thermoreversibel

Thermoreversibel describes materials or processes that undergo a reversible change in phase, structure, or properties in response to temperature. In a thermoreversible system, heating and cooling cause the system to switch between two states, and the transition can occur repeatedly with little or no permanent chemical change. The term is used in chemistry, polymer science, and materials science to distinguish reversible temperature-driven transitions from irreversible thermal decomposition.

Mechanisms often rely on physical interactions rather than permanent bonds. Examples include gels formed by physical crosslinks such as hydrogen bonding or hydrophobic interactions, and polymers that exhibit a thermoresponsive phase transition, like gels that solidify on cooling and liquefy on heating (gelatin) or PNIPAM-based hydrogels with a lower critical solution temperature around body temperature. Thermoreversible covalent chemistries also exist, where bonds can break upon heating and re-form upon cooling, enabling reversible crosslinking.

Applications span biomedical materials, drug delivery, soft robotics, self-healing polymers, and smart coatings. In medicine, thermoreversible gels can be injected as liquids that gel in situ at body temperature, or swell/shrink with temperature to release drugs. In coatings and adhesives, thermoreversibility allows temporary bonding and subsequent detachment with a temperature cue.

Key properties include the transition temperature (or range), reversibility over many cycles, mechanical integrity, and response time. Practical use requires control of hysteresis, fatigue under cycling, and environmental sensitivity (pH, solvents, moisture). The concept is closely related to thermo-responsive polymers and phase-change phenomena.