Issue 25, 2015

Elaborate fabrication of well-defined side-chain liquid crystalline polyurethane networks with triple-shape memory capacity

Abstract

Targeting triple-shape memory capacity, a series of side-chain liquid crystalline polyurethane networks (SCLCPU-Ns) with well-defined architecture were prepared via an elaborately designed synthetic route: the liquid-crystalline (LC) functionalized monomer was polymerized with diisocyanate to produce a linear polyurethane precursor with a uniform distribution of pendant mesogenic units; and then, tetra-functional pentaerythritol (PTOL) was used as a crosslinker to produce a PU network with a similar backbone length between each crosslinking point. The chemical structures of the monomer and linear polyurethane precursor were characterized using nuclear magnetic resonance (NMR) spectroscopy. Differential scanning calorimetry (DSC), polarized optical microscopy (POM), and wide angle X-ray diffraction (WAXD) were employed to verify the nematic nature of the liquid crystalline state. DSC analysis combined with POM observation reveals that almost all the SCLCPU-Ns display two thermal transitions (Tg and Tcl), which can be utilized as Ttrans to trigger triple shape memory behavior. The cyclic thermomechanical analysis, which was performed using DMA, reveals that the networks exhibit excellent triple-shape memory properties, although the architecture of the networks influences their performance. Taking advantage of the overlap of Tg and Tcl in the SCLCPU-Ns, which can be regarded as one broad thermal transition, a well-controllable gradual recovery process was realized in a broad temperature range.

Graphical abstract: Elaborate fabrication of well-defined side-chain liquid crystalline polyurethane networks with triple-shape memory capacity

Supplementary files

Article information

Article type
Paper
Submitted
08 Apr 2015
Accepted
12 May 2015
First published
14 May 2015

J. Mater. Chem. A, 2015,3, 13435-13444

Elaborate fabrication of well-defined side-chain liquid crystalline polyurethane networks with triple-shape memory capacity

Z. Wen, T. Zhang, Y. Hui, W. Wang, K. Yang, Q. Zhou and Y. Wang, J. Mater. Chem. A, 2015, 3, 13435 DOI: 10.1039/C5TA02537K

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