groups: Theory and Simulation

2021 ◽  
Author(s):  
Emmanuel N. Skountzos ◽  
Dimitrios G. Tsalikis ◽  
Pavlos S. Stephanou ◽  
Vlasis G. Mavrantzas
2006 ◽  
Vol 39 (26) ◽  
pp. 9396-9401 ◽  
Author(s):  
Mark A. Even ◽  
Chunyan Chen ◽  
Jie Wang ◽  
Zhan Chen

RSC Advances ◽  
2015 ◽  
Vol 5 (71) ◽  
pp. 57678-57685 ◽  
Author(s):  
Zhi Wei Low ◽  
Pei Lin Chee ◽  
Dan Kai ◽  
Xian Jun Loh

Hybrid hydrogels, with an elastic modulus and compressive toughness of 350 kPa and 70 J m−3, was synthesized and reported here.


Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1269
Author(s):  
Daniel González-Fernández ◽  
Mercedes Torneiro ◽  
Massimo Lazzari

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.


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