A Comparison of Hydrogen Bonding and Order in a Polyurethane and Poly(urethane−urea) and Their Blends with Poly(ethylene glycol)

2007 ◽  
Vol 40 (5) ◽  
pp. 1546-1554 ◽  
Author(s):  
Jason Mattia ◽  
Paul Painter
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 ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2235
Author(s):  
Ana Brás ◽  
Ana Arizaga ◽  
Uxue Agirre ◽  
Marie Dorau ◽  
Judith Houston ◽  
...  

In this work we present a fundamental analysis based on small-angle scattering, linear rheology and differential scanning calorimetry (DSC) experiments of the role of different hydrogen bonding (H-bonding) types on the structure and dynamics of chain-end modified poly(ethylene glycol) (PEG) in bulk. As such bifunctional PEG with a molar mass below the entanglement mass Me is symmetrically end-functionalized with three different hydrogen bonding (H-bonding) groups: thymine-1-acetic acid (thy), diamino-triazine (dat) and 2-ureido-4[1H]-pyrimidinone (upy). A linear block copolymer structure and a Newtonian-like dynamics is observed for PEG-thy/dat while results for PEG-upy structure and dynamics reveal a sphere and a network-like behavior, respectively. These observations are concomitant with an increase of the Flory–Huggins interaction parameter from PEG-thy/dat to PEG-upy that is used to quantify the difference between the H-bonding types. The upy association into spherical clusters is established by the Percus–Yevick approximation that models the inter-particle structure factor for PEG-upy. Moreover, the viscosity study reveals for PEG-upy a shear thickening behavior interpreted in terms of the free path model and related to the time for PEG-upy to dissociate from the upy clusters, seen as virtual crosslinks of the formed network. Moreover, a second relaxation time of different nature is also obtained from the complex shear modulus measurements of PEG-upy by the inverse of the angular frequency where G’ and G’’ crosses from the network-like to glass-like transition relaxation time, which is related to the segmental friction of PEG-upy polymeric network strands. In fact, not only do PEG-thy/dat and PEG-upy have different viscoelastic properties, but the relaxation times found for PEG-upy are much slower than the ones for PEG-thy/dat. However, the activation energy related to the association dynamics is very similar for both PEG-thy/dat and PEG-upy. Concerning the segmental dynamics, the glass transition temperature obtained from both rheological and calorimetric analysis is similar and increases for PEG-upy while for PEG-thy/dat is almost independent of association behavior. Our results show how supramolecular PEG properties vary by modifying the H-bonding association type and changing the molecular Flory–Huggins interaction parameter, which can be further explored for possible applications.


2019 ◽  
Vol 307 ◽  
pp. 413-422 ◽  
Author(s):  
Whuisu Shim ◽  
Chae Eun Kim ◽  
Mihyun Lee ◽  
Soo Hyeon Lee ◽  
Joseph Park ◽  
...  

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