Dynamic covalent bonds in self-healing, shape memory, and controllable stiffness hydrogels

2020 ◽  
Vol 11 (8) ◽  
pp. 1410-1423 ◽  
Author(s):  
M. Mario Perera ◽  
Neil Ayres
Keyword(s):  
Shape Memory ◽  
Self Healing ◽  
Covalent Bonds

A review of hydrogels containing dynamic bonds that are shown to provide benefits for applications including self-healing and stimuli-induced stiffness changes.

Imine Based Self-Healing Hydrogel Triggered by Periodate

2020 ◽  
Author(s):  
Alexis Wolfel ◽  
Cecilia Inés Alvarez Igarzabal ◽  
Marcelo Ricardo Romero
Keyword(s):  
Functional Groups ◽  
Time Window ◽  
Crosslinking Reaction ◽  
Self Healing ◽  
Swelling Properties ◽  
Covalent Bonds ◽  
Smart Systems ◽  
Primary Amino ◽  
Vicinal Diols ◽  
Aldehyde Groups

<p>Design of materials with novel sensitivities and smart behaviour is important for the development of smart systems with automated responsiveness. We have recently reported the synthesis of hydrogels, cross-linked by <i>N,N'</i>-diallyltartardiamide (DAT). The covalent DAT-crosslinking points have vicinal diols which can be easily cleaved with periodate, generating valuable a-oxo-aldehyde functional groups, useful for further chemical modification. Based on those findings, we envisioned that a self-healable hydrogel could be obtained by incorporation of primary amino functional groups, from <a>2-aminoethyl methacrylate </a>hydrochloride (AEMA), coexisting with DAT into the same network. The a-oxo-aldehyde groups generated after the reaction with periodate would arise in the immediate environment of amine groups to form imine cross-links. For this purpose, DAT-crosslinked hydrogels were synthesized and carefully characterized. The cleavage of DAT-crosslinks with periodate promoted changes in the mechanical and swelling properties of the materials. As expected, a self-healing behavior was observed, based on the spontaneous formation of imine covalent bonds. In addition, we surprisingly found a combination of fast vicinal diols cleavage and a low speed self-crosslinking reaction by imine formation. Consequently, it was found a time-window in which a periodate-treated polymer was obtained in a transient liquid state, which can be exploited to choose the final shape of the material, before automated gelling. The singular properties attained on these hydrogels could be useful for developing sensors, actuators, among other smart systems.</p>

New star-shape memory polyurethanes capable of thermally induced recovery and hydrogen bond-self-healing

2021 ◽  
Author(s):  
Zonghui Huang ◽  
Jianfeng Ban ◽  
Lulu Pan ◽  
Shuqing Cai ◽  
Junqiu Liao
Keyword(s):  
Hydrogen Bond ◽  
Shape Memory ◽  
Self Healing ◽  
Thermally Induced ◽  
Thermally Responsive

Star-shape memory polyurethanes that combine thermally responsive and self-healing properties.

Self-healing poly(siloxane-urethane) elastomers with remoldability, shape memory and biocompatibility

2016 ◽  
Vol 7 (47) ◽  
pp. 7278-7286 ◽  
Author(s):  
Jian Zhao ◽  
Rui Xu ◽  
Gaoxing Luo ◽  
Jun Wu ◽  
Hesheng Xia
Keyword(s):  
Mechanical Property ◽  
Shape Memory ◽  
Microphase Separation ◽  
Diels Alder ◽  
Good Mechanical Property ◽  
Self Healing ◽  
Healing Efficiency ◽  
Good Biocompatibility

The poly(siloxane-urethane) elastomers with microphase separation structure and Diels–Alder bonds show high healing efficiency, good mechanical property and good biocompatibility.

Catalyst-free self-healing fully bio-based vitrimers derived from tung oil: Strong mechanical properties, shape memory, and recyclability

2021 ◽  
Vol 171 ◽  
pp. 113978
Author(s):  
Ya-zhou Xu ◽  
Pan Fu ◽  
Song-lin Dai ◽  
Hai-bo Zhang ◽  
Liang-wu Bi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Self Healing ◽  
Tung Oil ◽  
Catalyst Free
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