High-Temperature Shape Memory Behavior of Semicrystalline Polyamide Thermosets

Ming Li; Qingbao Guan; Theo J Dingemans

doi:10.1021/acsami.8b03658

High-Temperature Shape Memory Behavior of Semicrystalline Polyamide Thermosets

ACS Appl Mater Interfaces. 2018 Jun 6;10(22):19106-19115. doi: 10.1021/acsami.8b03658. Epub 2018 May 21.

Authors

Ming Li^{1

2

3}, Qingbao Guan⁴, Theo J Dingemans^{2

5}

Affiliations

¹ National Engineering Research Center for Biotechnology , Nanjing Tech University , Nanjing 211800 , China.
² Faculty of Aerospace Engineering , Delft University of Technology , Kluyverweg 1 , 2629 HS Delft , The Netherlands.
³ Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven , The Netherlands.
⁴ Department of Material Science and Engineering , Soochow University , Suzhou 215123 , China.
⁵ Department of Applied Physical Sciences , University of North Carolina at Chapel Hill , 1113 Murray Hall , Chapel Hill , North Carolina 27599-3050 , United States.

Abstract

We have explored semicrystalline poly(decamethylene terephthalamide) (PA 10T) based thermosets as single-component high-temperature (>200 °C) shape memory polymers (SMPs). The PA 10T thermosets were prepared from reactive thermoplastic precursors. Reactive phenylethynyl (PE) functionalities were either attached at the chain termini or placed as side groups along the polymer main chain. The shape fixation and recovery performance of the thermoset films were investigated using a rheometer in torsion mode. By controlling the M_n of the reactive oligomers, or the PE concentration of the PE side-group functionalized copolyamides, we were able to design dual-shape memory PA 10T thermosets with a broad recovery temperature range of 227-285 °C. The thermosets based on the 1000 g mol^-1 reactive PE precursor and the copolyamide with 15 mol % PE side groups show the highest fixation rate (99%) and recovery rate (≥90%). High temperature triple-shape memory behavior can be achieved as well when we use the melt transition ( T_m ≥ 200 °C) and the glass transition ( T_g = ∼125 °C) as the two switches. The recovery rate of the two recovery steps are highly dependent on the crystallinity of the thermosets and vary within a wide range of 74%-139% and 40-82% for the two steps, respectively. Reversible shape memory events could also be demonstrated when we perform a forward and backward deformation in a triple shape memory cycle. We also studied the angular recovery velocity as a function of temperature, which provides a thermokinematic picture of the shape recovery process and helps to program for desired shape memory behavior.

Keywords: dual-shape memory; high-temperature shape memory; recovery velocity; semiaromatic polyamides; semicrystalline thermosets; triple-shape memory.