Interaction of thermoresponsive polymers with hydrophobic compounds: from phase transition to design strategies

Stimuli-responsive polymers, also known as smart polymers, are cutting-edge materials able to reversibly respond to external stimuli with an extensive range of applications, including encapsulation and adsorption of hydrophobic compounds. Temperature-responsive polymers are the most explored smart materials, with easy and cheap control and a wide range of available compositions, from linear to self-assembly structures, with an outstanding podium to hydrogel systems. The thermoresponsive behavior can modulate and enable encapsulation or adsorption by dynamically switching the temperature phase transition or the polymer composition and, thus, the affinity between the polymer matrix and the hydrophobic compound. However, the interaction faces competition, such as hydrophobic interaction and hydrogen bonding, and predicting drug encapsulation and releasing or adsorption efficiencies can be challenging. This review addresses the fundamental aspects of thermoresponsive polymers' interaction with hydrophobic compounds, considering experimental and theoretical literature findings, highlighting successful cases, and the responsible factors for efficient encapsulation and adsorption rates.