Investigating Fundamental Principles of Nonequilibrium Assembly Using Temperature-Sensitive Copolymers

Both natural biomaterials and synthetic materials benefit from complex energy landscapes that provide the foundation for structure???function relationships and environmental sensitivity. Understanding these nonequilibrium dynamics is important for the development of design principles to harness this behavior. Using a model system of poly(ethylene glycol) methacrylate-based thermor-esponsive lower critical solution temperature (LCST) copolymers, we explored the impact of composition and stimulus path on nonequilibrium thermal hysteretic behavior. Through turbidimetry analysis of nonsuperimposable heat???cool cycles, we observe that LCST copolymers show clear hysteresis that varies as a function of pendent side chain length and hydrophobicity. Hysteresis is further impacted by the temperature ramp rate, as insoluble states can be kinetically trapped under optimized temperature protocols. This systematic study brings to light fundamental principles that can enable the harnessing of out-of-equilibrium effects in synthetic soft materials.

Automated summary

Through studying thermoresponsive copolymers, it is found that the nonequilibrium thermal hysteretic behavior is influenced by composition and stimulus path. Analysis of heat-cool cycles reveals that hysteresis in copolymers varies based on side chain length and hydrophobicity. The temperature ramp rate also affects hysteresis, as optimized temperature protocols can trap the material in insoluble states. This study uncovers fundamental principles for harnessing out-of-equilibrium effects in synthetic soft materials.