High-Temperature Shape Memory Behavior of Semicrystalline Polyamide Thermosets.

Area of Science:

• Polymer Science
• Materials Science
• Materials Engineering

Background:

• Shape memory polymers (SMPs) are stimuli-responsive materials capable of recovering their original shape upon exposure to an external trigger.
• High-temperature SMPs (>200 °C) are crucial for demanding applications, but their development often faces challenges in achieving efficient shape control and recovery.
• Poly(decamethylene terephthalamide) (PA 10T) offers potential for high-temperature applications due to its inherent thermal stability.

Purpose of the Study:

• To explore semicrystalline poly(decamethylene terephthalamide) (PA 10T) based thermosets as single-component high-temperature shape memory polymers.
• To investigate the influence of reactive phenylethynyl (PE) functionalities on the shape memory performance of PA 10T thermosets.
• To design and characterize dual- and triple-shape memory behaviors in PA 10T thermosets for advanced applications.

Main Methods:

• Synthesis of PA 10T thermosets from reactive thermoplastic precursors with PE functionalities at chain termini or as side groups.
• Investigation of shape fixation and recovery performance using rheometry in torsion mode.
• Characterization of dual- and triple-shape memory behaviors by controlling molecular weight and PE concentration.

Main Results:

• Designed dual-shape memory PA 10T thermosets with a recovery temperature range of 227-285 °C.
• Achieved high shape fixation (99%) and recovery (≥90%) rates with optimized PE precursor (1000 g mol⁻¹) and PE side-group concentration (15 mol %).
• Demonstrated high-temperature triple-shape memory behavior utilizing melt and glass transitions, with recovery rates varying from 74%-139% and 40-82% for the two steps.

Conclusions:

• Semicrystalline PA 10T thermosets are promising single-component high-temperature SMPs.
• Controlling PE functionality allows for tunable dual- and triple-shape memory properties.
• The study provides insights into thermokinematic control for programming desired shape memory behavior.