Optimizing Thermo-Responsive Polymers for Enhanced Mechanical Durability Under Fatigue Loading

Thermo-responsive polymers (TRPs) present significant potential for applications such as desalination, dehumidification, and oil recovery, by offering energy-efficient solutions for water management and separation. However, for these polymers to be viable in such demanding environments, they must exhibit a combination of mechanical strength, elasticity, and durability while maintaining their water-absorption and release capabilities under dynamic mechanical loads.
This investigation focuses on the optimization of the formulation of TRPs targeted to applications where mechanical integrity and functionality under stress are crucial. The TRP developed herein was engineered to balance mechanical strength and elasticity while efficiently managing water absorption and release in response to thermal stimuli. A parametric study of the polymer's formulations, implemented through a systematic variation of its constituents, was conducted to identify formulations that enhance their mechanical properties to meet the demands in various applications.
Mechanical characterization was conducted through a series of tensile and compressive tests in compliance with ASTM standards. Digital Image Correlation (DIC) was used to monitor strain distribution of a specimen in its gage length and the failure behavior in real-time, to reach measurements of deformation and stress concentration with high precision. Additionally, dynamic mechanical analysis (DMA) was performed to measure viscoelastic properties, which are analyzed to predict long-term durability.
The TRP's endurance was further evaluated via a fatigue bending test, where it was subjected to one million bending cycles. Scanning Electron Microscopy (SEM) imaging, conducted before and after fatigue testing, provided microstructural changes and mechanisms for failure damage. The results demonstrated that the optimized TRP has demonstrated increased mechanical stability and structural integrity, while maintaining the water absorption and desorption capabilities, making it a promising material for applications that involve cyclic mechanical loading.