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4796204 
Journal Article 
Chemically-crosslinked zwitterionic polyurethanes with excellent thermally-induced multi-shape memory effect and moisture-induced shape memory effect 
Zhuo, H; Mei, Z; Chen, H; Chen, S 
2018 
1 
Polymer
ISSN: 0032-3861 
148 
119-126 
WOS:000437378000012 
In this contribution, shape memory polymers (SMPs) of chemically-crosslinked zwitterionic polyurethanes (CZPUs) were fabricated by crosslinking of the N,N-bis(2-hydroxyethyl) isonicotinamide (BINA)/hexamethylene diisocyanate (HDI) polyurethanes system by using pentaerythritol (PER), followed by zwitterionization with 1, 3-propanesultone (PS). As the zwitterionic units increased, it was found that the glass transition of hard phase in CZPUs remains constant while that of soft phase shifted at lower temperature, and a broad glass transition was obtained. The broad glass transition enables CZPUs to display triple, quadruple, and quintuple shape memory behaviours. Meanwhile, due to the chemically-crosslinked structure, the CZPUs exhibited an excellent shape fixation and recovery. Furthermore, the CZPU also exhibited good moisture-induced shape memory effect (SME) with a fast and high shape recovery observed below 70% RH and at 37 degrees C. The excellent thermally-induced multi-shape memory effect and moisture-induced shape memory effect enable CZPUs to be applied as smart materials for many applications among them the biomedical fields. (C) 2018 Elsevier Ltd. All rights reserved. 
Shape memory; Polyurethane; Zwitterionic polymer; Chemical-crosslinking