TY - JOUR
T1 - Reconfigurable Poly(urea-urethane) Thermoset Based on Hindered Urea Bonds with Triple-Shape-Memory Performance
AU - Jia, Yunchao
AU - Ying, Hanze
AU - Zhang, Yanfeng
AU - He, Hui
AU - Cheng, Jianjun
N1 - Y.J. and H.Y. contributed equally to this work. All the dynamic mechanical analyzer relative tests were carried out in the Frederick Seitz Materials Research Laboratory Central Research Facilities, University of Illinois, at Urbana-Champaign. The authors acknowledge the financial support from China Scholarship Council (CSC, grant No. 201706150045), the Science and Technology Project of Guangdong Province (2015B010122002), and NSF (CHE 1508710).
PY - 2019/6
Y1 - 2019/6
N2 - Thermoset shape memory polymers (SMPs) have a series of advantages in practical applications when compared with thermoplastic SMPs. However, the reprocessing and reshaping of thermosets are difficult due to the covalent crosslinking which severely limits the reconfiguration of polymer networks even under high temperature. Here, hinered urea bond (HUB), a urea bearing a bulky substituent on its nitrogen atom that can reversibly dissociate to the corresponding bulky amine and isocyanate, is integrated into the poly(urea-urethane) (PUU) crosslinked networks, enabling the networks to topologically reconfigure to other structures. Instead of having to cure the thermoset in a mold, the incorporation of HUBs can decouple the synthesis and shape-forming steps, which is a huge advantage for the processing of thermoset materials compared to conventional thermosets. This new PUU thermoset shows a broad glass transition behavior and exhibits excellent triple-shape-memory performance. With the incorporation of this dynamic urea bonds, permanent shapes can be flexibly tuned via the network reconfiguration, which is often neglected but significant to the practical application of SMPs.
AB - Thermoset shape memory polymers (SMPs) have a series of advantages in practical applications when compared with thermoplastic SMPs. However, the reprocessing and reshaping of thermosets are difficult due to the covalent crosslinking which severely limits the reconfiguration of polymer networks even under high temperature. Here, hinered urea bond (HUB), a urea bearing a bulky substituent on its nitrogen atom that can reversibly dissociate to the corresponding bulky amine and isocyanate, is integrated into the poly(urea-urethane) (PUU) crosslinked networks, enabling the networks to topologically reconfigure to other structures. Instead of having to cure the thermoset in a mold, the incorporation of HUBs can decouple the synthesis and shape-forming steps, which is a huge advantage for the processing of thermoset materials compared to conventional thermosets. This new PUU thermoset shows a broad glass transition behavior and exhibits excellent triple-shape-memory performance. With the incorporation of this dynamic urea bonds, permanent shapes can be flexibly tuned via the network reconfiguration, which is often neglected but significant to the practical application of SMPs.
KW - dynamic covalent bonds
KW - hindered urea bonds
KW - reconfigurable thermoset
KW - triple-shape-memory polymers
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U2 - 10.1002/macp.201900148
DO - 10.1002/macp.201900148
M3 - Article
AN - SCOPUS:85065670072
SN - 1022-1352
VL - 220
JO - Macromolecular Chemistry and Physics
JF - Macromolecular Chemistry and Physics
IS - 12
M1 - 1900148
ER -